The systematics of the freshwater (: Brachyura: ) of southern , and freshwater zoogeography of China

Chao Huang

Supervisors: Malte C. Ebach, Shane T. Ahyong, Shawn W. Laffan

A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy

School of Biological Earth and Environmental Sciences Faculty of Science

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February 2020

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Tiwaripotamon sp., a miniature undescribed from the karstic forests of Guangxi, China. 6

Preface

This thesis is a compilation of my works during the course of my PhD candidature, conducted under the guidance of my supervisors Malte C. Ebach, Shane T. Ahyong and Shawn W. Laffan. It consists of one introductory chapter which is partly derived from a book chapter (Chapter 1), six published research papers (Chapters 2-7) and a summary chapter (Chapter 8). The research paper chapters are presented as they would appear in a journal except the acknowledgements and references have been moved to the start and end of the thesis, respectively. The introduction of the research paper in chapter 8 has been moved under chapter 1. I conceptualized the research, conducted field collections, gathered data, performed analyses, wrote the manuscripts and prepared the tables and figures. The contributions of my supervisors/co-authors are as follows:

Chapter 1: This Chapter is partially derived from my part of the book chapter S. T. Ahyong & C. Huang (2020). Colonization, adaptation, radiation, and diversity in fresh water. In: Thiel, M. & Poore, G.C.B. (eds.), The Natural History of the Crustacea, Volume 8, 319: Evolution and Biogeography. Oxford University Press. STA provided some reference material and gave advice in the preparation of the manuscript.

Chapter 2: Huang, C., H. T. Shih and P. K. Ng 2017. A new and new species of Potamidae (Crustacea: Decapoda: Brachyura: ), the first stygomorphic cave known from China and East . Zootaxa, 4232 (1). HTS conducted the phylogenetic analysis and contributed to the “DNA analyses and discussion” part of the paper. PKN and STA gave advice in interpretation of data, morphological comparison and in the preparation of the manuscript.

Chapter 3: Huang, C., S. T. Ahyong and H. T. Shih 2017. Cantopotamon, a new genus of freshwater crabs from , China, with descriptions of four new species (Crustacea: Decapoda: Brachyura: Potamidae). Zoological Studies, 56 (41). STA gave advice in interpretation of results, scientific illustrations and in the preparation of the manuscript.

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HTS conducted the phylogenetic analysis and contributed to the “phylogenetic analysis” and “discussion” parts of the paper.

Chapter 4: Huang, C. 2018. Revision of Yarepotamon Dai & Türkay, 1997 (Brachyura: Potamidae), freshwater crabs endemic to southern China, with descriptions of two new genera and four new species. Journal of Biology, 38 (2). HTS and STA gave advice in the interpretation of data and preparation of the manuscript.

Chapter 5: Huang, C., H. T. Shih and S. T. Ahyong 2018. Two new genera and two new species of narrow-range freshwater crabs from Guangdong, China (Decapoda: Brachyura: Potamidae). Journal of Crustacean Biology, 38 (5). HTS conducted the phylogenetic analysis and contributed to the “phylogenetic analysis and discussion” part of the paper. STA gave advice in interpretation of data, scientific illustrations and in the preparation of the manuscript.

Chapter 6: Huang, C., K. C. Wong and S. T. Ahyong 2018. The freshwater crabs of , with the description of a new species of Nanhaipotamon Bott, 1968 and the redescription of Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003 (Crustacea, Decapoda, Potamidae). ZooKeys, 810. KCW accompanied me in the field collection and contributed some ecological observations. STA gave advice in interpretation of data, scientific illustrations and in the preparation of the manuscript.

Chapter 7: Huang, C., S. Z. Huang and Z. X. Shen 2020. A new long-legged terrestrial , Calcipotamon puglabrum n. gen., n. sp. (Crustacea, Decapoda, Potamidae), from Island, China. Zootaxa, 4766 (3). SZH first discovered the new species and contributed to the “habitat” section of the description. ZXS organized the collaboration and contributed to the “introduction” section.

Chapter 8: Huang, C., M. C. Ebach and S. T. Ahyong 2020. Bioregionalisation of the freshwater zoogeographical areas of mainland China. Zootaxa, 4742 (2). MCE gave advice 8

in conceptualizing the research and in the preparation of the manuscript. STA gave advice in the structure and preparation of the manuscript.

Disclaimer: The new taxonomic names in this work are disclaimed for nomenclatural purposes and as such are not available from this thesis.

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Acknowledgements

I thank my supervisors, Malte Ebach, Shane Ahyong and Shawn Laffan, for their support and guidance throughout my candidature. I also thank the people in the School of Biological, Earth and Environmental Sciences of UNSW, the Australian Museum and Sun Yat-sen University Biology Museum of SYSU for their support and advice during my research. I thank the Australian Government for providing the tuition fees for my research degree, and also to the Graduate Research School and PANGEA at UNSW for funding some of my overseas field trips and conference attendances. I thank my previous supervisor at SYSU, Jian Rong Huang, and Peter Ng from NUS for initiating me into the field of carcinology. I thank carcinologists Hsi-Te Shih, Xian Min Zhou, Jie Xin Zou, Hong Ying Sun and many others for their support in my research. I also thank my many naturalist/researcher friends who have accompanied me in the field and/or provided information or specimens for me, especially Zhuo Cheng Zhou, who helped me build connections within the Chinese naturalist and researcher community. I am also grateful to the colleagues who have reviewed the papers included in this thesis. Their constructive criticisms have improved the quality of my research. Last but not least, I would like to give thanks to my parents for their many years of love and financial support, to my eight-year- old younger sister whom I strive to be a good role model for and to my loving wife who has always been supportive of me.

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Abstract

Freshwater crabs make up close to 20% of brachyuran diversity with over 1300 species. China is the most species rich country for freshwater crabs with two families, 49 genera and 321 species, yet there are still large areas that are unsurveyed for them. To fill in these blanks, multiple field surveys have been carried out during the last few years which have resulted in the accumulation of new distribution records and the discovery of 13 new species (Calcipotamon puglabrum, Cantopotamon hengqinense, Cantopotamon shangchuanense, Cantopotamon yangxiense, Cantopotamon zhuhaiense, Diyutamon cereum, Luteomon spinapodum, Megapleonum ehuangzhang, Nanhaipotamon macau, Qianguimon elongatum, Qianguimon splendidum, Yarepotamon meridianum, Yarepotamon fossor) and the establishment of seven new genera (Calcipotamon, Cantopotamon, Diyutamon, Eurusamon, Luteomon, Megapleonum, Qianguimon). These new taxa have since been described and are included herein. Freshwater crabs are also good candidates for biogeographical research due to their very limited dispersal abilities. The large scale freshwater zoogeographic bioregionalisation studies of China were revised. In order to study the freshwater zoogeographical areas of mainland China, a dataset of close to ten thousand distributional records of freshwater that covers 80% of the , 60% of the freshwater and 90% of the freshwater crab species of mainland China was compiled. According to the results from cluster analysis and network analysis, four , three dominions and five provinces were found, of which one dominion and two provinces were newly proposed. In addition, the endemic areas of each group were individually studied and were all found to reflect the bioregionalisation at the level but differed from each other in the dominion and province levels. The first quantitative, multi-taxon based bioregionalisation of the freshwater zoogeographic areas of mainland China is herein proposed.

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Table of contents

Preface ...... 7

Acknowledgements ...... 10

Abstract ...... 11

Table of contents ...... 12

Chapter 1. Introduction ...... 15

General introduction to freshwater crabs ...... 15

Research history of systematics of the Chinese Potamidae ...... 18

History of freshwater zoogeographic bioregionalisation of China ...... 23

Research aims...... 33

Thesis structure ...... 34

Chapter 2. A new genus and new species of Potamidae (Crustacea: Decapoda: Brachyura: Potamoidea), the first stygomorphic cave crab known from China and East Asia ...... 35

Abstract ...... 35

Key words ...... 35

Introduction ...... 35

Material and methods ...... 36

Systematics ...... 39

DNA analyses and discussion ...... 49

Chapter 3. Cantopotamon, a new genus of freshwater crabs from Guangdong, China, with descriptions of four new species (Crustacea: Decapoda: Brachyura: Potamidae) ...... 53

Abstract ...... 53

Key words ...... 53 12

Background ...... 53

Materials and methods ...... 54

Results ...... 56

Phylogenetic relationships ...... 79

Discussion and conclusions ...... 80

Chapter 4. Revision of Yarepotamon Dai & Türkay, 1997 (Brachyura: Potamidae), freshwater crabs endemic to southern China, with descriptions of two new genera and four new species ...... 83

Abstract ...... 83

Key words ...... 83

Introduction ...... 84

Materials and methods ...... 84

Systematics ...... 88

Phylogenetic analysis and discussion ...... 120

Chapter 5. Two new genera and two new species of narrow-range freshwater crabs from Guangdong, China (Decapoda: Brachyura: Potamidae) ...... 124

Abstract ...... 124

Key words ...... 124

Introduction ...... 124

Materials and methods ...... 125

Systematics ...... 127

Phylogenetic analysis and discussion ...... 140

Chapter 6. The freshwater crabs of Macau, with description of a new species of Nanhaipotamon Bott, 1968 and the redescription of Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003 (Crustacea, Decapoda, Potamidae) ...... 143

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Abstract ...... 143

Key words ...... 143

Introduction ...... 144

Materials and methods ...... 144

Taxonomy ...... 145

Chapter 7. A new long-legged terrestrial freshwater crab, Calcipotamon puglabrum n. gen., n. sp. (Crustacea, Decapoda, Potamidae), from Hainan Island, China ...... 168

Abstract ...... 168

Key words ...... 168

Introduction ...... 168

Material and methods ...... 169

Systematics ...... 171

Phylogenetic analysis and discussion ...... 178

Chapter 8. Bioregionalisation of the freshwater zoogeographical areas of mainland China ...... 181

Abstract ...... 181

Key words ...... 182

Introduction ...... 182

Material and methods ...... 184

Results ...... 188

Discussion ...... 190

References ...... 209

Supplementary material ...... 231

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Chapter 1.

General Introduction

General introduction to freshwater crabs

Primary freshwater crabs or True freshwater crabs (hereafter, freshwater crabs) are independent of a marine environment for larval development and dispersal and have no immediate marine relatives (Fig. 1.1; Yeo et al., 2008). With over 1300 species (1394 as of Kawai & Cumberlidge, 2016), the five families of freshwater crabs (Potamidae, , , , and ) comprise close to 20% of all brachyuran crabs (Yeo et al., 2008). The distribution of freshwater crabs is circumtropical and includes the Palaearctic, Oriental, Australian, Ethiopian, and Neotropical (Fig. 1.2). Being the largest freshwater crab family with around 550 known species (548 as of Cumberlidge, 2016), Potamidae contains two sub-families, the western Palaearctic Potaminae, and the eastern Palaearctic and Oriental Potamiscinae (Yeo & Ng, 2003). Interestingly, the three species on the Afrotropical Socotra Island also belong to the latter (Shih et al., 2009). The family Gecarcinucidae consists of close to 400 (361 as of Kawai & Cumberlidge, 2016) known species and is mainly found in the Oriental , although its distribution extends to the neighboring east Palaearctic and Australasian regions. The approximately 150 species (152 as of Cumberlidge, 2016) of the Potamonautidae dominate the Afrotropical region and can also be found at the southern extremes of the western Palaearctic. The families Pseudothelphusidae and Trichodactylidae are both strictly confined to the Neotropics, being found only in the warmer parts of Central and . However, pseudothelphusid crabs greatly outnumber trichodactylids with around 270 species (268 as of Cumberlidge, 2016) in the former and around 50 (47 as of Cumberlidge, 2016) in the latter. The earliest known fossil record of a freshwater crab dates back to the Late Oligocene, less than 30 million years ago (Tanzanonautes tuerkai; Feldmann et al., 2007). Freshwater crab fossils are relatively rare and the current record is likely far from comprehensive. Though earlier studies (Rodriguez, 1986; Ng & Rodriguez, 1995) have 15

speculated a Gondwanan origin for freshwater crabs due to their circumtropical contemporary distribution, phylogenetic relationships and molecular divergence estimates within the freshwater crabs do not correspond to the successive fragmentation of supercontinent (Klaus et al., 2011). A recent molecular study by Tsang et al. (2014) suggests that freshwater crabs were derived early in the evolution of , around 135 million years ago, which significantly post-dates the split of Gondwana (around 184 million years ago). Although it is quite clear that Trichodactylidae has a separate origin from other freshwater crabs, difficulties in identifying the respective marine sister group of Potamidae, Gecarcinucidae, Potamonautidae and Pseudothelphusidae have made it hard to test their monophyly (Tsang et al., 2014). Recent phylogenetic evidence strongly supports the presence of transoceanic dispersal events (Klaus et. al., 2013, Cumberlidge, 2008). Therefore, post-Gondwanan dispersal seems likely to be a contributing factor in shaping the contemporary distribution of these crabs (Tsang et al., 2014).

Figure 1.1 Teoswamon scolasticum, a recently described freshwater crab species of the family Potamidae from Puning, Guangdong.

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Originating from a marine environment, the marine ancestors of freshwater crabs had to overcome various obstacles to adapt to living in freshwater and terrestrial environments, such as different osmoregulation abilities, breathing atmospheric air and suitable breeding strategies. The much greater ionic concentrations of seawater to which the marine ancestors of freshwater crabs were adapted presents a significant challenge. Freshwater crabs face greatly reduced osmotic pressure and must adapt by being able to hyper-osmoregulate (Anger, 2016). The more highly terrestrialized freshwater crabs face the problem of respiration on land and many have swollen branchial regions that promote gaseous exchange. The branchial chamber linings are often vascularized to form a functional “lung” (Cumberlidge, 1991). Freshwater crabs have direct development of offspring. This strategy is obviously advantageous in freshwater environments as it ensures the survival of offspring even in oligotrophic environments where planktonic larvae would otherwise die of starvation. It also prevents juveniles from being washed downstream into unfavorable habitats. Different routes of entry into freshwater and land have been proposed by different authors. Little (1983), proposed two routes to terrestrialization, directly from marine habitats to land and indirectly from marine to freshwater and finally to land, and implied that brackish environments such as estuaries and river mouths could have been a transient stage from marine to freshwater. This proposal makes osmoregulation a key factor in adaptation to freshwater with change in reproduction strategy occurring subsequently. Other studies, however, have suggested that reproduction strategy is the key factor in freshwater adaptation and estuarine environments select against abbreviated larval development. Near shore partially land-locked habitats such as mangroves, salt marshes and anchialine pools therefore are more likely transitional habitats for freshwater adaptation (Diesel et al., 2000; Anger, 2016). It is likely that both these factors have played important roles in the adaptation of freshwater in crabs. Being so speciose, freshwater crabs can be found in a wide range of habitats, from near sea level to an altitude of almost 3000 m (Dai, 1999). A large portion of these crabs are suited to a mainly aquatic lifestyle and can be found in hillstreams, rivers, lakes, ponds etc. Despite spending most of their time underwater, many aquatic species often venture onto land to forage and disperse, especially after heavy rain. Of the more terrestrial 17

freshwater crabs, many are burrowers that make holes in mud, often in close proximity to hillstreams or rivers (Ng, 1988). Some specialized species like those from the genera Socotra and Tiwaripotamon, have adapted to live in karst environments where no permanent surface water can be observed. It is assumed that crabs of this ecotype rely on rainwater collected in crevices and holes in the eroded calcareous substratum (Cumberlidge & Wranik, 2002). Arboreal species such as Neotiwaripotamon whiteheadi, Globonautes macropus and Kani maranjandu dwell in tree holes and also rely on collected rainwater. Though rare, there are also a few cave dwellers that possess elongated ambulatory legs, reduced eyes and loss of pigmentation as a result of living in complete darkness. Whereas most freshwater crabs are omnivorous scavengers and opportunistic predators, some species have specialized feeding habits, such as Sinopotamon cochlearidigitum which has spoon-shaped chela tips that are presumably used for scraping algae from rock surfaces, and the molluscivorous Syntripsa flavichela that possesses molariform teeth on the chelae for cracking snail shells (Dai, 1999; Chia & Ng, 2006). Freshwater crabs often become prey items themselves and are food sources for certain species of fish, amphibians, reptiles, birds and mammals. They also host a variety of animals, from parasitic leeches to commensal temnocephalid flatworms that are often seen on the body surface of aquatic species (Ng, 1988). Freshwater crabs are also notorious for being the second intermediate host for lung flukes of the genus Paragonimus. The lung flukes can infect humans directly when freshwater crabs are consumed raw or indirectly when raw meat of wild animals such as wild boars are consumed (Blair et al., 2016).

Research history of systematics of the Chinese Potamidae

This thesis focuses on the freshwater crabs of mainland China, namely, the geographical area of continental China with the inclusion Hainan Island and other small surrounding islands. The freshwater crabs of Taiwan Island are much more closely related to those of Japan and are almost an entirely different assemblage from those of mainland China, therefore they are not further discussed in this thesis. The first potamid crab species that was scientifically documented from mainland China was Longpotamon denticulatum (Milne-Edwards, 1853) from Province. The 18

English zoologist James Wood-Mason (1871) described Indochinamon edwardsii, Indochinamon andersonianum and Eosamon tumidum from Province. It was not until 1896 that naturalist and zoologist Arnold Edward Ortmann (1896) established the family Potamidae; it was named Potamonidae at the time. German zoologist Franz Theodor Doflein (1902) described Longpotamon lansi, which he found in Hankou, Wuhan Province. American zoologist Mary Jane Rathbun (1904, 1906) described Longpotamon shensiense, Sinopotamon davidi and Longpotamon koatenense in her monographs. Scottish zoologist William Thomas Calman (1905) described the Yunnan species Parapotamon spinescens from specimens acquired by The British Museum. Dutch zoologist Johannes Govertus de Man (1906) described Parapotamonoides endymion which is also from Yunnan. Neotiwaripotamon whiteheadi, Apotamonautes hainanense and Hainanpotamon orientale were described from Hainan Island by Italian zoologist Bruno Parisi (1916). Kemp (1918) described Cryptopotamon anacoluthon from Hong Kong and Potamiscus yunnanense from Yunnan. A list of potamid crabs from China was published by Gee (1925), with only 12 species. Rathbun (1929) described Aparapotamon grahami from . The first Chinese researcher to work on the Chinese potamid crabs was Hsien-wen (1934), who described Potamiscus loshingense, Heterochelamon purpureomanualis and Sinolapotamon patellifer. Jia-Rui Shen (1940) described Nanhaipotamon hongkongense from Hong Kong. After this, there was a period of time when no progress was made due to regional and global political instability. Richard Bott (1967) published a review on the Asian potamid crabs, describing new species Bottapotamon engelhardti, Longpotamon tinghsiangense and Longpotamon yangtsekiense. The period after this can be described as the golden age of Chinese freshwater crab research and saw a soar in species being described. The main contributors were from the Chinese Academy of Sciences, namely leading authors Guo-Xiao Chen, You-Zhu Cheng, Ai-Yun Dai and Yu-Zhi Song. From the 1970s to the 1990s, this team described the vast majority of the Chinese potamids that we know of today (Chen, 1980; Chen & Chang, 1982; Chen et al., 1993; Dai, 1990a; Dai, 1990b; Dai, 1992; Dai, 1993; Dai, 1995a; Dai, 1995b; Dai, 1995c; Dai, 1997a; Dai, 1997b; Dai & Bo, 1994; Dai & Chen, 1979; Dai & Chen, 1981; Dai & Chen, 1985; Dai & Chen, 1987; Dai, Chen & Cai, 1993; Dai, Chen & Liu, 1990; Dai, Feng & Zheng, 1977; 19

Dai & Giang, 1991; Dai & Liu, 1994; Dai & Naiyanetr, 1994; Dai & Ng, 1994; Dai & Song, 1982; Dai & Türkay, 1997; Dai & Xing, 1993; Dai & Xing, 1994; Dai & Yuan, 1988; Dai, Zhou & Peng, 1995; Dai et al., 1975; Dai et al., 1979; Dai et al., 1980; Dai et al., 1984a; Dai et al., 1984b; Dai et al., 1985; Dai et al., 1986; Song, 1984; Tai & Song, 1975; Türkay & Dai, 1997; Li et al., 1985; Ng & Dai, 1997; Cheng, Li & Xu, 1998). Around the same time, two other groups also contributed to the knowledge of Chinese potamids, but on a smaller scale. Nan-Shan Du et al. (1979, 1981) published two papers about the potamid crabs from Anhui and Zhejiang Province, while Ming-Xian Huang et al. (1986) published a paper on the potamids of Sichuan Province. Ng & Dudgeon (1992) reviewed the freshwater crabs of Hong Kong. Dai (1999) published a monograph with descriptions and illustrations of 203 Chinese potamids species and sub-species with the description of a few new ones as well. The monograph became a robust foundation upon which future research was built on. Some species that were described at that time, but were not included in the book include three species from Chen’s (1993) review of the genus Tenuipotamon: T. panxiense Chen, 1993, T. tonghaiense Chen, 1993, T. baishuiense Chen, 1993, five species of Longpotamon previously described: L. wuyiense (Li, Lin, Cheng & Tang, 1985), L. baiyanense (Ng & Dai, 1997), L. koatenense (Rathbun, 1904), L. chengkuense (Huang, Luo & Liu, 1986), L. mindongense (Cheng, Li & Xu, 1998), and Daipotamon minos Ng & Trontelj, 1996, which was described in honor of Dai. Yeo and Naruse (2007) revised the genus Hainanpotamon from Hainan Island in 2007. In the same year, Yeo and Ng (2007) published an important paper on the genus “” and allies in Indochina. This extensive research revised the genus “Potamon” and found that it was a hotchpotch o/ f many species of numerous genera. 91 former “Potamon” species and their allies were re-assigned to eight known genera and 18 new genera, with the real Potamon species being restricted to species from and northern to northwestern . As for the “Potamon” species that occur in China, all were moved to either Indochinamon or Eosamon. Researchers from the parasitology discipline also took interest in freshwater crabs because some are the secondary hosts of the parasitic lung fluke. From Fujian Center for Disease Control and Prevention, You-Zhu Cheng and others made numerous publications from 2000-2013 on local findings in Fujian Province, 20

describing four new species of Nanhaipotamon, four new species of Huananpotamon, one new species of Longpotamon and one new species of Bottapotamon (Li & Cheng, 2000; Cheng et al., 2003; Cheng et al., 2008; Li et al., 2008; Cheng, Li & Zhang, 2009; Cheng, Lin & Li, 2010; Lin, Cheng & Chen, 2012; Lin, Cheng & Chen, 2013). The descriptions, however, may prove to be difficult to access for future researchers as they are in Chinese and quite brief. From the Medical College of Nanchang University, Xian-Min Zhou and his team have had some collaborations in publishing two new species of Latopotamon, one new species of Trichopotamon, both from Yunnan, three new species of Longpotamon from Hu’nan and Jiangxi and one new species of Bottapotamon from Fujian (Naruse, Yeo & Zhou., 2008; Zhou, Zhu & Naruse, 2008; Zou, Naruse & Zhou, 2008). They also described two new species of Sinolapotamon (Naruse, Zhu & Zhou, 2008), two new species of Heterochelamon (Naruse, Zhu & Zhou, 2013), eight new species from Yunnan (Naruse, Chia & Zhou, 2018), a new species of Chinapotamon (Zou, Bai & Zhou, 2018), a new species of Qianguimon (Wang, Huang & Zou, 2019), and a new species of Mediapotamon (Wang, Zhou & Zou, 2019). Ng (2017b) described two new cavernicolous species from Guangxi. From Nanjing Normal University, Ke-Lin Chu, Hong-Ying Sun and others described two new genera and four new species (Chu, Zhou & Sun, 2017; Chu, Sun & Sun, 2017; Chu, Wang & Sun, 2018). They also compiled a checklist of 283 species and subspecies from 44 genera of Chinese Potamidae (Chu et al., 2018).

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Figure 1.2 World biogeographical regionalisation, with indication of the regions (white) and transition zones (grey). Transition zones: 1, Mexican; 2, Saharo-Arabian; 3, Chinese; 4, Indo- Malayan; 5, South American. (Morrone, 2015; reproduced with permission from CSIRO Publishing).

Starting from 2011, the author has taken interest in Chinese freshwater crabs and attempted to identify some specimens collected from the local area in Guangdong Province. It soon became apparent there were species that could not be identified with the available literature and many areas in southern China lacked surveying. I therefore have been studying Chinese freshwater crabs and conducted many field surveys in southern China since then. So far, the author and co-authors have described nine new genera (Calcipotamon, Cantopotamon, Diyutamon, Eurusamon, Longpotamon, Luteomon, Megapleonum, Qianguimon, Teoswamon) and 17 new species (Calcipotamon puglabrum, Cantopotamon hengqinense, Cantopotamon shangchuanense, Cantopotamon yangxiense, Cantopotamon zhuhaiense, Diyutamon cereum, Lacunipotamon cymatile, Lacunipotamon yuanshi, Luteomon spinapodum, Megapleonum ehuangzhang, Minpotamon kityang, Nanhaipotamon macau, Qianguimon elongatum, Qianguimon splendidum, Teoswamon scolasticum, Yarepotamon meridianum, Yarepotamon fossor) of which some are featured in this thesis (Huang, Huang & Ng, 2012; Huang, Mao & Huang, 2014; Shih, Huang & Ng, 22

2016; Do, Shih & Huang, 2016; Huang, Shih & Mao, 2016; Huang, Shih & Ng, 2017; Huang, Ahyong & Shih, 2017; Huang, 2018; Huang, Wong & Ahyong, 2018; Huang, Shih & Ahyong, 2018; Wang, Huang & Zou, 2018; Mao & Huang, in press; Huang, Shih & Ahyong, in press; Huang, Huang & Shen, 2020). There are currently 49 genera and 321 species of freshwater crabs known from China.

History of freshwater zoogeographic bioregionalisation of China

Biogeographic regionalisations or bioregionalisations extract patterns of co-occurrence from different taxa to form a system of geographical units of different scales. In order to contribute to a universal and revisable system of biogeographic areas, I herein follow the International Code of Area Nomenclature (ICAN), which emphasizes examining previously proposed areas before creating new area names. Therefore, the history of Chinese freshwater zoogeographic bioregionalisation is reviewed herein. The concept of bioregionalisation was first explored by Augustin Pyramus de Candolle (in Lamarck & Candolle, 1805) when he illustrated the first biogeographical map (Ebach & Goujet 2006: fig. 1). Alfred Russel Wallace (1876), through keen observation of terrestrial animals, proposed his biogeographic regions of the world, with China spanning both the Palearctic and Oriental realms. The Palearctic consists of the Siberian region, which extends from Russia down to Tibet, and the Manchurian region, which includes central and northern China. Southern China and the islands of Taiwan and Hainan were included in the Indochinese region. Subsequently, the Palearctic and the Nearctic were combined as the Holarctic (Heilprin, 1882). Using varied freshwater taxa with a heavy emphasis on , Banarescu (1960, 1991: fig. 1) proposed a global freshwater bioregionalisation in which he restricted the Holarctic to northern China and proposed the Sino-Indian region, which includes the East Asian, High-Asian and South Asian subregions. Only the former two subregions are within China. A major shortcoming of the Banarescu (1960, 1991) bioregionalisation, however, is the treatment of freshwater crabs, which are generally dismissed as poor biogeographic indicators (Rodriguez & Ng, 1995). More recently, Abell et al. (2008) proposed the Freshwater Ecoregions of the World (FEOW; www.feow.org/), in which they propose numerous regions for China based on 23

Figure 1.3 Part of Bănărescu’s (1991) (after Bănărescu, 1960, modified) freshwater zoogeographical areas of the world (redrawn). IA, Siberian subregion. IB, Baikal subregion. IC, Western Mongolian subregion. IIA, East Asian subregion. IIB, High Asian subregion. IIC, South Asian subregion. river basins and expert assessment on the distribution of various groups of freshwater animals, with a heavy emphasis on freshwater fishes. Freshwater zoogeographic bioregionalisations based on single taxon groups are much more numerous and are discussed individually below.

Fishes Berg (1912) studied the biogeography of freshwater fishes and proposed three subregions (the Circumpolar, Asian mountains, Chinese and Indian) and one transitional area between the Circumpolar and the Chinese subregion (the transitional area) for China (Fig. 1.4). Berg (1916) started focusing exclusively on the Palearctic and revised his bioregionalisation putting more emphasis on anadromous fishes (Fig. 1.5). The subregions remain mostly the same; however, he proposed the Amur subregion as part of the Amur transitional area and also proposed the Tarim and Tibetan provinces for China and the

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Figure 1.4 Berg’s (1912) freshwater fish areas of the world with captions inserted (in German).

Figure 1.5 Berg’s (1916) freshwater fish areas of with captions inserted (in Russian), downloaded from https://archive.org/details/rybypriesnykhvod00berg/page/n8.

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Figure 1.6 Berg’s (1933) freshwater fish areas of north Asia with captions inserted (in Russian).

Figure 1.7 Berg’s (1934) freshwater fish areas of the Palaearctic with captions inserted (in Russian).

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Figure 1.8 Mori’s (1936) freshwater fish areas of eastern Asia.

Asian mountains subregion, which is now named as High-Asian subregion. Berg (1933, 1934a, 1934b) proposed the combined basin, and Korea as part of a newly proposed Korea-Manchurian province as part of the Amur transitional area (Fig. 1.6, 1.7). Mori (1936) acknowledged the works of Berg but arrived at a different conclusion with his proposal of the China, Siberian, Mongolian and Indo-China subregions (Fig. 1.8). The Mongolian subregion is similar to that of Berg (1912), but the dividing line between the China and Indo-China subregions (corresponding to the Chinese and Indian subregions of Berg, 1912), is moved northward. The combined Amur transitional region and circumpolar subregion from Berg (1912) roughly equates to Mori’s Siberian subregion. The Indo-China subregion consists of the South China, Hainan and Taiwan districts. The China subregion consists of the North China district, Middle & Lower Yangtse-Kiang district and Upper Yangtse-Kiang district. Only the Amur district is part of China in the Siberian subregion. The regions proposed by Zhang (1954), whose study focused exclusively on China, are Heilongjiang (Amur), Xibeigaoyuan (Northwest Highland), Jianghepingyuan (River Plains), Dongyang (Oriental) and Nulan (Salween-Lancang) (Fig. 1.9). The

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Heilongjiang region and the Dongyang region correspond to the Amur district of the Siberian subregion and the South China district of the Indo-China subregion of Mori (1936), respectively, whereas the other regions differ substantially from previously proposed regions. Almost 30 years later, Li’s (1981) China-focused study found the following five regions: Beifang (Northern), Huaxi (West China), Ningmeng (Ningxia-Mongol), Huadong (East China) and

Figure 1.9 Zhang’s (1954) freshwater fish regions of China (redrawn). I, Heilongjiang (Amur). II, Xibeigaoyuan (Northwest Highland). III, Jianghepingyuan (River Plains). IV, Dongyang (Oriental). V, Nulan (Salween-Lancang).

Huanan (South China) (Fig. 1.10). The Huanan, Huadong and Beifang regions loosely correspond to Zhang’s (1954) Dongyang, Jianghepingyuan and Heilongjiang regions, respectively. Notably, Li’s Beifang region also includes a small part of Northwest China north of the Tarim basin. Much more recently, Kang et al. (2014) used distribution data and clustering methods to propose nine regions: Qinghai-Tibetan Plateau, Oriental, Northwest, South, Loess Plateau, Heilongjiang, upper , 3H (Huang, Huai & Hai rivers) plain and the middle-lower Yangtze plain regions (Fig. 1.11). Leroy et al. (2019) conducted the first quantitative global study on the zoogeographic regions of freshwater fishes using

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basin-specific species occurrence data. According to their results, China is almost entirely within the one of the two subregions in his Sino-Oriental region. In summary, the area boundaries of Berg’s (1912), Mori’s (1936) and Li’s (1981) bioregionalisations are comparable, whereas only the Heilongjiang region of Zhang’s (1954) bioregionalisation is similar to those of the former. Kang’s et al. (2014) regions are distinctly different from the others as the basic geographic units of the analyses were political provinces.

Figure 1.10 Li’s (1981) freshwater fish areas of China (redrawn). Regions: I1–I2, Beifang (Northern); II3–II10, Huaxi (West China); III11–III12, Ningmeng (Ningxia-Mongol); IV13–IV15, Huadong (East China); V16–V21, Huanan (South China). Subregions: I1, E’erqisihe ( River); I2, Heilongjiang (Amur); II3, Zhungaer (Dzungar); II4, Yili-Emin (- Emin); II5, Talimu (Tarim); II6, Zangxi (West Tibet); II7, Qingzang (Qinghai-Tibet); II8, Longxi; II9, Kangzang; II10, Chuanxi (West Sichuan); III11, Ningmeng (Ningxia-Mongol); III12, Hetao; IV13, Liaohe (Liao River); IV14, Haihe (); IV15, Jianghuai (Changjiang-Huaihe); V16, Nulan (Salween-Lancang); V17, Zhujiang (); V18, Hainandao (Hainan Island); V19, Zhemin (Zhejiang-Fujian); V20, Taiwan; V21, Nanhaizhudao ( Islands).

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Figure 1.11 Kang et al. (2014) freshwater fish regions of China. I, Qinghai–Tibetan Plateau. II, Oriental. III, Northwest. IV, South. V, Loess Plateau. VI, Heilongjiang. VII, Upper Yangtze. VIII, 3H Plain. IX, Middle-Lower Yangtze Plain (reproduced with permission from John Wiley and Sons).

Amphibians The edited volume, Bioregionalisation of Chinese amphibians (Zhao, 1995), contains a series of bioregionalisations for each political province in China, but regrettably did not include a large-scale study. Using political provinces as the basic geographic units, Chen & Bi (2007) found seven endemic regions for species in China based on cluster analysis and Parsimony Analysis of Endemicity (PAE). These regions included: Southwest, Southeast, Northeast, Middle-East, Middle-Northwest and Hainan Island and Taiwan Island; however, the study largely lacked data from northern and western China (Fig. 1.12). The global zoogeographic studies by Holt (2013), Rueda et al. (2013), Vilhena & Antonelli (2015) and Edler et al. (2016) all included individual analyses on amphibians. Holt et al. (2013) found China to be part of three different amphibian zoogeographic regions while the areas found by Rueda et al. (2013), using genera occurrence data, resembled those of Wallace’s (1876) regions. Vilhena & Antonelli (2015) and Edler et al. (2016) both used a network approach and obtained areas with similar margins. These global studies provided

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region-level areas that give insight into large scale amphibian zoogeographic patterns, but are not of sufficient resolution to discover smaller, regional patterns.

Figure 1.12 Chen & Bi’s (2007) amphibian areas (redrawn). A, Southwest Region. B, Southeast Region. C, Northeast Region. D, Middle to East Region. E, Middle to Northwest Region. F, Hainan Island. G, Taiwan Island.

Freshwater crabs A preliminary descriptive definition of the Chinese freshwater crab endemic areas by Dai (1999) was loosely based on the biogeographic regions for terrestrial vertebrates of Zhang (1999). Dai (1999) proposed the Xinan (Southwest) region that includes the Hengduanshanxibu (West Hengduan) and Hengduanshandongbeibu (Northeast Hengduan) subregions; Huazhong (Central China) region that includes the Xibushandigaoyuan (Western Highlands) and Dongbuqiulingpingyuan (Eastern Lowlands) subregions; Huanan (South China) region that includes the Diannan (Southern Yunnan), Guiyue (Guangxi- Guangdong), Minyue (Fujian-Guangdong), Hainandao (Hainan Island) and Taiwan subregions; and Huabei (North China) region that includes the Huanghuaipingyuan (Huang-Huai plains) and Huangtugaoyuan (Loess plateau) subregions (Fig. 1.13). Shih &

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Ng (2011) used clustering methods to study the biogeography of the freshwater crabs from East Asia. Their study proposed six biogeographical districts of freshwater crabs in East Asia: Hengduanshan Area, Karst Area, Yangtze River Basin, Wuyishan Area and Pearl River Basin, Hainan Island and East Asian Islands (Fig. 1.14). The biotic and geographic units used were genera and administrative provinces respectively. Owing to the different methods and geographical units used, the two bioregionalisations are largely dissimilar with only the Hengduanshan Area of Shih & Ng (2011) comparable to the Northeast Hengduan subregion of Dai (1999).

Figure 1.13 Dai’s (1999) freshwater crab areas (redrawn). Regions: I, Xinan (Southwest); II, Huazhong (Central China); III, Huanan (South China); IV, Huabei (North China). Subregions: IA, Hengduanshanxibu (West Hengduan); IB, Hengduanshandongbeibu (Northeast Hengduan); IIA, Xibushandigaoyuan (Western Highlands); IIB, Dongbuqiulingpingyuan (Eastern Lowlands); IIIA, Diannan (Southern Yunnan); IIIB, Guiyue (Guangxi-Guangdong); IIIC, Minyue (Fujian- Guangdong); IIID, Hainandao (Hainan Island); IIIE, Taiwan; IVA, Huanghuaipingyuan (Huang- Huai plains); IVB, Huangtugaoyuan (Loess plateau).

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Figure 1.14 Shih & Ng’s (2011) freshwater crab areas (reproduced with permission from Taylor & Francis).

Research aims

The aims of this study were to: 1. To fill in some surveying blanks of the potamid crabs of China and accumulate distribution data for the biogeographical analyses. 2. Scientifically describe and name the new taxa that are discovered from the field surveys. 3. Revise the history of freshwater zoogeographic bioregionalisations of the freshwater fishes, amphibians and freshwater crabs of mainland China. 4. Quantify and map the freshwater zoogeographic areas of mainland China through spatial analyses using the combined distribution data of the above-mentioned groups. 5. Compare these areas with previous regionalisations and formally propose a formal bioregionalisation (i.e., area ) of the freshwater zoogeographic areas of mainland China according to the naming rules of the International Code of Area Nomenclature (ICAN).

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6. Quantify and map the endemic areas for each of the three groups and discuss their biogeographic patterns and how these patterns influence the regionalisation.

Thesis structure

Chapters 2-7 are studies on freshwater crab systematics. Chapter 2 describes the first stygomorphic cave crab known from China and East Asia, Diyutamon cereum. Chapter 3 describes a new genus (Cantopotamon) and four new species from southern Guangdong. Chapter 4 revises the systematics of the genus Yarepotamon. Chapter 5 describes yet another two new genera and two new species (Megapleonum ehuangzhang and Luteomon spinapodum) from southern Guangdong. Chapter 6 for the first time records the four freshwater crab species of Macau and describes a new species, Nanhaipotamon macau. Chapter 7 describes a new genus new species from central Hainan, Calcipotamon puglabrum. In the process of describing these new taxa, the author obtained distribution data of freshwater crabs in southern China which is used in the biogeographical analysis in the next chapter. In Chapter 8, the first quantitative bioregionalisation of the freshwater zoogeographic areas of mainland China based on multiple animal groups is presented. The combined occurrence data of amphibians, freshwater fishes and freshwater crabs were subjected to cluster and network analyses. Four freshwater zoogeographical subregions (Beifang, Tarim, China, and the Tibetan subregion), three dominions for the China subregion (Jianghuai, Dongyang, and the new Dian dominion), three provinces for the Dian dominion (West Hengduan, Diannan Highlands and the new Yungui Plateau province) and two provinces for the Dongyang dominion (Zhemin and the new Huanan province) are proposed according to the naming rules of ICAN. The endemic areas of each animal group were then individually studied and compared with the bioregionalisation.

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Chapter 2.

A new genus and new species of Potamidae (Crustacea: Decapoda: Brachyura: Potamoidea), the first stygomorphic cave crab known from China and East Asia

Chao Huang, Hsi-Te Shih and Peter K. L. Ng Zootaxa, 4232 (1), 71–84

Abstract

A new genus and species of freshwater crab, Diyutamon cereum n. gen., n. sp., is described from a cave in Guizhou, China. This is the first record of a true stygomorphic crab from China and East Asia, possessing pale body coloration, strongly reduced eyes, and long ambulatory legs. While superficially similar to Chinapotamon Dai & Naiyanetr, 1994, and Tiwaripotamon Bott, 1970, the new genus possesses a diagnostic combination of carapace, ambulatory leg, thoracic sternal, and male abdominal characters that easily distinguishes it from other genera. Molecular data derived from the mitochondrial 16S rDNA supports the establishment of the new genus.

Key words: Diyutamon cereum, new genus, new species, caves, stygobite, 16S rDNA.

Introduction

Freshwater crabs of the family Potamidae are very well represented in China with over 200 species (Dai, 1999; Cumberlidge et al., 2011; Shih & Ng, 2011; Shih et al., 2016a). Guizhou, a province in southwestern China, is rich in karst landscapes, which include many limestone caves (see Shih & Ng, 2011). A recent survey of a cave in Anlong County, Guizhou by the first author with assistance from expert cavers from the China Karst

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Exploration Projects, found crabs in a subterranean stream that differed markedly from all other known Chinese potamids. The crab, a new species, possesses characters that fit the criteria of stygobitic crabs proposed by Holthuis (1986), Ng & Goh (1987), and Guinot (1988, 1994). The new species resembles members of Chinapotamon Dai & Naiyanetr, 1994, with regards to the gonopod morphology, and Tiwaripotamon Bott, 1970, in terms of the long ambulatory legs, but can be immediately distinguished from these two and other known genera by its distinctive combination of carapace, eye, ambulatory leg, thoracic sternum, and male abdominal characters. Molecular analysis using the mitochondrial 16S rRNA marker also confirms that it does not belong to any known potamid genus. A new genus, Diyutamon n. gen., is therefore established for this new species.

Material and methods

Specimens were collected by hand from Guizhou Province, southwestern China and were preserved in 75% ethanol. The following museum acronyms are used: SYSBM, Sun Yat- Sen Museum of Biology, Sun Yat-Sen University, , China; ZRC, Zoological Reference Collection, Lee Kong Chian Natural History Museum, National University of Singapore, Singapore; NCHUZOOL, Zoology Collection of the National Chung Hsing University, Taichung, Taiwan; and MNHN, Musèum national d’Histoire naturelle, Paris, France. Measurements, in millimeters, are of the carapace width and length, respectively. The following abbreviations are used: G1 - male first gonopod; G2 - male second gonopod. The comparative Chinese material examined in this study include Chinapotamon glabrum (Dai, Song, Li & Liang, 1980): 1 male (34.2 × 24.7 mm) (SYSBM 001133), Qiannan Autonomous Prefecture, Guizhou Province, Jul. 2013; Tiwaripotamon pingguoense Dai & Naiyanetr, 1994: female (42.2 × 32.6 mm) (SYSBM 001166), Pingguo County, Baise City, Guangxi Province, coll. local collector, Sep. 2013; Tiwaripotamon xiurenense Dai & Naiyanetr, 1994: 1 male (39.6  29.7 mm) (NCHUZOOL 13610), Lipu, Guangxi, coll. local collector, May 2009. Sequences of 16S were obtained following the method described by Shih et al. (2016b), with the primers of 16H10 and 16L29 (Schubart, 2009), and aligned with the aid of ClustalW (vers. 1.4, Thompson et al., 1994), after verification with the complimentary 36

strand. To confirm the systematic position of this species, the 16S sequences of genera from the eastern Asian (Shih et al., 2009), as well as additional species (with accession numbers of DNA Data Bank of Japan, DDBJ) distributed in southern China and northern Vietnam (Huang et al., 2016; Shih et al., 2016a) were included for comparison. These specimens are Chinapotamon cf. longlinense (SYSBM 1185: Baise, Guangxi, China), Daipotamon minos Ng & Trontelj, 1996 (ZRC 1996.1045, 1046 paratypes: Libo, Guizhou, China), Mediapotamon leishanense (Dai, 1995) (SYSBM 1094: Leishan, Guizhou, China; LC155164), Minutomon shanweiense Huang, Mao & Huang, 2014 (SYSBM 1128: Shanwei, Guangdong, China; LC176065), Sinopotamon davidi (Rathbun, 1904) (MNHN- IU-2014-8620, lectotype: , , China; LC155132), Tiwaripotamon edostilus Ng & Yeo, 2001 (ZRC 2000.0096, holotype: Haiphong, Vietnam), T. xiurenense Dai & Naiyanetr, 1994 (NCHUZOOL 13610: Lipu, Guangxi, China), and Yuebeipotamon calciatile Huang, Shih & Mao, 2016 (SYSBM 1298: Yingde, Guangdong, China; LC176064). Following Shih et al. (2009), Socotrapotamon nojidensis Apel & Brandis, 2000, is closely related to the genera from continental eastern Asia, and it is therefore treated as an outgroup in this study. We followed Shih et al. (2009) to exclude the variable regions in loop regions of the 16S which could not be aligned adequately for phylogenetic analyses. The best-fitting model for sequence evolution of the 16S dataset was determined by MrModeltest (vers. 2.2, Nylander 2005), selected by the Akaike information criterion (AIC). The best model obtained was HKY+I+G, and was subsequently applied for Bayesian inference (BI) and maximum likelihood (ML) analyses. The BI analysis was performed with MrBayes (vers. 3.2.2, Ronquist et al. 2012) and the search was run with four chains for 10 million generations, with trees sampled every 1000 generations. The convergence of chains was determined by the average standard deviation of split frequency values below the recommended 0.01 (Ronquist et al., 2005) and the first 1000 trees were discarded as the burnin accordingly, and the adequate mixing of chains was assessed by the effective sample size (ESS) (>200 as recommended) in Tracer (vers. 1.5, Rambaut & Drummond 2009). ML analysis was conducted in GARLI (vers. 2.0, Zwickl 2006), with 10 replicate searches (searchreps = 10) and 100 bootstraps (bootstrapreps = 100) and the 37

consensus tree from the GARLI output was computed using the program PAUP* (vers. 4.0b10, Swofford 2003) to assess node supports. Basepair (bp) difference and pairwise estimates of Kimura 2-parameter (K2P) distance (Kimura, 1980) for genetic diversities between haplotypes were also calculated by MEGA (vers. 5.2.2, Tamura et al. 2011).

Figure 2.1 Diyutamon cereum n. gen., n. sp., color in life. A, male, specimen not collected; B, underground stream at type locality.

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Systematics

Family Potamidae Ortmann, 1896 Subfamily Potamiscinae Bott, 1970 (sensu Yeo & Ng, 2004) Diyutamon n. gen. (Figs. 2.1A, 2.2–2.7)

Figure 2.2 Diyutamon cereum n. gen., n. sp., male holotype (32.3 × 23.9 mm) (SYSBM 001551). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view showing anterior thoracic sternum and abdomen; D, ventral view showing sterno-abdominal cavity with right G1 in situ (left G1 removed).

Diagnosis. Carapace subtrapezoidal, dorsal surface gently convex, appearing almost flat in frontal view, smooth, regions barely indicated (Figs. 2.2A, B, 2.3A, 2.7A); frontal margin not prominently protruding anteriorly; postorbital, epigastric cristae not distinct (Figs. 2.2A, 2.3A, 2.7A); external orbital angle broadly triangular, almost confluent with anterolateral margin (Figs. 2.2A, B, 2.3A–D, 2.7A); median lobe of posterior margin of epistome broadly triangular (Figs. 2.2B, 2.3B, D); third maxilliped with relatively broad 39

ischium, exopod reaches beyond anterior edge of ischium, with long flagellum (Fig. 2.5D); pollex of male, female major chela with basal molariform tooth on cutting edge (Figs. 2.4C, 2.7C); male thoracic sternite 8 exposed when abdomen closed (Figs. 2.2C, 2.3E, F); male abdomen triangular, telson with almost straight lateral margins, rounded tip (Figs. 2.2C, 2.3E); G1 generally slender, terminal segment slightly curved upwards, tapered (Figs. 2.5A, C, 2.6A, B); basal segment of G2 subrectangular (Fig. 2.5B).

Figure 2.3 Diyutamon cereum n. gen., n. sp., paratype male (30.6 × 22.6 mm) (SYSBM). A, dorsal view of carapace; B, frontal view of cephalothorax showing antennules, antennae, orbit, eye and epistome; C, right anterolateral margin; D, frontal view of cephalothorax showing orbit, eye, pterygostomial and suborbital regions; E, ventral view showing anterior thoracic sternum and abdomen; F, posteroventral view showing posterior thoracic sternum and abdomen. Abbreviations: 40

a1–a6 = male abdominal somites 1–6, respectively; cx5 = coxa of fifth ambulatory leg; st5–8 = thoracic sternites 5–8, respectively; t = telson.

Figure 2.4 Diyutamon cereum n. gen., n. sp., paratype male (30.6 × 22.6 mm) (SYSBM). A, right ambulatory legs; B, dorsal view of right major cheliped; C, outer view of right major chela showing molariform teeth; D, outer view of left minor chela. C and D same scales.

Etymology. The genus name is derived from the Chinese word Diyu, for hell, which alludes to the subterranean habitat of the type species. The suffix is derived from “Potamon”, the type genus of the family. Gender of genus neuter.

Remarks. Although Diyutamon n. gen., is superficially similar to Chinapotamon and Tiwaripotamon in terms of G1 morphology, it can easily be distinguished in possessing almost undiscernible postorbital cristae, the external orbital angle is confluent with the anterolateral margin which is lined with small spines and sharp granules, the ambulatory legs are conspicuously long and slender, and most significantly, the edge of thoracic 41

Table 2.1 Morphological differences among Diyutamon n. gen., Chinapotamon Dai & Naiyanetr, 1994, Tiwaripotamon Bott, 1970. Character Diyutamon Chinapotamon Tiwaripotamon not prominently prominently protruding prominently protruding Frontal margin protruding anteriorly anteriorly (cf. Dai, 1999: anteriorly (cf. Shih & Do, (Figs. 2.2A, 2.3A, 2.7A) plates IV, V) 2014: figs. 4A, 6A, 7A) almost undiscernible Postorbital low (cf. Dai, 1999: low (cf. Shih & Do, 2014: (Figs. 2.2A, B, 2.3A-C, cristae plates IV, V) figs. 4A, 6A, 7A) 2.7A) almost confluent with not confluent with not confluent with External anterolateral margin anterolateral margin (cf. anterolateral margin (cf. orbital angle (Figs. 2.2A, B, 2.3A, C, Shih & Do, 2014: figs. 4A, Dai, 1999: plates IV, V) 2.7A) 6A, 7A) lined with low spines lined with small lined with small granules Anterolateral and sharp granules granules (cf. Dai, 1999: (cf. Shih & Do, 2014: figs. margin (Figs. 2.2A, B, 2.3A, C, plates IV, V) 4A, 6A, 7A) 2.7A) Ambulatory slender (Figs. 2.2A, stout (cf. Dai, 1999: slender (cf. Shih & Do, legs 2.4A, 2.7A) plates IV, V) 2014: figs. 4A, 6A, 7A) edge visible when not visible when not visible when abdomen Male thoracic abdomen closed (Figs. abdomen closed closed (cf. Shih & Do, sternite 8 2.2C, 2.3E, F) (unpublished data) 2014: figs. 4C, 6B) sternite 8 remains visible even when the abdomen is closed (Table 2.1). While the strongly reduced eyes, with short peduncles short, and small corneas without pigmentation (Figs. 2.2B, 2.3B, D), are very diagnostic features of the type species (not know for any species of Chinapotamon or Tiwaripotamon), these are probably highly derived characters associated with its stygobitic habits. As such, they are probably not phylogenetically significant (see Ng & Sket, 1996; Klaus et al., 2013). Other potamids known from caves in China include Sinopotamon baiyanense Ng & Dai, 1997, Daipotamon minos Ng & Trontelj, 1996, Chinapotamon dashiwei Ng, 2017b, Chinapotamon clarkei Ng, 2017b and Tiwaripotamon

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xiurenense Dai & Naiyanetr, 1994. None are completely blind like the type species of the new genus.

Diyutamon cereum n. gen., n. sp. (Figs. 2.1A, 2.2–2.4)

Material examined. Holotype: male (32.3 × 23.9 mm) (SYSBM 001551), Anlong, Guizhou, China, subterranean stream inside a cave at the bottom of sinkhole, coll. C. Huang, May 2016. Paratypes: 1 female (allotype) (27.3 × 20.4 mm) (SYSBM 001552), same data as holotype; 5 males (30.6  22.6 mm, 30.4 × 21.7 mm, 28.5 × 21.5 mm, 23.5 × 17.2 mm, 17.6 × 13.2 mm), 4 females (25.8 × 18.3 mm, 26.5 × 19.2 mm, 21.3 × 15.8 mm, 18.6 × 14.2 mm) (SYSBM), same data as holotype.

Figure 2.5 Diyutamon cereum n. gen., n. sp., male holotype (32.3 × 23.9 mm) (SYSBM 001551). A, left G1 (ventral view); B, left G2; C, G1 terminal segment (ventral view); D, left third maxilliped. Scales = 1.0 mm.

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Description of male. Carapace transversely subquadrate; dorsal surface gently convex transversely, longitudinally, generally smooth, weakly pitted, appearing almost flat in frontal view; regions barely indicated (Figs. 2.2A, B, 2.3A, 2.7A). Frontal margin not distinctly protruding anteriorly, very broad, deflexed, margin divided into 2 broad, gently convex lobes on dorsal view; margin lined with closely packed, low rounded granules; confluent with supraorbital margin (Figs. 2.2A, 2.3A, 2.7A). Epigastric cristae very low, almost undiscernible, area marked by distinct transverse rugosities (Figs. 2.2A, B, 2.3A–C, 2.7A). Postorbital cristae undiscernible (Figs. 2.2A, B, 2.3A–C, 2.7A). Branchial regions gently swollen (Figs. 2.2A, B, 2.3A–C, 2.7A). Cervical groove very shallow, barely visible; H-shaped gastro-cardiac groove shallow but visible (Figs. 2.2A, 2.3A, 2.7A). External orbital angle distinct, very low, broadly triangular, lined with spinules, separated from supraorbital margin by small spine, just discernible from rest of anterolateral margin, separated by broad shallow cleft (Figs. 2.2A, B, 2.3A–D, 2.7A). Anterolateral margin convex, cristate, not clearly dentate or lobate, with approximately 20 low spines, sharp granules, some in clumps (Figs. 2.2A, B, 2.3A, C, 2.7A). Posterolateral margin uneven, gently sinuous, surface lined with oblique striae; strongly converging towards gently concave posterior carapace margin (Figs. 2.2A, 2.3A, 2.7A). Orbits large, clearly demarcated; supraorbital, infraorbital margins cristate, lined with numerous low granules (Figs. 2.2B, 2.3B, D). Eye mobile, greatly reduced, reaching mesial third of orbit width; peduncle short, stout; cornea small, without pigmentation (Figs. 2.2B, 2.3B, D). Suborbital region smooth; pterygostomial region covered with distinct granules; subhepatic, subbranchial regions smooth or with low striae (Figs. 2.2B, 2.3B, D). Antennules relatively short, folding transversely into rectangular fossae (Figs. 2.2B, 2.3B, D). Antennae very short; first (urinary) article round, prominent; basal article subquadrate, mobile, lodged in orbital hiatus; remaining articles very short, just touching basal part of ocular peduncle (Figs. 2.2B, 2.3B, D). Epistome longitudinally narrow; posterior margin with median lobe broadly triangular, lateral margins unevenly sinuous, separated by distinct clefts (Figs. 2.2B, 2.3B, D). Third maxilliped with merus subtrapezoidal, with submarginal depression, about 1.2 times as broad as long; ischium rectangular, about 1.5 times as long as broad, with shallow, 44

broad median sulcus; exopod slender, reaching to proximal third of merus, flagellum distinct, reaching lateral three-fifths or almost to width of merus (Figs. 2.2B, 2.3B, D, 2.5D).

Figure 2.6 Diyutamon cereum n. gen., n. sp., male holotype (32.3 × 23.9 mm) (SYSBM 001551). A, left G1 (ventral view); B, G1 terminal segment (ventral view); C, anterior thoracic sternum.

Chelipeds unequal (Figs. 2.2A, 2.7A). Basis-ischium fused, separated by clear suture; ventral margin with row of low granules (Figs. 2.2B, 2.4C, D). Merus cross-section trigonal; dorsal margin lined with low, uneven rounded granules; ventro-inner margin lined with relatively sharper granules, subdistal part with short spines; surfaces otherwise smooth, pitted (Fig. 2.2B). Carpus subovate; surfaces pitted; outer surface with low sharp granules on distal part; inner surface with 1 or 2 prominent sharp spines at inner-distal angle, with several sharp granules basal to these (Figs. 2.2A, 2.4B). Palm of major chela about 1.5 times as long as high; fingers subequal in length to palm; dactylus, pollex subequal in

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length, dactylus gently curved inwards; cutting margin of dactylus lined with denticles except for basal molariform tooth; cutting margin of pollex lined with denticles along distal half, proximal part with prominent molariform tooth with gently concave occlusal surface (Fig. 2.4C); fingers forming small gap when closed (Figs. 2.2A, 2.4B, C, 2.7C). Palm of smaller chela slender; fingers longer than palm; fingers slender, cutting edges evenly lined with denticles (Figs. 2.2A, 2.4D, 2.7D). Ambulatory legs very long, slender, surfaces smooth or pitted; second leg longest (Figs. 2.2A, 2.4A, 2.7A). Merus laterally flattened; dorsal margin subcristate, margin uneven but entire, subdistal angle low, without spine or tooth (Figs. 2.2A, 2.4A, 2.7A). Carpus smooth, without distinct ridges (Figs. 2.2A, 2.4A, 2.7A). Propodus elongated, ventral margin of that of fourth leg distinctly serrate (Figs. 2.2A, 2.4A, 2.7A). Dactylus elongated, margins with short pectinate spines, those of second, third legs longest (Figs. 2.2A, 2.4A, 2.7A). Fourth leg with propodus about 4.4 times as long as board, approximately same length as dactylus (Figs. 2.2A, 2.4A, 2.7A). Thoracic sternum almost smooth, pitted; sternites 1, 2 completely fused to form subtriangular structure, separated from sternite 3 by relatively shallow but distinct suture; sternites 3, 4 completely fused without trace of median suture; male sterno-abdominal cavity reaching to imaginary line joining posterior ends of coxae of cheliped; tubercle of male abdominal locking mechanism peg-like, on posterior third of sternite 5; sternites 4/5, 5/6 medially interrupted; median longitudinal groove between sternites 7, 8 deep, on sternite 7 extending along posterior three-quarters (Figs. 2.2C, D, 2.3E, F, 2.6C). Part of sternite 8 clearly visible when abdomen closed (Figs. 2.2C, 2.3E, F). Penis on condyle of coxa of fourth ambulatory leg. Male abdomen narrowly triangular; all somites, telson freely articulating; somites 1–3 very broad, reaching to episternite 7, bases of coxae of fourth ambulatory legs; somites 3–6 progressively broader longitudinally; somite 6 about 2.1 times as board as long; telson about 1.6 times as board as long with a rounded tip, lateral margins of telson almost straight (Figs. 2.2C, 2.3E, F). G1 generally slender, terminal segment slightly curved anteriorly, tapered (Figs. 2.5A, C, 2.6A, B); tip of terminal segment barely reaches tubercle lock of abdominal 46

Figure 2.7 Diyutamon cereum n. gen., n. sp., female paratype (26.5 × 19.2 mm) (SYSBM). A, dorsal overall view; B, ventral view showing anterior thoracic sternum and abdomen; C, outer view of right chela; D, outer view of left chela; E, ventral view of abdomen, showing the vulvae (vu). locking structure in situ (Fig. 2.2D); subterminal segment about 2.7 times as long as terminal segment, lateral, mesial margins of distal part of subterminal segment almost

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parallel, (Figs. 2.5A, 2.6A). Basal segment of G2 subrectangular; G2 basal segment about 2.6 times length of flagelliform distal segment (Fig. 2.5B).

Variation. The male specimens on hand show no substantial variation in the key characters of the species discussed above.

Females. Carapace similar to male (Fig. 2.7A). Abdomen broadly ovate, covering median parts of thoracic sternum (Fig. 2.7B). Chelipeds unequal as male, but chelae not as strongly inflated (Fig. 2.7C, D); pollex of major chela with relatively smaller basal molariform tooth on cutting edge (Fig. 2.7C). Vulva relatively large, ovate, on anterior half of sternite 5, edge of vulvae on suture between sternites 5, 6, without operculum (Fig. 2.7E).

Etymology. The species name, from the Latin cereum for wax-like referring to the white coloration and smooth surfaces of this species.

Color. Generally white to cream all over (Fig. 2.1A).

Ecology. The new species inhabits subterranean streams. During the time of the collection, the rainy season had already started and the water in the stream was murky and fast flowing, making observation difficult. Crabs were nevertheless observed to intermittently appear near the water edge, waving their chelae and legs as if foraging for food. It is unclear whether this behavior is normal or induced by the presence of the survey team (vibrations from the team’s footsteps, water disturbance, lights). Crabs were abundant at the locality and were all found in water, indicating it is primarily an aquatic species. The subterranean stream at the type locality was less than 100 m from the cave entrance where there was still a hint of light. The stream is nevertheless situated below an approximately 30 m flowstone drop off and can only be safely accessed with the aid of Single-Rope Technique (SRT) for caving. The cave entrance is at the bottom of a large sinkhole about 200 meters deep. The presence of a molariform tooth on the major chela on both males and females is noteworthy. Such a character is present in molluscivorous gecarcinucid freshwater crab

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species from Sulawesi, Indonesia (Chia & Ng, 2006; Schubart & Ng, 2008). It seems likely that the function of the molariform teeth in Diyutamon cereum n. gen., n. sp. is also for crushing the hard shells of freshwater snails. Though snails could not be observed in the subterranean stream due to the murky water, they were found clinging on the flowstone at the drop off. Further research using methods such as gut content analysis would be needed to further confirm this.

DNA analyses and discussion

In total, 54 species from 44 potamid genera were included in the phylogenetic analyses. A 503 bp segment, excluding the variable regions, of the 16S rDNA was amplified and aligned. The 16S sequences obtained in this study, with carapace width and the accession numbers, include Diyutamon cereum (2 females, 21.3 mm and 25.8 mm: LC198519; female 18.6 mm: LC198520), Chinapotamon cf. longlinense (LC198521), Daipotamon minos (LC198524), Tiwaripotamon edostilus (LC198523), and T. xiurenense (LC198522). The phylogenetic tree of the 16S was reconstructed using BI analysis, with support values from ML analysis (Fig. 2.8). The tree shows Diyutamon n. gen. is sister to Chinapotamon, with the mean K2P distance between being 5.17% (5.06–5.28%). This intergeneric K2P distance is not large but still substantial when compared to other genera (e.g. 5.07–5.97% between Sinolapotamon, Huananpotamon and Nanhaipotamon; 4.44–5.97% between Sinopotamon, Longpotamon and Daipotamon; 2.71–3.57% between Daipotamon, Tenuilapotamon and Mediapotamon; 4.85% between Thaiphusa and Demaniella; and 4.43– 5.09% between Pararanguna, Potamiscus and Trichopotamon), giving support to the generic treatment. Although cave crabs have been reported from China over the years, no species can be regarded as stygophiles or stygoxenes (sensu Chapman 1982; Ng & Goh 1987; Guinot 1988, 1994), with the exception of Chinapotamon clarkei, Ng, 2017b, which has reduced body pigment and partially reduced but functional eyes. Longpotamon baiyanense (Ng & Dai, 1997) and Daipotamon minos Ng & Trontelj, 1996, are both believed to be primarily epigean or at most, stygophilic taxa (Ng & Dai, 1997; Ng & Trontelj, 1996). Chen & Zhang (2002) described “Chinapotamon tiankengense” from the giant caves of the Dashiwei 49

Figure 2.8 A Bayesian inference (BI) tree of 16S rDNA for the subfamily Potamiscinae, with the sequences and accession numbers in Shih et al. (2009), as well as some additional species (see Material and methods). The species inhabited in Chinese caves are highlighted in gray. Probability values at the nodes represent support values for BI and maximum likelihood (ML). Only values > 50% are shown.

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Tiankeng, Guangxi, but the diagnosis was brief, there were no figures and the name is not available because it did not fulfil the necessary requirements of the ICZN (1999) code. From the brief description provided by Chen & Zhang (2002) of “C. tiankengense”, this species is also not a stygobite as its eyes were fully developed and the body fully pigmented. It is likely the same species as Chinapotamon dashiwei Ng, 2017b. All these species, like other stygophiles, are probably closely or even wholly associated with caves, but have not, as yet, completely adapted to this habitat (see Guinot, 1988; Ng, 2013; Ng & Guinot, 2014). Shih & Ng (2011), in their review of the Chinese freshwater crabs, speculated on the possible eventual discovery of a stygobitic freshwater crab from China. They noted that the general scarcity of cave crabs from China could be caused by the relatively young geological history of its karst formations. They commented that the period between the Middle and Late Cenozoic was one of the most important periods of karstification in southwestern China (Zhang, 1989; Xiong et al., 1997), and the process was intensified by the uplift of plateau and climatic fluctuations since the Quaternary period (Li, 2001; Li, 2011). Most caves and underground water systems of these karst areas are generally considered to have been formed during the tropical climate of the Middle Pliocene (ca. 3 million year ago, mya) to the Early Pleistocene (Liu & Zhou, 2011). Guizhou Province has the highest percentage (up to 75%) of karst topology coverage in China (cf. Shih & Ng, 2011). That been said, many species of endemic troglobitic and stygobitic and fish have been recorded from these caves in China. The discovery of Diyutamon cereum n. gen., n. sp., is therefore significant as it is the first stygobitic freshwater crab discovered from China and East Asia- it has lost the body pigmentation, reduced eye stalks, no pigmentation in the cornea and elongated ambulatory legs. When the substitution rates of 0.88% for 16S rDNA for terrestrial Sesarma (see Schubart et al., 1998) is applied, the divergence time between the genera Diyutamon n. gen. and Chinapotamon is estimated at about 5.7 mya (with uncorrected p-distance divergences of 4.98%). The divergence time of the Chinese stygophilic species (highlighted in gray, Fig. 2.8) is considerably younger, e.g. 3.0 mya of Longpotamon baiyanense from L. planum (p- distance 2.65%) and 3.9 mya of Daipotamon minos from Tenuilapotamon latilum and Mediapotamon leishanense (p-distance 3.46% and 3.45%), which roughly corresponds to 51

the approximate time of formation of most cave and underground water systems from this region as mentioned above and is usually not old enough for stygobites to have evolved (Shih & Ng, 2011). The discovery of this new genus and new species, however, suggests that there are at least some karst systems in the Guizhou area which are old enough for the evolution of stygobitic organisms.

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Chapter 3.

Cantopotamon, a new genus of freshwater crabs from Guangdong, China, with descriptions of four new species (Crustacea: Decapoda: Brachyura: Potamidae)

Chao Huang, Shane T. Ahyong and Hsi-Te Shih Zoological Studies, 56 (41), 1–20

Abstract

A new genus and four new species of freshwater crab, Cantopotamon zhuhaiense n. gen., n. sp., C. shangchuanense n. gen., n. sp., C. hengqinense n. gen., n. sp. and C. yangxiense n. gen., n. sp. are described from Guangdong, China, based on morphology and two mitochondrial markers (16S rDNA and cytochrome oxidase subunit I). Species of Cantopotamon closely resemble species of Yarepotamon Dai & Türkay, 1997, but differ by the combination of carapace, third maxilliped, male pleon, male first gonopod and female gonopore characters. Molecular data derived from the mitochondrial 16S rDNA also supports the establishment of the new genus.

Key words: Potamidae, Cantopotamon, new genus, new species, freshwater crab, morphology, 16S rDNA, cytochrome oxidase subunit I.

Background

The discovery of new species of freshwater crabs, especially in China and India, continues at a significant rate (e.g., Cumberlidge et al., 2011, Pati & Devi, 2015, Huang et al., 2017, Mitra & Valarmathi, 2017). China has the highest species richness of freshwater crabs globally (Cumberlidge et al., 2011). South China, the region comprising Guangdong,

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Guangxi, Hainan, Hong Kong and Macau, has a high diversity of potamid crabs (Dai, 1999; Shih & Ng, 2011), but many parts, including the southern coastline of Guangdong, remain largely unexplored for freshwater crabs. This monsoon subtropical coastline consists of a complex topography of lowlands, estuaries, islands and low mountains and hills. Recent surveys have revealed the presence of four closely allied new taxa in coastal regions west of the Pearl River, Guangdong, which could not be morphologically assigned to any existing genus. These crabs seem to be mainly aquatic, being found in small and oligotrophic low-altitude hillstreams. Although they are similar to some species of Yarepotamon Dai & Türkay, 1997 in external appearance, the of the postorbital cristae and the epigastric cristae, the distinctly twisted terminal segment of the male first gonopod and the distinctly smaller female vulvae clearly set them apart. Molecular analyses using mitochondrial 16S rRNA and COI sequences confirm the monophyly of these four new taxa and their separation from other genera. Therefore, we recognize herein a new genus for these four new species.

Materials and methods

Specimens were collected by hand, preserved in 75% ethanol and deposited in the Sun Yat- Sen Museum of Biology, Sun Yat-sen University, Guangzhou, China (SYSBM); Chinese Academy of Science, , China (CAS); and the Zoological Reference Collection of the Lee Kong Chian Natural History Museum, National University of Singapore, Singapore (ZRC). Measurements, in millimeters, are of the carapace width and length, respectively. The following abbreviations are used: G1 – male first gonopod; G2 – male second gonopod. Sequences of 16S were obtained following Shih et al. (2016), using the primers of 16H10 and 16L29 (Schubart, 2009), and aligned with the aid of ClustalW (vers. 1.4, Thompson et al., 1994), after verification with the complementary strand. To confirm the systematic position of this species, the 16S sequences of genera from the eastern Asian continent in Shih et al. (2009) and Huang et al. (2017) are included for comparison; Socotrapotamon nojidensis Apel and Brandis, 2000 is used as an outgroup. We followed Shih et al. (2009) to exclude the variable regions in loop regions of the 16S which could not be aligned adequately for phylogenetic analyses. The best-fitting model for sequence evolution of the 54

16S dataset was determined by MrModeltest (vers. 2.2, Nylander 2005), selected by the Akaike information criterion (AIC). The best model obtained was HKY+I+G, and was subsequently applied for Bayesian inference (BI) analysis. The BI analysis was performed with MrBayes (vers. 3.2.2, Ronquist et al. 2012) and the search was run with four chains for 10 million generations, with trees sampled every 1000 generations. The convergence of chains was determined by the average standard deviation of split frequency values below the recommended 0.01 (Ronquist et al. 2005) and the first 1050 trees were discarded as the burnin accordingly. ML analysis was conducted in RAxML (vers. 7.2.6, Stamatakis 2006). The model GTR + G (i.e. GTRGAMMA) was used for all subsets with 100 runs, and found the best ML tree by comparing the likelihood scores. The robustness of the ML tree was evaluated by 1000 bootstrap pseudoreplicates under the model GTRGAMMA. Additional sequences of COI for the species of the new genus, also obtained following the method described by Shih et al. (2016), were combined with 16S and analyzed by BI and ML methods mentioned above. Both the best models obtained for 16S and COI datasets were GTR + I. Sequences of the different haplotypes of 16S and COI have been deposited in the DNA Data Bank of Japan (DDBJ) database (accession numbers in Table 3.1). Basepair (bp) difference, as well as the pairwise estimates of Kimura 2-parameter (K2P) distance (Kimura, 1980) and the uncorrected p-distance for genetic diversities between haplotypes were also calculated by MEGA (vers. 7.0, Kumar et al. 2016).

Table 3.1 The haplotypes of 16S rRNA and COI genes of Cantopotamon new genus from China. Museum Species Localities of sp. 16S acces. no. COI acces. no. catalogue identified China no. haplotypes 16S haplotypes COI no. Xiangzhou, SYSBM C. zhuhaiense Zhuhai City, 001439 1 Cz1 LC342045 Cz-C LC342051 Guangdong (paratype) Xiangzhou, SYSBM Zhuhai City, 001440, 2 Cz2 LC342046 Cz-C LC342051 Guangdong 001441

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(paratype) Xiangzhou, Zhuhai City, ZRC 1 Cz2 LC342046 Cz-C LC342051 Guangdong Island, SYSBM C. hengqinense Zhuhai City, 001559 1 Ch LC342047 Ch-Ca LC342052 Guangdong (paratype) Hengqin Island, SYSBM Zhuhai City, 001561 1 Ch LC342047 Ch-Cb LC342053 Guangdong (paratype) Shangchuan SYSBM C. island, Taishan 001428 1 Cs1 LC342048 Cs-C1 LC342054 shangchuanense City, (paratype) Guangdong Shangchuan SYSBM island, Taishan 001429 1 Cs2 LC342049 Cs-C2 LC342055 City, (paratype) Guangdong E'huang Ridge, Yangxi, SYSBM C. yangxiense 1 Cy LC342050 Cy-C LC342056 Yangjiang City, 001564 Guangdong

Results

Taxonomy Family Potamidae Ortmann, 1896 Subfamily Potamiscinae Bott, 1970 Genus Cantopotamon n. gen.

Type species: Cantopotamon zhuhaiense n. gen., n. sp., by present designation.

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Diagnosis. Carapace broader than long; dorsal surface slightly convex, branchial regions relatively flat (Fig. 3.1A); postorbital and epigastric cristae visible, confluent (Fig. 3.1A); external orbital angle bluntly triangular, separated from anterolateral margin by gap (Fig. 3.1A, B); median lobe of posterior margin of epistome triangular (Fig. 3.1B). Third maxilliped ischium relatively broad; exopod reaching beyond anterior margin of ischium, with flagellum (Fig. 3.2D). Male pleon triangular, reaching anteriorly almost to level of posterior margins of cheliped coxae (Fig. 3.1C). G1 slender, inner proximal section of sub- terminal segment curved dorsally, terminal segment relatively short, sinistrally twisted on left G1 (Figs. 3.1D, 3.2B, C, 3.9). G2 basal segment subovate (Fig. 3.2A). Vulva small, ovate, not reaching suture of sternites 5/6 (Fig. 3.11).

Etymology. The genus name is a combination of Canton, synonym for Guangdong, the province in which this genus occurs, and the generic name Potamon. Gender: neuter.

Remarks. Although superficially similar to some species of Yarepotamon in general carapace physiognomy, Cantopotamon n. gen. can easily be distinguished by its confluent postorbital cristate and epigastric cristate (Fig. 3.1A) (versus separate in Yarepotamon, cf. Dai & Türkay, 1997: pl. II, fig. 2), twisted terminal segment of the G1 (Fig. 3.2C) (versus not twisted in Yarepotamon, cf. Dai & Türkay, 1997: fig. 6, 4) and relatively small female vulvae that do not reach the suture of sternites 5/6 (Fig. 3.11A) (versus female vulvae reaching suture of sternites 5/6 in Yarepotamon, cf. Dai & Türkay, 1997: fig. 6, 7). Specimen details of comparative material are given in Appendix 3.1.

Key to the species of Cantopotamon 1. G1 relatively short, tip of terminal segment not reaching male pleonal locking tubercle (Fig. 3.1D) ……………………………………………………C. zhuhaiense - G1 relatively long, tip of terminal segment exceeding male pleonal locking tubercle (Figs. 3.3D, 3.5D, 3.7D) ………………………………………………… 2 2. Tip of G1 terminal segment horn-shaped …………………………... C. hengqinense - Tip of G1 terminal segment blunt ……………………………………………… 3 57

3. Inner margin of G1 terminal segment with blunt projection ………… C. yangxiense - Inner margin of G1 terminal segment convex ………………... C. shangchuanense

Cantopotamon zhuhaiense n. sp. (Figs. 3.1–2, 3.9A, 3.10A, 3.11A, 3.12A)

Type material. Holotype: SYSBM 001438, male (29.1 × 22.9 mm), Xiangzhou (22.25°N, 113.56°E), Zhuhai City, Guangdong, small hillstreams, under rocks, coll. C. Huang, July, 2013. Paratypes: SYSBM 001440, 1 female (24.6 × 20.0 mm), same data as holotype. SYSBM 001439, 1 male (24.1 × 20.1 mm), same data as holotype, SYSBM 001441, 1 female (22.3 × 17.3 mm), same data as holotype.

Other material examined. SYSBM 001425, 1 male (30.2 × 24.0 mm), Xiangzhou, Zhuhai City, Guangdong, small hillstreams, under rocks, coll. C. Huang, March, 2012. SYSBM 001426, 1 female (17.8 × 14.5 mm), same as above male; ZRC, 1 male, 2 females, Xiangzhou, Zhuhai City, Guangdong, June 2011.

Etymology. This species is named after the type locality, Zhuhai City, Guangdong Province, China.

Diagnosis. Third maxilliped merus width about 1.2 × length; ischium width about 0.77 × length (Figs. 3.1B, 3.2D). Major cheliped palm length about 1.3 × height (Fig. 3.1A). Male pleonite 6 width about 2.2 × length; telson width about 1.2 × length (Fig. 3.1C). Tip of G1 terminal segment not reaching tubercle forming pleonal locking structure, scarcely exceeding sternite 5/6 suture (Fig. 3.1D); subterminal segment length about 2.2 × length of terminal segment, inner proximal section curved dorsally; terminal segment inner margin broadly triangular, tip cone-shaped (Figs. 3.1D, 3.2B, C, 3.9A, B). G2 about 2.6 × length of flagelliform distal segment (Fig. 3.2A).

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Figure 3.1 Cantopotamon zhuhaiense n. gen., n. sp., male holotype (29.1 × 22.9 mm) (SYSBM 001038). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view showing anterior thoracic sternum and pleon; D, ventral view showing sterno–pleonal cavity with right G1 in situ (left G1 removed).

Description of male. Carapace broader than long, regions not entirely distinct; dorsal surface slightly convex transversely and longitudinally; surface generally smooth with fused rugae on anterolateral region (Fig. 3.1A). Front slightly deflexed, margin slightly ridged on dorsal view (Fig. 3.1A). Epigastric cristae distinct, separated by narrow gap (Fig. 3.1A, B). Postorbital cristae sharp, laterally expanded, fused with epigastric cristae and epibranchial teeth (Fig. 3.1A, B). Branchial regions relatively flat (Fig. 3.1A). Cervical groove shallow, inconspicuous (Fig. 3.1A). Mesogastric region slightly convex (Fig. 3.1A). External orbital angle triangular (Fig. 3.1A). Epibranchial tooth small, granular, but distinct (Fig. 3.1A, B). Anterolateral margin distinctly cristate, lined with approximately 16-18 granules; lateral part bent inward (Fig. 3.1A). Posterolateral margin comparatively smooth, lined with oblique striae, converging towards posterior carapace margin (Fig. 3.1A). Orbits small; supraorbital and infraorbital margins cristate, lined with numerous inconspicuous

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granules (Fig. 3.1B). Sub-orbital and upper parts of pterygostomial regions covered with large rounded granules; sub-hepatic region lined with oblique striae (Fig. 3.1B). Epistome posterior margin narrow; median lobe sharply triangular, lateral margins almost straight (Fig. 3.1B). Third maxilliped merus width about 1.2 × length; ischium width about 0.8 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus. Exopod reaching to proximal one-third of merus; flagellum long; dorsomesial margin of ischium subauriculiform (Figs. 3.1B, 3.2D). Chelipeds (pereopod 1) unequal (Fig. 3.1A). Merus cross-section trigonal; margins crenulated (Fig. 3.1B). Carpus with sharp distomesial spine and spinule at base; dorsal surface with curved striae (Fig. 3.1A). Major cheliped palm length about 1.3 × height (Fig. 3.1A). Movable finger as long as fixed finger (Fig. 3.1A). Occlusal margin of fingers with rounded, blunt teeth; with gape when closed (Fig. 3.1A). Ambulatory legs slender (pereopods 2–5); dactylus with dense, short setae; propodus, carpus and merus with relatively sparse, short, setae (Fig. 3.1A). Pereopod 5 propodus about 2 times as long as broad, about as long as dactylus (Fig. 3.1A). Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused without obvious median suture (Figs. 3.1C, 3.10A). Male sterno-pleonal cavity reaching anteriorly to level of midlength of cheliped coxae; deep median longitudinal groove between sternites 7, 8 (Fig. 3.1D). Pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 3.1D). Male pleon triangular, almost reaching anteriorly to level of posterior margin of cheliped coxae; somites 3–6 progressively broader longitudinally, lateral margins straight; somite 6 width about 2.2 × length; telson width about 1.2 × length; apex rounded (Fig. 3.1C). G1 generally slender, relatively short, tip of terminal segment not reaching tubercle forming pleonal locking structure, barely exceeding sternite 5/6 suture (Fig. 3.1D); subterminal segment length about 2.2 × length of terminal segment, inner proximal section curved dorsally; terminal segment relatively short, sinistrally twisted (on left G1), curved inwards and pointing anteriorly, inner margin broadly triangular, tip cone-shaped (Figs. 60

3.1D, 3.2B, C, 3.9A, B). G2 basal segment subovate, about 2.6 × length of flagelliform distal segment (Fig. 3.2A).

Figure 3.2 Cantopotamon zhuhaiense n. gen., n. sp., male (29.1 × 22.9 mm) (SYSBM 001038). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, right third maxilliped. Scale bar = 1.0 mm.

Size range. Male (n = 3) 24.1 × 20.1 to 30.2 × 24.0 mm; female (n = 3) 17.8 × 14.5 to 24.6 × 20.0 mm.

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Remarks. Cantopotamon zhuhaiense n. sp. is closest to C. shangchuanense n. sp. and C. hengqinense n. sp. in overall external morphology, but can be distinguished by its shorter G1 that does not reach tubercle of pleonal locking structure in situ (Fig. 3.1D) [versus long G1 that reaches beyond in both C. shangchuanense n. sp. (Fig. 3.3D) and C. hengqinense n. sp. (Fig. 3.5D)]; broadly triangular inner margin of G1 terminal segment (Fig. 3.2C) [versus convex in C. shangchuanense n. sp. (Fig. 3.4C) and sinuous in C. hengqinense n. sp. (Fig. 3.6C)]; and other characters as shown in Table 3.2.

Colour in life. Mottled brown overall (Fig. 3.12A).

Ecology. This species is mainly aquatic, living under rocks in small hillstreams. At its type locality, C. zhuhaiense is syntopic with Nanhaipotamon cf. guangdongense Dai, 1997 and Nanhaipotamon zhuhaiense Huang, Huang and Ng, 2012. One individual, still moving, was observed within the grasp of a Nanhaipotamon cf. guangdongense in the latter’s mud burrow, suggesting they are at least occasional prey items of Nanhaipotamon.

Distribution. Xiangzhou, Zhuhai, Guangdong.

Cantopotamon shangchuanense n. sp. (Figs. 3.3–3.4, 3.9B, 3.10B, 3.11B, 3.12B)

Type material. Holotype: SYSBM 001427, male (24.1 × 19.5 mm), Shangchuan island (21.63°N, 112.78°E), Taishan City, Guangdong, small hillstreams, under rocks, coll. C. Huang, March, 2015. Paratypes: SYSBM 001429, 1 female (17.3 × 14.1 mm), same data as holotype. SYSBM 001428, 1 male (21.0 × 17.2 mm), same data as holotype, SYSBM 001430, 1 female (14.8 × 11.9 mm), same data as holotype.

Etymology. This species is named after the type locality, Shangchuan Island, Taishan City, Guangdong Province, China.

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Diagnosis. Third maxilliped with merus width about 1.2 × length; ischium width about 0.71 × length (Figs. 3.3B, 3.4D). Major cheliped palm length about 1.2 × height (Fig. 3.3A). Male pleonite 6 width about 2.3 × length; telson width about 1.4 × length (Fig. 3.3C). Tip of G1 terminal segment reaching well beyond tubercle forming pleonal locking structure, exceeding sternite 4/5 suture (Fig. 3.3D); subterminal segment about 2.5 times as long as terminal segment, inner proximal section curved dorsally; terminal segment inner distal margin strongly convex, tip blunt (Figs. 3.3D, 3.4B, C, 3.9C, D). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment (Fig. 3.4A).

Figure 3.3 Cantopotamon shangchuanense n. gen., n. sp., male (24.1 × 19.5 mm) (SYSBM 001427). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view showing anterior thoracic sternum and pleon; D, ventral view showing sterno-pleonal cavity with right G1 in situ (left G1 removed).

Description of male. Carapace broader than long, regions not entirely distinct; dorsal surface slightly convex transversely and longitudinally; surface generally smooth with fused rugae on anterolateral region (Fig. 3.3A). Front slightly deflexed, margin slightly ridged on dorsal view (Fig. 3.3A). Epigastric cristae distinct, separated by narrow gap (Fig.

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3.3A, B). Postorbital cristae sharp, laterally expanded, fused with epigastric cristae and epibranchial teeth (Fig. 3.3A, B). Branchial regions slightly swollen (Fig. 3.3A). Cervical groove shallow, inconspicuous (Fig. 3.3A). Mesogastric region slightly convex (Fig. 3.3A). External orbital angle triangular (Fig. 3.3A). Epibranchial tooth small, granular, but distinct (Fig. 3.3A, B). Anterolateral margin distinctly cristate, lined with approximately 17-19 granules; lateral part bent inward (Fig. 3.3A). Posterolateral margin comparatively smooth, lined with oblique striae, converging towards posterior carapace margin (Fig. 3.3A). Orbits small; supraorbital and infraorbital margins cristate, lined with numerous inconspicuous granules (Fig. 3.3B). Sub-orbital and upper parts of pterygostomial regions covered with large rounded granules, sub-hepatic region lined with oblique striae (Fig. 3.3B). Epistome posterior margin narrow; median lobe sharply triangular, lateral margins almost straight (Fig. 3.3B). Third maxilliped with merus width about 1.2 × length; ischium width about 0.7 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus; exopod reaching to proximal one-third of merus, flagellum long; dorsomesial margin of ischium subauriculiform (Figs. 3.3B, 3.4D). Chelipeds (pereopod 1) unequal (Fig. 3.3A). Merus cross-section trigonal; margins crenulated (Fig. 3.3B). Carpus with sharp distomesial spine and spinule at base, dorsal surface with curved striae (Fig. 3.3A). Major cheliped palm length about 1.2 × height (Fig. 3.3A). Movable finger as long as fixed finger (Fig. 3.3A). Occlusal margin of fingers with rounded, blunt teeth; with very small gape when closed (Fig. 3.3A). Ambulatory legs (pereopods 2–5) slender, with dense short setae on dactylus, relatively sparse short setae on the propodus, carpus and merus (Fig. 3.3A). Pereopod 5 with propodus about 2 times as long as board, subequal to dactylus (Fig. 3.3A). Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused without obvious median suture (Figs. 3.3C, 3.10B). Male sterno-pleonal cavity reaching anteriorly to midlength of cheliped coxae; median longitudinal groove between sternites 7/8 deep (Fig. 3.3D). Pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 3.3D).

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Male pleon triangular, almost reaching anteriorly to level of posterior margin of cheliped coxae; pleonites 3–6 progressively broader longitudinally, lateral margins straight; somite 6 width about 2.3 × length; telson width about 1.4 × length, apex rounded (Fig. 3.3C).

Figure 3.4 Cantopotamon shangchuanense n. gen., n. sp., male (24.1 × 19.5 mm) (SYSBM 001427). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, left third maxilliped. Scale bar = 1.0 mm.

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G1 generally slender, tip of terminal segment reaching well beyond tubercle forming pleonal locking structure, exceeding sternite 4/5 suture (Fig. 3.3D); subterminal segment about 2.5 times as long as terminal segment, inner proximal section curved dorsally; terminal segment relatively short, sinistrally twisted (on left G1), curved inwards and pointing anteriorly, inner distal margin strongly convex, tip blunt (Figs. 3.3D, 3.4B, C, 3.9C, D). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment (Fig. 3.4A).

Size range. Male (n = 2) 21.0 × 17.2 to 24.1 × 19.5 mm; female (n = 2) 14.8 × 11.9 to 17.3 × 14.1 mm.

Remarks. Cantopotamon shangchuanense n. sp. is close to C. zhuhaiense n. sp., in overall external morphology, but can be separated by a unique combination of characters as shown in the Remarks section for C. zhuhaiense n. sp. and Table 3.2.

Colour in life. Mottled brown overall (Fig. 3.12B).

Ecology. This species is mainly aquatic, living under rocks in small hillstreams. The hillstream in which it was found drains directly to the sea, with Eriocheir sp. also inhabiting the lower reaches. The species of Eriocheir was not confirmed, but give the location, it was probably E. hepuensis (see Naser et al., 2012). No other potamids where found in the type locality.

Distribution. Shangchuan Island, Taishan, Guangdong.

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Table 3.2 Morphological differences among Cantopotamon zhuhaiense n. sp., C. shangchuanense n. sp., C. hengqinense n. sp. and C. yangxiense n. sp. Characters C. zhuhaiense C. shangchuanense C. hengqinense C. yangxiense Male pleonite 6 2.2 (Fig. 3.1C) 2.3 (Fig. 3.3C) 2.5 (Fig. 3.5C) 2 (Fig. 3.7C) (width/length) Male telson 1.2 (Fig. 3.1C) 1.4 (Fig. 3.3C) 1.6 (Fig. 3.5C) 1.4 (Fig. 3.7C) (width/length) not reaching reaches well reaches beyond tubercle reaches well beyond beyond tubercle tubercle forming forming pleonal tubercle forming forming pleonal G1 in situ pleonal locking locking pleonal locking locking structure (Fig. structure (Fig. structure (Fig. 3.3D) structure (Fig. 3.5D) 3.1D) 3.7D) G1 subterminal segment length 2.2 (Fig. 3.2B) 2.5 (Fig. 3.4B) 2.3 (Fig. 3.6B) 2.3 (Fig. 3.8B) relative to terminal segment broadly Inner margin of with blunt triangular convex (Figs. 3.4C, sinuous (Figs. G1 terminal projection (Figs. (Figs. 3.2C, 3.9C, D) 3.6C, 3.9E, F) segment 3.8C, 3.9G, H) 3.9A, B) cone-shaped horn-shaped blunt (Figs. 3.4C, blunt (Figs. Tip of G1 (Figs. 3.2C, (Figs. 3.6C, 3.9C, D) 3.8C, 3.9G, H) 3.9A, B) 3.9E, F)

Cantopotamon hengqinense n. sp. (Figs. 3.5–3.6, 3.9C, 3.10C, 3.11C, 3.12C)

Type material. Holotype: SYSBM 001558, male (19.9 × 16.0 mm), Dahengqin Mountain (22.11°N, 113.50°E), Hengqin Island, Zhuhai City, Guangdong, small hillstream, under rocks, coll. C. Huang, Feb, 2016. Paratypes: SYSBM 001559, 1 female (13.0 × 10.6 mm),

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same data as holotype. SYSBM 001560–001561, 2 males (15.5 × 12.4 mm, 13.2 × 10.7 mm), same data as holotype.

Other material examined. SYSBM 001640, 1 male (17.5 × 13.6 mm), Hengqin Island, Zhuhai City, Guangdong, small hillstream, under rocks, coll. C. Huang, Aug, 2017. SYSBM 001641-1644, 4 females (20.5 × 16.0 mm, 15.1 × 11.8 mm, 14.1 × 10.8 mm, 12.3 × 10.0 mm), same as above male.

Figure 3.5 Cantopotamon hengqinense n. gen., n. sp., male (19.9 × 16.0 mm) (SYSBM 001558). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view showing anterior thoracic sternum and pleon; D, ventral view showing sterno-pleonal cavity with right G1 in situ (left G1 removed).

Etymology. This species is named after the type locality, Hengqin Island (also known as Ilha de Montanha in Portuguese), Zhuhai City, Guangdong Province, China.

Diagnosis. Third maxilliped merus width about 1.1 × length; ischium width about 0.71 × length (Fig. 3.5B, 6D). Major cheliped palm length about 1.3 × height (Fig. 3.5A). Male

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pleonite 6 width about 2.5 × length; telson width about 1.6 × length (Fig. 3.5C). Tip of G1 terminal segment (in situ) reaching well beyond tubercle forming pleonal locking structure, exceeding sternal suture 4/5 (Fig. 3.5D); subterminal segment about 2.3 times as long as terminal segment, inner proximal section curved dorsally; terminal segment curved inwards and pointing anteriorly, outer proximal region swollen, with strongly convex margins, tip horn-shaped (Figs. 3.5D, 3.6B, C, 3.9E, F). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment (Fig. 3.6A).

Description of male. Carapace broader than long, regions not entirely distinct; dorsal surface slightly convex transversely and longitudinally; surface generally smooth with fused rugae on anterolateral region (Fig. 3.5A). Front slightly deflexed, margin slightly ridged on dorsal view (Fig. 3.5A). Epigastric cristae distinct, separated by narrow gap (Fig. 3.5A, B). Postorbital cristae sharp, laterally expanded, fused with epigastric cristae and epibranchial teeth (Fig. 3.5A, B). Branchial regions relatively flat (Fig. 3.5A). Cervical groove shallow, inconspicuous (Fig. 3.5A). Mesogastric region slightly convex (Fig. 3.5A). External orbital angle triangular (Fig. 3.5A). Epibranchial tooth small, granular, but distinct (Fig. 3.5A. B). Anterolateral margin distinctly cristate, lined with approximately 19-21 granules; lateral part bent inward (Fig. 3.5A). Posterolateral margin comparatively smooth, lined with oblique striae, converging towards posterior carapace margin (Fig. 3.5A). Orbits small; supraorbital and infraorbital margins cristate, lined with numerous inconspicuous (Fig. 3.5B). Sub-orbital and upper parts of pterygostomial regions covered with large rounded granules, sub-hepatic region lined with oblique striae (Fig. 3.5B). Epistome posterior margin narrow; median lobe sharply triangular, lateral margins almost straight (Fig. 3.5B). Third maxilliped merus width about 1.1 × length; ischium width about 0.7 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus; exopod reaching to proximal third of merus, flagellum long; dorsomesial margin of ischium subauriculiform (Fig. 3.5B, 3.6D). Chelipeds (pereopod 1) unequal (Fig. 3.5A). Merus cross-section trigonal; margins crenulated (Fig. 3.5B). Carpus with sharp distomesial spine and spinule at base, dorsal 69

surface with curved striae (Fig. 3.5A). Major cheliped palm length about 1.3 × height (Fig. 3.5A). Movable finger as long as fixed finger (Fig. 3.5A). Occlusal margin of fingers with rounded, blunt teeth; with very slight gape when closed (Fig. 3.5A). Ambulatory legs (pereopods 2–5) slender; dactylus with dense short setae; propodus, carpus and merus with relatively sparse short setae (Fig. 3.5A). Pereopod 5 with propodus length about 2 × width, subequal to dactylus (Fig. 3.5A).

Figure 3.6 Cantopotamon hengqinense n. gen., n. sp., male holotype (19.9 × 16.0 mm) (SYSBM 001558). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, left third maxilliped. Scale bar = 1.0 mm.

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Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused without obvious median suture (Figs. 3.5C, 3.10C). Male sterno-pleonal cavity reaching anteriorly to midlength of chelipeds coxae; median longitudinal groove between sternites 7, 8 deep (Fig. 3.5D). Pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 3.5D). Male pleon triangular, almost reaching anteriorly to level of posterior margin of cheliped coxae; pleonites 3–6 progressively broader longitudinally, lateral margins straight; somite 6 width about 2.5 × length; telson width about 1.6 × length, apex rounded (Fig. 3.5C). G1 generally slender, tip of terminal segment reaches well beyond tubercle forming pleonal locking structure in situ, exceeding sternal suture 4/5 (Fig. 3.5D); subterminal segment about 2.3 times as long as terminal segment, inner proximal section curved dorsally; terminal segment relatively short, sinistrally twisted on the left G1, curved inwards and pointing anteriorly, outer proximal region swollen, with strongly convex margins, tip horn-shaped (Figs. 3.5D, 3.6B, C, 3.9E, F). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment (Fig. 3.6A).

Size range. Male (n = 4) 13.2 × 10.7 to 19.9 × 16.0 mm; female (n = 5) 12.3 × 10.0 to 20.5 × 16.0 mm.

Remarks. Cantopotamon hengqinense n. sp. is closest to C. zhuhaiense n. sp., in overall external morphology, but can be separated by a unique combination of characters as outlined under the Remarks section of C. zhuhaiense n. sp. and Table 3.2.

Colour in life. Mottled brown overall (Fig. 3.12C).

Ecology. This species is mainly aquatic, living under rocks in small hillstreams.

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Conservation status. Currently, only 8% of Chinese freshwater crabs are assessed as threatened according to IUCN criteria, though the true percentage is likely much higher due to the high proportion of data deficient species (Cumberlidge, 2016). Situated at the south of Zhuhai City and adjacent to Macau, Hengqin Island is the largest of the 146 islands in Zhuhai. It was formerly composed of two islands: Xiaohengqin and Dahengqin, but was joined as one through land reclamation. It has seen rapid economic development in recent years with a significant degree of urbanization. The human population of the island was less than 8,000 in 2008, but, this number is expected to rise to 280,000 by 2020. Dahengqin Mountain is situated at the far south of Hengqin Island and covers an area of around 25 km2. The mountain is isolated, surrounded by sea to the east, west and south, and by residential areas to the north. Surveys conducted around the region indicate that C. hengqinense likely has an area of occupancy of only around 15 km2, being only known from three hillstreams in close proximity on Dahengqin Mountain. This extremely restricted distribution makes this species highly vulnerable to habitat degradation and destruction. According to the official development plans for Hengqin Island, an ecological park is to be built for tourism on Dahengqin Mountain. Although the plan does state conservation as a priority, the altering of the original habitat coupled by the significant increase in human activity in the area will no doubt impact the habitat. Given the limited area of occurrence and expected rise in the human population of the island, the area of occupancy and quality of the habitat of C. hengqinense can be reasonably projected to decline. Therefore, the conservation status of C. hengqinense under IUCN Red List criteria corresponds to Endangered B2(a)(b).

Distribution. Hengqin Island, Zhuhai, Guangdong.

Cantopotamon yangxiense n. sp. (Figs. 3.7–3.8, 3.9D, 3.10D, 3.11D, 3.12D)

Type material. Holotype: SYSBM 001562, male (19.3 × 16.0 mm), E'huang Ridge (21.82°N, 111.44°E), Yangxi, Yangjiang City, Guangdong, small hillstreams, under rocks, coll. C. Huang, May, 2015. Paratypes: SYSBM 001563, 1 female (18.5 × 14.9 mm), same 72

data as holotype. ZRC, 1 male (17.0 × 14.1 mm), same data as holotype. ZRC, 1 female (19.8 × 16.0 mm), same data as holotype.

Figure 3.7 Cantopotamon yangxiense n. gen., n. sp., male holotype (19.3 × 16.0 mm) (SYSBM 001562). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view showing anterior thoracic sternum and pleon; D, ventral view showing sterno-pleonal cavity with right G1 in situ (left G1 removed).

Other material examined. 1 male (20.5 × 17.0 mm) (SYSBM 001564), same data as holotype. 2 females (18.3 × 15.1 mm, 16.9 × 13.8 mm) (SYSBM 001565–001566), same data as holotype. 2 males (16.7 × 13.9 mm, 16.4 × 13.4 mm) (SYSBM 001567–001568), Longgao Mountain (21.67°N, 111.67°E), Yangxi, Yangjiang City, Guangdong, small hillstreams, under rocks, coll. C. Huang, May, 2015. 2 females (15.4 × 12.4 mm, 13.6 × 11.4 mm) (SYSBM 001569–001570), same data as above.

Etymology. This species is named after the type locality Yangxi, Yangjiang, Guangdong Province.

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Diagnosis. Third maxilliped with merus width about 1.1 × length; ischium width about 0.67 × length (Figs. 3.7B, 3.8D). Major cheliped palm length about 1.3 × height (Fig. 3.7A). Male pleonite 6 width about 2 × length; telson width about 1.4 × length, apex rounded (Fig. 3.7C). Tip of G1 terminal segment reaches well beyond tubercle forming pleonal locking structure in situ, exceeding sternal suture 4/5 (Fig. 3.7D); subterminal segment about 2.3 times as long as terminal segment, inner proximal section curved dorsally; terminal segment inner margin with sub-distal blunt projection, tip blunt (Figs. 3.7D, 3.8B, C, 3.9G, H). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment (Fig. 3.8A).

Description of male. Carapace broader than long, regions not entirely distinct; dorsal surface slightly convex transversely and longitudinally; surface generally smooth with fused rugae on anterolateral region (Fig. 3.7A). Front slightly deflexed, margin slightly ridged on dorsal view (Fig. 3.7A). Epigastric cristae distinct, separated by narrow gap (Fig. 3.7A, B). Postorbital cristae sharp, laterally expanded, fused with epigastric cristae and epibranchial teeth (Fig. 3.7A, B). Branchial regions relatively flat (Fig. 3.7A). Cervical groove shallow, inconspicuous (Fig. 3.7A). Mesogastric region slightly convex (Fig. 3.7A). External orbital angle triangular (Fig. 3.7A). Epibranchial tooth small, granular, but distinct (Fig. 3.7A, B). Anterolateral margin distinctly cristate, lined with approximately 20-24 granules; lateral part bent inward (Fig. 3.7A). Posterolateral margin comparatively smooth, lined with oblique striae, converging towards posterior carapace margin (Fig. 3.7A). Orbits small; supraorbital and infraorbital margins cristate, lined with numerous inconspicuous granules (Fig. 3.7B). Sub-orbital and upper parts of pterygostomial regions covered with large rounded granules, sub-hepatic region lined with oblique striae (Fig. 3.7B). Epistome posterior margin narrow; median lobe sharply triangular, lateral margins almost straight (Fig. 3.7B). Third maxilliped with merus width about 1.1 × length; ischium width about 0.67 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus; exopod reaching to proximal third of merus, flagellum long; dorsomesial 74

margin of ischium subauriculiform (Figs. 3.7B, 3.8D). Posterior margin of epistome narrow; median lobe sharply triangular, lateral margins almost straight (Fig. 3.7B).

Figure 3.8 Cantopotamon yangxiense n. gen., n. sp., male holotype (19.3 × 16.0 mm) (SYSBM 001562). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, left third maxilliped. Scale bar = 1.0 mm.

Chelipeds (pereopod 1) unequal (Fig. 3.7A). Merus cross-section trigonal; margins crenulated (Fig. 3.7B). Carpus with sharp distomesial spine and spinule at base, dorsal surface with curved striae (Fig. 3.7A). Major cheliped palm length about 1.3 × height (Fig.

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3.7A). Movable finger as long as fixed finger (Fig. 3.7A). Occlusal margin of fingers with rounded, blunt teeth; with small gape when closed (Fig. 3.7A).

Figure 3.9 G1 terminal segment. A, Cantopotamon zhuhaiense n. gen., n. sp., male holotype, ventral view; B, C. zhuhaiense, male holotype, dorsal view; C, C. shangchuanense n. gen., n. sp., male holotype, ventral view; D, C. shangchuanense, male holotype, dorsal view; E, C. hengqinense n. gen., n. sp., male holotype, ventral view; F, C. hengqinense, male holotype, dorsal view; G, C. yangxiense n. gen., n. sp., male holotype, ventral view; H, C. yangxiense, male holotype, dorsal view. Scale bar = 0.5 mm.

Ambulatory legs (pereopods 2–5) slender; dactylus with dense short setae; propodus, carpus and merus with relatively sparse, short setae (Fig. 3.7A). Pereopod 5 propodus length about 1.9 × width, subequal to dactylus (Fig. 3.7A). Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused, without obvious median suture (Figs. 3.7C, 3.10D). Male sterno-pleonal cavity reaching anteriorly to level of midlength of cheliped coxae; median

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longitudinal groove between sternites 7/8 deep (Fig. 3.7D). Pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 3.7D). Male pleon triangular, almost reaching anteriorly to level of posterior margins of cheliped coxae; pleonaites 3–6 progressively broader longitudinally, lateral margins straight; somite 6 width about 2 × length; telson width about 1.4 × length, apex rounded (Fig. 3.7C).

Figure 3.10 Male thoracic sternum. A, Cantopotamon zhuhaiense n. gen., n. sp., male holotype (29.1 × 22.9 mm) (SYSBM 001038); B, C. shangchuanense n. gen., n. sp., male holotype (24.1 × 19.5 mm) (SYSBM 001427); C, C. hengqinense n. gen., n. sp., male holotype (19.9 × 16.0 mm) (SYSBM 001558); D, C. yangxiense n. gen., n. sp., male holotype (19.3 × 16.0 mm) (SYSBM 001562).

G1 generally slender and straight, tip of terminal segment reaches well beyond tubercle forming pleonal locking structure in situ, exceeding sternal suture 4/ 5 (Fig. 3.7D); subterminal segment about 2.3 times as long as terminal segment, inner proximal section curved dorsally; terminal segment relatively short, sinistrally twisted on the left G1, pointing anteriorly, inner margin with sub-distal blunt projection, tip blunt (Figs. 3.7D,

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3.8B, C, 3.9G, H). G2 basal segment subovate, about 2.6 times length of flagelliform distal segment (Fig. 3.8A).

Figure 3.11 Female vulvae. A, Cantopotamon zhuhaiense n. gen., n. sp., female paratype (24.6 × 20.0 mm) (SYSBM 001440); B, C. shangchuanense n. gen., n. sp., female paratype (17.3 × 14.1 mm) (SYSBM 001429); C, C. hengqinense n. gen., n. sp., female paratype (13.0 × 10.6 mm) (SYSBM 001559); D, C. yangxiense n. gen., n. sp., female paratype (18.5 × 14.9 mm) (SYSBM 001563).

Size range. Male (n = 5) 16.4 × 13.4 to 20.5 × 17.0 mm; female (n = 6) 13.6 × 11.4 to 19.8 × 16.0 mm.

Remarks. Cantopotamon yangxiense n. sp. is closest to C. zhuhaiense n. sp., in overall external morphology, but can be separated by its longer G1 that reaches in situ well beyond the tubercle forming the pleonal locking structure (Fig. 3.7D) [versus not reaching in C. zhuhaiense n. sp. (Fig. 3.1D)], the blunt projection on the inner margin of the G1 terminal segment (Fig. 3.8C) [versus broadly triangular margin in C. zhuhaiense n. sp. (Fig. 3.2C)], and other characters as shown in Table 3.2.

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Colour in life. Generally mottled brown in life (Fig. 3.12D). Ecology. This species is mainly aquatic, living under rocks in small hillstreams.

Distribution. Yangxi, Yangjiang, Guangdong.

Figure 3.12 Colour in life. A, Cantopotamon zhuhaiense n. gen., n. sp., not collected; B, C. shangchuanense n. gen., n. sp., male paratype (21.0 × 17.2 mm) (SYSBM 001428); C, C. hengqinense n. gen., n. sp., male holotype (19.9 × 16.0 mm) (SYSBM 001558); D, C. yangxiense n. gen., n. sp., female paratype (18.5 × 14.9 mm) (SYSBM 001563).

Phylogenetic relationships

In the present phylogenetic analyses, 65 species from 49 potamid genera were included. A 502 bp segment, excluding the variable regions, of the 16S rDNA was amplified and aligned. The BI and ML analyses based on16S sequences resulted in similar topologies (Fig. 3.13). Monophyly of Cantopotamon is well supported as part of the “China-East Asia Islands” clade (Shih et al., 2009), although its position among these genera is ambiguous based on present data. Combined analysis of the 16S and COI data also supports the 79

validity of the four new species (Fig. 3.14), with two pairs of sister species, C. zhuhaiense and C. hengqinense, as well as C. shangchuanense and C. yangxiense. Minimum interspecific K2P and p-distance divergences in COI between the four new species is at 7.73% and 7.29% respectively, with bp difference being 48 bp, for C. zhuhaiense and C. hengqinense.

Discussion and conclusions

The distances estimated between K2P and the p-distance (recommended in Srivathsana and Meier, 2011) are close (see above), so the K2P distance was chosen to allow a consistent comparison with most barcoding studies. Minimum interspecific K2P divergence within Cantopotamon (7.73%) exceeds that of most other species of freshwater crabs: 6.89% between Geothelphusa albogilva Shy, Ng & Yu, 1994 and G. tawu Shy, Ng & Yu, 1994; 5.54% between G. marginata Naruse, Shokita & Shy, 2004 & G. fulva Naruse, Shokita & Shy, 2004; 6.22% between Tiwaripotamon pluviosum Do, Shih & Huang, 2016 and T. pingguoense Dai & Naiyanetr, 1994; 3% between Sayamia germani (Rathbun, 1902) and S. sexpunctata (Lanchester, 1906) (reviewed by Chu et al., 2015; Do et al., 2016). Both island species C. hengqinense and C. shangchuanense are more closely related to their respective adjacent mainland species than they are to each other, suggesting vicariant speciation has likely occurred. This is likely as both Shangchuan Island and Hengqin Island are inshore islands less than 10 km away from the mainland. There is also the possibility that the two island species dispersed from the mainland and colonized the islands after the islands were cut off from the mainland. Application of both morphological and molecular evidence supports recognition of the new genus Cantopotamon, comprising four new species. Cantopotamon is most closely related to other genera from South China as part of the “China-East Asia Islands” clade (Shih et al., 2009), although present data do not allow robust determination of its phylogenetic position among these genera; further research using other DNA markers will be required. Future collections on the other islands of southern Guangdong may reveal even more island-bound species of Cantopotamon. Their phylogenetic relations may provide us some insights as to the processes that formed these islands. 80

Figure 3.13 Bayesian inference (BI) tree of 16S rDNA for the subfamily Potamiscinae, with the sequences and accession numbers in Shih et al. (2009), as well as some additional species (see Material and methods). Cantopotamon is highlighted in gray. Bayesian (BI) posterior probabilites and maximum likelihood (ML) bootstrap proportions are indicated at nodes. Only values > 50% are shown.

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Figure 3.14 Bayesian inference (BI) tree of the combined 16S rDNA and COI for the four species of Cantopotamon. Bayesian (BI) posterior probabilites and maximum likelihood (ML) bootstrap proportions are indicated at nodes. Only values > 50% are shown.

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Chapter 4.

Revision of Yarepotamon Dai & Türkay, 1997 (Brachyura: Potamidae), freshwater crabs endemic to southern China, with descriptions of two new genera and four new species

Chao Huang Journal of Crustacean Biology, 38 (2), 173–189

Abstract

The systematics of the poorly studied potamid genus Yarepotamon Dai & Türkay, 1997 is reviewed based on morphological and molecular data. The species in this genus are assigned to three separate genera: Yarepotamon s. s., Qianguimon n. gen., and Eurusamon n. gen. Yarepotamon is restricted to Y. breviflagellum Dai & Türkay, 1997, Y. gracilipa (Dai, Song, Li & Liang, 1980), and two new species. Yuexipotamon arcophallus Huang, Mao & Huang, 2014 is revealed to be a junior synonym of Yarepotamon breviflagellum. Consequently, Yuexipotamon Huang, Mao & Huang, 2014 is also synonymized with Yarepotamon. A new genus, Qianguimon n. gen., is proposed for the clade that includes Yarepotamon aflagellum (Dai, Song, Li & Liang, 1980) and two new species described herein. A new monotypic genus, Eurusamon n. gen., is proposed for Yarepotamon guangdongense Dai & Türkay, 1997. Crabs of these three genera differ in the combination of character (third maxilliped, male pleon, male first gonopod, and vulvae) and adult size. Genetic data derived from the mitochondrial 16S rDNA support the monophyly of the six new taxa.

Key words: 16S rDNA, hillstreams, new taxa, phylogeny, systematics

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Introduction

Dai & Türkay (1997), in their revision of the freshwater crabs of south China, erected Yarepotamon Dai & Türkay, 1997 to include Malayopotamon gracillipa Dai, Song, Li & Liang, 1980, Isolapotamon aflagellum Dai, Song, Li & Liang, 1980, Yarepotamon breviflagellum Dai & Türkay, 1997, and Yarepotamon guangdongense Dai & Türkay, 1997. Recent surveys conducted in southern China have led to the discovery of new species of Yarepotamon and other allied taxa. Yarepotamon was found to be polyphyletic and consist of three distinct clades. Crabs of these three clades differ in their ecology, morphology, and are genetically distinct according to molecular data derived from the mitochondrial 16S rDNA. Yarepotamon is thus revised herein, resulting in the description of two new genera and four new species.

Materials and methods

Collection and treatment of samples Specimens were collected by hand from localities in southern China and preserved in 75% ethanol. Specimens are deposited in the Sun Yat-sen Museum of Biology, Sun Yat-sen University, Guangzhou, China (SYSBM); Australian Museum, Sydney, (AM); and Zoology Collection of the National Chung Hsing University, Taichung, Taiwan (NCHUZOOL). Measurements, in millimeters, are of the carapace width and length, respectively. Other abbreviations are as follows: G1, male first gonopod; G2, male second gonopod. The terminology used mainly follows that of Dai (1999).

DNA sequencing and analysis Genomic DNA was isolated from the muscle tissue of legs (males) or pleopods (females) using the universal DNA purification kit (Tiangen, Beijing, China). A region of ~550 basepairs (bp) of the 5'-end of the 16S gene was selected for amplification with polymerase chain reaction (PCR) using the primers 1471 and 1472 (Crandall & Fitzpatrick, 1996). The PCR conditions for the above primers were denaturation for 45 s at 94 °C, annealing for 40 s at 45 °C, and extension for 120 s at 72 °C (35 cycles), followed by extension for 10 min at

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72 °C. Sequences were obtained by automated sequencing (Applied Biosystems, Foster, America). Cantopotamon Huang, Ahyong & Shih, 2017, is morphologically similar and has an overlapping distribution with Yarepotamon s. s., therefore the 16S sequence of Cantopotamon zhuhaiense Huang, Ahyong & Shih, 2017, was included to study its relationship with the taxa studied herein. Shih et al. (2009) indicated that Yarepotamon gracilipa (Dai, Song, Li & Liang, 1980) belongs to the China-East Asia Islands clade (Shih et al., 2009). A preliminary phylogenetic analysis (unpublished data) of the species in this study along with species from other genera from the China-East Asia Islands clade (Sinolapotamon Tai & Sung, 1975, Minpotamon Dai & Türkay, 1997, Chinapotamon Dai & Naiyanetr, 1994, Huananpotamon Dai & Ng, 1994, Nanhaipotamon Bott, 1968, and Geothelphusa Stimpson, 1858) and a species that also occurs in the area but is not in the above mentioned clade (Longpotamon Shih, Huang & Ng, 2016) shows that Yarepotamon Dai & Türkay, 1997, Qianguimon n. gen. and Eurusamon n. gen. do not cluster with other genera. Due to the highly unresolved relations between the compared genera, however, only one species of Nanhaipotamon was been selected to root the analysis. Sequences are deposited in GenBank (accession numbers in Table 4.1). The sequences were aligned using ClustalW (vers. 2.1; Thompson et al., 1994) after verification with the complementary strand. Variable regions in loop regions of the 16S that could not be aligned adequately for phylogenetic analyses are excluded (Shih et al., 2009). The best-fitting model for sequence evolution (SYM + G) was determined by MrModeltest (ver. 2.3; Nylander 2004) selected by the Akaike information criterion (AIC). Bayesian inference (BI) analysis was performed with MrBayes (v. 3.2.4; Ronquist & Huelsenbeck, 2003), using the obtained best model. The search was run with four chains for 10 million generations and four independent runs, with trees sampled every 1,000 generations. The convergence of chains was determined by the effective sample size (ESS) in Tracer (v. 1.5; Rambaut & Drummond, 2009) and after inspection of the likelihoods of the sampled trees, the first 25% were discarded as burn-in. The maximum parsimony (MP) analysis was conducted in PAUP4 (Swofford, 2002) with a heuristic search (500 random addition sequence replicates using tree bisection-reconnection (TBR) branch-swapping). Gaps were treated as missing, and all characters equally weighted. Topological robustness was 85

Table 4.1 The 16S rDNA haplotypes and localities of the nine species and the outgroup in the study. The number in brackets after each locality corresponds to the collection localities shown in Figure 4.1. Museum catalogue DDBJ/GenBank Species Locality no. of sequenced access. no. specimen Heishiding Nature Reserve, Yarepotamon Fengkai, Zhaoqing, – – breviflagellum Guangdong [1] Zhijiliao, Huaiji, Zhaoqing, – – Guangdong [2] Chexia Village, Guangning, – – Zhaoqing, Guangdong [3] Gushui, Guangning, Zhaoqing, SYSBM 001442 MG709236 Guangdong [4] Duikeng, Guangning, – – Zhaoqing, Guangdong [5] Yunxi Village, Guangning, – – Zhaoqing, Guangdong [6]

Yarepotamon Jinxiu, Laibin, Guangxi [11] – – gracilipa

Zhaoping, Hezhou, Guangxi ZRC AB428452 [12] Yarepotamon Lutian Village, Foshan City, – – meridianum n. sp. Guangdong [7]

Yunyong Forest Park, Foshan – – City, Guangdong [8]

Zaomu Mountain, Foshan SYSBM 001581 MG709237 City, Guangdong [9]

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Daxikeng Reservoir, Jiangmen – – City, Guangdong [10]

Yarepotamon fossor Babu, Hezhou, Guangxi [13] SYSBM 001417 MG709238 n. sp. Qianguimon Zhaoping, Hezhou, Guangxi – – aflagellum n. comb. [14] Mengshan, Wuzhou, Guangxi SYSBM 001404 MG709239 [15] Chengzhong, Liuzhou, – – Guangxi [16]

Qianguimon Leishan, Qiandongnan Miao elongatum n. gen., n. and Dong Autonomous SYSBM 001424 MG709240 sp. Prefecture, Guizhou [18]

Qianguimon Yanghe, Liuzhou, Guangxi splendidum n. gen., SYSBM 001598 MG709241 [17] n. sp. Eurusamon Tongledashan Nature Reserve, guangdongense n. SYSBM 001408 MG709242 Yunfu, Guangdong [19] comb.

Datianding, Xinyi, Maoming, – – Guangdong [20]

Sihe, Xinyi, Maoming, – – Guangdong [21]

Cantopotamon Zhuhai, Guangdong SYSBM 001439 LC342045 zhuhaiense

Nanhaipotamon Hong Kong ZRC AB212869 hongkongense

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Figure 4.1 Localities of the sampling sites of materials examined. Numbers correspond to the localities in Table 4.1. assessed using bootstrap analysis (2,000 pseudoreplicates). Nucleotide composition, variable and parsimony informative positions, and the pairwise Kimura 2-parameter (K2P) distances (Kimura, 1980) were all calculated with the aid of MEGA6 (Tamura et al., 2013).

Systematics

Family Potamidae Ortmann, 1896 Subfamily Potamiscinae Bott, 1970 Genus Yarepotamon Dai & Türkay, 1997 (Figs. 4.2–4.7, 4.14A, 4.15A–D, 4.16A, B, 4.17A, B) Yarepotamon Dai & Türkay, 1997: 246, pl. 2 (2), fig. 6. Yuexipotamon Huang, Mao & Huang, 2014: 456, figs. 1–5.

Type species. Yarepotamon breviflagellum Dai & Türkay, 1997, by original designation. 88

Species included. Y. breviflagellum Dai & Türkay, 1997, Y. gracilipa (Dai, Song, Li & Liang, 1980), Y. meridianum n. sp., and Y. fossor n. sp.

Diagnosis. Small size (carapace width up to 30 mm). Carapace broader than long, dorsal surface slightly convex, branchial regions relatively flat (Fig. 4.1A); postorbital, epigastric cristae visible, not confluent (Fig. 4.1A); external orbital angle bluntly triangular, separated from anterolateral margin by gap (Fig. 4.1A, B). Median lobe of epistome posterior margin broadly triangular (Fig. 4.1B). Third maxilliped ischium relatively broad; exopod reaching beyond anterior edge of ischium, flagellum short or absent (Dai & Türkay, 1997: fig. 6 (1)). Male pleon triangular; somite 3 relatively wide (Fig. 4.1C). G1 generally slender (Figs. 4.1D, 4.15A). G2 basal segment subovate (Dai & Türkay, 1997: fig. 6 (6)). Vulvae medium-size, reaching proximal three-quarters width of sternite 6, lateral margin with narrow rim (Dai & Türkay, 1997: fig. 6 (7)).

Distribution. Guangxi and Guangdong provinces, southern China.

Remarks. The type species of Yarepotamon Dai & Türkay, 1997, incorrectly listed by Dai (1999) as Y. gracilipa (Dai, Song, Li & Liang, 1980), is Y. breviflagellum Dai & Türkay, 1997 as originally designated by Dai & Türkay (1997). The genus was not well defined. “Terminal segment of male first pleopod with sub-distal lobe, with or without projection” is incorrect as Y. gracilipa lacks a sub-distal lobe. Yarepotamon guangdongense Dai & Türkay, 1997 is herein transferred to Eurusamon n. gen., whereas Y. aflagellum (Dai, Song, Li & Liang, 1980) is transferred to Qianguimon n. gen. Yarepotamon Dai & Türkay, 1997 is now restricted to four species: Y. breviflagellum, Y. gracilipa, Y. meridianum n. sp. and Y. fossor n. sp. The diagnosis for Yarepotamon s.s. includes characters that were previously neglected such as the male pleon, size of the vulvae and body size, all of which set them apart from Qianguimon n. gen. and Eurusamon n. gen. Although quite similar externally, Yarepotamon can be separated from Qianguimon n. gen. by its generally slender G1 (Fig. 4.15A–D) (slender boot-shaped in Qianguimon n. gen.; Fig. 4.15E–G), narrow rim of 89

vulvae lateral margin (Fig. 4.16A, B) (wide in Qianguimon n. gen.; Fig. 4.16C–E), and smaller size (carapace width up to 30 mm) (up to 40 mm in Qianguimon n. gen.). Yarepotamon can be separated from Eurusamon n. gen. by the short to absent flagellum of the third maxilliped exopod (Figs. 4.5D, 4.7D) (long in Eurusamon n. gen. (Dai & Türkay, 1997: fig. 8 (1)), relatively wide male pleonal somite 3 (Figs. 4.2C, 4.3C, 4.4C, 4.6C) (narrow in Eurusamon n. gen.; Fig. 4.13C), larger female vulvae reaching proximal three- quarters width of sternite 6 (Fig. 4.16A, B) (smaller female vulvae reaching proximal three- fifths in Eurusamon n. gen.; Fig. 4.16F), and much smaller size (carapace width up to 30 mm) (up to 60 mm in Eurusamon n. gen.). These differences are listed in Table 4.2. Yuexipotamon Huang, Mao & Huang, 2014 is synonymized with Yarepotamon Dai & Türkay, 1997 (see remarks for Yarepotamon breviflagellum Dai & Türkay, 1997 for details).

Key to species of Yarepotamon 1. Carapace relatively high, branchial regions slightly swollen, G1 with blunt tip (Figs. 4.6B, 4.7C) ………………………………………………………… Y. fossor n. sp. - Carapace relatively low, branchial regions relatively flat, G1 with pointed tip (Figs. 4.2B, 4.3B, 4.4B, 4.15A–C) ……………………………………………………… 2 2. Carapace relatively wide in adults (width 1.3 × length), G1 pointing outwards ………………………………………………………………… Y. meridianum n. sp. - Carapace relatively narrow in adults (width 1.2 × length), G1 pointing anteriorly or inwards …………………………………………………………………………… 3 3. G1 pointing anteriorly, inner margin of terminal segment sinuous, sometimes with sub-distal projection ………………………... Y. breviflagellum Dai & Türkay, 1997 4. G1 pointing inwards, inner margin of terminal segment concave, without sub-distal projection ……………………………… Y. gracilipa (Dai, Song, Li & Liang, 1980)

Yarepotamon breviflagellum Dai & Türkay, 1997 (Figs. 4.2, 4.15A)

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Yarepotamon breviflagellum Dai & Türkay, 1997: 246, pl. 2 (2), fig. 6. — Dai, 1999: 400, pl. 27 (5), fig. 214. Yuexipotamon arcophallus Huang, Mao & Huang, 2014: 456, figs. 1–5.

Type material. CB 01370, 1 male paratype (23.1 × 19.5 mm), Gushui, Guangning, Zhaoqing, Guangdong province, 1984.

Figure 4.2 Yarepotamon breviflagellum Dai & Türkay, 1997, male (14.2 × 12.0 mm) (SYSBM 001442). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with right G1 in situ (left G1 removed).

Additional material. Gushui, Guangning, Zhaoqing, Guangdong province: SYSBM 001442–001443, 2 males (14.2 × 12.0 mm, 12.2 × 10.4 mm), shallow creek, under rocks, coll. C. Huang, November 2014. Heishiding Nature Reserve, Fengkai, Zhaoqing, Guangdong province: SYSBM 001005, 1 male (21.7 × 18.1 mm), China, shallow creek, among detritus, coll. J.Y. Li, May 2012. SYSBM 001007–001009, 3 males (19.6 × 17.2 mm, 21.6 × 18.1 mm, 18.6 × 15.1 mm), water-logged forest floor, mud burrow, coll. C.

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Huang, March 2013. SYSBM 001006, 1 female (16.7 × 12.9 mm), same data as above. Zhijiliao, Huaiji, Zhaoqing, Guangdong province: SYSBM 001627–001628, 2 males (15.1 × 12.0 mm, 12.8 × 10.4 mm), water-logged forest floor, mud burrow, coll. C. Huang, August 2017. SYSBM 001629, 1 female (17.0 × 13.1 mm), same data as above. Chexia Village, Guangning, Zhaoqing, Guangdong province: SYSBM 001630–001632, 3 males (17.0 × 13.9 mm, 14.0 × 11.3 mm, 13.9 × 10.8 mm), water-logged forest floor, mud burrow, coll. C. Huang, August 2017. SYSBM 001633, 1 female (13.6 × 10.8 mm), same data as above. Duikeng, Guangning, Zhaoqing, Guangdong province: SYSBM 001634–1635, 2 males (14.6 × 12.1 mm, 14.2 × 11.7 mm), shallow creek, under rocks, coll. C. Huang, August 2017. SYSBM 001636–001637, 2 females (19.2 × 14.5 mm, 17.2 × 13.9 mm), same data as above. Yunxi Village, Guangning, Zhaoqing, Guangdong province: SYSBM 001574–001576, 3 males (17.6 × 14.2 mm, 15.2 × 12.8 mm, 11.5 × 9.0 mm), water-logged forest floor, mud burrow, coll. C. Huang, August 2017. SYSBM 001577, 1 female (19.1 × 14.8 mm), same data as above.

Colour in life. Generally brown to dark-brown in life.

Habitat. Most specimens were collected from shallow burrows on wet forest floors, but a few were found hiding under rocks near the banks of hillstreams. Yarepotamon breviflagellum shares a habitat similar to that of small individuals of Chinapotamon depressum (Dai, Song, Li & Liang, 1980) and are likely outcompeted in deeper areas of hillstreams (cf. Huang et al., 2014). According to Dai (1999), this species can be found under rocks or amongst vegetation in small hillstreams.

Distribution. Zhaoqing, Guangdong province: Guangning, Fengkai Huaiji.

Remarks. Yuexipotamon arcophallus Huang, Mao & Huang, 2014, was placed in a genus of its own mainly due to its distinct G1, having a sharp and prominent sub-distal projection, which is not seen in any known species of Yarepotamon. Huang et al. (2014) failed to observe its other similarities with Yarepotamon, and only compared it with species of 92

Huananpotamon. Although the G1 is useful for distinguishing between potamid genera in most cases, it can be deceiving when there is unexpectedly too much or too little morphological variation of the G1 within a genus. A comprehensive morphological revision has found that apart from the unique G1, all other characters of Yuexipotamon arcophallus fall within Yarepotamon, and are identical with Y. breviflagellum. A study of a larger series of specimens from additional field collections have revealed that the presence or absence of the sub-distal projection of the G1 varies intraspecifically. Specimens collected by the author from Heishiding Natural Reserve (corresponding to Yuexipotamon arcophallus) always have a prominent projection (Huang et al., 2014: fig. 5), whereas those collected from Guangning County (type locality of Yarepotamon breviflagellum) always lack the projection (Fig. 4.15A), having a sinuous inner margin of the G1 terminal segment at most. The paratype examined herein is very similar to the specimens collected from Guangning in this aspect. At intermediate localities, the subdistal projection is variable and likewise intermediate. The G1 of Yarepotamon breviflagellum illustrated in Dai & Türkay (1997) is intermediate, with a small sub-distal bump (Dai & Türkay, 1997: fig. 6 (5)), although the specimen was collected from Guangning County. The molecular results also suggest that Yuexipotamon arcophallus is conspecific with Yarepotamon breviflagellum (see below). In light of these new data, Yuexipotamon arcophallus Huang, Mao & Huang, 2014 is herein synonymized with Yarepotamon breviflagellum Dai & Türkay, 1997.

Yarepotamon gracilipa (Dai, Song, Li & Liang, 1980) (Figs. 4.3, 4.15B) Malayopotamon gracilipa Dai, Song, Li & Liang, 1980: 327, fig. 5. Yarepotamon gracilipa — Dai & Türkay, 1997: 246, pl. 2 (3), fig. 7. — Dai, 1999: 400, pl. 27 (3), fig. 212.

Type material. CB 01372, male (holotype) (19.9 × 16.8 mm), Zhaoping, Hezhou, Guangxi province, 1977. CB 01373, 1 male (paratype) (22.5 × 18.3 mm), same data as above.

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Figure 4.3 Yarepotamon gracilipa (Dai, Song, Li & Liang, 1980), male (22.5 × 18.3 mm) (CB 01373). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with left G1 in situ (right G1 removed).

Additional material. Jinxiu, Laibin, Guangxi province: SYSBM 001549, 1 male (14.1 × 11.1 mm), coll. Unknown collector, June 2015.

Colour in life. Unknown.

Habitat. This is a small-size species that can be found under rocks in hillstreams at an altitude of approximately 100 m (Dai, 1999). No live specimens where observed.

Distribution. Guangxi province, southern China: Zhaoping, Hezhou; Jinxiu, Laibin.

Remarks. The morphology of the types agrees well with the description in Dai & Türkay, 1997. The examined specimen from Jinxiu, Laibin is a sub-adult with its G1 differing

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slightly from the types by being straighter and the opening at the tip being more visible. Comparisons with additional collections are required to see whether this specimen represents a new species or it is one of the variations of Y. gracilipa.

Table 4.2 Morphological differences among species of Yarepotamon, Qianguimon n. gen., and Eurusamon n. gen. Character Yarepotman Qianguimon n. gen. Eurusamon n. gen. Flagellum of Short to absent (cf. Dai & exopod of Short to absent (Dai & Long (cf. Dai & Türkay, Türkay, 1997: fig. 5 (1); third Türkay, 1997: fig. 6 (1)) 1997: fig. 8 (1)) Figs. 4.10D, 4.12D) maxilliped Male pleonal Relatively wide (Figs. Relatively wide (Figs. Relatively narrow (Fig. somite 3 4.1C, 4.3C, 4.6C) 4.8C, 4.9C, 4.11C) 4.13C) Generally slender (Fig. Slender, boot-shaped Generally slender (Fig. G1 4.15A–D) (Fig. 4.15E–G) 4.15H) Vulvae Medium-sized, reaching Medium-sized, reaching Relatively small, proximal three-quarters proximal three-quarters reaching proximal three- width of sternite 6, lateral width of sternite 6, lateral fifths width of sternite 6, margin with narrow rim margin with wide rim lateral margin with (Fig. 4.16A, B) (Fig. 4.16C–E) narrow rim (Fig. 4.16F)

Small (carapace width up Medium (carapace width Large (carapace width Carapace size to 30 mm) up to 40 mm) up to 60 mm)

Yarepotamon meridianum n. sp. (Figs. 4.4, 4.5, 4.14A, 4.15C, 4.16A, 4.17A)

Type material. Holotype: SYSBM 001587, male (20.5 × 15.4 mm), Lutian village, Foshan, Guangdong province, shallow creek, under rocks, coll. C. Huang, August 2015. Paratypes: SYSBM 001588, 1 female (allotype) (19.3 × 15.4 mm), same data as above. SYSBM 001589–001590, 2 males (23.6 × 18.1 mm, 15.4 × 12.0 mm), same data as above. SYSBM 001591, 1 female (18.4 × 14.5 mm), same data as above.

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Additional material. Zaomu Mountain, Foshan, Guangdong province: SYSBM 001578– 001580, 3 males (19.4 × 15.2 mm, 16.2 × 13.1 mm, 15.7 × 12.6 mm), shallow creek, under rocks, coll. C. Huang, April 2015. SYSBM 001581, 1 female (18.4 × 14.8 mm), same data as above. Yunyong Forest Park, Foshan, Guangdong province: SYSBM 001582, 1 male (20.0 × 15.3 mm), shallow creek, under rocks, coll. C. Huang, April 2015. SYSBM 001583–001585, 3 females (20.9 × 16.2 mm, 20.7 × 16.2 mm, 20.6 × 16.1 mm), same data as above. Daxikeng Reservoir, Jiangmen, Guangdong province: SYSBM 001604, 1 male (15.2 × 12.4 mm), shallow creek, under rocks, coll. C. Huang, August 2015. SYSBM 001605, 1 females (17.0 × 13.3 mm), same data as above.

Figure 4.4 Yarepotamon meridianum n. sp., male (20.5 × 15.4 mm) (SYSBM 001587). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with right G1 in situ (left G1 removed).

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Figure 4.5 Yarepotamon meridianum n. sp., male (20.5 × 15.4 mm) (SYSBM 001587). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, left third maxilliped. Scale bar = 1.0 mm.

Description. Carapace 1.3 times as broad as long (CW > 2.0mm, N = 5), subtrapezoidal, regions not entirely distinct; dorsal surface slightly convex; surface generally smooth with fused rugae on anterolateral region (Fig. 4.4A). Front slightly deflexed, margin slightly ridged on dorsal view (Fig. 4.4A). Epigastric cristae conspicuous, separated by narrow gap (Fig. 4.4A, B). Postorbital cristae blunt, laterally expanded, not confluent with epigastric

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cristae or anterolateral margin (Fig. 4.4A, B). Branchial regions relatively flat (Fig. 4.4A). Cervical groove shallow, inconspicuous (Fig. 4.4A). Mesogastric region convex (Fig. 4.4A). External orbital angle broadly triangular (Fig. 4.4A). Epibranchial tooth small, granular (Fig. 4.4A, B). Anterolateral margin distinctly cristate, lined with approximately 20 granules; lateral part bent inward (Fig. 4.4A). Posterolateral margin comparatively smooth, lined with multiple oblique striae, converging towards posterior carapace margin (Fig. 4.4A). Orbits large; supraorbital and infraorbital margins cristate, lined with numerous inconspicuous granules (Fig. 4.4B). Sub-orbital with small rounded granules, sub-hepatic and upper parts of pterygostomial regions covered with large rounded granules (Fig. 4.4B). Epistome posterior margin narrow; median lobe widely triangular, lateral margins almost straight (Fig. 4.4B). Third maxilliped merus width about 1.2 × length; ischium width about 0.71 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus, mesial margin subauriculiform. Exopod reaching to proximal one-third of merus; flagellum short (Figs. 4.4B, 4.5D). Chelipeds (pereiopod 1) unequal (Fig. 4.4A). Merus trigonal in cross section; margins crenulated (Fig. 4.4B). Carpus with sharp spine at inner-distal angle, spinule at base; dorsal surface smooth (Fig. 4.4A). Major cheliped palm length about 1.2 × height (Fig. 4.4A). Movable finger as long as fixed finger (Fig. 4.4A). Occlusal margin of fingers with rounded, blunt teeth; gape when closed (Fig. 4.4A). Ambulatory legs (pereiopods 2–5) slender, dactylus with dense, short setae; propodus, carpus with relatively sparse, short setae (Fig. 4.4A). Pereiopods 5 propodus about 2.1 times as long as broad, slightly shorter than dactylus (Fig. 4.4A). Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused with barely visible median suture (Fig. 4.4C). Male sterno- pleonal cavity barely reaching anteriorly to level of mid-length of cheliped coxae; deep median longitudinal groove between sternites 7, 8 (Fig. 4.4D). Male pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 4.4D).

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Male pleon triangular; somites 3–6 progressively broader longitudinally, lateral margins slightly concave; somite 6 width about 2 × length; telson width about 1.3 × length; apex rounded (Fig. 4.4C). G1 generally slender, tip of terminal segment reaching beyond pleonal locking tubercle; subterminal segment length about 2.2 × length of terminal segment; terminal segment finger shaped, bent outwards, inner margin slightly concave (Figs. 4.4D, 4.5B, C, 4.14A, 4.15C). Basal segment of G2 subtrapezoidal, about 2.2 × length of flagelliform distal segment (Fig. 4.5A).

Etymology. The species name means “southern” in reference to the distribution of the species, being at the known southernmost distribution of the genus.

Colour in life. Generally mottled brown in life (Fig. 4.17A).

Habitat. The new species is mainly an aquatic species, with all specimens collected from under rocks in shallow hillstreams.

Distribution. Guangdong province, southern China: Foshan, Jiangmen.

Remarks. Yarepotamon meridianum n. sp. is very similar to the closely related Y. breviflagellum but can be identified by its wider carapace in adults (1.3 times as broad as long, CW > 2.0mm, N = 5) (Fig. 4.4C), whereas adult specimens of Y. breviflagellum have a narrower carapace (1.2 times as broad as long, CW > 2.0mm, N = 3) (Fig. 4.2C). The G1 in Y. meridianum n. sp. is also similar to that of Y. breviflagellum but can be distinguished by the more strongly bent terminal segment, which always points outwards in situ (Figs. 4.4D, 4.5B, C, 4.15C), whereas the G1 of Y. breviflagellum is less bent and always points inwards in situ (Figs. 4.2D, 4.15A). The outward-pointing G1 of the new species was found to be consistent between specimens from all the localities where found.

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Yarepotamon fossor n. sp. (Figs. 4.6, 4.7, 4.14B, 4.15D, 4.16B, 4.17B)

Type material. Holotype: SYSBM 001416, male (25.3 × 21.7 mm), Babu, Hezhou, Guangxi province, mud burrows at the side of hillstreams, coll. C. Huang, April 2014. Paratypes: SYSBM 001417, 1 female (allotype) (23.3 × 19.4 mm), same data as holotype. SYSBM 001418–001420, 3 females (22.4 × 18.6 mm, 20.2 × 17.1 mm, 18.7 × 16.0 mm), same data as holotype.

Figure 4.6 Yarepotamon fossor n. sp., male (25.3 × 21.7 mm) (SYSBM 001416). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with right G1 in situ (left G1 removed).

Description. Carapace relatively high, subovate, regions not entirely distinct; dorsal surface almost flat transversely, slightly convex longitudinally; surface generally smooth with fused rugae on anterolateral region (Fig. 4.6A). Front slightly deflexed, margin slightly ridged on dorsal view (Fig. 4.6A). Epigastric cristae conspicuous, separated by narrow gap (Fig. 4.6A, B). Postorbital cristae sharp, laterally expanded, not confluent with

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epigastric cristae, almost fused with anterolateral margin (Fig. 4.6A, B). Branchial regions slightly swollen (Fig. 4.6A). Cervical groove shallow, inconspicuous (Fig. 4.6A). Mesogastric region convex (Fig. 4.6A). External orbital angle broadly triangular, lateral margin strongly convex, separated from anterolateral region by wide gap (Fig. 4.6A, B). Epibranchial tooth small, granular (Fig. 4.6A, B). Anterolateral margin distinctly cristate, lined with approximately 23 granules; lateral part bent inward (Fig. 4.6A). Posterolateral margin comparatively smooth, lined with multiple oblique striae, converging towards posterior carapace margin (Fig. 4.6A). Orbits large; supraorbital, infraorbital margins cristate, lined with numerous inconspicuous granules (Fig. 4.6B). Sub-orbital with small rounded granules, sub-hepatic, upper parts of pterygostomial regions covered with large rounded granules (Fig. 4.6B). Epistome posterior margin narrow; median lobe widely triangular, lateral margins almost straight (Fig. 4.6B). Third maxilliped merus width about 1.1 × length; ischium width about 0.71 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus. Exopod reaching to proximal one-third of merus; flagellum short or absent; mesial margin of ischium subauriculiform (Figs. 4.6B, 4.7D, 4.17B). Chelipeds (pereiopod 1) unequal (Fig. 4.6A). Merus trigonal in cross section; margins crenulated (Fig. 4.6B). Carpus with sharp spine at inner-distal angle, spinule at base; dorsal surface smooth (Fig. 4.6A). Major cheliped palm length about 1.3 × height (Fig. 4.6A). Movable finger as long as fixed finger (Fig. 4.6A). Occlusal margin of fingers with rounded, blunt teeth; gape when closed (Fig. 4.6A). Ambulatory legs (pereiopods 2–5) slender, dactylus with dense, short setae; propodus, carpus with relatively sparse, short setae (Fig. 4.6A). Pereiopods 5 propodus about 2 times as long as broad, slightly shorter than dactylus (Fig. 4.6A). Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused with incomplete median suture (Fig. 4.6C). Male sterno- pleonal cavity barely reaching anteriorly to level of midlength of cheliped coxae; deep median longitudinal groove between sternites 7, 8 (Fig. 4.6D). Male pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 4.6D).

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Male pleon triangular; somites 3–6 progressively broader longitudinally, lateral margins slightly concave; somite 6 width about 2.1 × length; telson width about 1.3 × length; apex rounded (Fig. 4.6C).

Figure 4.7 Yarepotamon fossor n. sp., male (25.3 × 21.7 mm) (SYSBM 001416). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, right third maxilliped. Scale bar = 1.0 mm.

G1 generally slender, tip of terminal segment reaches beyond pleonal locking tubercle, approaches but does not reach sternites 4/5 suture; subterminal segment length

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about 2.2 × length of terminal segment; terminal segment distinctly elongated, subrectangular, inner margin slightly concave (Figs. 4.6D, 4.7B, C, 4.14B, 4.15D). Basal segment of G2 subovate, about 2.2 × length of flagelliform distal segment (Fig. 4.7A).

Etymology. The species name is from the Latin word fossor, meaning “digger”, attributing to the burrowing habits of this species.

Colour in life. Generally mottled brown in life (Fig. 4.17B).

Habitat. The new species dwells in mud burrows at the banks of small hillstreams. Large specimens sometimes totally lack the flagellum, whereas smaller individuals have short ones. The lack of flagellum on the exopod of the third maxilliped is thought to be related to terrestrial habits (Ng & Shokita, 1995). This could suggest that these crabs gradually transition into a more terrestrial lifestyle as they mature. No other freshwater crabs were found in the type locality, although this could be due to insufficient surveying.

Distribution. Guangxi province, southern China: Hezhou, southern China.

Remarks. This new species can easily be separated from congeners by its higher carapace, which is likely a morphological adaptation to a more terrestrial lifestyle (i.e., Ng & Shokita, 1995; Ng & Kosuge, 1997; Yeo & Ng, 2005). It is closest to Y. breviflagellum but can be identified by its sharp epigastric cristate (Fig. 4.6A, B) (blunt in Y. breviflagellum; Fig. 4.2A, B), relatively wide gap between external orbital angle and anterolateral region (Fig. 4.6A, B) (narrow gap in Y. breviflagellum; Fig. 4.2A, B), slightly swollen branchial regions (Fig. 4.6A) (relatively flat in Y. breviflagellum; Fig. 4.2A) and blunt tip of G1 (Figs. 4.7B, C, 4.14A, 4.15D) (pointed tip in Y. breviflagellum; Fig. 4.15A).

Genus Qianguimon n. gen. (Figs. 4.8–4.12, 4.14C, D, 4.15E–G, 4.16C–E, 4.17C–E)

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Type species. Yarepotamon aflagellum Dai & Türkay, 1997, by present designation. Species included: Qianguimon aflagellum n. comb., Qianguimon elongatum n. gen., n. sp., and Qianguimon splendidum n. gen., n. sp.

Diagnosis. Medium sized (carapace width up to 40 mm). Carapace broader than long, dorsal surface convex, branchial regions relatively swollen (Fig. 4.8A); postorbital, epigastric cristae visible, not confluent (Fig. 4.8A); external orbital angle bluntly triangular, separated from anterolateral margin by gap (Fig. 8A, B). Median lobe of epistome posterior margin broadly triangular (Fig. 4.8B). Third maxilliped with relatively broad ischium, exopod of third maxilliped reaches beyond anterior edge of ischium, with short or no flagellum (Dai & Türkay, 1997: fig. 5 (1); Figs. 4.10D, 4.12D). Male pleon triangular; somite 3 relatively wide (Fig. 4.8C). G1 generally slender, boot-shaped, terminal segment with sub-distal projection (Figs. 4.8D, 4.15E). Basal segment of G2 subovate (Dai & Türkay, 1997: fig. 5 (6)). Vulvae medium-sized, reaching proximal three-quarters width of sternite 6, lateral margin with wide rim (Fig. 4.16C).

Etymology. The genus name is a combination of the Chinese Qian and Gui for Guizhou and Guangxi provinces, respectively, and mon, in reference to Potamon, the type genus of the family. Gender of genus neuter.

Distribution. Guizhou and Guangxi provinces, southern China.

Remarks. Qianguimon n. gen. is erected for Yarepotamon aflagellum and two new species, Q. elongatum n. gen., n. sp. and Q. splendidum n. gen., n. sp. The new genus can be separated from Yarepotamon by characters discussed for Yarepotamon. Qianguimon n. gen. can be distinguished from Eurusamon n. gen. by the short to absent flagellum of the third maxilliped exopod (Dai & Türkay, 1997: fig. 5 (1); Figs. 4.10D, 4.12D) (long in Eurusamon n. gen.; Dai & Türkay, 1997: fig. 8 (1)), relatively wide male pleonal somite 3 (Fig. 4.8C) (narrow in Eurusamon n. gen.; Fig. 4.13C), boot-shaped G1 (Fig. 4.15E–G) (generally slender in Eurusamon n. gen.; Fig. 4.15H), larger female vulvae reaching 104

proximal three-quarters width of sternite 6; Fig. 4.16C–E) (smaller female vulvae reaching proximal three-fifths in Eurusamon n. gen.; Fig. 4.16F) and smaller size (carapace width up to 40 mm) (up to 60 mm in Eurusamon n. gen.). These differences are listed in Table 4.2.

Key to species of Qianguimon n. gen. 1. Branchial regions less swollen (Fig. 4.8A), G1 barely exceeds suture between sternites 4 and 5 in situ ……………………………………. Q. aflagellum n. comb. - Branchial regions more swollen (Figs. 4.9A, 4.11A), G1 exceeds suture between sternites 4 and 5 in situ …………………………………………………………… 2 2. Carapace smooth, G1 with prominent sub-distal projection ……………………… ……………………………………………………… Q. splendidum n. gen., n. sp. - Carapace with fused rugae on anterolateral region, G1 with less prominent sub- distal projection ……………………………………… Q. elongatum n. gen., n. sp.

Qianguimon aflagellum n. comb. (Figs. 4.8, 4.15E, 4.17C) Isolapotamon aflagellum Dai, Song, Li & Liang, 1980: 373, pl. 1, 6, fig. 6. Yarepotamon aflagellum — Dai & Türkay, 1997: 246, pl. 2 (1), fig. 5. — Dai, 1999: 400, pl. 27 (6): fig. 215.

Material examined. Mengshan, Wuzhou, Guangxi province: SYSBM 0014033, 1 male (19.4 × 15.8 mm), shallow creek, coll. C. Huang, April 2014. SYSBM 001404–001406, 3 females (22.7 × 18.0 mm, 19.4 × 15.2 mm, 14.1 × 11.7 mm), same data as above. Chengzhong, Liuzhou, Guangxi province: SYSBM 001592–001594, 3 males (29.1 × 22.7 mm, 23.7 × 18.7 mm, 19.1 × 14.8 mm), in mud holes or under rocks in the hillstream, coll. C. Huang, September 2015. SYSBM 001595–001596, 2 females (26.2 × 20.5 mm, 23.2 × 17.7 mm), same data as above.

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Figure 4.8 Qianguimon aflagellum n. comb., male (19.4 × 15.8 mm) (SYSBM 0014033). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with right G1 in situ (left G1 removed).

Colour in life. Generally mottled brown in life (Fig. 4.17C).

Habitat. According to Dai (1999), the species is usually found hiding under rocks in small hillstreams at an altitude of approximately 100m. Some large specimens have nevertheless been collected from deep mud burrows at the bank of hillstreams, suggesting a semi- terrestrial lifestyle.

Distribution. Guangxi province, southern China: Mengshan, Wuzhou, Chengzhong, Liuzhou.

Remarks. Although no type material was examined, the specimens from Wuzhou agree well with the descriptions and illustrations in Dai (1999). Specimens from Liuzhou,

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however, consistently have relatively longer G1 and could represent an undescribed species. Additional specimens are needed for confirmation.

Qianguimon elongatum n. gen., n. sp. (Figs. 4.9, 4.10, 4.14C, 4.15F, 4.16D, 4.17D)

Type material. Holotype: SYSBM 001421 male (22.0 × 16.8 mm), Leishan, Qiandongnan Miao and Dong Autonomous Prefecture, Guizhou province, mud burrows at the side of hillstreams, coll. C. Huang, July 2013. Paratypes: SYSBM 001423, 1 female (allotype) (29.0 × 21.5 mm), same data as holotype. SYSBM 001422, 1 male (15.2 × 11.6 mm), same data as holotype. SYSBM 001424, 1 female (21.1 × 16.0 mm), same data as holotype.

Figure 4.9 Qianguimon elongatum n. gen., n. sp., male (22.0 × 16.8 mm) (SYSBM 001421). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with right G1 in situ (left G1 removed).

Description. Carapace broader than long, regions not entirely distinct, dorsal surface transversely and longitudinally convex; surface generally smooth with fused rugae on

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anterolateral region (Fig. 4.9A). Front slightly deflexed, margin slightly ridged on dorsal view (Fig. 4.9A). Epigastric cristae conspicuous, separated by narrow gap (Fig. 4.9A, B). Postorbital cristae sharp, laterally expanded, not confluent with epigastric cristae, not fused with anterolateral margin (Fig. 4.9A, B). Branchial regions relatively swollen (Fig. 4.9A). Cervical groove shallow, inconspicuous (Fig. 4.9A). Mesogastric region slightly convex (Fig. 4.9A). External orbital angle triangular (Fig. 4.9A). Epibranchial tooth small, granular but distinct (Fig. 4.9A, B). Anterolateral margin distinctly cristate, lined with approximately 19 granules; lateral part bent inward (Fig. 4.9A). Posterolateral margin comparatively smooth, lined with multiple oblique striae, converging towards posterior carapace margin (Fig. 4.9A). Orbits medium-sized; supraorbital, infraorbital margins cristate, lined with numerous inconspicuous granules (Fig. 4.9B). Sub-orbital, sub-hepatic, upper parts of pterygostomial regions covered with large rounded granules (Fig. 4.9B). Epistome posterior margin narrow; median lobe broadly triangular, lateral margins almost straight (Fig. 4.9B). Third maxilliped merus width about 1.2 × length; ischium width about 0.77 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus. Exopod reaching to proximal one-third of merus; flagellum short or absent; mesial margin of ischium subauriculiform (Figs. 4.9B, 4.10D). Chelipeds (pereiopod 1) unequal (Fig. 4.9A). Merus trigonal in cross section; margins crenulated (Fig. 4.9B). Carpus with sharp spine at inner-distal angle, spinule at base; inner-dorsal surface with curved striae (Fig. 4.9A). Major cheliped palm length about 1.2 × height (Fig. 4.9A). Movable finger as long as fixed finger (Fig. 4.9A). Occlusal margin of fingers with rounded, blunt teeth; gape when closed (Fig. 4.9A). Ambulatory legs (pereiopods 2–5) slender, dactylus with dense, short setae; propodus, carpus, merus with relatively sparse, short setae (Fig. 4.9A). Pereiopods 5 propodus about 2.1 times as long as broad, slightly shorter than dactylus (Fig. 4.9A). Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused with subtle median suture (Fig. 4.9C). Male sterno-pleonal cavity exceeds anteriorly to level of midlength of cheliped coxae; deep median longitudinal

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groove between sternites 7, 8 (Fig. 4.9D). Male pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 4.9D).

Figure 4.10 Qianguimon elongatum n. gen., n. sp., male (22.0 × 16.8 mm) (SYSBM 001421). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, left third maxilliped. Scale bar = 1.0 mm.

Male pleon triangular; somites 3–6 progressively broader longitudinally, lateral margins almost straight; somite 6 width about 2.1 × length; telson width about 1.4 × length; apex rounded (Fig. 4.9C).

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G1 conspicuously slender, tip of terminal segment reaching well beyond pleonal locking tubercle, well exceeding sternites 4/5 suture; subterminal segment length about 1.7 × length of terminal segment; terminal segment distinctly elongated, boot-shaped, inner margin slightly concave, with blunt sub-terminal projection (Figs. 4.9D, 4.10B, C, 4.14C, 4.15F). Basal segment of G2 subovate, about 2 × length of flagelliform distal segment (Fig. 4.10C).

Etymology. The species name is derived from the Latin elongatum for elongated, attributing to the very slender G1 of this species.

Colour in life. Generally dark brown to purplish brown (Fig. 4.17D).

Habitat. This species was found at an altitude of approximately 1,500 m and is likely more terrestrial than Q. aflagellum n. comb., as specimens of all sizes were collected from mud holes at the banks of a hillstream. It is sympatric with Mediapotamon leishanense Dai, 1995 (cf. Dai, 1995a) at its type locality.

Distribution. Guizhou province, southern China: Leishan, Qiandongnan Miao, and Dong Autonomous Prefecture.

Remarks. Qianguimon elongatum n. gen., n. sp. is close to Q. aflagellum n. comb., but can be distinguished by the more swollen branchial regions (Fig. 4.9A) (relatively less swollen in Q. aflagellum n. comb.; Fig. 4.8A), smaller orbits (Fig. 4.9B) (relatively larger orbits in Q. aflagellum n. comb.; Fig. 4.8B), much longer G1 that well exceeds suture between sternites 4 and 5 in situ (Fig. 4.9D) (relatively short G1 that barely exceeds suture between sternites 4 and 5 in situ in Q. aflagellum n. comb.; Fig. 4.8D) and more slender terminal segment of G1 with less prominent sub-distal projection (Figs. 4.10B, C, 4.14C, 4.15F) (stouter terminal segment of G1 with more prominent sub-distal projection in Q. aflagellum n. comb.; Fig. 4.15E). The new species can also be distinguished from Q. splendidum n. gen., n. sp. (see remarks for Q. splendidum n. gen., n. sp.). 110

Qianguimon splendidum n. gen., n. sp. (Figs. 4.11, 4.12, 4.14D, 4.15G, 4.16E, 4.17E)

Figure 4.11 Qianguimon splendidum n. gen., n. sp., male (27.8 × 21.1 mm) (SYSBM 001597). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with G1 in situ.

Type material. Holotype: SYSBM 001597, male (27.8 × 21.1 mm), Yanghe, Liuzhou, Guangxi province, mud burrows at the side of hillstreams, coll. C. Huang, September 2015. Paratypes: SYSBM 001598, 1 female (allotype) (30.8 × 23.0 mm), same data as holotype. AM, 1 male (22.7 × 17.6 mm), same data as holotype. NCHUZOOL 14931, 1 male, 1 female (23.9 × 18.7 mm, 22.4 × 17.8 mm), same data as holotype.

Additional material. SYSBM 001599, 1 male (30.6 × 22.8 mm), same data as holotype. SYSBM 001600, 1 female (18.8 × 14.8 mm), same data as holotype.

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Description. Carapace broader than long, regions not entirely distinct, dorsal surface transversely and longitudinally convex; surface generally smooth (Fig. 4.11A). Front deflexed, margin slightly ridged on dorsal view (Fig. 4.11A). Epigastric cristae discernable, separated by narrow gap (Fig. 4.11A, B). Postorbital cristae blunt, not confluent with epigastric cristae, not fused with anterolateral margin (Fig. 4.11A, B). Branchial regions very swollen (Fig. 4.11A). Cervical groove shallow, inconspicuous (Fig. 4.11A). Mesogastric region slightly convex (Fig. 4.11A). External orbital angle triangular (Fig. 4.11A). Epibranchial tooth small, granular, but distinct (Fig. 4.11A, B). Anterolateral margin indistinctly cristate, lined with numerous fused granules; lateral part bent inward (Fig. 4.11A). Posterolateral margin comparatively smooth (Fig. 4.11A). Orbits medium- sized; supraorbital, infraorbital margins cristate (Fig. 4.11B). Sub-orbital region generally smooth, sub-hepatic and upper parts of pterygostomial regions covered with large, rounded granules (Fig. 4.11B). Epistome posterior margin narrow; median lobe broadly triangular, lateral margins almost straight (Fig. 4.11B). Third maxilliped merus width about 1.1 × length; ischium width about 0.67 × length; merus trapezoidal, with median depression; ischium trapezoidal, with distinct median sulcus. Exopod reaching to proximal one-third of merus; flagellum absent; mesial margin of ischium subauriculiform (Figs. 4.11B, 4.12D). Chelipeds (pereiopod 1) unequal (Fig. 4.11A). Merus trigonal in cross section; margins crenulated (Fig. 4.11B). Carpus with sharp spine at inner-distal angle, spinule at base; dorsal surface smooth (Fig. 4.11A). Major cheliped palm length about 1.4 × height (Fig. 4.11A). Movable finger as long as fixed finger (Fig. 4.11A). Occlusal margin of fingers with rounded, blunt teeth; gape when closed (Fig. 4.11A). Ambulatory legs (pereiopods 2–5) slender, dactylus with dense, short setae; propodus, carpus, merus with relatively sparse, short setae (Fig. 4.11A). Pereiopods 5 propodus about 2.6 times as long as broad, about same length as dactylus (Fig. 4.11A). Thoracic sternum generally smooth, weakly pitted; sternites 1, 2 completely fused, triangular; sternites 3, 4 fused with subtle median suture (Fig. 4.11C). Male sterno-pleonal cavity exceeds anteriorly to level of midlength of cheliped coxae; deep median longitudinal

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groove between sternites 7, 8 (Fig. 4.11D). Male pleonal locking tubercle slightly posterior to mid-length of sternite 5 (Fig. 4.11D).

Figure 4.12 Qianguimon splendidum n. gen., n. sp., male (27.8 × 21.1 mm) (SYSBM 001597). A, left G2; B, left G1 (ventral view); C, G1 terminal segment (ventral view); D, left third maxilliped. Scale bar = 1.0 mm.

Male pleon triangular; somites 3–6 progressively broader longitudinally, lateral margins almost straight; somite 6 width about 2 × length; telson width about 1.3 × length; apex rounded (Fig. 4.11C).

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G1 very slender, tip of terminal segment reaching well beyond pleonal locking, exceeding sternites 4/5 suture; subterminal segment length about 1.9 × length of terminal segment; terminal segment elongated, inner margin slightly concave, with large triangular sub-terminal projection (Fig. 4.11D, 4.12B, C, 4.14D, 4.15G). Basal segment of G2 subovate, about 2 × length of flagelliform distal segment (Fig. 4.12A).

Etymology. The species name is derived from the Latin splendidum, alluding to the striking colour of individuals.

Colour in life. Carapace dorsal surface greyish green to sky blue with orange margins; legs orange; chelipeds pale orange or pale blue (Fig. 4.17E).

Habitat. The new species is semi-terrestrial like Q. elongatum n. gen., n. sp., with both mature and juvenile individuals found in mud holes in the banks of hillstreams. Its bright coloration could be the result of a lack of selective pressure for camouflage as they spend much of their time inside their mud holes. It has been suggested that bright colours in male fiddler crabs increase their predation risk (Koga et al., 2001). Most species of Nanhaipotamon and Hainanpotamon Dai, 1995 (cf. Dai, 1995b) also share a similar lifestyle and are often also vividly colored, whereas the vast majority of aquatic potamid species in China have dark and dull colourations.

Distribution. Guangxi province, southern China: Yanghe, Liuzhou.

Remarks. With similar G1, Q. splendidum n. gen., n. sp. is likely closely related to Q. aflagellum n. comb., but its smoother dorsal carapace (Fig. 4.11A) (fused rugae on anterolateral region in Q. aflagellum n. comb.; Fig. 4.8A), more swollen branchial regions (Fig. 4.11A) (less swollen in Q. aflagellum n. comb.; Fig. 4.8A), longer G1 that exceeds suture between sternites 4 and 5 in situ (Fig. 4.11D) (relatively short G1 that barely exceeds suture between sternites 4 and 5 in situ in Q. aflagellum n. comb.; Fig. 4.8D), and more slender terminal segment of G1 (Figs. 4.12B, C, 4.14D, 4.15G) (stouter terminal segment 114

of G1 in Q. aflagellum n. comb.; Fig. 4.15E) clearly set them apart. The new species is also similar to Q. elongatum n. gen., n. sp., but has a smoother dorsal carapace surface (Fig. 4.11A) (fused rugae on anterolateral region in Q. elongatum n. gen., n. sp.; Fig. 4.9A), slightly more swollen branchial regions (Fig. 4.11A) (slightly less swollen in Q. elongatum n. gen., n. sp.; Fig. 4.9A), relatively shorter G1 that exceeds suture between sternites 4 and 5 in situ (Fig. 4.11D) (longer G1 that well exceeds suture between sternites 4 and 5 in situ in Q. elongatum n. gen., n. sp.; Fig. 4.9D), and more prominent sub-terminal projection in the terminal segment of the G1 (Figs. 4.12B, C, 4.14D, 4.15G) (less prominent in Q. elongatum n. gen., n. sp.; Figs. 4.10B, C, 4.14C, 4.15F).

Genus Eurusamon n. gen. (Figs. 4.13, 4.15H, 4.16F, 4.17F)

Type species. Yarepotamon guangdongense Dai & Türkay, 1997, by original designation. Species included: E. guangdongense n. comb.

Diagnosis. Large sized (carapace width up to 60 mm). Carapace broader than long, dorsal surface slightly convex, branchial regions relatively flat (Fig. 4.13A); postorbital, epigastric cristae visible, not confluent (Fig. 4.13A); external orbital angle bluntly triangular, separated from anterolateral margin by gap (Fig. 4.13A). Median lobe of epistome posterior margin broadly triangular (Fig. 4.13B). Third maxilliped with relatively broad ischium, exopod of third maxilliped reaches beyond anterior edge of ischium, with long flagellum (Dai & Türkay, 1997: fig. 8 (1)). Male pleon triangular; somite 3 relatively narrow (Fig. 4.13C). G1 slender, sinuous (Figs. 4.13D, 4.15H). Basal segment of G2 subovate (Dai & Türkay, 1997: fig. 8 (5)). Vulvae relatively small, reaching proximal three-fifths width of sternite 6, lateral margin with narrow rim (Fig. 4.16F).

Etymology. The genus name is derived from the Latin Eurus, the Greek god of the east wind, which alludes to occurrence of the new genus in East Asia. The suffix is derived from Potamon, the type genus of the family. Gender of genus neuter. 115

Distribution. Guangdong province, southern China.

Remarks. Eurusamon n. gen. is erected for Yarepotamon guangdongense Dai & Türkay, 1997. This new genus can be distinguished from Yarepotamon and Qianguimon n. gen. by a unique suite of characters listed in the section for Yarepotamon and Qianguimon n. gen., respectively. These differences are also shown in Table 4.2.

Eurusamon guangdongense n. comb. (Figs. 4.13, 4.15H, 4.16F, 4.17F) Yarepotamon guangdongense Dai & Türkay, 1997: 246, pl. 2 (4), fig. 8. — Dai, 1999: 400, pl. 27 (4), fig. 213.

Material examined. Tongledashan Nature Reserve, Yunan, Yunfu, Guangdong province: SYSBM 001407, 1 male (34.3 × 27.0 mm), large creek, coll. C. Huang, October 2014. SYSBM 001408–001410, 3 females (25.9 × 20.4 mm, 23.9 × 19.2 mm, 50.0 × 39.1 mm), same data as above. SYSBM 001411, 1 male (33.8 × 24.5 mm), coll. B. M. Wang, September 2014. Sihe, Xinyi, Maoming, Guangdong province: SYSBM 001412–001413, 2 males (34.2 × 26.5 mm, 24.3 × 19.5 mm), large creek, coll. C. Huang, April 2015. SYSBM 001414–001415, 2 females (24.5 × 18.8 mm, 24.9 × 19.6 mm), same data as above males. Datianding, Xinyi, Maoming, Guangdong province: SYSBM 001622–001623, 2 males (31.1 × 23.6 mm, 21.3 × 16.6 mm), coll. J. Wang, April, 2017.

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Figure 4.13 Eurusamon guangdongense n. comb., male (33.8 × 24.5 mm) (SYSBM 001411). A, dorsal overall view; B, frontal view of cephalothorax; C, ventral view of anterior thoracic sternum and pleon; D, ventral view of sterno-pleonal cavity with right G1 in situ (left G1 removed).

Colour in life. Generally yellowish brown to dark brown in life (Fig. 4.17F).

Habitat. Eurusamon guangdongense n. comb. is ecologically similar to species of Longpotamon, being a fully aquatic generalist occurring in larger hillstreams. The species is syntopic with Chinapotamon depressum in Xinyi, Maoming City, Guangdong province. Distribution: Guangdong province, southern China: Yunan, Yunfu, Xinyi, Maoming. Remarks: Though no types of Eurusamon guangdongense n. comb. were examined, the morphology of the examined specimens agrees very well with the descriptions and illustrations in Dai (1999). There seems to be little variation between the populations of the surveyed localities.

Table 4.3 Matrix of percentage pairwise nucleotide K2P divergences based on the 16S sequences of species of Yarepotamon, Qianguimon n. gen., and Eurusamon n. gen.

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Q. Q. Y. Y. Q. Y. Y. fossor elongatum splendidu Species breviflagel meridianu aflagellum gracilipa n. sp. n. gen., n. m n. gen., lum m n. sp. n. comb. sp. n. sp.

Y. meridianu 3.97 m n. sp.

Y. 3.77 4.19 gracilipa

Y. fossor 2.76 3.15 2.16 n. sp.

Q. aflagellum 7.52 8.12 7.33 5.81 n. comb.

Q. elongatum 7.72 7.93 7.97 5.82 2.34 n. gen., n. sp. Q. splendidu 8.81 7.88 8.17 6.21 3.12 3.73 m n. gen., n. sp. E. guangdon 7.53 7.73 7.98 6.26 6.01 5.99 6.2 gense n. comb.

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Figure 4.14 Left G1 terminal segment. A, Yarepotamon meridianum n. sp., ventral view; B, Y. fossor n. sp., ventral view; C, Qianguimon elongatum n. gen., n. sp., ventral view; D, Q. splendidum n. gen., n. sp., ventral view. Scale bar = 0.5 mm.

Figure 4.15 Left G1s. A, Yarepotamon breviflagellum Dai & Türkay, 1997, (CB 01370); B, Y. gracilipa (Dai, Song, Li & Liang, 1980) (CB 01372) (right G1 image flipped for comparison); C, Y. meridianum n. sp., (SYSBM 001587); D, Y. fossor n. sp. (SYSBM 001416); E, Qianguimon aflagellum n. comb. (SYSBM 0014033); F, Q. elongatum n. gen., n. sp. (SYSBM 001421); G, Q. splendidum n. gen., n. sp. (SYSBM 001597); H, Eurusamon guangdongense n. comb. (SYSBM 001411). 119

Figure 4.16 Female vulvae. A, Yarepotamon meridianum n. sp., (19.3 × 15.4 mm) (SYSBM 001588); B, Y. fossor n. sp., (23.3 × 19.4 mm) (SYSBM 001417); C, Qianguimon aflagellum n. comb., (22.7 × 18.0 mm) (SYSBM 001404); D, Q. elongatum n. gen., n. sp., (29.0 × 21.5 mm) (SYSBM 001423); E, Q. splendidum n. gen., n. sp., (30.8 × 23.0 mm) (SYSBM 001598); F. Eurusamon guangdongense n. comb. (50.0 × 39.1 mm) (SYSBM 001410).

Phylogenetic analysis and discussion

Ten species from five genera were included in the phylogenetic analysis. A 527 bp segment of the 16S mtDNA gene was aligned; 88 positions were variable and 44 parsimony informative. The studied segment of the 16S sequences was AT rich (71.7%) (T: 35.9%, A: 35.8%, G: 17.7%, C: 10.6%). The interspecific base-pair difference between species of Yarepotamon, ranges from 11 to 21 (mean is 16.83) and K2P divergence ranges from 2.16% to 4.19% (mean is 3.33%); the basepair difference within Qianguimon n. gen. ranges from

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12 to 19 (mean 15.67) and K2P divergence ranges from 2.34% to 3.73% (mean is 3.06%) (Table. 4.3). The phylogenetic results under both BI and MP (Fig. 4.18) show that Yarepotamon and Qianguimon n. gen. both form well supported clades and are not sister taxa, with the mean K2P divergence between them being 7.44%. Eurusamon n. gen. is not clustered within any of the above two genera and is sister to Qianguimon n. gen. in this analysis, with its mean intrageneric K2P divergence 7.38% from Yarepotamon and 6.07% from Qianguimon n. gen. Yarepotamon s.l., was proposed by Dai & Türkay (1997) to include Y. breviflagellum, Y. gracilipa, Qianguimon aflagellum n. comb., and Eurusamon guangdongense n. comb. mainly based on their similar G1. Although the G1 is superficially similar, being generally straight and having a curved terminal segment (i.e., Y. breviflagellum, Q. aflagellum n. comb., and E. guangdongense n. comb.; Fig. 4.15), it is herein shown that these similarities are not synapomorphies and do not reflect immediate common ancestry (Fig. 4.18). The similarity in the morphology of the G1 in some species of Yarepotamon, Qianguimon n. gen., and Eurusamon n. gen. is most likely due to the simple and unspecialized state of the gonopods, which could have been derived before cladogenesis but have changed little. In fact, the G1 morphology of the closely related Cantopotamon is also quite similar to the abovementioned three genera (Fig. 4.18; Huang et al., 2017). The extensively used G1 character can be problematic when assigning taxa to the genus level (Huang et al., 2014). Even in the extreme case of Sinopotamon and Longpotamon, where convergence has led to their strikingly similar external morphology and the G1 was the main separating character in separating these taxa, other characters such as the male pleon, female vulvae, and DNA have provided much needed confidence in the generic treatment (Shih et al., 2016). The habitats of the species Yarepotamon and Qianguimon n. gen. species vary, with Y. breviflagellum, Y. gracilipa, and Y. meridianum n. sp. being the smallest and most aquatic, Y. fossor n. sp. and Q. aflagellum n. comb. being intermediate, and Q. elongatum n. gen., n. sp. and Q. splendidum n. gen., n. sp. the largest and most terrestrial. The ecological overlap in Y. fossor n. sp. and Q. aflagellum n. comb.

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Figure 4.17 Colours in life. A, Yarepotamon meridianum n. sp., male (20.5 × 15.4 mm) (SYSBM 001587); B, Yarepotamon fossor n. sp., male (25.3 × 21.7 mm) (SYSBM 001416); C, Qianguimon aflagellum n. comb., male (23.7 × 18.7 mm) (SYSBM 001593); D, Q. elongatum n. gen., n. sp., male (22.0 × 16.8 mm) (SYSBM 001421); E, Q. splendidum n. gen., n. sp., female (30.8 × 23.0 mm) (SYSBM 001598); F, Eurusamon guangdongense n. comb., female (50.0 × 39.1 mm) (SYSBM 001410). complicates generic identification due to their convergent external morphology. Other characters that are apparently under less environmental selective pressure, such as male pleon (Figs. 4.6C, 4.8C), male first gonopod (Fig. 4.15D, E), and female vulvae (Fig. 4.16B, C), have nevertheless been found useful for generic placement. Recently, there has even been evidence that there is coevolution between the female vulvae and male G1 in 122

freshwater crabs (Yao et al., 2020), highlighting the importance of the female vulvae character which has been largely neglected in older studies. Yarepotamon ranges from eastern Guangxi to western Guangdong provinces, south of the Nanling mountain range, around the Xijiang drainage system, whereas Qianguimon n. gen. has been found along the Liujiang drainage system, from eastern Guizhou to northeastern Guangxi. The two genera overlap in the area between Guijiang and Liujiang rivers. Both have broad altitude ranges, from close to sea level to over 1,000 m, with Qianguimon elongatum n. gen., n. sp. from Guizhou being found at the highest altitude of around 1,500 m. The known distribution of Eurusamon n. gen. is in western Guangdong, south of the Xijiang River, at altitudes between 200 and 600 m, but it is possibly distributed in adjacent eastern Guangxi as well. The distribution of low-altitude species, such as those of Nanhaipotamon, which are usually found below 500 m, has been thought to be heavily influenced by mountain ranges due to their apparent inability to cross over these barriers (Shih et al., 2011). The presence of Yarepotamon and Qianguimon n. gen. at relatively high altitudes could nevertheless indicate that they are able to disperse through the Nanling mountain range and be found in neighboring province.

Figure 4.18 A Bayesian inference (BI) tree of Yarepotamon Dai & Türkay, 1997, Qianguimon n. gen., Eurusamon n. gen. and others, based on the 16SrDNA sequence. Support values are represented at the nodes. Only ≥ 50% are shown for MP (-, not supported). The numbers in parenthesis correspond to the localities in Table 4.1. 123

Chapter 5.

Two new genera and two new species of narrow-range freshwater crabs from Guangdong, China (Decapoda: Brachyura: Potamidae)

Chao Huang, Hsi-Te Shih and Shane T. Ahyong Journal of Crustacean Biology, 38 (5), 614–624

Abstract Two new genera and two new species of freshwater crab Megapleonum ehuangzhang n. gen., n. sp. and Luteomon spinapodum n. gen., n. sp. are described from Guangdong Province, China, based on morphology and mitochondrial 16S rDNA sequences. Megapleonum n. gen. is similar in external appearance to Cantopotamon Huang, Ahyong & Shih, 2017, and Longpotamon Shih, Huang & Ng, 2016, whereas Luteomon n. gen. most closely resembles Yarepotamon Dai & Türkay, 1997, and Tiwaripotamon Bott, 1970. The two new genera however, are distinctive in their combination of maxilliped 3, male thoracic sternum, male pleon, male gonopod and female gonopore characters. Molecular data also supports the establishment of the two new genera, with Megapleonum belonging to a distinct subclade and Luteomon related to Tiwaripotamon.

Key words: East Asia, 16S rDNA, new taxa, phylogeny, Potamidae, systematics

Introduction

In recent years, new freshwater crab species are being described at a rapid rate from southern China, with many belonging to new genera (Huang et al., 2014, 2016, 2017a, b; Shih et al., 2016; Chu et al., 2017; Huang, 2018). As a result, the known freshwater crab species diversity of this region has increased substantially, especially in Guangdong Province. Recent surveys conducted in Guangdong have led to the discovery of two new 124

species that could not be assigned to any known genera, either morphologically or genetically; both are described herein as new to science. Including the two new genera, 11 potamid crab genera are now known from Guangdong (including Hong Kong and Macau) (Cantopotamon Huang, Ahyong & Shih, 2017, Chinapotamon Dai & Naiyanetr, 1994, Cryptopotamon Ng & Dudgeon, 1992, Eurusamon Huang, 2018, Longpotamon Shih, Huang & Ng, 2016, Luteomon n. gen., Megapleonum n. gen., Minutomon Huang, Mao & Huang, 2014, Nanhaipotamon Bott, 1968, Yarepotamon Dai & Türkay, 1997, Yuebeipotamon Huang, Shih & Mao, 2016); more than double of that recorded by Shih & Ng (2011).

Materials and methods

Collection and treatment of samples Specimens were collected by hand from localities in Guangdong Province, China and preserved in 75% ethanol. Specimens are deposited in the Sun Yat-sen Museum of Biology, Sun Yat-sen University, Guangzhou, China (SYSBM); Australian Museum, Sydney, Australia (AM); and Zoology Collection of the National Chung Hsing University, Taichung, Taiwan (NCHUZOOL). Measurements, in millimetres, are of the carapace width and length, respectively. Other abbreviations are as follows: G1, male first gonopod; G2, male second gonopod. The terminology used primarily follows that of Dai (1999) and Davie et al. (2015). The width of the anterior thoracic sternum is measured as the distance between the outermost extremities of the episternites of thoracic sternite 4. Anterior thoracic sternum length is measured as the longitudinal distance between the anteriormost point of thoracic sternite 1 and the level of the posterior-most point of anterior thoracic sternite 4.

DNA sequencing and analysis Sequences of 16S were obtained following Shih et al. (2009), using the primers 16H10 and 16L29 (Schubart, 2009), and aligned with the aid of ClustalW (vers. 1.4, Thompson et al., 1994), after verification with the complementary strand. Sequences of different haplotypes have been deposited in the DNA Data Bank of Japan (DDBJ). To confirm the systematic 125

position of the taxa, the 16S sequences of genera from the eastern Asian continent in Shih et al. (2009) and Huang et al. (2014, 2016, 2017a, b) are included for comparison.

Figure 5.1 Colour in life. A, Megapleonum ehuangzhang n. gen., n. sp., paratype female (19.3 × 14.5 mm), SYSBM 001615; B, Luteomon spinapodum n. gen., n. sp., paratype female (15.9 × 12.9 mm), SYSBM 001612.

A preliminary analysis showed that the two taxa studied belong to the “China-East Asia Islands” group (Shih et al., 2009). As a result, taxa from closely related groups, i.e., 126

Megacephalomon kittikooni (Yeo & Naiyanetr, 1999), Esanpotamon namsom Naiyanetr & Ng, 1997, Mindoron balssi (Bott, 1968) and Ovitamon artifrons (Bürger, 1894), were used as outgroups. Twenty-nine ingroup species from 23 potamid genera were genetically analysed. We followed Shih et al. (2009) in excluding the variable regions in loop regions of the 16S that could not be aligned adequately for phylogenetic analyses. The best-fitting model for sequence evolution of 16S was determined by jModelTest (vers. 2.1.4; Darriba et al., 2012), selected by the Bayesian information criterion (BIC). The best model obtained, TPM1uf+I+G, was subsequently used for the Bayesian inference (BI) analysis. The BI was performed with MrBayes (vers. 3.2.6; Ronquist et al., 2012), run with four chains for 10 million generations, with trees sampled every 1000 generations. The convergence of chains was deemed to have occurred when the average standard deviation of split frequency values fell below the recommended 0.01 (Ronquist et al., 2005); accordingly, the first 1000 trees were discarded as burnin. A maximum parsimony (MP) consensus tree was constructed using MEGA vers. 7.0 (Kumar et al., 2016), with 2000 bootstrap reiterations of a simple heuristic search, TBR branch-swapping (tree bisection-reconnection) (100 random-addition sequence replications; max no. of trees to retain = 10000).

Systematics

Family Potamidae Ortmann, 1896 Subfamily Potamiscinae Bott, 1970 Genus Megapleonum n. gen. (Figs. 5.1A, 5.2–5.4)

Type species. Megapleonum ehuangzhang n. gen., n. sp., by original designation.

Diagnosis. Carapace broader than long, dorsal surface slightly convex, branchial regions relatively flat (Fig. 5.2A); postorbital and epigastric cristae confluent (Fig. 5.2A); external orbital angle bluntly triangular, almost confluent with anterolateral margin (Fig. 5.2A). Median lobe of epistome broadly triangular (Fig. 5.2B). Maxilliped 3 with relatively broad ischium; exopod reaching beyond anterior edge of ischium, flagellum absent (Fig. 5.3D). 127

Male anterior thoracic sternum very broad, width 1.9 × length (Fig. 5.4A). Male pleon large, broadly triangular (Fig. 5.2C). Female pleon linguiform (Fig. 5.4C). G1 as long as G2; G2 distal article 0.4 × length of proximal article. G1 sinuous, subterminal segment bent inwards, terminal segment bent laterally, with curved flap on ventral side (Fig. 5.3B, C, E, F, H). G2 subterminal segment relatively thick, flagelliform terminal segment with blunt tip (Fig. 5.3A, G). Vulvae widely ovate, large, reaching the suture of sternites 5/6, relatively widely separated (Fig. 5.4D).

Etymology. The genus name is an arbitrary combination of Greek mega and pleon, alluding to the extraordinarily large male pleon present in the type species, compared to other potamids. Gender: neuter.

Distribution. Yangjiang, Guangdong Province.

Remarks: Megapleonum n. gen. is included in Potamiscinae sensu Yeo & Ng (2004). Although dorsally similar to Cantopotamon in terms of carapace physiognomy, Megapleonum n. gen. can be separated by the absence of the flagellum on the maxilliped 3 exopod (Fig. 5.3D) (versus flagellum present in Cantopotamon; Huang et al., 2017b: figs. 2D, 4D, 6D, 8D), a large and broadly triangular male pleon with convex lateral margins that extends anteriorly well beyond level of posterior margins of cheliped coxae (Fig. 5.2C) (versus triangular with almost straight lateral margins, reaching anteriorly almost to level of posterior margins of cheliped coxae; Huang et al., 2017b: figs. 1C, 3C, 5C, 7C), sinuous G1 with the subterminal segment bent inwards and the terminal segment bent outwards with curved flap on ventral side (Fig. 5.3B, C, E, F, H) (versus generally slender, terminal segment without flap and sinistrally twisted on left G1; Huang et al., 2017b: figs. 2B, C 4B, C, 6B, C, 8B, C), a relatively thick G2 subterminal segment with blunt tipped flagelliform terminal segment (Fig. 5.3A, G) (versus subterminal segment relatively thin, flagelliform terminal segment with pointed tip; Huang et al., 2017b: figs. 2A, 4A, 6A, 8A), large, widely ovate vulvae, reaching the suture of sternites 5/6 (Fig. 5.4D) (versus ovate, relatively small, not reaching the suture of sternites 5/6; Huang et al., 2017b: fig. 11), and a 128

male anterior thoracic sternum with width 1.9 × length (Fig. 5.4A) (versus width 1.8 × length; Huang et al., 2017b: fig. 10). The difference in the width/length ratio of the anterior thoracic sternum between Megapleonum and Cantopotamon, though small, is consistent.

Figure 5.2 Megapleonum ehuangzhang n. gen., n. sp., holotype male (23.1 × 18.6 mm), SYSBM 001614. A, dorsal habitus; B, cephalothorax, anterior view; C, anterior thoracic sternum and pleon, ventral view; D, sterno-pleonal cavity with right G1 in situ (left G1 removed), ventral view.

The mesially directed terminal segment of the G1 of Megapleonum n. gen. is somewhat similar in some species of Longpotamon (e.g. L. bilobatum Dai & Jiang, 1991). However, Megapleonum can be easily distinguished from Longpotamon by its confluent postorbital and epigastric cristae (Fig. 5.2A) (versus not confluent; Shih et al., 2016: fig. 6A), large and broadly triangular male pleon with convex lateral margins that well extends anteriorly beyond level of posterior margins of cheliped coxae (Fig. 5.2C) (versus triangular with almost straight lateral margins, reaching anteriorly to level of posterior margins of cheliped coxae; Shih et al., 2016: figs. 6C), sinuous G1 with the subterminal segment bent inwards and the terminal segment bent outwards with curved flap on ventral side (Fig. 5.3B, C, E, F, H) (versus subterminal segment generally straight and without flap

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on terminal segment; Shih et al., 2016: fig. 7B), relatively thick G2 subterminal segment with blunt tipped flagelliform terminal segment (Fig. 5.3A, G) (versus subterminal segment relatively thin, flagelliform terminal segment with pointed tip; Dai, 1999: fig. 108 (7)). All these differences are listed in Table 5.1.

Megapleonum ehuangzhang n. gen., n. sp. (Figs. 5.1A, 5.2–5.4)

Type material. Holotype: SYSBM 001614, male (23.1 × 18.6 mm), E’huang Ridge (21.82°N, 111.44°E), Yangxi, Yangjiang City, Guangdong Province, China, small hillstream, under rock, coll. C. Huang, May, 2015. Paratypes: SYSBM 001615, 1 female (19.3 × 14.5 mm), same data as holotype. NCHUZOOL 14343, 1 male (19.3 × 15.7 mm), same data as holotype. AM P101297, 1 male (18.5 × 14.7 mm), same data as holotype.

Additional material. SYSBM 001616–001617, 2 males (16.9 × 13.3 mm, 14.9 × 11.5 mm), same data as holotype.

Description. Carapace broader than long, regions indistinct, dorsal surface slightly convex transversely and longitudinally; surface generally smooth with fused rugae on anterolateral region (Fig. 5.2A). Front deflexed, margin ridged, distinctly concave medially on dorsal view (Fig. 5.2A). Epigastric cristae distinct, separated by narrow gap (Fig. 5.2A, B). Postorbital cristae sharp, laterally expanded, fused with epigastric cristae but not with epibranchial teeth (Figs. 5.2A, B). Branchial regions relatively flat (Fig. 5.2A). Cervical groove shallow, inconspicuous (Fig. 5.2A). Mesogastric region slightly convex (Fig. 5.2A). External orbital angle bluntly triangular (Fig. 5.2A). Epibranchial tooth small, granular, indistinct (Fig. 5.2A, B). Anterolateral margin distinctly cristate, lined with 12–16 granules; bent inward posteriorly (Fig. 5.2A). Posterolateral margin comparatively smooth (Fig. 5.2A). Orbits small; supraorbital, infraorbital margins cristate (Fig. 5.2B). Sub-orbital, sub- hepatic and pterygostomial regions generally smooth (Fig. 5.2B). Epistome posterior margin narrow; median lobe broadly triangular, lateral margins almost straight (Fig. 5.2B). 130

Figure 5.3 Megapleonum ehuangzhang n. gen., n. sp., holotype male (23.1 × 18.6 mm), SYSBM 001614. A, Left G2, ventral view; B, left G1, ventral view; C, G1 terminal segment, ventral view; D, left maxilliped 3; E, left G1 terminal segment, ventral view; F, left G1 terminal segment, dorsal view; G, left G2, ventral view; H, left G1, ventral view. Scale bars: A–D = 1.0 mm; E–H = 0.5 mm.

Maxilliped 3 merus width about 1.2 × length; ischium width about 0.7 × length; merus subtrapezoidal, with median depression; ischium subtrapezoidal, with distinct median sulcus, mesial margin rounded. Exopod reaching to proximal one-third of merus; flagellum absent (Figs. 5.2B, 5.3D). Chelipeds (pereiopod 1) unequal (Fig. 5.2A); less inflated in females (Fig. 5.4B). Merus trigonal in cross section; margins weakly crenulated (Fig. 5.2B). Carpus with sharp 131

spine at inner-distal angle, spinule at base; dorsal surface with weak striae (Fig. 5.2A). Major cheliped palm length 1.4–1.5 × height (n = 4) in both sexes (Fig. 5.2A, 5.4B); dactylus 0.8–0.9 × palm length in males (n = 3) (Fig. 5.2A), 0.8 in female (n = 1). Palm outer surface generally smooth, sparsely pitted, with short setae; long setae on pollex, dactylus and palm inner surface. Dactylus finger as long as pollex (Fig. 5.2A). Occlusal margin of fingers with irregular blunt teeth; slight gape when closed (Fig. 5.2A). Ambulatory legs (pereiopods 2–5) relatively stout, dactylus with dense setae; propodus with relatively sparse, short, setae (Fig. 5.2A). Pereiopod 3 merus 0.7 × carapace length (n = 4) in both sexes (Fig. 5.2A). Pereiopod 5 propodus about 1.7–1.9 × as long as broad, about same length as dactylus (n = 4) in both sexes (Fig. 5.2A). Thoracic sternum generally smooth, weakly pitted; anterior thoracic sternum (sternites 1–4) very broad, width about 1.9 × length; sternites 1, 2 forming triangular structure; sternites 3, 4 fused with subtle median suture (Fig. 5.4A). Male sterno-pleonal cavity extends anteriorly beyond level of midlength of cheliped coxae base; deep median longitudinal groove between sternites 7, 8 (Fig. 5.2D). Male pleonal locking tubercle positioned at mid-length of sternite 5 (Fig. 5.2D). Female vulvae widely ovate, large, reaching suture of sternites 5/6, relatively widely separated (Fig. 5.4D). Male pleon large, broadly triangular; somites 3–6 progressively broader longitudinally, lateral margins convex; somite 6 width about 2.6 × length; telson width about 1.7 × length; apex rounded (Fig. 5.2C). Female pleon linguiform with parallel lateral margins (Fig. 5.4C). G1 sinuous; tip of terminal segment barely exceeding pleonal locking tubercle; subterminal segment length about 3 × length of terminal segment; subterminal segment bent inwards, wide proximally and distally, increasingly constricted towards middle; terminal segment bent outwards, with large curved flap on ventral side and bulbous tip (Fig. 5.3B, C, E, F, H). G2 subterminal segment relatively thick, about 2.6 × length of blunt- tipped flagelliform distal segment; exopod absent (Fig. 5.3A, G).

Etymology. This species is named after the type locality E’huang Ridge (E’huangzhang in Pinyin), Yangxi, Yangjiang City, Guangdong. The name is used as a noun in apposition. 132

Colour in life. Generally mottled brown (Fig. 5.1).

Habitat. All specimens of Megapleonum ehuangzhang were collected under submerged rocks in a small hillstream, suggesting a mainly aquatic lifestyle. The new species was found in sympatry with Cantopotamon yangxiense Huang, Ahyong & Shih, 2017 and Eurusamon guangdongense (Dai & Türkay, 1997) at the type locality.

Remarks. Little intraspecific variation was observed. The chelipeds are more inflated in males than in size-matched females, except in juveniles. In the field, the new species can easily be distinguished from juvenile Eurusamon guangdongense by its wider male pleon, proportionately shorter legs and colouration. Juvenile Eurusamon guangdongense tend to be a uniform dark purple, while the new species is generally mottled brown. The wide pleon of male Megapleonum ehuangzhang n. gen., n. sp. is also a very useful character that can be used to separate it from the otherwise very similar looking Cantopotamon yangxiense. Females are harder to distinguish, but the carapace is proportionately wider in the new species. The walking legs of the new species appear to be darker in life than in C. yangxiense. Megapleonum ehuangzhang n. gen., n. sp., lacks the exopod flagellum on maxilliped 3, which, in Ryukyum yaeyamense (Minei, 1973), has been interpreted as a terrestrial adaptation (Ng & Shokita, 1995). Notably, reduction or loss of the maxilliped 3 flagellum is also evident in the semi-terrestrial species of Yarepotamon (Huang, 2018). Megapleonum ehuangzhang, however, appears to be an aquatic species. If the loss of the exopod flagellum on maxilliped 3 is associated with terrestrialization, it is possible that M. ehuangzhang derives from a semi-terrestrial lineage that has recently adopted an aquatic lifestyle. Our present phylogenetic results (Fig. 5.8) are inconclusive on this issue given that Megapleonum is weakly supported as sister to a large geographically and phylogenetically diverse clade of mainly aquatic groups; further taxon sampling is required.

Distribution. E’huang Ridge, Yangxi, Yangjiang City, Guangdong. 133

Figure 5.4 Megapleonum ehuangzhang n. gen., n. sp. A, holotype male (23.1 × 18.6 mm), SYSBM 001614; B–D, female (19.3 × 14.5 mm) (SYSBM 001615). A, anterior thoracic sternum; B, dorsal habitus; C, pleon, ventral view; D, vulvae, ventral view.

Genus Luteomon n. gen. (Figs. 5.1B, 5.5–5.7)

Type species. Luteomon spinapodum n. gen., n. sp., by original designation.

Diagnosis. Carapace squarish, dorsal surface convex, branchial regions slightly swollen (Fig. 5.5A); postorbital and epigastric cristae not confluent (Fig. 5.5A); external orbital angle sharply and acutely triangular, separated from anterolateral margin by conspicuous gap (Fig. 5.5A); front almost twice width of orbits (Figs. 5.5A, B, 5.7B). Median lobe of epistome broadly triangular (Fig. 5.5B). Maxilliped 3 ischium small, relatively narrow; exopod reaching beyond anterior edge of ischium, with long flagellum over-reaching merus width (Fig. 5.6D). Male pleon triangular (Fig. 5.5C). Female pleon broadly rounded (Fig. 5.7C). G1 as long as G2; G2 distal article 0.6 × length of proximal article. G1 spine-like,

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subterminal segment stout (Fig. 5.8B, C, E, F, H). Basal segment of G2 subovate (Fig. 5.8A, G). Vulvae widely ovate, medium-sized, reaching the suture of sternites 5/6, position close to midline, almost adjacent (Fig. 5.7D).

Etymology. The genus name is an arbitrary combination of Luteo (Latin, Luteum, meaning mud) and the generic name, Potamon. It alludes to the mud burrowing habits of the type species. Gender: neuter.

Distribution. Jiangmen, Guangdong Province.

Figure 5.5 Luteomon spinapodum n. gen., n. sp., holotype male (19.4 × 16.4 mm), SYSBM 001608. A, dorsal habitus; B, cephalothorax, anterior view; C, anterior thoracic sternum and pleon, ventral view; D, sterno-pleonal cavity with right G1 in situ (left G1 removed), ventral view.

Remarks. Luteomon n. gen. may be closely related to Tiwaripotamon (Fig. 5.8). The G1 of Luteomon is similar to that of Tiwaripotamon, but the new genus differs in having a carapace that is more squarish with a proportionally wider front almost twice width of orbits (versus anterior half wider than the posterior half with front as wide as the orbits in

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Tiwaripotamon; e.g., Dai, 1999: pl. 22 (7, 8)), a relatively narrower maxilliped 3 ischium with width about 0.6 × length (Fig. 5.6D) (versus relatively broad, width about 0.8 × length in Tiwaripotamon; e.g., Dai 1999: figs. 184 (1), 185 (1)), a long flagellum on maxilliped 3 exopod that over-reaches merus width (Fig. 5.6D) (versus short in Tiwaripotamon; e.g., Dai, 1999: figs. 184 (1), 185 (1)), much shorter legs (versus long and slender legs in Tiwaripotamon; e.g., Dai, 1999: pl. 22 (7, 8)). These differences are listed in Table 5.1. Although similar externally to Yarepotamon, Luteomon n. gen. can be separated by its relatively narrower maxilliped 3 ischium with width about 0.6 × length (Fig. 5.6D) (versus relatively broad, width about 0.7 × length in Yarepotamon; Dai & Türkay, 1997: figs. 6 (1), 7(1); Huang, 2018: figs. 5D, 7D), the long flagellum on the maxilliped 3 exopod that over- reaches the merus width (Fig. 5.6D) (versus short to absent in Yarepotamon; Dai & Türkay, 1997: figs. 6 (1), 7(1); Huang, 2018: figs. 5D, 7D), transversely narrower male anterior thoracic sternum, width about 1.6 × length (Fig. 5.7A) (versus broader, width about 1.7 × length in Yarepotamon; Huang, 2018: figs. 2C, 3C, 4C, 6C), spine-like G1 with stout subterminal segment (Fig. 5.8B, C, E, F, H) (versus generally slender in Yarepotamon; Huang, 2018: fig. 15A–D), and the widely ovate vulvae that are almost adjacent to one another (Fig. 5.7D) (versus ovate and relatively widely separated in Yarepotamon; Dai & Türkay, 1997: figs. 6 (7); Huang, 2018: fig. 16A, B).

Luteomon spinapodum n. gen., n. sp. (Figs. 5.1B, 5.5–5.7)

Type material. Holotype: SYSBM 001608, male (19.4 × 16.4 mm), Daxikeng Reservoir (22.64°N, 113.04°E), Jiangmen City, Guangdong, inside mud burrow next to small hillstream, coll. C. Huang, August, 2015. Paratypes: SYSBM 001609, 1 female (20.5 × 17.1 mm), same data as holotype. NCHUZOOL 14344, 1 male, 1 female (15.2 × 12.9 mm, 16.8 × 13.9 mm), same data as holotype. AM P101298, 1 male, 1 female (14.3 × 11.9 mm, 13.1 × 10.9 mm), same data as holotype.

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Figure 5.6 Luteomon spinapodum n. gen., n. sp., holotype male (19.4 × 16.4 mm), SYSBM 001608. A, left G2, ventral view; B, left G1, ventral view; C, G1 terminal segment, ventral view; D, left maxilliped 3; E, left G1 terminal segment, ventral view; F, left G1 terminal segment, dorsal view; G, left G2, ventral view; H, left G1, ventral view. Scale bars: A–D = 1.0 mm; E–H = 0.5 mm.

Additional material. SYSBM 001610–001611, 2 males (13.1 × 10.8 mm, 11.9 × 10.2 mm), same data as holotype. SYSBM 001612–001613, 2 females (15.9 × 12.9 mm, 12.5 × 10.0 mm), same data as holotype.

Description. Carapace broader than long, regions indistinct, dorsal surface convex transversely and longitudinally; surface generally smooth with granules on frontal and 137

anterolateral regions (Fig. 5.7A). Front deflexed, margin slightly ridged on dorsal view (Fig. 5.5A). Epigastric cristae low, separated by narrow gap (Fig. 5.5A, B). Postorbital cristae sharp, laterally expanded, fused with epibranchial teeth but not with epigastric cristae (Figs. 5.5A, B). Branchial regions slightly swollen (Fig. 5.5A). Cervical groove very shallow, inconspicuous (Fig. 5.5A). Mesogastric region slightly convex (Fig. 5.5A). External orbital angle sharply triangular, separated from anterolateral margin by conspicuous gap (Fig. 5.5A). Epibranchial tooth blunt, triangular (Fig. 5.5A, B). Anterolateral margin distinctly cristate, lined with 14–17 granules; bent inward posteriorly (Fig. 5.5A). Posterolateral margin with straight striae converging to posterior of carapace (Fig. 5.5A). Orbits large; supraorbital, infraorbital margins cristate (Fig. 5.5B). Sub-orbital, sub-hepatic and pterygostomial regions lined with fused granules (Fig. 5.5B). Epistome posterior margin narrow; median lobe broadly triangular, lateral margins almost straight (Fig. 5.5B). Maxilliped 3 merus width about 1.1 × length; ischium width about 0.6 × length; merus subtrapezoidal, with median depression; ischium small, subtrapezoidal, with distinct sulcus slightly interior to mid-length, mesial margin rounded. Exopod reaching to proximal one-third of merus; flagellum long (Figs. 5.5B, 5.6D). Chelipeds (pereiopod 1) unequal (Fig. 5.5A); less inflated in females (Fig. 5.7B). Merus trigonal in cross section; margins crenulated, dorsal-outer surface granulated (Fig. 5.5B). Carpus with sharp spine at inner-distal angle, spinule at base; dorsal surface with rugae (Fig. 5.5A). Major cheliped palm length about 1.4–1.7 × height (n = 6) in both sexes (Fig. 5.5A); dactylus 0.8 × palm length in males (n = 3) (Fig. 5.7A) and 0.9–1.0 in females (n = 3) (Fig. 5.7B). Palm surface rugose with sparse, short setae, dorsal-outer surface granulated. Dactylus as long as pollex (Fig. 5.5A). Occlusal margin of fingers with irregular blunt teeth; slight gape when closed (Fig. 5.5A). Ambulatory legs (pereiopods 2–5) relatively stout, dactylus with dense, short setae; propodus, carpus and merus with relatively sparse, short, setae (Fig. 5.5A). Pereiopod 3 merus × 0.8 carapace length (n = 5) in both sexes (Fig. 5.5A). Pereiopods 5 propodus 2.1– 2.4 × as long as broad, about same length as dactylus (n = 5) in both sexes (Fig. 5.5A). Thoracic sternum with sparse setae; anterior thoracic sternum (sternites 1–4) 138

narrow, width about 1.6 × length; sternites 1, 2 forming triangular structure; sternites 3, 4 fused with subtle median suture (Fig. 5.7A). Male sterno-pleonal cavity barely reaching anteriorly to level of midlength of cheliped coxae base; deep median longitudinal groove between sternites 7, 8 (Fig. 5.5D). Male pleonal locking tubercle positioned slightly posterior to sternite 5 mid-length (Fig. 5.5D). Female vulvae widely ovate, medium-sized, reaching the suture of sternites 5/6, almost adjacent to one another (Fig. 5.7D). Male pleon triangular; somites 3–6 progressively broader longitudinally, lateral margins slightly concave; somite 6 width about 2 × length; telson width about 1.5 × length; apex rounded (Fig. 5.5C). Female pleon broadly ovate (Fig. 5.7C). G1 spine-like; tip of terminal segment well exceeds pleonal locking tubercle, exceeds suture between thoracic sternites 4/5; subterminal segment length about 2.3 × length of terminal segment; subterminal segment stout; terminal segment slender, spine- like, slightly curved inwards (Fig. 5.6B, C, E, F, H). G2 subterminal segment about 1.8 × length of flagelliform distal segment; exopod absent (Fig. 5.6A, G).

Figure 5.7 Luteomon spinapodum n. gen., n. sp. A, holotype male (19.4 × 16.4 mm), SYSBM 001608; B–D, female (20.5 × 17.1 mm), SYSBM 001609. A, anterior thoracic sternum, ventral view; B, dorsal habitus; C, pleon, ventral view; D, vulvae, ventral view.

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Etymology. The species name is derived from the Latin spīna, meaning spine, and Greek podos, meaning foot or appendage. It alludes to the spine-like male reproductive appendage (G1) of this species.

Colour in life. Generally purplish-brown with scattered orange specks (Fig. 5.6).

Habitat. Luteomon spinapodum is semi-terrestrial and burrows in very soft mud. To date, it is known only from a single patch of muddy habitat next to a small hillstream and was found to be sympatric with Cantopotamon cf. zhuhaiense Huang, Ahyong & Shih, 2017 and Yarepotamon meridianum Huang, 2018.

Remarks. Little intraspecific variation was observed. The chelipeds are more inflated in males than in size-matched females, except in juveniles, and the cheliped dactylus is proportionately longer in females. In the field, the new species is easily distinguishable from Cantopotamon cf. zhuhaiense and Yarepotamon meridianum by its proportionally narrower carapace and semi-terrestrial burrowing habits.

Distribution. Daxikeng reservoir, Jiangmen City, Guangdong.

Phylogenetic analysis and discussion

A 501 bp segment, excluding the variable regions, of the 16S rDNA was amplified and aligned. The accession numbers of the 16S sequences of Luteomon spinapodum n. sp. (two specimens shared the identical haplotype) and Megapleonum ehuangzhang n. sp. (with two haplotypes) are LC383796, LC383794, and LC383795, respectively. The BI and MP analyses based on 16S sequences resulted in similar phylogenetic topologies (Fig. 5.8). Five subgroups were delineated within the “China-East Asia Islands” clade (Shih et al., 2009). The “South China I” subgroup is well supported and is composed of taxa from Guangdong (including Hong Kong), Guangxi, Fujian, Guizhou and one insular species from Taiwan, Nanhaipotamon formosanum (Parisi, 1916), which most likely has only 140

recently dispersed from the mainland (Shih et al., 2011). The species in this subgroup are diverse in the shape of the G1 terminal segment, but the subterminal segment is generally slender and straight, the G2 subterminal segment is relatively thin. The “East Asian Island Arc” subgroup is also well supported and contains exclusively insular taxa from the main islands of Japan, the Ryukyus and Taiwan.

Figure 5.8 A Bayesian inference (BI) tree of 16S rDNA for “China-East Asian Islands” group of the subfamily Potamiscinae. Support values at the nodes represent posterior probabilities and bootstrap proportions > 50% for BI and maximum parsimony (MP), respectively. The five subgroups are explained in the text.

These crabs have a shorter G1 terminal segment that is usually simple in structure, the G2 subterminal segment is relatively thicker. The “South China-Vietnam” subgroup includes Tiwaripotamon Bott, 1970 and Luteomon n. gen., the stout G1 subterminal segment and small narrow ischium of the maxilliped 3 of the latter are distinctive amongst all other genera in the China-East Asia Islands group. The deep separation and strikingly different 141

morphologies between these two genera and the low support values suggest that they may belong to different subgroups, requiring further studies to clarify their interrelationships. The “Hainan Island” subgroup is composed of the three genera from the island, although the support values are not as high as those reported by Shih et al. (2009). The G1 terminal segment of species from this subgroup are also relatively simple structured. The “South China II” subgroup consists of only one genus, Megapleonum n. gen., distributed in Guangdong. The extraordinarily large male pleon, bent G1 subterminal segment and blunt tip of the G2 terminal segment are all unique within the China-East Asia Islands group. It is apparent that both Luteomon n. gen. and Megapleonum n. gen. are morphologically and genetically distinct from all other known genera. The ongoing discovery of evolutionarily distinctive taxa from Guangdong suggests the faunal origins of this area to be more complex than previously thought.

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Chapter 6.

The freshwater crabs of Macau, with description of a new species of Nanhaipotamon Bott, 1968 and the redescription of Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003 (Crustacea, Decapoda, Potamidae)

Chao Huang, Kai Chin Wong and Shane T. Ahyong ZooKeys, 810, 91–111.

Abstract

Four species of freshwater crabs from three genera and two families (Cantopotamon hengqinense Huang, Ahyong & Shih, 2017, Nanhaipotamon guangdongense Dai, 1997, Nanhaipotamon macau n. sp., and Somanniathelphusa zanklon Ng & Dudgeon, 1992) are documented from Macau for the first time. One new species, Nanhaipotamon macau n. sp., is described. The large flap on the male first gonopod terminal segment sets it apart from all other known congeners except N. wupingense Cheng, Yang, Zhong & Li, 2003, from Fujian. Characters of the carapace, male first gonopod and size, however, clearly differentiate these two species. Preliminary genetic studies also suggest that the two are not closely related. A neotype is designated for N. wupingense. The taxonomic status of Nanhaipotamon guangdongense is also discussed. Notes on the general biology and conservation status of these crabs are also included.

Key words: Freshwater crabs, Gecarcinucidae, Macau, new species, Potamidae, systematics.

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Introduction

Best known as the gambling capital of the world, Macau (also known as Macao) has a total land area of only 30.8 km2 but a population of more than 650,000 people, making it one of the most densely populated regions in the world (Government of Macao Special Administrative Region Statistics and Census Service). Macau historically consists of the (bordered by Zhuhai to the north) and two islands: Taipa and . The two islands are now joined by Cotai, an area created by land reclamation in 2005. The freshwater crabs of Macau have not been scientifically documented to the best of our knowledge. General wetland faunal surveys from 2007 onwards have found freshwater crabs in Coloane resulting in a small collection kept in the Macao Civic and Municipal Affairs Bureau. Upon examination, it was found that these freshwater crab specimens contained two species, Cantopotamon hengqinense Huang, Ahyong & Shih, 2017, and a new species of Nanhaipotamon, Bott 1968. This has led to more extensive surveys in 2018, covering 14 survey points (two in Taipa and 12 in Coloane; Fig. 6.1) focused exclusively on freshwater crabs. Three species of potamid crabs, Cantopotamon hengqinense Huang, Ahyong & Shih, 2017, Nanhaipotamon guangdongense Dai, 1997, and Nanhaipotamon macau n. sp. and one species of gecarcinucid crab, Somanniathelphusa zanklon Ng & Dudgeon, 1992, were found. Nanhaipotamon macau n. sp. is very similar to the poorly known, N. wupingense Cheng, Yang, Zhong & Li, 2003, from Fujian Province. Unfortunately, the identity of N. wupingense is ambiguous because the type account is inadequate and the type material lost, requiring a neotype designation.

Materials and methods

Specimens were collected by hand and preserved in 75% ethanol from 2007 onwards from South China. They are deposited in the Sun Yat-sen Museum of Biology, Sun Yat-sen University, Guangzhou, China (SYSBM); the Australian Museum, Sydney, Australia (AM); the Zoological Reference Collection of the Lee Kong Chian Natural History Museum, National University of Singapore, Singapore (ZRC); and the Macao Civic and Municipal Affairs Bureau (IACM). Measurements, in millimetres, are of the carapace width and

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length, respectively. Other abbreviations are as follows: G1, male first gonopod; G2, male second gonopod; CW, carapace width. The terminology used primarily follows that of Dai (1999) and Davie et al. (2015). The Kimura 2-parameter (K2P) COI sequence distances (Kimura, 1980) were calculated using MEGA6 (Tamura et al., 2013). H.-T. Shih kindly provided the COI sequence data of various species of Nanhaipotamon for use in this study (GenBank accession nos. MK226142-MK226145).

Figure 6.1 Localities of the sampling sites in and around Macau.

Taxonomy

Family Potamidae Ortmann, 1896 Subfamily Potamiscinae Bott, 1970 Genus Cantopotamon Huang, Ahyong & Shih, 2017 Cantopotamon hengqinense Huang, Ahyong & Shih, 2017 (Fig. 6.2C) Cantopotamon hengqinense Huang, Ahyong & Shih, 2017: 9, fig. 5.

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Type material. Holotype: SYSBM 001558, male (19.9 × 16.0 mm), Dahengqin Mountain (22.11°N, 113.50°E), Hengqin Island, Zhuhai City, Guangdong, China, small hillstream, under rocks, coll. C. Huang, February 2016. Paratypes: SYSBM 001559, 1 female (13.0 × 10.6 mm), same data as holotype. SYSBM 001560–001561, 2 males (15.5 × 12.4 mm, 13.2 × 10.7 mm), same data as holotype.

Other material examined. China: IACM, 2 males (20.5 × 16.5 mm, 19.5 × 16.5 mm), Coloane (22.12°N, 113.56°E), Macau, small hillstream, under rocks, coll. K.C. Wong, November 2009. SYSBM 001640, 1 male (17.5 × 13.6 mm), Dahengqin Mountain, Hengqin Island, Zhuhai City, Guangdong, small hillstream, under rocks, coll. C. Huang, August 2017. SYSBM 001641–1644, 4 females (20.5 × 16.0 mm, 15.1 × 11.8 mm, 14.1 × 10.8 mm, 12.3 × 10.0 mm), same as SYSBM 001640. ZRC, 1 male (19.7 × 15.4 mm), Coloane, Macau, small hillstream, under rocks, coll. C. Huang, January 2018. ZRC, female (16.7 × 13.2 mm), same data as above. AM P101300, male (19.0 × 15.4 mm), Coloane, Macau, small hillstream, under rocks, coll. C. Huang, February 2018.

Distribution. Hengqin Island, Zhuhai, Guangdong; Coloane, Macau.

Conservation status. Cantopotamon hengqinense was previously only known from three hill streams in Dahengqin Mountain in Hengqin Island. This study found it to be present in another three hill streams in the neighbouring southwest corner of Coloane, Macau, which extends its extent of occurrence to 34.6 km2 (excluding sea area), area of occupancy to 11.7 km2 and number of locations to two. The populations in Hengqin and Macau are currently isolated from each other by a narrow strip of sea. Unlike the Hengqin population, whose habitat is threatened by urban development (Huang et al. 2017), the Macau population does not face serious imminent threat as all localities at which it was found are not currently open to development. Specimens from Macau are morphologically indistinguishable from those found in Hengqin Island. Cantopotamon hengqinense has not been found in Xiangzhou, Zhuhai to the north and Sanzao Island to the west despite considerable survey efforts during 2011–2018. In fact, no species of Cantopotamon are known from Sanzao 146

Island, where instead Cryptopotamon anacoluthon (Kemp, 1918) is abundant. Given that the extent of occurrence and area of occupancy of C. hengqinense is much lower than 5, 000 km2 and 5000 km2, respectively, with fewer than five known locations and projected decline in habitat quality in Hengqin, the suggested corresponding conservation status of this species under IUCN Red List criteria remains as indicated by Huang et al. (2017), as Endangered B2(a)(b).

Figure 6.2 The freshwater crabs of Macau, colour in life.A, Nanhaipotamon macau n. sp., male (29.0 × 24.2 mm), SYSBM 001654; B, Nanhaipotamon guangdongense Dai, 1997, male (35.9 × 28.8 mm), SYSBM 001645; C, Cantopotamon hengqinense Huang, Ahyong & Shih, 2017, male, specimen not collected; D, Somanniathelphusa zanklon Ng & Dudgeon, 1992, photographed in Zhuhai, specimen not collected.

Genus Nanhaipotamon Bott, 1968 Nanhaipotamon macau n. sp. (Figs. 6.2A, 6.3–6.5, 6.6A–C)

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Type material. Holotype: SYSBM 001649, male (37.4 × 30.9 mm), Coloane (22.12°N, 113.56°E), Macau, China, forest floor, coll. K.C. Wong, July 2010. Paratypes: SYSBM 001650, female (31.3 × 25.5 mm), Coloane, Macau, China, mud burrow adjacent to small hill stream, coll. C. Huang, February 2018. SYSBM 001651, male (36.6 × 29.3 mm), same data as above. IACM, 2 males (36.5 × 31.1 mm, 34.6 × 28.5 mm), Coloane, Macau, forest floor, coll. J. Z. Huang, July 2009. AM P101301, male (27.7 × 22.9 mm), same data as above. ZRC, male (22.3 × 19.0 mm) Coloane, Macau, China, under rock in small hillstream, coll. C. Huang, January 2018.

Figure 6.3 Nanhaipotamon macau n. sp., male holotype (37.4 × 30.9 mm), SYSBM 001649. A, dorsal habitus; B, cephalothorax, anterior view; C, anterior thoracic sternum and pleon, ventral view; D, sterno-pleonal cavity with right G1 in situ (left G1 removed), ventral view.

Other material examined. Macau: SYSBM 001652-55, 4 males (35.3 × 28.8 mm, 32.1 × 26.5 mm, 29.0 × 24.2 mm, 28.9 × 24.1 mm), Coloane, in burrows adjacent to small hill stream, coll. C. Huang, February 2018.

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Diagnosis. Carapace broader than long, regions indistinct, dorsal surface convex, anterolateral region weakly rugose (Figs. 6.3A, 6.4B); postorbital cristae sharp, laterally expanded, almost fused with epibranchial teeth and epigastric cristae (Figs. 6.3A, 6.4B); external orbital angle sharply triangular, outer margin gently convex to almost straight, separated from anterolateral margin by conspicuous gap (Figs. 6.3A, B, 6.4B); sub-orbital regions covered by sparse low granules, pterygostomial regions covered with short rows of a few rounded granules; sub-hepatic regions covered with lined striae (Fig. 6.3B); maxilliped III exopod reaching to proximal one-third of merus with short flagellum (Fig. 6.5A); female vulva ovate, medium-sized, positioned closely to one another (Fig. 6.4D); male pleon triangular, lateral margins almost straight (Fig. 6.3C); G1 slender, subterminal segment tapering distally, terminal segment large, distally expanded, distal margin laminar, apex blunt, directed outward (Figs. 6.5C–E, 6.6A–C). G2 basal segment subovate (Fig. 6.5B).

Figure 6.4 A, Nanhaipotamon macau n. sp., male holotype (37.4 × 30.9 mm), SYSBM 001649; B– D, female paratype (31.3 × 25.5 mm), SYSBM 001650. A, anterior thoracic sternum; B, dorsal habitus; C, pleon, ventral view; D, vulvae, ventral view.

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Description. Carapace broader than long, width about 1.2 × length (n = 6); regions indistinct, dorsal surface convex; surface generally smooth, pitted, anterolateral region weakly rugose (Figs. 6.3A, 6.4B). Front deflexed, margin ridged in dorsal view (Figs. 6.3A, 6.4B). Epigastric cristae low, separated by narrow gap (Figs. 6.3A, 6.4B). Postorbital cristae sharp, laterally expanded, almost fused with epibranchial teeth and epigastric cristae (Figs. 6.3A, 6.4B). Branchial regions slightly swollen (Figs. 6.3A, B, 6.4B). Cervical groove shallow (Figs. 6.3A, 6.4B). Mesogastric region slightly convex (Figs. 6.3A, 6.4B). External orbital angle sharply triangular, outer margin gently convex to almost straight, separated from anterolateral margin by conspicuous gap (Figs. 6.3A, B, 6.4B). Epibranchial tooth small, granular, indistinct (Figs. 6.3A, B, 6.4B). Anterolateral margin cristate, lined with 20–23 granules, less distinct in some larger specimens; bent inward posteriorly (Figs. 6.3A, 6.4B). Posterolateral surface with low, oblique striae, converging towards posterior carapace margin (Figs. 6.3A, 6.4B). Orbits large; supraorbital, infraorbital margins cristate (Fig. 6.3B). Sub-orbital regions covered by sparse low granules, pterygostomial regions covered with short rows of a few rounded granules; sub-hepatic regions covered with lined striae (Fig. 6.3B). Epistome posterior margin narrow; median lobe broadly triangular, lateral margins slightly sinuous (Fig. 6.3B). Maxilliped III merus about as wide as long; ischium width about 0.7 × length; merus subtrapezoidal, with median depression; ischium subtrapezoidal, with distinct median sulcus, mesial margin rounded. Exopod reaching to proximal one-third of merus; flagellum short (Fig. 6.5A). Chelipeds (pereiopod I) unequal (Figs. 6.3A, 6.5F–I); less inflated in females (Figs. 6.4B, 6.5H, I). Merus trigonal in cross section; margins crenulated, dorsal-outer surface granulated. Carpus with sharp spine at inner-distal angle, spinule at base (Figs. 6.3A, 6.4B). Major cheliped palm length about 1.2–1.4 × height in males (n = 5), 1.3 × in female (n = 1); dactylus 0.9–1.0 × palm length in males (n = 5), 0.9 × in female (n = 1) (Figs. 6.5G, I). Palm surface pitted, dorsal-outer surface granulated in larger males (Fig. 6.5G). Dactylus as long as pollex (Fig. 6.5F–I). Occlusal margin of fingers with irregular blunt teeth; slight gape when closed (Fig. 6.5F–I).

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Figure 6.5 A–C, F, G, Nanhaipotamon macau n. sp., male holotype (37.4 × 30.9 mm), SYSBM 001649; D, male paratype (36.6 × 29.3 mm), SYSBM 001651; E, male (35.3 × 28.8 mm), SYSBM 001652; H–I, female paratype (31.3 × 25.5 mm), SYSBM 001650. A, Left maxilliped 3; B, left G2, ventral view; C–E, left G1, ventral view; F, H, minor cheliped; G, I, major cheliped. Scale bars A–E 1.0 mm; F–I 5.0 mm.

Ambulatory legs (pereiopods II–V) slender, setae short, very sparse (Figs. 6.3A, 6.4B). Pereiopod III merus 0.6–0.7 × carapace length in males (n = 5), 0.6 × carapace length in female (n = 1) (Figs. 6.3A, 6.4B). Pereiopods V propodus 2.1–2.2 × as long as

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broad in males (n = 5), 2.1 × as long as broad in female (n = 1), shorter than dactylus (Figs. 6.3A, 6.4B). Male thoracic sternum generally smooth; sternites I–IV narrow, width about 1.5 × length; sternites I, II forming triangular structure; sternites II, III fused, but demarcated by shallow transverse sulcus; sternites III, IV fused, demarcation inconspicuous (Fig. 6.4A). Male sterno-pleonal cavity reaching anteriorly beyond level of posterior articular condyle of cheliped coxa (Fig. 6.4A); deep median longitudinal groove between sternites VII, VIII (Fig. 6.3D). Male pleonal locking tubercle positioned at mid-length of sternite V (Fig. 6.3D). Female vulva ovate, medium-sized, not reaching the sutures of sternites V/VI or VI/VII, positioned closely to one another (Fig. 6.4D). Male pleon triangular; somites III–VI progressively narrower, lateral margins almost straight; somite VI width 1.8–2.1 × length (n = 6); telson width 1.3–1.4 × length (n = 6); apex rounded (Fig. 6.3C). Female pleon broadly ovate (Fig. 6.4C). G1 slender; in-situ, tip of terminal segment exceeding pleonal locking tubercle, almost reaching suture between thoracic sternites IV/V (Fig. 6.3D); subterminal segment length about 3.1 × length of terminal segment; subterminal segment tapering distally; terminal segment large, distally expanded, distal margin laminar, slightly sinuous to V- shaped, apex blunt, directed outward, orientation perpendicular to oblique to main axis of G1 (Figs. 6.5C–E, 6.6A–C). G2 subterminal segment about 1.9 × length of flagelliform distal segment; exopod absent (Fig. 6.5B).

Etymology. This species is named after the type locality, Macau; used as a noun in apposition.

Colour in life. Variable, carapace and ambulatory legs dark brown to purple; chelipeds a combination of brown, orange and white (Fig. 6.2A).

Habitat. Nanhaipotamon macau n. sp. is a typical semi-terrestrial species that burrows in wet soil in the bank adjacent to hill streams. It was syntopic with Cantopotamon

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hengqinense at three localities (22.117°N, 113.566°E, 22.118°N, 113.559°E, 22.128°N, 113.561°E).

Figure 6.6 A–C, Nanhaipotamon macau n. sp., male holotype (37.4 × 30.9 mm), SYSBM 001649; D–F, Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003, male neotype (22.4 × 18.3 mm), JX 050563; G, Nanhaipotamon guangdongense Dai, 1997, male, (30.9 × 24.8 mm), SYSBM 001646. A, D, E, left G1, ventral view; B, left G1, dorsal view; C, Left G1 terminal segment, ventral view; F, G, Left G2, ventral view. Scale bar 1.0 mm.

Distribution. Coloane, Macau. 153

Remarks. As with many other species of Nanhaipotamon, N. macau n. sp. shows intraspecific variation in G1 morphology. In the terminal segment, the curves of the inner- distal and distal margins vary (Fig. 6.5C–E). The general shape and large size of the terminal segment, however, readily separates N. macau from other congeners in the Pearl River Delta Region, such as N. guangdongense Dai, 1997 (Fig. 6.7). Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003, from Fujian Province, is the only other known congener that also possesses such a large terminal segment. Based on the redscription of N. wupingense below, N. macau n. sp. differs by its larger maximum size (CW to 37.4 mm vs 27.5 mm in N. wupingense; Cheng et. al., 2003); more inflated and less rugose branchial regions (compare Figs. 6.3A, B, 6.8A, B); pterygostomial region granules larger, less numerous (compare Figs. 6.3B, 6.8B); the G1 tip usually points laterally and the convex anterior margin next to the tip is often lower (Figs. 6.5C–E, 6.6A–C) (tip points anterolaterally with higher adjacent convex margin, Fig. 6.6D; Cheng et. al., 2003: fig. 7); G1 subterminal segment length about 3.0–3.2 × length of terminal segment in N. macau n. sp. (Figs. 6.5C–E, 6.6A) (2.7 in the neotype of N. wupingense, see below, Fig. 6.6D). In keeping with their wide geographic separation, sequences of the COI barcoding region between N. macau n. sp. (SYSBM 001654; GenBank accession number MK226142) and N. wupingense (GenBank accession number: AB470511.1), courtesy of Hsi-Te Shih, shows a high (13.51%) Kimura 2-parameter (K2P) distance, corroborating their separate species status.

Conservation status. Nanhaipotamon macau n. sp. has an extremely restricted distribution with an extent of occurrence of only 5.3 km2 (excluding sea area) and an area of occupancy of around 3 km2. However, all 12 hill streams at which N. macau was found are not currently open to urban development (one of these, Ka-Ho Reservoir Freshwater Wetland, is a protected area) and they seem to be locally abundant. We are unaware of any commercial harvesting of these crabs for human consumption or the aquarium trade. As such, no imminent threats to this species are apparent and we suggest the status of “Least Concern” according to the IUCN Red List criteria. However, we emphasize the fragility of

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this species due to its highly restricted distribution; the habitat integrity of the hills of Coloane is paramount to this species’ survival.

Nanhaipotamon guangdongense Dai, 1997 (Figs. 6.2B, 6.6G, 6.7) Nanhaipotamon guangdongense Dai, 1997: 229, fig. 9; Dai, 1999: 121, pl. 8(1), fig. 60 — Huang et al., 2012: 57, fig. 1A, 60; fig. 4, 61; fig. 5A–C.

Type material. Holotype: AS-CB 05141, male (33.2 × 26.4 mm), Guangdong Province, China, gift from Sun Yat-Sen Medical College, no date [photographs examined].

Other material examined. SYSU 001001, male (38.5 × 30.0 mm), Xiangzhou (22.25°N, 113.57°E), Zhuhai City, Guangdong, blue, mud hole next to small hillstream, coll. C. Huang, May 2012. SYSBM 001003, 1 male (36.2 × 28.4 mm), Xiangzhou, Zhuhai City, Guangdong, mud hole next to small hill stream, coll. C. Huang, February 2011. SYSBM 001004, 1 male (30.5 × 24.3 mm), Xiangzhou, Zhuhai City, Guangdong, mud hole next to small hill stream, coll. C. Huang, August 2012. SYSBM 001177, 1 male (35.4 × 29.4 mm), Xiangzhou, Zhuhai City, Guangdong, mud hole next to small hill stream, coll. C. Huang, May 2013. SYSBM 001178, 1 female, (35.9 × 29.4 mm), same data as above. SYSU 001758–001760, 3 males (40.1 × 32.7 mm, 36.0 × 29.8 mm, 30.2 × 25.1 mm), Xiangzhou, Zhuhai City, Guangdong, blue, mud hole next to small hillstream, coll. C. Huang, September 2018. SYSU 001761–001764, 4 males (42.1 × 33.5 mm, 40.5 × 32.4 mm, 38.1 × 32.0 mm, 32.5 × 27.0 mm), Xiangzhou, Zhuhai City, Guangdong, mud hole next to small hill stream, coll. C. Huang, September 2018. SYSBM 001141–001143, 3 males (38.4 × 31.5 mm, 40.8 × 32.2 mm, 36.7 × 29.4 mm), Gujing (22.36°N, 113.12°E), Jiangmen City, Guangdong, coll. local, August 2013. IACM, 2 males (39.5 × 31.5 mm, 25.2 × 21.1 mm), Taipa (22.16°N, 113.58°E), Macau, mud hole next to small hill stream, coll. K.C. Wong, March 2018. SYSBM 001645–001646, 2 males (35.9 × 28.8 mm, 30.9 × 24.8 mm), Taipa, Macau, mud hole next to small hill stream, coll. C. Huang, June 2018. SYSBM 001656, 1 male (45.5 × 37.0 mm), Dahengqin mountain (22.11°N, 113.50°E), Hengqin Island, Zhuhai 155

City, Guangdong, in small hill stream pool, coll. C. Huang, August 2017. SYSBM 001672, 1 male (22.4 × 18.5 mm), Jinwan (22.08°N, 113.35°E), Zhuhai City, Guangdong, mud hole next to small hill stream, coll. C. Huang, June 2018. SYSBM 001673–001674, 2 females (31.7 × 25.7 mm, 25.9 × 20.8 mm), same data as above. SYSBM 001017–001019, 3 males (33.4 × 26.5 mm, 29.2 × 23.6 mm, 27.6 × 21.7 mm), Doumen (22.19°N, 113.29°E), Zhuhai City, Guangdong, coll. local, April 2013. SYSBM 001657–001658, 2 males (36.9 × 30.4 mm, 23.0 × 19.5 mm), Reservoir (22.48°N, 113.38°E), Zhongshan City, Guangdong, mud hole next to small hill stream, coll. C. Huang, January 2018. SYSBM 001659, 1 female (23.6 × 19.8), same data as above. SYSBM 001016, 1 male (40.5 × 33.1 mm), Qi’ao Island (22.43°N, 113.66°E), Zhuhai City, Guangdong, mud hole next to small hill stream, coll. C. Huang, May 2011. SYSBM 001023, 1 female (40.5 × 33.1 mm), same data as above. SYSBM 001750, 1 male (39.6 × 32.5 mm), Gudou Mountain (22.22°N, 112.97°E), Jiangmen City, Guangdong, coll. local, July 2018. SYSBM 001751, 1 male (35.1 × 26.0 mm), Xinhui (22.52°N, 113.08°E), Jiangmen City, Guangdong, coll. local, July 2018.

Colour in life. Highly variable, even within the same population. Carapace and ambulatory legs dark brown to purple; chelipeds a combination of brown, orange and white (Fig. 6.2B). Blue variants are sometimes seen.

Distribution. Guangdong: Zhuhai, Zhongshan, Jiangmen; Macau: Taipa.

Remarks. Nanhaipotamon guangdongense has been found at only one locality in Macau (Tai Tam Hill, Taipa). One specimen (SYSBM 001646) has exopods on the G2 on both sides, the first such report for a freshwater crab (Fig. 6.6G). The G2 exopod is likely the result of a developmental abnormality and is an extremely rare occurrence (Gordon, 1963). The majority of brachyurans lack the male G2 exopod although it is being increasingly recognized as a normal feature among many pinnotherid crabs (Ahyong et al. 2012; Ng & Ho, 2016).

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Figure 6.7 Comparison of G1 of Nanhaipotamon guangdongense Dai, 1997, from different localities. A, male (38.4 × 31.5 mm), SYSBM 001141, Gujing, Jiangmen; B, male (40.8 × 32.2 mm), SYSBM 001142, Gujing, Jiangmen; C, male (36.7 × 29.4 mm), SYSBM 001143, Gujing, Jiangmen; D, male (35.4 × 29.4 mm), SYSBM 001177, Xiangzhou, Zhuhai; E, male (32.5 × 27.0 mm), SYSBM 001764, Xiangzhou, Zhuhai; F, male (40.1 × 32.7 mm), SYSBM 001758, Xiangzhou, Zhuhai; G, male (35.9 × 28.8 mm), SYSBM 001645, Coloane, Macau; H, male (45.5 × 37.0 mm), SYSBM 001656, Hengqin Island, Zhuhai; I, male (22.4 × 18.5 mm), SYSBM 001672, Jinwan, Zhuhai; J, male (33.4 × 26.5 mm), SYSBM 001017, Doumen, Zhuhai; K, male (36.9 × 30.4 mm), SYSBM 001657, Jinzhong Reservoir, Zhongshan; L, male (40.5 × 33.1 mm), SYSBM 001016, Qi’ao Island, Zhuhai. Scale bars 1.0 mm.

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Little was previously known about N. guangdongense as it was described from a single specimen without a precise locality. Attempts to sequence the DNA of N. guangdongense were unsuccessful, probably because of formalin fixation, compounding the problem of its identification (Shih et al., 2011). Huang et al. (2012) reported N. guangdongense from Zhuhai. Small differences in the G1 morphology, however, suggest the holotype of N. guangdongense was probably collected from another locality (Peter Ng, pers. comm.). More recent collection efforts in Guangdong have found this species at multiple locations in Zhuhai, Zhongshan, and Jiangmen. Specimens from Gujing, Jiangmen (Figs. 6.7A–C) most closely resemble the holotype in G1 morphology suggesting that the holotype was probably collected from that area. Normal and blue coloured Nanhaipotamon were syntopic at a locality in Xiangzhou, Zhuhai. Nanhaipotamon zhuhaiense Huang, Huang & Ng, 2012 was described based on only three blue specimens that had a distinctive G1 that pointed laterally and not anterolaterally as seen in the normal coloured comparative specimens. More recent collections from Xiangzhou, Zhuhai, however, have found a normal coloured specimen that has a laterally pointing G1 (Fig. 6.7E) and also a blue specimen that has an anterolaterally pointing G1 (Fig. 6.7F). Therefore, the colouration of the crab does not always correspond to a particular gonopod morphology. Specimens of intermediate G1 morphology have also been collected, while one uncollected female specimen was observed to be of intermediate colour. Furthermore, the COI K2P distances between the blue specimens SYSBM 001001 (GenBank no: MK226143), SYSBM001249 (GenBank no: MK226144) and the normal coloured specimen SYSBM 001015 (GenBank no: MK226145) are 1.23% and 0.77% respectively, which is of intraspecific level among closely related congeners. This new evidence strongly suggests that the normal and blue coloured crabs are different colour phases of the same species, but the G1 morphological differences between different specimens remains to be further studied. This seems to be a similar case to that of N. hepingense Dai, 1977, and N. pinghense Dai, 1977 (see Shih et al., 2011; Huang et al., 2012). Given that we are unable to confidently separate N. zhuhaiense from N. guangdongense, we regard them as probably conspecific, but refrain from making formal taxonomic changes until further detailed comparisons can be completed. 158

The G1 of specimens of N. guangdongense from different localities varies (Fig. 6.7). It is becoming increasingly evident that intraspecific variation of gonopodal morphology in some species of Nanhaipotamon is wider than previously recognized, while external differences are often hard to detect between species, making the taxonomy of this genus problematic (Figs. 6.5C–E, 6.7, Huang et al., 2012: fig. 5; unpublished data). Clearly, there is need for a revision of this genus. To avoid compounding the problem in the future, we strongly recommend that new species of Nanhaipotamon should only be described when a large series of specimens is available to account for intraspecific variation.

Conservation status. Nanhaipotamon guangdongense was previously assessed as Data Deficient, being known from one unspecified location in Guangdong (Cumberlidge, 2008). This species is sometimes collected for food and for the pet trade, though we are uncertain as to the extent. Nevertheless, this species has been found in many locations with a wider range than previously thought, having an extent of occurrence of around 2,400 km2 (excluding sea area) and an area of occupancy of around 1,600 km2. As such, we suggest the conservation status of this species under IUCN criteria would be more appropriate as Least Concern (LC). Nevertheless, N. guangdongense is quite rare in Macau, being found in only one location in the Ecological Pond of Grand Taipa, and thus may warrant local conservation attention.

Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003 (Figs. 6.6D–F, 6.8) Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003: 678, figs 1–8.

Type material. Neotype: JX 050563, male (22.4 × 18.3 mm), Xiaba (24.89°N, 116.05°E), Wuping county, Longyan City, Fujian Province, China, coll. X. M. Zhou, May 2007.

Other material examined. JX 050564, JX 050566, JX 050568–050569, 4 males (16.2 × 13.2 mm, 15.5 × 12.6 mm, 13.0 × 10.9 mm, 14.0 × 11.5 mm), same data as neotype. JX 050565, JX 050567, JX050570–050576, 9 females (16.1 × 13.2 mm, 13.0 × 10.5 mm, 25.3 159

× 20.8 mm, 23.4 × 19.5 mm, 24.9 × 20.3 mm, 21.6 × 17.6 mm, 16.9 × 13.7 mm, 14.8 × 11.7 mm, 15.2 × 12.4 mm), same data as neotype.

Figure 6.8 A–D, Nanhaipotamon wupingense Cheng, Yang, Zhong & Li, 2003, male neotype (22.4 × 18.3 mm), JX 050563; E–F, female (25.3 × 20.8 mm), JX050570. A, dorsal habitus; B, cephalothorax, anterior view; C, anterior thoracic sternum and pleon, ventral view; D, sterno- pleonal cavity with right G1 in situ (left G1 removed), ventral view; E, pleon, ventral view; F, vulvae, ventral view.

Description. Carapace broader than long, width about 1.2 × length (n = 14); regions indistinct, dorsal surface convex; surface generally smooth, pitted, anterolateral region slightly rugose (Fig. 6.8A). Front deflexed, margin ridged in dorsal view (Fig. 6.8A). Epigastric cristae low, separated by narrow gap (Fig. 6.8A). Postorbital cristae sharp, laterally expanded, almost confluent with epibranchial teeth and epigastric cristae (Fig. 160

6.8A). Branchial regions slightly swollen (Fig. 6.8A, B). Cervical groove shallow (Fig. 6.8A). Mesogastric region slightly convex (Fig. 6.8A). External orbital angle sharply triangular, outer margin gently convex, separated from anterolateral margin by conspicuous gap (Fig. 6.8A, B). Epibranchial tooth small, granular, indistinct (Fig. 6.8A, B). Anterolateral margin cristate, lined with 17–20 granules, less distinct in some larger specimens; curved inward posteriorly (Fig. 6.8A). Posterolateral surface with low, oblique striae, converging towards posterior carapace margin (Fig. 6.8A). Orbits large; supraorbital, infraorbital margins cristate (Fig. 6.8B). Sub-orbital, pterygostomial and sub-hepatic regions covered with numerous rounded granules (Fig. 6.8B). Epistome posterior margin narrow; median lobe broadly triangular, lateral margins slightly sinuous (Fig. 6.8B). Maxilliped III merus about as wide as long; ischium width about 0.7 × length; merus subtrapezoidal, with median depression; ischium subtrapezoidal, with distinct median sulcus, mesial margin rounded. Exopod reaching to proximal one-third of merus; flagellum short. Chelipeds (pereiopod I) unequal (Fig. 6.8A); less inflated in females. Merus trigonal in cross section; margins crenulated, dorsal-outer surface granulated (Fig. 6.8A). Carpus with sharp spine at inner-distal angle, spinule at base (Fig. 6.8A). Major cheliped palm length about 1.3 × height (n = 1) in males, 1.3–1.4 × height (n = 4) in females; dactylus about 1.0 × palm length (n = 1) in males, 1.0–1.1 × palm length (n = 4) in females. Palm surface pitted. Dactylus as long as pollex (Cheng, Yang, Zhong & Li, 2003: fig. 1). Occlusal margin of fingers with irregular blunt teeth; slight gape when closed. Ambulatory legs (pereiopods II–V) slender, setae short, very sparse (Fig. 6.8A). Pereiopod III merus 0.6 × carapace length (n = 3) in males, 0.6–0.7 × carapace length (n = 7) in females (Fig. 6.8A). Pereiopods V propodus 2.3–2.4 × as long as broad in males (n = 3), 2.3–2.4 × as long as broad in females (n = 5), shorter than dactylus (Fig. 6.8A). Male thoracic sternum generally smooth; anterior thoracic sternum (sternites I–IV) narrow, width about 1.5 × length; sternites I, II forming triangular structure; demarcation between sternites II, III complete; sternites III, IV fused with vestigial median suture (Fig. 6.8C). Male sterno-pleonal cavity reaching anteriorly beyond level of posterior articular condyle of cheliped coxa (Fig. 6.8C); deep median longitudinal groove between sternites 161

VII, VIII (Fig. 6.8D). Male pleonal locking tubercle positioned at mid-length of sternite V (Fig. 6.8D). Female vulva ovate, not reaching the sutures of sternites V/VI or VI/VII, positioned closely to one another (Fig. 6.8F). Male pleon triangular, lateral margins almost straight; somites III–VI progressively narrower; somite VI width 2.1–2.2 × length (n=2); telson width 1.2–1.3 × length (n=2); apex rounded (Fig. 6.8C). Female pleon broadly ovate (Fig. 6.8E). G1 slender; in-situ, tip of terminal segment exceeding pleonal locking tubercle, reaching suture between thoracic sternites IV/V (Fig. 6.8D, G1 not flat against the body); subterminal segment length about 2.7 × length of terminal segment; subterminal segment tapering posteriorly; terminal segment large, distally expanded, anterior margin laminar, convex anterior margin next to the tip high, tip blunt (Fig. 6.6D, E). G2 subterminal segment about 2.1 × length of flagelliform distal segment; exopod absent (Fig. 6.6F).

Distribution. Currently only known from Xiaba, Wuping County, Longyan City, Fujian.

Remarks. The original description of Nanhaipotamon wupingense is brief and minimally illustrated (Cheng et al., 2003), neither describing nor figuring details of the carapace physiognomy and pterygostomial ornamentation, which are diagnostic differences between N. wupingense and N. macau n. sp. Although the gonopods of N. wupingense were described and figured, and were distinctive at the time of original description, they are similar to that to the newly discovered N. macau n. sp. As such the type account of N. wupingense could apply equally to N. macau n. sp. Unfortunately, the type material of N. wupingense is now lost: according to the first author of N. wupingense, the type material of N. wupingense, which was originally deposited in Fujian Research Institute of Parasite Disease, Fuzhou, Fujian Province, was lost during relocation (YZ Cheng, pers. comm.). Therefore, in order to fix the identity of N. wupingense and allow adequate characterization of both species, we hereby designate a neotype for N. wupingense in accordance to ICZN (1999: art. 75.3). The neotype of N. wupingense (male, 22.4 × 18.3 mm, JX 050563) and other examined specimens of the species were collected from the original type locality. The neotype G1 corresponds well to that originally described and figured for N. wupingense, 162

although we note some minor differences in morphometrics compared to the original type description (Cheng et al., 2003). The G1 subterminal/terminal segment length ratio of N. wupingense is 3.0 according to Cheng et al. (2003), but, we measure the ratio at 2.7 in the neotype (Fig. 6.6D) and 2.6 based on the illustration of the G1 of the holotype (Cheng et al., 2003: fig. 7). The G2 subterminal/terminal segment length ratio of N. wupingense is inconsistently recorded in Cheng et al. (2003): 1.8 in the Chinese description, erroneously as 2.7 in the English abstract, and 2.0 if is based on the figure of the holotype G2 (Cheng et. al., 2003: fig. 6). This ratio could not be measured for the neotype as the G2 terminal segment broke off inside the G1 during dissection, although the ratio in JX 050564, a sub- adult, is 2.2 (Fig. 6.6F). The G1 is not fully developed in this specimen (Fig. 6.6E).

Family Gecarcinucidae Rathbun, 1904 Genus Somanniathelphusa Bott, 1968 Somanniathelphusa zanklon Ng & Dudgeon, 1992 (Figs. 6.2D, 9) Somanniathelphusa zanklon Ng & Dudgeon, 1992: figs 11–13. Somanniathelphusa sinensis — Dai, 1999: 67, fig. 29, pl. 2. (not Parathelphusa sinensis H. Milne Edwards, 1853) Parathelphusa sinensis — Doflein, 1902: 662. (not Parathelphusa sinensis H. Milne Edwards, 1853) Parathelphusa (Parathelphusa) sinensis — Gee, 1925: 159; Wu, 1934: 339. (not Parathelphusa sinensis H. Milne Edwards, 1853) Somanniathelphusa sinensis sinensis — Bott, 1968b: 409, figs 11, 12, 30; Bott, 1970a: 338; Bott, 1970b: 111, pl. 20, figs 42–44; Ng, 1988: 105. (not Parathelphusa sinensis H. Milne Edwards, 1853)

Material examined. SYSBM 101001, 1 male (27.2 × 23.1 mm), Nanping (22.19°N, 113.5°E), Zhuhai City, Guangdong, reservoir, coll. C. Huang, April 2015. SYSBM 101002–101003, 2 males (38.8 × 31.9 mm, 30.4 × 25.6 mm), Jinding (22.38°N, 113.54°E), Zhuhai City, Guangdong, coll. local, May 2014. SYSBM 101004–101005, 2 males (42.0 × 163

33.5 mm, 34.2 × 28.1 mm), Sun Yat-sen University (23.10°N, 113.30°E), Guangzhou City, Guangdong, fish pond, coll. C. Huang, June 2013. SYSBM 101006, 1 female (37.1 × 29.5 mm), same data as above. SYSBM 101007, 1 male (30.6 × 24.5 mm), Coloane (22.12°N, 113.56°E), Macau, reservoir, coll. K.C. Wong, July 2008. SYSBM 101008, 1 male (28.2 × 22.5 mm), Coloane, Macau, reservoir, coll. K.C. Wong, July 2009. IACM, 1 male (24.2 × 19.8 mm), Coloane, Macau, reservoir, coll. K.C. Wong, February 2013. SYSBM 101009– 101010, 2 males (19.5 × 16.8 mm, 19.2 × 16.4 mm), Shenzhen City (22.6°N, 114.0°E), Guangdong, coll. local, August 2015. SYSBM 101011, 1 female (19.6 × 16.4 mm), same data as above. SYSBM 101015–101016, 2 males (35.7 × 28.4 mm, 37.2 × 29.9 mm), Sihui City (23.12°N, 113.56°E), Guangdong, coll. local, August 2013. SYSBM 101017, 1 female (31.6 × 25.9 mm), same data as above. SYSBM 101018–101020, 3 males (38.2 × 30.8 mm, 35.4 × 28.1 mm, 28.3 × 21.3 mm), Renhua, Shaoguan City, Guangdong, coll. local, August 2013. SYSBM 101021, 1 male (31.5 × 26.6 mm), Lianhua Mountain, Shanwei City, Guangdong, coll. local, October 2013. SYSBM 101022, 1 female (27.3 × 23.2 mm), same data as above. SYSBM 101030, 1 male (39.4 × 33.0 mm), Heyuan City, Guangdong, coll. Z.C. Zhou, January 2014. SYSBM 101031, 1 female (32.4 × 27.3 mm), same data as above. SYSBM 101032–101035, 4 males (35.0 × 28.3 mm, 32.7 × 26.9 mm, 30.8 × 25.0 mm, 25.9 × 21.7 mm), Raoping, Chaozhou City, Guangdong, coll. Z.C. Zhou, January 2014. SYSBM 101036, 1 female (24.6 × 20.8 mm), same data as above. SYSBM 101037–101040, 4 males (26.3 × 20.4 mm, 30.9 × 25.8 mm, 26.6 × 23.0 mm, 27.0 × 22.5 mm), Wenzhou City, Zhejiang, coll. local, October 2013. SYSBM 101041, 1 female (29.8 × 24.6 mm), same data as above.

Colour in life. Generally brown overall; larger individuals may have dark markings near the cardiac region (Fig. 6.2D).

Distribution. Coloane, Macau; Guangdong: Guangzhou City, Shenzhen City, Zhuhai City, Sihui City, Shaoguan City, Shanwei City, Heyuan City, Chaozhou City; Zhejiang: Wenzhou City.

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Figure 6.9 Comparison of G1 of Somanniathelphusa zanklon Ng & Dudgeon, 1992, from different localities. A, Male (30.6 × 24.5 mm), SYSBM 101007, Coloane, Macau; B, male (38.8 × 31.9 mm), SYSBM 101002, Jinding, Zhuhai City, Guangdong; C, male (42.0 × 33.5 mm), SYSBM 101004, Sun Yat-sen University, Guangzhou City, Guangdong; D, male (35.7 × 28.4 mm), SYSBM 101015, Sihui City, Guangdong; E, male (28.3 × 21.3 mm), SYSBM 101020, Renhua, Shaoguan City, Guangdong; F, male (31.5 × 26.6 mm), SYSBM 101021, Lianhua Mountain, Shanwei City, Guangdong; G, male (35.0 × 28.3 mm), SYSBM 101032, Raoping, Chaozhou City, Guangdong; H, male (26.3 × 20.4 mm), SYSBM 101037, Wenzhou City, Zhejiang. Scale bars 1.0 mm.

Remarks. Ng & Dudgeon (1992) showed former records of Somanniathelphusa sinensis (H. Milne Edwards, 1853) from southern China (Bott, 1968, 1970; Dai, 1999) to represent a

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new species, S. zanklon. Shih et al. (2007) included S. zanklon from Hong Kong and Guangdong (Dongguan City and Nanhai City) and showed that specimens of Somanniathelphusa from eastern Guangdong, Fujian and west-central Taiwan were all very closely related genetically, probably even conspecific. Specimens examined here from different localities were all very similar morphologically (Fig. 6.9), with those from Zhejiang Province having a slightly longer G1 distal part (Fig. 6.9H), though the overall shape is very much like the others. We tentatively treat all of these as the same species pending a full revision. Interestingly, Dai (1999) also reported the genus from Zhejiang, but none of the species of Somanniathelphusa in her monograph lists Zhejiang among its localities. The Chinese Somanniathelphusa are particularly problematic as many species look identical externally and were described based on minute differences that we find difficult to detect. Furthermore, being lowland species, they are readily dispersed by floods and are commonly found in aquaculture ponds where their newly hatched crablings are easily translocated. Preliminary genetic evidence suggests that the species diversity of Somanniathelphusa may have been overestimated (Shih et al., 2007).

Conservation status. Somanniathelphusa zanklon is currently assessed as Endangered (Esser & Cumberlidge, 2008) as it was known from fewer than five locations in Hong Kong with a extant of occurrence less than 5,000 km2, with degrading habitat quality. Our study, however, finds this species to have a widespread occurrence in south-east China with an area of occupancy estimated at over 120,000 km2. Though habitat quality in some of these locations is declining, this resilient lowland species seems to be able to thrive in most water bodies that are not heavily polluted. As such, we find that S. zanklon does not satisfy any IUCN Red List threat categories and thus we suggest Least Concern would be a more appropriate determination at present. In Macau, all known occurrences of S. zanklon are from Hac-Sa Reservoir, Coloane, although it most likely also occurs in other water bodies in Coloane. There was an unconfirmed sighting of S. zanklon in Taipa a few years ago by the second author, though more recent surveys have failed to locate any specimens. There are three large water bodies on the Macau peninsula, of which only one reservoir on the east, next to Parque Municipal do Monte da Guia, which sources freshwater from the 166

mainland, is suitable for lowland freshwater crabs. Although we did not survey this reservoir, it very likely also holds S. zanklon as this species was found in one of its water source reservoirs in Zhuhai. The other two water bodies, and , were once bays that have mostly been artificially closed off by landfill and currently hold sea water.

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Chapter 7.

A new long-legged terrestrial freshwater crab, Calcipotamon puglabrum n. gen., n. sp. (Crustacea: Decapoda: Potamidae), from Hainan Island, China

Chao Huang, Sheng-Zhuo Huang and Zhi-Xin Shen Zootaxa, 4766 (3), 447–456

Abstract

A new genus and new species of terrestrial freshwater crab, Calcipotamon puglabrum gen. nov. et sp. nov., is described from the limestone forests of Changjiang, Hainan Island, China, based on morphology and mitochondrial 16S rDNA sequences. The new genus is closest to Neotiwaripotamon Dai & Naiyanetr, 1994, and Tiwaripotamon Bott, 1970, but differs in a combination of carapace, third maxilliped, ambulatory leg and male gonopod characters. Molecular analysis shows that the new genus is closely related with but not clustered within other Hainan potamid genera. Notes on the general biology of this new species are also provided.

Key words: freshwater crab, Hainan, new genus, new species, Potamidae, systematics

Introduction

Being the most southern province of China, Hainan has a mostly tropical monsoonal climate and is home to a vast array of flora and fauna. The island is within the Huanan, Huang, Ebach & Ahyong, 2020, freshwater zoogeographic province, which belongs to the Dongyang, Zhang, 1954, dominion of the China, Berg, 1933, subregion (Huang et al. 2020). Currently, there are seven potamid species from three genera that have been recorded from

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the island (Apotamonautes hainanensis (Parisi, 1916), Hainanpotamon daiae Yeo & Naruse, 2008, Hainanpotamon fuchengense Dai, 1995, Hainanpotamon helense Dai, 1995, Hainanpotamon orientale (Parisi, 1916), Neotiwaripotamon jianfengense Dai & Naiyanetr, 1994 and Neotiwaripotamon whiteheadi (Parisi, 1916)). In addition, Apotamonautes hainanensis has four subspecies (Apotamonautes hainanensis banshuiensis Dai & Xing, 1993, Apotamonautes hainanensis bawanglingensis Dai & Xing, 1993, Apotamonautes hainanensis hainanensis (Parisi, 1916) and Apotamonautes hainanensis nanlinensis Dai & Xing, 1993). From 2018, the Institute of Freshwater Fishery of the Hainan Academy of Ocean and Fisheries Sciences has been engaged in the surveying of freshwater fauna from , Changhua River, , Mt. Jianfeng, Mt. Bawang, Mt. Diaoluo, Mt. E’xian, Mt. Yingge, Mt. Limu etc. During a joint survey in Changjiang Li Autonomous County, the second author discovered some interesting terrestrial crabs from a karst forest in around 900 m a.s.l. Being purple, long-legged and very smooth allover, these crabs are obviously different from all known potamid species of Hainan. Though species from the genus Neotiwaripotamon Dai & Naiyanetr, 1994, and Tiwaripotamon Bott, 1970, are also long-legged, the new species’ unique combination of carapace, third maxilliped, ambulatory leg and male gonopod characters suggests that it does not belong to any known genera. Molecular analysis based on mitochondrial 16S rDNA sequences shows that the new species is closely related with but not clustered within other Hainan potamid genera, giving support to our taxonomic treatment. As of such, we herein establish a new genus for this new species, Calcipotamon puglabrum gen. nov. et sp. nov.

Material and methods

Specimens were collected by hand and preserved in 75% ethanol from Hainan Island and deposited in the Sun Yat-sen Museum of Biology, Sun Yat-sen University, Guangzhou, China (SYSBM) and the Australian Museum, Sydney, Australia (AM). Measurements, in millimeters, are of the carapace width and length, respectively. Other abbreviations are as follows: G1, male first gonopod; G2, male second gonopod; CW, carapace width. The terminology used primarily follows that of Dai (1999) and Davie et al. (2015).

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Genomic DNA was isolated from the muscle tissue of legs (males) or pleopods (females) using the universal DNA purification kit (Tiangen, Beijing, China). A region of ~550 basepairs (bp) of the 5’-end of the 16S gene was selected for amplification with polymerase chain reaction (PCR) using the primers 1471 and 1472 (Crandall & Fitzpatrick 1996). The PCR conditions for the above primers were denaturation for 50 s at 94 °C, annealing for 40 s at 52 °C, and extension for 60 s at 72 °C (35 cycles), followed by extension for 5 min at 72 °C. Sequences were obtained by automated sequencing (BGI Genomics, Qingdao, China). Comparative sequences were acquired from GenBank. Sequences were aligned with the aid of ClustalW (Thompson et al., 1994) in MEGA X (Kumar et al., 2018), after verification with the complementary strand. We followed Shih et al. (2009) in excluding the variable regions in loop regions of the 16S that could not be aligned adequately for phylogenetic analyses. Sequences of the new taxa have been deposited in GenBank (access numbers: MN401337 and MN401338). To confirm the systematic position of the new taxa, a preliminary analysis showed that the new species belongs to the “Hainan Island” (Huang et al.,2018) sub-clade of the “China- East Asia Islands” clade (Shih et al. 2009). Megapleonum ehuangzhang Huang, Shih & Ahyong, 2018, which is basal to all other species within the “China-East Asia Islands” clade was selected as the outgroup. All three known Hainanese genera (Apotamonautes Dai, 1993, Hainanpotamon Dai, 1995, and Neotiwaripotamon) and some representatives from the “South China #1” subclade (Cantopotamon Huang, Ahyong & Shih, 2017, Minutomon Huang, Mao & Huang, 2014 and Yarepotamon Dai & Türkay, 1997), “East Asia Island Arc” subclade (Candidiopotamon Bott, 1967, Geothelphusa Stimpson, 1858, Ryukyum Ng & Shokita, 1995) and the “South China-Vietnam” subclade (Tiwaripotamon Bott, 1970, Luteomon Huang, Shih & Ahyong, 2018) were selected for the analysis. In total, 13 ingroup species from 12 genera and one outgroup species were genetically analysed. Bayesian inference (BI) analysis was performed with MrBayes (v. 3.2.7; Ronquist & Huelsenbeck 2003). Model parameters were sampled across the substitution model space. The search was run with four chains for 10 million generations, with trees sampled every 1,000 generations. Convergence of the analyses was assessed by the standard deviation of split frequencies (<0.01), the first 1000 trees were discarded as burn-in accordingly. A 170

maximum parsimony (MP) analysis was conducted using PAUP4 (v. 4.0a165; Swofford 2002) with a simple heuristic search (500 random-addition sequence replications using TBR branch-swapping). Gaps were treated as missing and all characters equally weighted. Topological robustness was assessed using 2000 bootstrap reiterations.

Systematics

Family Potamidae Ortmann, 1896 Subfamily Potamiscinae Bott, 1970 Genus Calcipotamon n. gen. (Figs. 7.1–7.3, 7.5)

Type species. Calcipotamon puglabrum n. gen., n. sp., by current designation.

Diagnosis. Carapace broader than long, smooth allover, generally convex (Fig. 7.1); epigastric cristae smooth, low (Fig. 7.1); external orbital tooth prominent, sharp, separated from anterolateral margin by gap (Fig. 7.1). Median lobe of epistome broadly triangular (Fig. 7.2A). Maxilliped III with relatively broad ischium, exopod reaching beyond anterior edge of ischium, flagellum very short to absent (Fig. 7.3A). Cheliped palm surface smooth (Figs. 7.1, 7.3F–G). Ambulatory legs very slender (Fig. 7.1). Male anterior thoracic sternum relatively narrow, width 1.5 × length (Fig. 7.2B). Male pleon narrowly triangular (Fig. 7.2C). Female pleon ovate (Fig. 7.4E). G1 generally slender, terminal segment elongated with basal flap (Figs. 7.3C–E, H–I). G2 with long flagellum-like terminal segment (Fig. 7.3B). Female vulva positioned closely to one another, ovate, medium-sized, with relatively wide outer rim, reaching sternite suture V/VI but not VI/VII (Fig. 7.2F).

Etymology. The genus name is an arbitrary combination of Latin calcium and the type genus of Potamidae, Potamon. It alludes to the limestone habitat of the type species. Gender: neuter.

Distribution. Changjiang Li Autonomous County, Hainan Island, China.

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Figure 7.1 Dorsal habitus. A, Calcipotamon puglabrum n. gen., n. sp., male holotype (31.6 × 24.5 mm), SYSBM 001961; B, female paratype (31.5 × 24.6 mm), SYSBM 001964.

Remarks. Calcipotamon n. gen. is included in Potamiscinae sensu Yeo & Ng (2004). Although superficially similar to Neotiwaripotamon in overall physiognomy, especially the slender legs, the new genus can be separated by the smooth carapace (Fig. 7.1) (versus anterolateral and sub-orbital regions rugose, sub-hepatic and posterolateral striated in Neotiwaripotamon), low and smooth postorbital cristate (Fig. 7.1) (versus sharp in Neotiwaripotamon; Dai, 1999: plate IV. figs. 2, 3), very short or absent flagellum of the

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maxilliped III exopod (Fig. 7.3A) (versus medium-length flagellum in Neotiwaripotamon; Dai, 1999: fig. 40 (1), fig. 41 (1)), smooth cheliped palm surface (Fig. 7.1) (versus granulated in Neotiwaripotamon), very slender ambulatory legs (Fig. 7.1) (versus relatively stouter in Neotiwaripotamon; Dai, 1999: plate IV. fig. 2, 3) and terminal segment of G1 with large basal flap (Figs. 7.3C–E, H–I) (versus absent in Neotiwaripotamon; Dai, 1999: figs. 40 (4), (5), 41 (4), (5)). Calcipotamon n. gen. is similar to Hainanpotamon in terms of G1 morphology, but can be immediately separated by its less swollen carapace (Fig. 7.1) (very convex in Hainanpotamon; Yeo & Naruse, 2007: fig. 1), smooth carapace (Figs. 7.1, 7.2A) (Sub- orbital, sub-hepatic and pterygostomial granulated in Hainanpotamon; Yeo & Naruse, 2007: fig. 1B), very short or absent flagellum of the maxilliped III exopod (Fig. 7.3A) (versus long flagellum in Hainanpotamon; Yeo & Naruse, 2007: fig. 2A), epistome median lobe broadly triangular (Fig. 7.2A) (versus very broadly rounded in Hainanpotamon; Yeo & Naruse, 2007: fig. 1B), relatively wider anterior thoracic sternum, width around 1.5 × length (Fig. 7.2B) (versus anterior thoracic sternites narrow in Hainanpotamon, width around 1.3 × length; Yeo & Naruse, 2007: fig. 2D), slender legs (Fig. 7.1) (versus stout in Hainanpotamon; Yeo & Naruse, 2007: fig. 1A). Calcipotamon n. gen. is also morphologically similar to Tiwaripotamon, but can be separated by the broadly triangular epistome median lobe (Fig. 7.2A) (versus very broadly rounded in Tiwaripotamon; Do et al., 2016: fig. 3B, 4B, 5B), narrowly triangular pleon (Fig. 7.2C) (versus broadly triangular in Tiwaripotamon; Dai, 1999: fig. 184 (2), fig. 185 (2)) and terminal segment of G1 with large basal flap (versus small to no flap in Tiwaripotamon; Do et al., 2016: fig. 2A–F; Dai, 1999: figs. 184 (4), (5), 185 (4), (5)).

Calcipotamon puglabrum n. gen., n. sp. (Figs. 7.1–7.4, 7.6)

Type material. Holotype: SYSBM 001961, male (31.6 × 24.5 mm), Wangxia Village (19.00°N, 109.15°E), Changjiang Li Autonomous County, Hainan Province, China, rock crevice in karst forest, 600-900 m a.s.l., coll. C. Huang, June, 2019. Paratypes: SYSBM 173

001962, male (30.3 × 23.8 mm), same data as holotype. SYSBM 001963-001964, 2 females (39.7 × 30.9 mm, 31.5 × 24.6 mm), same data as holotype. AM P.104569, male (29.3 × 22.6 mm), same data as holotype. AM P.104570, female (30.4 × 23.7 mm), same data as holotype.

Figure 7.2 A–D, Calcipotamon puglabrum n. gen., n. sp., male holotype (31.6 × 24.5 mm), SYSBM 001961; E–F, female paratype (31.5 × 24.6 mm), SYSBM 001964. A, cephalothorax, anterior view; B, anterior thoracic sternum; C, anterior thoracic sternum and pleon, ventral view; D, sterno-pleonal cavity with G1 in situ, ventral view; E, pleon, ventral view; F, vulvae, ventral view.

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Description. Carapace broader than long, width 1.3 × length (n = 6), regions indistinct. Dorsal surface smooth, finely pitted, convex (Fig. 7.1). Front deflexed, margin slightly ridged in dorsal view (Fig. 7.1). Epigastric cristae low, blunt, divided by a narrow gap (Figs. 7.1, 7.2A). Postorbital cristae smooth, very low (Fig. 7.1). Branchial regions swollen; cervical groove very shallow; mesogastric region convex (Fig. 7.1). External orbital tooth prominent, sharp, triangular with almost straight outer margins, separated from anterolateral margin by gap (Figs. 7.1, 7.2A). Epibranchial tooth blunt (Figs. 7.1, 7.2A). Anterolateral margin cristate, lined with smoothly fused granules. Posterolateral surface smooth (Fig. 7.1). Orbits large, supraorbital and infraorbital margins ridged, smooth (Figs. 7.1, 7.2A). Sub-orbital, sub-hepatic and pterygostomial regions divided by sutures; surfaces smooth (Fig. 7.2A). Epistome median lobe broadly triangular, lateral margins sinuous (Fig. 7.2A). Maxilliped III merus width about 1.1 × length; ischium width about 0.7 × length; merus subtrapezoidal with median depression; ischium subtrapezoidal, with distinct median sulcus, mesial margin rounded; exopod reaching to proximal one-fifth of merus height, flagellum very short to absent (Fig. 7.3A). Chelipeds (pereiopod I) unequal (Figs. 7.1, 7.3F–G). Merus trigonal in cross section, margins weakly crenulated, surfaces generally smooth (Figs. 7.1, 7.2A). Carpus with sharp spine at inner-distal angle, spinule at base, surfaces smooth (Fig. 7.1). Major cheliped palm length about 1.5–1.6 × height in males (n = 2), 1.5–1.7 × in females (n = 3); dactylus 0.9– 1.0 × palm length in both males (n = 2) and females (n = 3) (Fig. 7.3F–G). Palm surface smooth, pitted. Occlusal margin of fingers lined with large and small blunt, round teeth; small gape when closed (Fig. 7.3F–G). Ambulatory legs (pereiopods II–V) slender, smooth. Pereiopod III merus 0.9 × carapace length in males (n = 3) and females (n = 2). Pereiopods V propodus 3.8–4.0 × as long as broad in males (n = 3), and 4.0–4.1 × in females (n = 3), shorter than dactylus (Fig. 7.1). Male thoracic sternum generally smooth, pitted; sternites I–IV relatively narrow, width 1.5 × as length. Sternites I, II fused, forming a subtriangular structure; sternites II, III fused, separated by a deep transverse sulcus; sternites III, IV fused, with inconspicuous 175

Figure 7.3 A–C, F–G, H–I, Calcipotamon puglabrum n. gen., n. sp., male holotype (31.6 × 24.5 mm), SYSBM 001961; D, male paratype (30.3 × 23.8 mm), SYSBM 001962; E, male paratype (29.3 × 22.6 mm), AM P.104569. A, Left maxilliped 3; B, left G2, ventral view; C–E, left G1, ventral view; F, major cheliped; G, minor chelipeds; H, left G1 terminal segment, ventral view; I, left G1 terminal segment, dorsal view. Scale bars: A–E, H–I = 1.0 mm; F–G = 5.0 mm.

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sulcus (Fig. 7.2B). Male sterno-pleonal cavity reaching anteriorly to level of midlength of chelipeds coxae base (Fig. 7.2B); median longtitudinal groove separating sternites VII, VIII deep (Fig. 7.2D). Male pleonal locking tubercle positioned posterior to mid-length of sternites V (Fig. 7.2D). Female vulva ovate, medium-sized, with relatively wide outer rim, reaching sternite suture V/VI but not VI/VII; positioned closely to one another, orientation slightly oblique to the longitudinal axis of the abdomen (Fig. 7.2F). Pleon narrowly triangular in males (Fig. 7.2C) and broadly ovate in females (Fig. 7.2E). Male pleonites III–VI progressively narrower, lateral margins almost straight; pleonite VI 2.1 × as broad as long; telson 1.4 × as broad as long, with blunt apex (Fig. 7.2C). G1 generally slender, reaching beyond the pleonal locking tubercle but not to sternites IV/V suture in situ (Fig. 7.2D). Subterminal segment 2.7–2.9 × as long as terminal segment (n=3), tapering anteriorly, inner margin slightly convex to convex, outer margin slightly concave. Terminal segment elongated, basal region curved anterolaterally, apex pointed anteriorly, with large rounded basal flap and sharp tip (Fig. 7.3C–E, H–I). G2 subterminal segment 1.7–1.9 × as long as the flagellum-like terminal segment (n=3) (Fig. 7.3B).

Etymology. The species name is an arbitrary combination of Latin purpura and glaber, which means purple and smooth.

Colour in life. Generally dark purple. Joints of chelipeds and ambulatory legs, orbit margins, posterior margin of epistome and upper inner margins of pterygostomial regions orange (Fig. 7.5A).

Habitat. This terrestrial species is found from a karstic mountain where they hide in the water-filled crevices of limestone outcrop formed by weathering (Fig. 7.5B). Suitable crevices were almost all occupied by at least one crab at the type locality. The new species possesses slender legs which give it increased climbing abilities and mobility on land, which is likely an adaptation to the volatile nature of their preferred habitat and their 177

predatory nature. One specimen was found residing inside a water-filled tree hole, suggesting some plasticity in habitat choice. Several ovigerous females were found during our collection in June but were released after inspection. No other potamids were observed at the type locality.

Remarks. See remarks for genus.

Figure 7.4 A Bayesian inference (BI) tree based on the 16S rDNA for the “China-East Asian Islands” clade of the subfamily Potamiscinae. Support values at the nodes represent the > 50% posterior probabilities and bootstrap proportions for BI and maximum parsimony (MP), respectively.

Distribution. Wangxia Village, Changjiang Li Autonomous County, Hainan, China.

Phylogenetic analysis and discussion

A 531 bp segment, excluding the variable regions, of the 16S rDNA was amplified and aligned. Both BI and MP methods produced identical topologies, but with varying degrees of support. All subclades within the “China-East Asia Islands” clade were recovered with

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varying levels of support except the “South China-Vietnam” subclade which consists of Luteomon and Tiwaripotamon (Huang et al. 2018). The phylogenetic relationships between the subclades and the positions of Luteomon and Tiwaripotamon require further investigation. Calcipotamon puglabrum gen. nov. et sp. nov. is nested within the “Hainan Island” subclade with other Hainan taxa with support from the BI analysis, basal to the group containing Neotiwaripotamon and Hainanpotamon. Apotamonautes is the most basal lineage of this subclade. The new genus and new species closely resembles Tiwaripotamon externally, especially in terms of the long slender legs and smooth outer surface that both possess (Ng et al. 2001; Shih & Do 2014; Do et al. 2016). The two, however, are apparently not closely related. According to our analysis, the latter does not belong in the “Hainan Island” subclade. The high degree of external morphology convergence is likely the result of their similar habitats, as is the case with many potamids (Huang 2018; Wang et al. 2019). Neotiwaripotamon are widespread in Hainan and also have slender legs, but they are considerably stouter and their external surfaces are much rougher when compared to the new species. The two genera also have some overlap in habitat choice. Both adult and juvenile Calcipotamon gen. nov. are mostly found living in karstic crevices, whereas juvenile Neotiwaripotamon are often found in mud burrows whereas large adults are more commonly seen occupying tree holes or rock crevices (unpublished data). According to the phylogeny, the two are closely related, but not directly so. Including Calcipotamon puglabrum gen. nov. et sp. nov., there are now eight species from four genera recorded from Hainan. The Hainanese freshwater crabs remain understudied and are in need of revision.

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Figure 7.5 A, colour in life. Calcipotamon puglabrum n. gen., n. sp. from the type locality, Changjiang, Hainan Island. B, weathered limestone outcrop in a montane tropical forest at the type locality, the typical habitat of the new genus new species.

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Chapter 8.

Bioregionalisation of the freshwater zoogeographical areas of mainland China

Chao Huang, Malte C. Ebach and Shane T. Ahyong Zootaxa, 4742 (2), 271–298 Abstract

Biogeographic regionalisations extract patterns of co-occurrence from different taxa to form a hierarchical system of geographical units of different scales. This system is useful for revealing biogeographic patterns and can be used as the basis for scientific communication between different fields. The history of Chinese freshwater biogeography is not well known to most modern biogeographers and is reviewed herein. We produce the first quantitative bioregionalisation of the freshwater zoogeographic areas of mainland China based on multiple animal groups. The combined occurrence data of amphibians, freshwater fish and freshwater crabs were subjected to cluster and network analyses. The two different methods yielded largely similar results. We propose four freshwater zoogeographical sub-regions (Beifang, Tarim, China, and the Tibetan sub-region), three dominions for the China sub-region (Jianghuai, Dongyang, and the new Dian dominion), three provinces for the Dian dominion (West Hengduan, Diannan Highlands and the new Yungui Plateau province) and two provinces for the Dongyang dominion (Zhemin and the new Huanan province) according to the naming rules of ICAN. The endemic areas of each animal group were then individually studied and were found to reflect the bioregionalisation at the sub-region level, but differed from each other at the dominion and province level. Our analyses show that: (1) previous biogeographical studies have found similar areas; (2) there are recurring large scale biogeographic patterns in Chinese freshwater fishes, amphibians and freshwater crabs; and (3) bioregionalisations derived

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from quantitative methods can be effective for partitioning areas into biogeographically meaningful units.

Key words: amphibians, area taxonomy, Asia, biogeography, freshwater crabs, freshwater fish.

Introduction

Freshwater regions are hotspots of biodiversity and home to 9.5% of all described species, despite only covering 0.01% of the Earth’s surface (Balian et al. 2008). Endemic areas represent non-random overlap in the geographic distribution of two or more taxa that reflects a common spatial history (Apodaca & Crisci, 2018). Biogeographical regionalisation or bioregionalisation is a hierarchical system of endemic areas that can be used as a stable foundation for scientific communication between different studies (Ebach, 2017). In the early days of biogeography, researchers mainly used comparative and descriptive methods in their attempts to unravel biogeographic patterns. However, since the Modern Synthesis of the 20th century, the field of biogeography has almost entirely turned away from this tradition and became focused on using population-level molecular and parametric approaches to propose elaborate biogeographic scenarios for single taxa. Many of these recent studies ignore the patterns of co-occurrence of different taxa, which are in fact fundamental to a more holistic understanding of general biogeographic patterns. Despite this, the importance of bioregionalisations is again becoming increasingly recognized, with a number of works being published in recent years (see Ebach, 2013; Gonzalez-Orozco et al., 2014; Morrone, 2015; Vilhena & Antonelli, 2015; Edler et al., 2016; He et al., 2017; Leroy et al., 2019). The landscape and climate of mainland China is extremely variable across its great expanse, from the humid rainforests of Yunnan to the Gobi desert of Inner Mongolia, and from the coastal plains of the lower Yangtze to the alpine tundras of the Tibetan Plateau. Modern biogeographers have a poor understanding of the history of Chinese freshwater zoogeographic bioregionalisation, because there is little modern literature that has been

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published in English. The earliest of these studies focused on East Asian freshwater fish (Berg, 1912, 1916; Mori, 1936), after which Chinese researchers studied the zoogeographic divisions of individual freshwater faunas at a national level (Zhang, 1954; Li, 1981; Dai, 1999). More recently, the biogeographic divisions for freshwater fishes, amphibians and freshwater crabs, in China or globally, have all been variously studied individually (Chen & Bi, 2007; Shih & Ng, 2011; Rueda et al., 2013; Holt et al., 2013; Kang et al., 2014; Vilhena & Antonelli, 2015; Edler et al., 2016; Leroy et al. 2019). Freshwater ecoregions of the world have been proposed (Abell et al., 2008), but they are not necessarily based on species distributions and not quantitatively derived. As such, a quantitative, multi-taxon based bioregionalisation and area taxonomy of the freshwater zoogeographic regions of China has yet to be achieved with any confidence. With the aid of published distribution data, a recently available database (AmphibiaChina), modern spatial analysis software (Biodiverse, Infomap Bioregions) and our new distribution data, it is now possible to attempt such a study. Freshwater fishes, amphibians and freshwater crabs were chosen as representatives of the freshwater fauna, as these animal groups are well represented and also relatively well documented in China. We used specific-location species occurrence data for analysis with latitude-longitude grid cells as the basic geographic unit. Many studies use geopolitical areas as the basic geographic unit (Chen & Bi, 2007; Shih & Ng, 2011, Kang et al., 2014), resulting in artificial area boundaries. Due to the geographical scope of the present study, the outer boundaries of our areas may also be artificial and will have to be refined by future larger scaled studies. Others use freshwater drainage basins as the basic geographic unit (Abell et al., 2008; Leroy et al., 2019). This incorrectly assumes a priori that drainage basins are necessarily natural biogeographic areas (Dagosta et al., 2017). To quantify the zoogeographic areas, we used species turnover, which is the rate of change in species composition between sites. The acquired areas were then compared with previously proposed bioregionalisations, after which we formally proposed area names according to the International Code of Area Nomenclature (ICAN; Ebach et al., 2008). To discover the biogeographic patterns of each taxon group individually, the same method was applied to

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each group. Finally, how the endemic areas of each group affect the combined bioregionalisation is discussed through comparison.

The aims of this study were to:

1. Review the history of freshwater zoogeographic bioregionalisations of the freshwater fish, amphibians and freshwater crabs of mainland China. 2. Quantify and map the freshwater zoogeographic areas of mainland China through spatial analyses of the combined distribution data of amphibians, freshwater crabs and freshwater fishes to test previous bioregionalisation hypotheses. 3. Compare these areas with previous regionalisations and propose a formal bioregionalisation (i.e., area taxonomy) of the freshwater zoogeographic areas of mainland China according to the naming rules of ICAN. 4. Quantify and map the endemic areas for each of the three groups and discuss their biogeographic patterns and how these patterns influence regionalisation.

Material and methods

Spatial dataset 2678 records of 389 species of amphibians (80% species coverage), 5829 records of 787 species of freshwater fishes (60% species coverage), 1195 records of 295 species of primary freshwater crabs (90% species coverage) were examined, a total of 9702 records. GPS coordinates were manually extracted from locality names from reference sources with the aid of a web-based map. Precision is estimated to be around 0.01 degrees. Widespread freshwater fishes and amphibians (extent of occurrence or area of occupancy typically larger than 1,000,000 km2) are not used as the inclusion of widespread species to spatial analyses has been shown to reveal basins rather than historic patterns (Ebach et. al, 2013). Primary freshwater fishes have little to no tolerance to brackish waters and are unable to traverse marine environments to disperse whereas secondary freshwater fishes have some tolerance to brackish waters but normally occur in inland aquatic systems. Fish distribution data included in the dataset are almost all from primary freshwater species, with exception 184

of a couple of secondary freshwater species from areas where data on primary freshwater fishes are absent. Owing to their poor dispersal abilities, true or primary freshwater crabs are typically narrow-ranged and excellent candidates for biogeographic research. The term “true freshwater crabs” as defined by Ng (2004, 2017a), includes those that spend their entire lives in fresh water, without having to return to the sea for whatever reason, whereas “primary freshwater crabs” as defined by Yeo et al. (2014) are more restrictive and only include the five exclusively freshwater families (Pseudothelphusidae, Potamidae, Potamonautidae, Gecarcinucidae and Trichodactylidae). We use crabs from Potamidae in this study as they are mostly highly endemic hillstream species and by far the most speciose primary freshwater crab family in China. The other freshwater crab family that is found in China, Gecarcinucidae, is not included due to serious taxonomic problems arising from apparent over splitting (Shih et al., 2007; Huang et al., 2018). The majority of described Chinese gecarcinucid “species” are almost morphologically undistinuishable. The Chinese potamid crabs also carry a fair share of taxonomic complications, but to a much lesser extent. Most Chinese amphibian species were used in this study with only the widespread species excluded. Tedesco et al. (2017) compiled a global database for freshwater fish species occurrence in drainage basins, but to our knowledge there is currently still no database available for location-specific distribution data for Chinese freshwater fishes. Therefore, freshwater fish species occurrence records were manually extracted from available Chinese and English literature, including family-specific and provincial monographs and surveying reports, with questionable records excluded. The amphibian species occurrence records were extracted from The Database of Chinese Amphibians (AmphibiaChina, 2018), with minor corrections by herpetologist Mian Hou (Sichuan Normal University). Freshwater crab species occurrence records were mainly extracted from Dai (1999), recently published accounts and our unpublished records were also included. Reference sources are listed in Appendix I.

Cluster analysis The hierarchical cluster analysis was conducted using Biodiverse v2.1 (Laffan et al., 2010). Species occurrence records were first imported into 1.2° × 1.2° grid cells. The sample 185

redundancy of a species is calculated as (1 – v / s), where v is the number of cells in which the species occurs and s is the number of times this species occurs across all cells. Generally, the closer this value is to one, the better the species is sampled. A value of zero for a species can mean that there is only a single distribution point for it or that there is on average, one occurrence per spatial cell. Only 50% of our included species have a sample redundancy value above 0, meaning that many are either highly endemic or not well sampled. A species turnover matrix was generated for all pair-wise grid cell combinations using Simpson’s beta (S2) as the index to quantify dissimilarity. In the equation, the number of species shared by both example cells i and j is represented by a, b is the number of species unique to cell j and c is the number of species unique to cell i. When two cells are similar, the number of species that are unique to either cell is small, and thus the values of b and c will be small, resulting in a S2 value close to 1. By using the smallest value in b and c, Simpson’s beta decreases the influence caused by differences in species richness between cells. 푎 푆 = 1 − 2 푎 + min(푏, 푐)

A WPGMA (link-average) cluster analysis was then performed for the S2 species turnover matrix dataset. Maximum Corrected Weighted Endemism (ENDW_CWE) was used as a tie-breaker condition to improve the consistency and endemicity of the analysis results (Gonzalez-Orozco et al., 2014). Biogeographical areas were identified by a contiguous or near-contiguous cluster of grid cells that appear as a distinct clade in the dendrogram. The results of this analysis were used as the basis of the area taxonomy. Owing to the limitations of our data and scale of study, the outer political boundaries of our areas may be artificial and will have to be further refined in future studies that include neighboring regions. The endemic areas of freshwater fish and amphibians were found following the same method. Freshwater crab genera occurrence data, instead of species, was used to find the freshwater crab endemic areas, owing to the high level of endemicity of these animals and the large number of species only known from single collection points.

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Network analysis Recent studies have shown that a network approach has several advantages over distance based approaches (sensu Leroy et al., 2019). In this approach, an association network in which species and grid cells form two disjoint sets of nodes with no links between nodes of the same set is made. This is known as a bipartite network. A community detection algorithm (such as the map equation algorithm) from network science is then used to group more interconnected groups of grid cells into clusters (Vilhena & Antonelli, 2015). More recently, a web-based interactive mapping tool based on bipartite network clustering, Infomap Bioregions, was developed by Elder et al. (2017). We use this application in our network analysis. The resolution was set at 1°–2°, cell capacity was set at 1–10, with patching of sparse grid cells enabled and number of trials set at 10. Clustering cost (Markov time) tunes resolution of the clustering algorithm to find more or fewer clusters. Most likely as a result of the limitations of our data (see above), we found area boundaries to be unstable to the adjustments of clustering cost (Markov time) in some analyses. Therefore we used the results from the distance-based cluster analysis as the basis for selecting the optimal clustering cost that produces the closest matching bioregionalisation. Network analysis at the subregional level and provincial level were performed with a clustering cost of 3.8 and 2.4, respectively. Endemic areas of freshwater fish, amphibians and freshwater crabs were produced with a clustering cost of 2.8, 2.1 and 2.8, respectively. Freshwater crab genera occurrence data were used instead of species data as with the cluster analysis.

Area taxonomy, area nomenclature and terminology A formal bioregionalisation requires a systematic hierarchy (or taxonomy) of diagnosed and described areas and their names (Ebach & Michaux, 2017). As in a biological taxonomy (i.e., species, genera and families etc.), a formal area taxonomy means that areas of one study may be compared to areas of another, thereby allowing for a comparative biogeography. A formal nomenclatural use of area names prevents confusion as to what is being named and a proliferation of redundant area names (Ebach et al., 2008). We herein formally propose area names according to the International Code of Area Nomenclature

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(ICAN; Ebach et al., 2008). As with biological taxonomic studies, the area taxonomy is presented as a discussion. Due to the availability of data, our scope of study is limited to mainland China. The term “mainland China” used herein refers to the geographical area of continental China and closely adjacent (less than 100 km distance from the mainland) islands. It is a purely utilitarian definition that suits the scope of the current study and should not be interpreted in any political way.

Results

The distance-based cluster analysis of the combined occurrence data resulted in four freshwater zoogeographical subregions (Beifang, Tarim, China, and Tibetan), three dominions for the China subregion (Jianghuai, Dongyang, and the new Dian dominion), three provinces for the Dian dominion (West Hengduan, Diannan Highlands and the new Yungui Plateau province) and two provinces for the Dongyang dominion (Zhemin and the new Huanan province) (Fig. 8.1B, E). Details of these areas are found below in the area taxonomy. The analysis also shows a small area in Ngari, Tibet, which, due to its small size and being at the China-India border, is likely artefactual. The early splits of the subregions are on very short branches (branch length ≤ 0.01) (Fig. 8.1C) resulting in unresolved relationships between them. The Beifang (branch length = 0.08), Tibetan (branch length = 0.06) and Tarim subregions (branch length = 0.05) are relatively well defined and on long branches, whereas the China subregion is on a short branch (branch length = 0.02) and complex. Further splits in the Beifang, Tibetan and Tarim subregions do not correspond with contiguous or near-contiguous clusters of grid cells and therefore no dominions are recognized in these. The China region, however, can be readily sub-divided into three subregions: Jianghuai (branch length = 0.03), Dongyang (branch length = 0.03) and Dian (branch length = 0.04) (Fig. 8.1F). Cluster analysis on freshwater fish revealed seven major endemic areas (Fig. 8.2B, C). The four subregions are reflected quite well in these areas with the three endemic areas in the southeast similar to the three dominions of the China subregion. A minor portion of

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the Tarim subregion comes out as a separate endemic area. Analysis on only amphibian data also shows seven major endemic areas that also correspond to the four subregions with the four endemic areas in the south combining to form the China subregion (Fig. 8.2E, F). Two cells in Ngari of Tibet, which represent the occurrences of the Zamda Toad (Bufotes zamdaensis), show up as a separate area. This signal is carried on to the combined analysis as mentioned above. The distribution of freshwater crabs roughly corresponds with the China subregion. Cluster analysis of genera occurrence data reveals six endemic areas (Fig. 8.2H, I). In the network analysis of the combined occurrence data, a clustering cost of 3.2-4.4 produced almost identical results, which are similar to that of the distance based cluster analysis (Fig. 8.1A). Other than slight differences in the China subregion northern boundary, all other boundaries are very similar. Once the clustering cost falls below 3.1, the China subregion fragments and boundaries become unstable. At the dominion level, a clustering cost of 2.4 produced results most similar to that of the distance based cluster analysis, but differences in the boundaries of the dominions are still quite large (Fig. 8.1D). The endemic areas found by individual network analyses of occurrence data of freshwater fish species, amphibian species and freshwater crab genera are generally similar to that of the cluster analysis (Fig. 8.2A, D, G). Most notable differences include the freshwater fish endemic area in the Tarim subregion being one area (vs. split into two in the cluster analysis), and the Tibetan and Tarim subregion including two amphibian endemic areas each (vs. one each in the cluster analysis).

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Figure 8.1 Spatial analysis results for the combined freshwater fauna occurrence data showing subregions and smaller areas within the China subregion. A, D, network analysis results; B, E, distance-based cluster analysis results; C, F, corresponding dendrograms of B and E, respectively.

Discussion

Both the Simpson’s-beta-based clustering and network analyses produced largely similar results. The network analysis, however, sometimes produced inconsistent area partitions when different clustering costs were applied. This is more apparent in higher resolutions due to the higher degree of uncertainty in the smaller scale patterns. In this aspect at least, the traditional clustering method outperforms the network analysis in producing a stable area partition. From the analyses, four subregions, three dominions and five provinces are delineated (Fig. 8.3). The Beifang subregion is likely to have been formed as a result of its high latitude, which has given it a temperate to subarctic climate, historically and presently. Its southern boundary roughly corresponds to the Huaihe (Qin Mountains and Huai River) line, which traditionally is known as the climatic separating line between northern

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and southern China. This line can also be seen in the endemic areas of freshwater fishes and amphibians (Fig. 8.2A, B, D, E); the mammal, bird and amphibian zoogeographic areas of Rueda et al. (2013); the amphibian zoogeographic areas of Vilhena & Antonelli (2015) and Edler et al. (2016); the terrestrial vertebrate zoogeographic areas of He et al. (2017); and even the phytogeographic regions of Ye et al. (2019). The Chinese transition zone, situated between the Palearctic and Oriental regions (see Morrone, 2015), is also recognized from around this area, with its northern boundary corresponding to this line. Our results agree with this hypothesis with both clustering and network methods showing a fuzzy boundary in this area (Fig. 8.1A, B), indicating biotic overlap in an area of transition. Fossil evidence suggests that Quaternary climatic oscillations played a key role in the biota distribution of this area, with tropical species being found further north during interglacial periods and boreal species being found further south during the glacial periods (Zhang et al., 2000). Other studies have also suggested that climate is the determining factor of zoogeographic boundaries in this area (He et al., 2017; Ficetola et al., 2017). To the south of this line is the China subregion which is characterized by subtropical and tropical monsoon climate. This subregion is the only one within China that can be further split into smaller areas, suggesting a higher level of endemicity than the other subregions. The and Nanling Mountains separate the Jianghuai and Dongyang dominions and act as a barrier against seasonal cold weather originating from the Siberian high-pressure system and also to some extent an orographic barrier for taxa with poor dispersal abilities (Shih et al., 2011). Further division of the Dongyang dominion corresponds to the presence of two major drainage systems, the Pearl River basin, which characterizes the Huanan province and the Southeast Rivers basin which characterizes the Zhemin province. To the southwest are the highlands of the Dian dominion, which consists of three provinces and slopes downward from northwest to southeast, typically ranging from 1000–4000 m above sea level (asl). The Yungui Plateau province is only found in the clustering analysis results and not in the network analysis results. This dispute may be derived from the network clustering algorithm prioritizing recognition of small areas near the Yunnan-Guizhou border, which is karstic and contains numerous highly endemic freshwater fauna. The western boundary of the China subregion is marked by the eastern 191

edge of the Qingzang Plateau, corresponding to the 4000 m asl contour line. This dividing line is also clearly visible in the endemic areas of freshwater fishes and amphibians (Fig. 8.2A, B, D, E), the amphibian areas of Edler et al. (2016) and the terrestrial vertebrate zoogeographic areas of He et al. (2017). Areas within the Tibetan subregion are extremely high, typically above 4000 m asl. The biotic composition of this area is greatly influenced by Quaternary uplifting (Zhang et al., 2000; Zheng et al., 2002). The Kunlun Mountains, at the northern edges of the plateau, steeply drop off, giving way to the Tarim basin of the Tarim subregion. This boundary can also clearly be seen in the endemic areas of freshwater fish (Fig. 8.2A, B) and the terrestrial vertebrate zoogeographic areas of He et al. (2017). The uplifting of the Kunlun Mountains effectively prevented Indian monsoon derived moisture from penetrating into the basin, causing its current arid state (Sun et al., 2008). The majority of the occurrence data comes from freshwater fish (60%), so it is expected that the endemic areas of freshwater fishes are well reflected in the combined bioregionalisation. Six of the freshwater fish endemic areas found correspond to the Beifang, Tarim and Tibetan subregions, and the Jianghuai, Dongyang and Dian dominions of the China subregion (Fig. 8.2B, purple, yellow, orange, red, blue and green, respectively). Within China, some nemacheilid, salmonid and cold-water cyprinid genera such as , Hucho, Leuciscus, Phoxinus and Thymallus are only found in the Beifang area. Freshwater fishes from the Tarim and Tibetan endemic area are mainly from Schizothoracinae and . Species such as Aspiorhynchus laticeps, biddulphi and Hedinichthys yarkandensis are characteristic of the Tarim area, whereas high-altitude specialists such as Platypharodon extremus, Schizopygopsis anteroventris and Gymnocypris waddellii are endemic to the Tibetan area. Bagridae, and are prominent families within the China subregion. Species such as elongata, Onychostoma rarum and macrops are representative of the Jianghuai area, whereas species like Channa maculata, Tachysurus virgatus and Traccatichthys pulcher are only found in the Dongyang area. The Dian area is highly diverse and includes many tropical fish genera that are much better represented in neighboring South and/or than in China, such as Danio, Bagarius, Hampala, and Trichogaster. This area consists only the outer border of Yunnan and does not include the Yungui Plateau province, 192

which is instead part of the Tibetan and Jianghuai freshwater fish endemic areas. The freshwater fish endemic areas identified here are closest to those proposed by Li (1981), especially in regards to the Beifang and Jianghuai areas that corresponds to the Beifang region and Jianghuai subregion in Li (1981), respectively. The same boundaries between the Jianghuai and Dongyang endemic areas can also be seen in Li (1981). That Li was able to find these same patterns mainly relying on intuition, showed a broad and intimate understanding of the Chinese freshwater fishes. The endemic areas of amphibians also reflect the four subregions quite well. We recognize three endemic areas that correspond to the Beifang, Tarim, Tibetan subregions (Fig. 8.2E, orange, brown and yellow, respectively), and four areas (Fig. 8.2E, purple: Qinling, blue: Southwest, green: East and red: South) that, when combined, correspond to the China subregion (Fig. 8.2E). The Beifang amphibian endmic area does not include the northwestern parts of the Beifang subregion and hosts temperate and boreal genera such as Onychodactylus, Salamandrella and Strauchbufo. Only six amphibian species (Ranodon sibiricus, Bufotes pewzowi, asiatica, Rana arvalis, Pelophylax terentievi and Pelophylax nigromaculatus) occur in the depauperate endemic area of Tarim. The Tibetan amphibian endemic area is more restricted to the lower southeast when compared to the Tibetan freshwater fish endemic area, suggesting that amphibians are less adaptable to extreme altitudes than freshwater fishes. Most amphibians of this area include high-altitude specialists such as Nanorana parkeri and species from the genus Scutiger. The Qinling area includes the Qin mountain range and surrounding areas and is represented by species such as Liua shihi, L. tsinpaensis and Scutiger ningshanensis. It is more likely to be a transition zone than an endemic area. The Southwest amphibian endemic area mainly consists of northeast Yunnan and hosts species such as Amolops mantzorum, Bombina maximum, Cynops cyanurus, Glyphoglossus yunnanensis and Nidirana pleuraden. The East endemic area is roughly triangular in shape, delimited by Yancheng, and Xiamen at the points. Typical amphibians of this area include Amolops wuyiense, Cynops orientalis, Leptobrachium liui, exiliversabilis and Paramesotriton chinensis. The Southwest and East areas intersect and partially overlap in the . This is apparently caused by the overlapping distributions of Hyla annectans and Dryophytes immaculatus, as 193

the removal of these two species from the cluster analysis also removes the overlap in the areas. The South endemic area covers the warmer subtropical and tropical regions of south and southwestern China and roughly corresponds to the combined Diannan Highlands province and Huanan province. Representative amphibians of this area include Kalophrynus interlineatus, Kaloula pulchra, Kurixalus hainanus, Microhyla pulchra and Occidozyga lima. Family-level and genus-level patterns are not as obvious as species-level patterns in the Chinese amphibians. The distribution of freshwater crabs roughly corresponds to the China subregion. Though its northern boundary is also marked by the Qin mountain range, it extends north of the Huai river basin up to Beijing. Four major freshwater crab endemic areas are identified, three of which loosely correspond to the Jianghuai, Dongyang and Dian subregions (Fig. 8.2H, red, blue and green, respectively) and one in Hainan Island (Fig. 8.2H, orange). By far the largest is the Jianghuai endemic area, which covers most of the China subregion area and strongly coincides with the distribution of the speciose and widespread genus Longpotamon, but also includes genera such as Sinopotamon, Aparapotamon and Tenuilapotamon. The Dongyang freshwater crab endemic area loosely resembles to the “Wuyishan Area and Pearl River Basin” in Shih & Ng (2011), stretching from Guangxi to the Fujian/Zhejiang border, but much more restricted to the coast. This area is represented by genera such as Nanhaipotamon, Cantopotamon, Megapleonum and Yarepotamon. The Dian endemic area covers most of Yunnan and corresponds to the “Hengduanshan Area” in Shih & Ng (2011) but does not extend to Tibet. Yunnan is the richest political province in freshwater crab species and genera in China (Shih & Ng, 2011). The Dian area strongly coincides with the distribution of the mainly Indochinese genus Indochinamon and includes many endemic genera such as Artopotamon, Eosamon, Parapotamon and Semicirculara. The analyses from both methods show slight fragmentation within the Dian area, which is likely caused by the abundance of highly endemic narrow-ranged genera. The Hainan area was also recognized in Shih & Ng (2011). The region contains only three genera, Apotamonautes, Hainanpotamon and Neotiwaripotamon, that until recently were thought to be endemic to the island. We have specimens of Apotamonautes hainanensis from the Leizhou Peninsula that are morphologically almost identical to those from the island. 194

Figure 8.2 Spatial analysis results for the occurrence data of each individual animal group. A, network analysis results of freshwater fish data; B, distance-based cluster analysis results of freshwater fish data; C, corresponding dendrogram of B; D, network analysis results of amphibian data; E, distance-based cluster analysis results of amphibian; F, corresponding dendrogram of E; G, network analysis results of freshwater crabs data; H, distance-based cluster analysis results of freshwater crab data; I, corresponding dendrogram of H.

More recently, we have received photographic and video reports of what looks to be Hainanpotamon and Neotiwaripotamon from the Peninsula. The Qiongzhou Strait between Hainan and the continent is relatively narrow and shallow, so the presence of a land-bridge

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during past glaciations is almost certain (Shih & Ng, 2011). These new data suggest that populations of species in these three genera were only very recently separated by the strait. A focused study of this region with more collection data will probably show the Leizhou Peninsula is in fact part of the Hainan freshwater crab endemic area. A single cell in Medog of southeastern Tibet represents the known distribution of Potamiscus motuoensis. In Medog, the tropical rainforests of the river valleys are refugia within the otherwise alpine landscape. It is very rich in biodiversity and as the recent discovery of a new endemic primate species here makes evident, still remains understudied (Li et al., 2015). That only a single species of freshwater crab has been found here is perplexing and could be the result of either insufficient sampling effort or taxonomic effort; discerning which limitation causes this pattern would require further investigation.. The subregions of mainland China are generally well supported by the individual analyses of the three animal groups using both network and cluster analysis methods, indicating a certain extent of congruence of large scale biogeographic patterns. These patterns are shaped by a shared history: past and present climate and geological transformations. The freshwater fish and crab endemic areas in the China subregion are comparable, especially the Dian areas, which are strikingly similar. Many species of amphibians, such as Duttaphrynus melanostictus, only require small temporary pools of water to reproduce and are thus able to disperse across much larger areas of land than fishes or crabs (van Dijk et al., 2004). Their distributions seem to be less associated with drainage basins and more so with climatic factors such as precipitation (Vargas et al., 1998). This is reflected in the amphibian endemic areas in this subregion being distinctly different from the former two. In another study, noteworthy differences in the endemic areas of different groups of terrestrial vertebrates in China have also been observed (He et al., 2017). Biogeographic patterns are also influenced by factors unique to a particular group (e.g., life histories, dispersal abilities, ecological adaptations), which seem to be more obvious in smaller scales. Before the availability of software to make analytical spatial analyses practical, historical biogeographical studies based purely on intuition have also found areas similar to those in the current bioregionalisation. To be able to do so required a truly intimate 196

knowledge of the research subject that regrettably many modern researchers lack. The Chinsese freshwater fishes and crabs lack updated databases that include the distributional records of species. To unravel more precise and fine scaled biogeographic patterns, much more distributional data would have to be collected and made readily accessible for researchers. The very high amount of human activity in China, however, has intentionally or not knowingly artificially altered the natural distributions of many freshwater taxa. Whether we will ever be able to recover the true distributions of some species and ultimately the real bioregionalisation remains an uncertainty. In summary, a rudimentary framework for Chinese freshwater biogeography is established herein through bioregionalisation, which future larger scaled and higher resolution studies can test and build upon.

Area Taxonomy (freshwater zoogeography)

Nomenclature The following area taxonomy is based on the results discussed above. The ICAN (Ebach et al., 2008) is used for new and synonymized names.

HOLARCTIC realm Heilprin, 1887 PALEARTIC region Wallace, 1876 BEIFANG subregion Li, 1981 Amur province Berg, 1916: map. Amur district Mori, 1936: 54–46. Amur region Zhang, 1954: 279. Beifang region Li, 1981: 31. Northeast region Chen & Bi, 2007: 485. Heilongjiang region Kang et al., 2014: 216. (Fig. 8.3)

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Diagnosis. This large subregion includes most of Northern and Northeast China and also most of Altay Prefecture in northern Xinjiang. Its southern border stretches from the northern edges of the Tibetan Plateau (roughly the 3000 m asl contour line) to the Qin Mountains of to the river mouth of the Yangtze River.

Type locality. , Harbin City, Heilongjiang Province, China. 45°46’01.29”N, 126°35’06.459”E.

Remarks. The recognition of a subregion in the northeast of China amongst freshwater fish researchers started with Berg (1916) who recognized an Amur subregion that included most of the Amur River drainage basin (Fig. 1.5). Mori (1936) named this same area the Amur district (Fig. 1.8). Zhang (1954), followed Mori in the recognition of this area, but due to his scope of study restricted it to areas within China (Fig. 1.9). Li’s (1981) Beifang region included “the Amur River, and Yalu River from northeast China and the Irtysh River, Ulungur River etc. from northwest China”, whereas Kang’s et al. (2014) Heilongjiang region consisted of Heilongjiang Province, Jilin Province and Inner Mongolia (Fig. 1.10, 1.11). Both these areas resemble our proposed subregion, however, Li’s region does not include Northern China whereas Kang’s region does not include Northern Xinjiang. We attribute this subregion to Li on the principle of precedence. Concerning amphibians, Chen & Bi’s (2007) Northeast region, defined as the area including Ningxia, Jilin, Liaoning, Heilongjiang and Shandong provinces, also partially resembles our proposed area (Fig. 1.12). The Beifang subregion likely also includes Mongolia, North Korea and South Korea and parts of Russia and Kazakhstan. Further studies in these neighboring regions will be needed to confirm this before extending this subregion. Etymology. The subregion name is the Chinese pinyin for North.

Representative fauna. Barbatula nuda, Leuciscus waleckii and Salamandrella tridactyla.

TARIM subregion Li, 1981 Tarim district Berg, 1916: map. 198

Xibeigaoyuan region Zhang, 1954: 279. Tarim subregion Li, 1981: 31. Northwest region Kang et al., 2014: 216. (Fig. 8.3)

Diagnosis. This subregion includes the inner parts of Tian Shan mountain range to Mingsha Mountain, the Kunlun mountain range and the endorheic basin in between.

Type locality. Bosten Lake, Bayingolin Mongol Autonomous Prefecture, Xinjiang Uygur Autonomous Region, China. 41°59’50.32”N, 87°03’15.77”E.

Remarks. Berg (1916) proposed the Tarim basin and a large portion of Inner Mongolia as the Tarim district as part of his High-Asian subregion (Fig. 1.5). Zhang’s (1954) Xibeigaoyuan region is even larger and also included parts of the Qingzang Plateau and central China (Fig. 1.9). Li (1981) recognized this subregion to the basin between the Tian Shan mountain range and Kunlun mountain range and named it the Tarim subregion (Fig. 1.10). This is closest to our findings and thus we attribute this subregion to Li. Kang et al. (2014) proposed the whole of Xinjiang Province as the Northwest region (Fig. 1.11).

Etymology. This subregion is named after the Tarim basin.

Representative fauna. Aspiorhynchus laticeps, Schizothorax biddulphi and Pelophylax terentievi.

TIBETAN subregion Berg, 1916 Tibetan district Berg, 1916: map. Nulan region Zhang, 1954: 279. Kangzang subregion Li, 1981: 31. Qinghai-Tibetan Plateau region Kang et al., 2014: 216. (Fig. 8.3) 199

Diagnosis. The plateau regions of Tibet, Qinghai, southern Gansu, southern Ningxia, northwest Sichuan and northern extremes of Yunnan, typically above 4000 m.

Type locality. Lhasa River, Lhasa City, Tibet Autonomous Region, China. 29°39’11.96”N, 91°11’53.89”E.

Remarks. Berg (1916) proposed the Tibetan district as part of his High-Asian subregion (Fig. 1.5), but it was not until Berg (1934) that this region was illustrated in a map (Fig. 1.7). This proposed district is closest to our findings and thus we attribute this subregion to Berg. Zhang’s (1954) Nulan region has a similar shape to ours, but is much more to the southeast (Fig. 1.9). Li’s (1981) Kangzang subregion only comprises the southern parts of our subregion (Fig. 1.10). Kang et al. (2014) proposed the combined area of Tibet and Qinghai as the Qinghai-Tibetan Plateau region (Fig. 1.11).

Etymology. This subregion is named after Tibet.

Representative fauna. Schizopygopsis anteroventris, Gymnocypris waddellii and Nanorana parkeri.

HOLOTROPICAL realm Rapoport 1968 ORIENTAL region Wallace 1876 CHINA subregion Berg, 1916 China subregion Berg, 1933: map. China subregion Mori, 1936: 54–46. (Fig. 8.3)

Diagnosis. This area includes almost all of central, east and south mainland China. It is bordered by the eastern edges of the Tibetan Plateau (roughly the 3000 m asl contour line)

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to the west and the Qin Mountains of southern Shaanxi to the river mouth of the Yangtze River to the north. Type locality. Dongting Lake, Yueyang City, Hunan Province, China. 28°49’57.82”N, 112°49’18.30”E.

Remarks. Berg (1912) first recognized the China subregion as part of his Sino-Indian Region (Fig. 1.5). Berg (1933) later refined this area by excluding northeast China and Japan from it (Fig. 1.6). The redefined China subregion is similar to our findings, except the northern and western boundaries are extended with the western part of Yunnan left out and Taiwan included. Mori (1936) follows Berg in recognizing a China subregion, but the northern boundaries are extended to include Korea, while leaving out Taiwan and much of southern and eastern mainland China (Fig. 1.8). We attribute this subregion to Berg due to both similarity and precedence. Further studies will be needed to confirm whether this subregion also includes neighboring areas to the southwest and east.

Etymology. This subregion is named after China.

Representative fauna. , Microhyla pulchra and Longpotamon exiguum.

JIANGHUAI dominion Li, 1981 Jianghuai subregion Li, 1981: 31. Yangtze River Basin district Shih & Ng, 2011: 4. (Fig. 8.3)

Diagnosis. The vast area of lowland in central and east China bordered by the Wuyi Mountains and Nanling Mountains to the east and south, the eastern edges of the Tibetan Plateau to the west and the Qin Mountains of southern Shaanxi to the river mouth of the Yangtze River to the north. It includes much of the Yangtze (Changjiang) River basin and the southern parts of the Huai River basin.

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Type locality. Dongting Lake, Yueyang City, Hunan Province, China. 28°49’57.82”N, 112°49’18.30”E.

Remarks. Li’s (1981) Jianghuai subregion consists of “the river systems of the Qiantang, Yangtze, Huai etc. that are north of the Nanling Mountains”. Though the area around the river mouth of the Yangtze River is more restricted in our findings, it is similar to his depiction (Fig. 1.10). As such, this dominion is attributed to Li. Shih & Ng (2011), proposed a Yangtze River Basin area for freshwater crabs (Fig. 1.14). This area is also similar to ours apart from the inclusion of Shandong and northern Jiangsu.

Etymology. The dominion name is derived from Changjiang and Huaihe, which are the Chinese names of the Yangtze River and Huai River.

Representative fauna. Sinibrama macrops, Pelophylax hubeiensis and Longpotamon denticulatum.

DONGYANG dominion Zhang, 1954 South China district Mori, 1936: 54–46. Dongyang region Zhang, 1954: 279. Huanan region Li, 1981: 31. Huanan region Dai, 1999: 32. Wuyishan Area and Pearl River Basin district Shih & Ng, 2011: 4. (Fig. 8.3)

Diagnosis. This dominion stretches from Guangxi to the junction of Zhejiang, Anhui and Jiangsu. It includes the Wuyi mountain range, Pearl River basin and Hainan Island.

Type locality. Jiulong River, Zhangzhou City, Fujian Province, China. 24°30’18.08”N, 117°38’6.28”E.

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Remarks. Mori (1936) was the first to propose an area that includes south and east China and named it the South China district (Fig. 1.8). This area includes Fujian, Guangdong, southern Guangxi and southern Yunnan. Zhang’s (1954) Dongyang region is similar to Mori’s South China district, but also includes the islands of Hainan and Taiwan and does not include most of Yunnan (Fig. 1.9). Li (1981) proposed the Huanan region, which is also similar to Li’s Dongyang region, only differing in the inclusion of southern Yunnan and the southeast half of Zhejiang (Fig. 1.10). Dai (1999) also uses the Huanan region in her study of freshwater crabs, but with differences in the northern boundary (Fig. 1.13). Also based on freshwater crabs, Shih & Ng (2011) proposed the combined areas of Guangxi, Guangdong, Fujian, Jiangxi and Zhejiang as the Wuyishan Area and Pearl River Basin district (Fig. 1.14). Our findings are similar to Zhang’s (1954) and as such this dominion is attributed to him. Whether this dominion also includes Taiwan Island will need to be further investigated.

Etymology. The dominion name is the Chinese pinyin for the orient.

Representative fauna. Channa maculata, Rana longicrus and Huananpotamon angulatum.

HUANAN province, provincium novum Zhujiang subregion Li, 1981: 31. Guiyue subregion Dai, 1999: 32. South region Kang et al., 2014: 216. (Fig. 8.3)

Diagnosis. The south China area, including Guangxi, Guangdong, Hainan Island, along with parts of southern Hunan and Guizhou. It includes almost the entirety of the Pearl River basin.

Type locality. Xijiang River, Zhaoqing City, Guangdong Province, China. 23°02’20.67”N, 112°28’14.52”E. 203

Remarks. Li’s (1981) Zhujiang subregion includes river systems “west of , south of the Nanling Mountains and east of Tonghai and Fuyuan of Yunnan” (Fig. 1.10). Dai’s (1999) Guiyue sun-region is similar to Li’s, with less defined boundaries (Fig. 1.13). Kang et al. (2014) proposed the South region, which includes Guangxi, Guangdong, Hainan Island and Taiwan Island (Fig. 1.11). Other than Taiwan Island, this region is very similar with our findings. According to Article 4 (4) of the International Code of Area Nomenclature (ICAN), however, “A name proposed after 2007 can be rejected if it is not linked to a type-locality with geographical coordinates or lacks a diagnosis, description or map.” Therefore, we propose the novel Huanan province herein.

Etymology. The province name is the pinyin for South China.

Representative fauna. Bangana wui, Tylototriton asperrimus and Cantopotamon zhuhaiense.

ZHEMIN province Li, 1981 Zhemin subregion Li, 1981: 31. (Fig. 8.3)

Diagnosis. An area in east China that includes Fujian, Jiangxi, Zhejiang and small parts of eastern Guangdong, southeastern Hunan, southern Hubei, Anhui and Jiangsu.

Type locality. Jiulong River, Zhangzhou City, Fujian Province, China. 24°30’18.08”N, 117°38’06.28”E.

Remarks. According to Li (1981), the Zhemin subregion includes areas “south of Zhoushan islands to Tiantai Mountains, east of Wuyi Mountains and Han River” (Fig. 1.10). We basically follow this definition, but extend the western boundaries to include areas west of the Wuyi Mountain range. 204

Etymology. The province name is the combination of the abbreviated pinyin Zhe and Min, which mean Zhejiang Province and Fujian Province, respectively.

Representative fauna. Formosania davidi, Pelophylax fukienensis and Bottapotamon fukienense.

DIAN dominion, dominion novus Hengduanshan Area district Shih & Ng, 2011: 4. Oriental region Kang et al., 2014: 216. (Fig. 8.3)

Diagnosis. This dominion consists highlands typically above 1000 m asl, it includes most of Yunnan (except a small part in the northwest), southern Sichuan, the northwestern half of Guizhou and the western extremities of Guangxi.

Type locality. Lancang River, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China. 22°0’38.86”N, 100°48’24.23”E.

Remarks. Shih & Ng (2011), who studied freshwater crabs, recognized the area of Yunnan and parts of southeastern Tibet as the Hengduanshan area (Fig. 1.14). Kang et al. (2014) recognized Yunnan as the Oriental region for fishes (Fig. 1.11). The Dian dominion is substantially different from these two areas as it also includes large parts of neighboring Guizhou and Sichuan. Therefore, it is herein proposed as a new dominion. The southwestern boundaries of this dominion are currently artificial and will have to be further refined by future studies.

Etymology. The dominion name is the abbreviated Chinese pinyin for Yunnan Province.

Representative fauna. Tor sinensis, Kaloula verrucose and Parapotamon spinescens. 205

YUNGUI PLATEAU province, provincium novum Hengduanshandongbei subregion Dai, 1999: 32. (Fig. 8.3)

Diagnosis. The highland regions of northeast Yunnan, southern Sichuan, the northwestern half of Guizhou and the western extremities of Guangxi.

Type locality. , Panzhihua City, Sichuan Province, China. 26°35’15.03”N, 101°42’55.96”E.

Remarks. Dai’s (1999) Hengduanshandongbei subregion consists of a small southwestern part of our area (Fig. 1.13), therefore we propose our area as a new province.

Etymology. The province is named after the Yungui Plateau.

Representative fauna. Percocypris pingi, Rana weiningensis and Aparapotamon emineoforaminum.

WEST HENGDUAN province Dai, 1999 Hengduanshanxibu subregion Dai, 1999: 32. (Fig. 8.3)

Diagnosis. This province covers most of northwest Yunnan, its boundary stretches from Lincang City in the south to Dali City in the east to Gongshan Derung and Nu Autonomous County in the north.

Type locality. , Dehong Dai and Jingpo Autonomous Prefecture, Yunnan Province, China. 24°40’54.01”N, 97°57’39.71”E.

206

Remarks. Dai’s (1999) definition of this area includes “areas south of like Zayü and Mêdog County, Hengduan Mountains of west Yunnan, southwestern highlands of Sichuan” (Fig. 1.13). It is very similar to our corresponding area, except ours does not include southwest Sichuan. We attribute this province to Dai, but partially translate the name to be more understandable.

Etymology. This province is named after the Hengduan Mountains.

Representative fauna. Microrasbora microphthalma, Odorrana andersonii and Eosamon tengchongense.

DIANNAN HIGHLANDS province Dai, 1999 Nulan subregion Li, 1981: 31. Diannanshandi subregion Dai, 1999: 32. (Fig. 8.3)

Diagnosis. This province covers most of southern Yunnan, its boundary stretches from Lincang City in the west to Yuxi City in the north to the Yunnan/Guangxi border in the east.

Type locality. Lancang River, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China. 22°0’38.86”N, 100°48’24.23”E.

Remarks. Li’s (1981) Nulan subregion is defined as “areas in Yunnan west of the headwaters of the Pearl River, south of Fuyuan, Tonghai, Xiaguan, Tengchong etc.” (Fig. 1.10). Dai’s (1999) definition of this area includes “Xishuangbanna and the areas west of it in South Yunnan. Its boundary stretches from Napo County, Guangxi, to Guangnan and Xilin County, Yunnan, to Anlong County of Guizhou” (Fig. 1.13). Our area is closest with Dai’s (1999) definition and therefore it is attributed to her. The name is partially translated to be more understandable.

207

Etymology. “Diannan” is the Chinese pinyin for southern Yunnan.

Representative fauna. Mystacoleucus marginatus, Leptobrachium promustache and Lacunipotamon albusorbitum.

Figure 8.3 The proposed freshwater zoogeographical areas of mainland China.

208

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Supplementary material

Supporting information for chapter 3.

Appendix 3.1 Comparative material. Yarepotamon breviflagellum Dai & Türkay, 1997: 1 males (23.1 × 19.5 mm) (CB 01370), Gushui, Guangning City, Guangdong, China, 1984. 2 males (14.2 × 12.0 mm, 12.2 × 10.4 mm) (SYSBM 001400–001401), Gushui, Guangning City, Guangdong, China, shallow creek, under rocks, coll. C. Huang, November, 2014. Yarepotamon gracilipa (Dai, Song, Li & Liang, 1980): Holotype: 1 male (19.9 × 16.8 mm) (CB 01372), Zhaoping, Hezhou City, Guangxi, China, 1977. Paratype: 1 male (22.5 × 18.3 mm) (CB 01373), same data as above. 1 male (14.1 × 11.1 mm) (SYSBM 001549), Jinxiu, Laibin City, Guangxi, China, coll. local, June 2015. Yarepotamon aflagellum (Dai, Song, Li & Liang, 1980): 1 male (19.4 × 15.8 mm) (SYSBM 0014033), Mengshan, Wuzhou City, Guangxi, China, shallow creek, coll. C. Huang, April 2014. 3 females (22.7 × 18.0 mm, 19.4 × 15.2 mm, 14.1 × 11.7 mm) (SYSBM 001404–001406), same data as above. Yarepotamon guangdongense Dai & Türkay, 1997: 1 male (34.3 × 27.0 mm) (SYSBM 001407), Yunan, Yunfu City, Guangdong, China, large creek, coll. C. Huang, October, 2014. 3 females (25.9 × 20.4 mm, 23.9 × 19.2 mm, 50.0 × 39.1 mm) (SYSBM 001408–001410), same data as above male. 1 males (33.8 × 24.5 mm) (SYSBM 001411), Cenxi, Wuzhou City, Guangxi, China, large creek, coll. B. M. Wang, September, 2014. 2 males (34.2 × 26.5 mm, 24.3 × 19.5 mm) (SYSBM 001412–001413) Xinyi, Maoming City, Guangdong, China, large creek, coll. C. Huang, April, 2015. 2 females (24.5 × 18.8 mm, 24.9 × 19.6 mm) (SYSBM 001414–001415), same data as above males. 2 males (31.1 × 23.6 mm, 21.3 × 16.6 mm) (SYSBM 001622– 001623), Xinyi, Maoming City, Guangdong, China, coll. J. Wang, April, 2017.

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Supporting information for chapter 8.

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