ASIAN MYRMECOLOGY Volume 7, 19 – 36, 2015 ISSN 1985-1944 © ZHENGHUI XU AND XUEYING ZHOU Species grouping and key to known species of the ant genus Echinopla Smith (Hymenoptera: Formicidae) with reports of Chinese species ZHENGHUI XU* AND XUEYING ZHOU Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, College of Forestry, Southwest Forestry University, Kunming, Yunnan Prov- ince 650224, P.R. China. *Corresponding author's e-mail: [email protected] ABSTRACT. Twenty-three valid species of the formicine ant genus Echinopla Smith are recorded in the world. Body surface sculptures of the genus are sum- marized into four types: shagreened, longitudinally striate, bluntly spined with background retirugose and cribrate with interstice retirugose. The twenty-three species are divided into five species-groups based on the body surface sculpture types and other important characters. A key to known species of the genus is provided based on worker and queen castes. E. striata Smith, 1857 is recorded in China for the first time,E. cherapunjiensis Bharti & Gul, 2012 is recorded in Tibet and Guangxi regions of China, and this is the northernmost record of the genus in the world. Keywords: Hymenoptera, Formicidae, Echinopla, species-groups, key, Chi- nese species. INTRODUCTON 1943; AntWiki, 2015). Four species were record- ed in Philippines (Smith, 1858; AntWiki, 2015). The formicine ant genus Echinopla Smith, 1857 Two species were recorded in Australia (Forel, is distributed in the Oriental, Indo-Australian, 1901), Sulawesi (AntWiki, 2015), Thailand (An- and Australasian regions (Bolton, 1995). Wheeler tWiki, 2015) and India (Mayr, 1862; Bharti & (1911) designated Echinopla melanarctos as the Gul, 2012) respectively. And one species was type-species of the genus. Bolton (1994) treated recorded in Malaysia (Smith, 1857), Singapore Mesoxena Smith, 1860 as a junior synonym of (Smith, 1857; AntWiki, 2015), Nicobar Island Echinopla. Emery (1896, 1900, 1925), Donis- (AntWiki, 2015), Kratakau Island (AntWiki, thorpe (1932, 1943), Taylor (1992) and Bolton 2015) and China (Liu et al., 2015) separately. (1995) revised some species of the genus. According to the distribution data of species, In- After the establishment of the genus, donesia, Borneo and New Guinea are the distri- twenty-three valid species of the genus were sep- bution center of the genus, meanwhile spreading arately recorded in the world (Bolton, 2014). Ten south to Australia, and north to India and China. species were described from Indonesia (Smith, Unfortunately, many early species de- 1859, 1860, 1862, 1863; Mayr, 1862; Emery, scriptions were very brief, providing quite lim- 1887, 1898; Forel, 1901; Karavaiev, 1927; Do- ited information. No systematic work has been nisthorpe, 1936a). Seven species were reported in done in the genus to date. The absence of a taxo- Borneo (Smith, 1857; André, 1892; Stitz, 1938; nomic key causes a lot of difficulty in identifying Forel, 1901; AntWiki, 2015) and New Guinea the species of this genus. (Stitz, 1911, 1938; Donisthorpe, 1936b, 1941, 4 - 12 - AM7 - Species Grouping and Key to Known Species.indd 19 10-Aug-15 2:45:31 PM 20 Zhenghui Xu & Xueying Zhou The establishment of the AntWeb (2014) Standard measurements and indices are by the California Academy of Sciences and Ant- as defined in Bolton (1975), with the addition of Base.Net (2014) by Martin Pfeiffer, and the in- ED and MSL outlined below: creasing of image resources make it easier to ob- serve the type specimens of most species. Based TL Total Length: The total outstretched on the AntWeb (2014) and AntBase.Net (2014) length of the individual, from the man- images, and the original descriptions, we summa- dibular apex to the gastral apex. rized the morphological characters of the genus. Body surface sculpture is important for species HL Head Length: The straight-line length identification in Echinopla. In the separate spe- of the head in perfect full-face view, cies descriptions, similar sculptures of the genus measured from the mid-point of the an- were described in different expressions by differ- terior clypeal margin to the midpoint of ent myrmecologists. In this study, we summarized the posterior margin including spines. the body surface sculptures of the genus into four In species where one or both of these types: (1) shagreened, (2) longitudinally striate, margins is concave, the measurement is (3) bluntly spined with background retirugose, taken from the mid-point of a transverse and (4) cribrate with interstice retirugose. Based line that spans the apices of the project- on the body surface sculpture types and other ing portions. important characters, the twenty-three known species of the genus are divided into five species- HW Head Width: The maximum width of the groups. A key to the known species is prepared, head in full-face view including spines, based on the worker and queen castes. excluding the eyes. Based on the long term collection from 1996 to 2014, E. striata Smith, 1857 is recorded CI Cephalic Index = HW×100/HL. in China for the first time, meanwhile E. chera- punjiensis Bharti & Gul, 2012 is recorded in Ti- SL Scape Length: The straight-line length bet and Guangxi Regions, China. Previously, the of the antennal scape, excluding the bas- latter species was recorded in Yunnan Province, al constriction or neck. China by Liu et al. (2015). This is the northern- most record of the genus in the world. SI Scape Index = SL×100/HW. ED Eye Diameter: The maximum diameter MATERIALS AND METHODS of the eye. Images of type specimens and identified specimens PW Pronotal Width: The maximum width of of most species were downloaded from AntWeb the pronotum measured in dorsal view and AntBase.Net. Original descriptions and including spines. figures of E. arfaki Donisthorpe, E. densistriata Stitz, E. maeandrina Stitz, E. octodentata MSL Mesosoma Length (=AL-Alitrunk Stitz and E. rugosa André were obtained from Length): The diagonal length of the me- AntCat. Chinese specimens of E. striata and E. sosoma in lateral view, measured from cherapunjiensis were collected through sample- the point at which the pronotum meets plot (Xu, 2002), search-collecting (Xu et al., the cervical shield to the posterior basal 2011) and Berlese (Burwell & Nakamura, 2011) angle of the metapleuron. methods. The Chinese specimens were observed and measured under a Jiangnan XTB-1 stereo PL Petiole Length: The length of the peti- microscope with a micrometer. Illustrations of the ole measured in lateral view from the Chinese species were drawn under a Motic-700Z anterior process to the posteriormost stereo microscope with illustrative equipment. point of the tergite, where it surrounds the gastral articulation. 4 - 12 - AM7 - Species Grouping and Key to Known Species.indd 20 10-Aug-15 2:45:31 PM Species Grouping and Key to Known Species of the Ant Genus Echinopla Smith 21 (Hymenoptera: Formicidae) PH Petiole Height: The height of the petiole usually spined, toothed, or angled, rarely un- measured in lateral view from the apex armed. Propodeal spiracles slit-like or elliptical, of the ventral (subpetiolar) process ver- relatively lower on the side. Metapleural bulla tically to a line intersecting the dorsal- and orifice present. most point of the node including spines. Petiole transverse and erect, narrowing dorsally, usually spined or toothed laterally and DPW Dorsal Petiole Width: The maximum dorsally, without subpetiolar process. Rarely peti- width of the petiole in dorsal view in- ole node-like and cubic, without spines and teeth. cluding spines. Gaster globose to ovate, the first seg- ment very large and usually concealing the other LPI Lateral Petiole Index = PH×100/PL. segments beneath it. Body surface usually strong sculptured, DPI Dorsal Petiole Index = DPW×100/PL. longitudinally striate, bluntly spined with back- ground retirugose or densely cribrate with inter- All measurements are expressed in millimeters. face retirugose. Rarely body surface shagreened or smooth. Pilosity and pubescence usually abun- ECHINOPLA SMITH, 1857 dant, rarely body dorsum hairless. Diagnosis of queen: With the common Echinopla Smith, 1857: 79. Type-species: Echi- characters of worker, but head with three dis- nopla melanarctos, by subsequent designation of tinct ocelli. Mesosoma with tegulae. Mesonotum Wheeler, 1911: 162. massive, each side with a tooth-like or lobe-like Mesoxena Smith, 1860: 106. Type-spe- process, scutum long and broad, scutellum short cies: Mesoxena mistura, by monotypy. Junior and broad. Metanotum very short and transverse. synonym of Echinopla: Bolton, 1994: 50. Dorsum of propodeum short and broad, posterior Diagnosis of worker: Robust arboreal margin rounded. ants with the following combination of characters. Systematic position: Formicinae: Cam- Head rectangular to trapezoidal, usu- ponotini. ally broader than long and narrowed anteriorly. Geographical range: Oriental, Indo- Mandibles robust, subtriangular, masticatory Australian and Australasian. margin with 5 teeth. Palpi formula 6, 4. Clyp- eus broad and relatively short, anterior margin usually weakly convex. Antennal fossae widely SPECIES GROUPING apart. Antennae long, 12-segmented, scapes dis- tinctly surpassing posterior head corners, flagella Based on the characters of sculptures types, weakly incrassate toward apex Frontal lobes well eyes, frontal lobes, mesosoma, petiole, and pi- developed, elevated or laterally expanded, usu- losity, the twenty-three species of the genus can ally concealing antennal fossae. Frontal carinae be divided into five species-groups. The serra- short, not surpassing the line connecting mid- ta-group is richest in species diversity, succes- points of the eyes. Eyes small, convex or pro- sively the striata-group and melanarctos-group, truding, placed laterally, well behind midpoint of the mistura-group and nitida-group each contain head side, rarely situated at midpoint of the side. one species only. Ocelli absent. Mesosoma oblong quadrate, dorsal 1. mistura-group: Eyes located at midlength of outline completely arched or interrupted by im- head. Frontal lobes very narrow and suber- pressed metanotal groove, at the latter case me- ect, antennal fossae exposed (Fig.