Distribution of Clam Shrimps (Crustacea: Laevicaudata and Spinicaudata) in South Africa, with New Records from the Northern Cape Province
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Zoological Studies 59:39 (2020) doi:10.6620/ZS.2020.59-39 Special Issue: Fossil and Modern Clam Shrimp (Branchiopoda: Spinicaudata, Laevicaudata) Open Access Distribution of Clam Shrimps (Crustacea: Laevicaudata and Spinicaudata) in South Africa, with New Records from the Northern Cape Province Elizabeth Meyer-Milne1,*, Musa C. Mlambo2,3, and D. Christopher Rogers4 1South African Environmental Observation Network, P.O. Box 110040, Hadison Park, Kimberley, 8306, South Africa. *Correspondence: E-mail: [email protected] (Meyer-Milne) 2Department of Freshwater Invertebrates, Albany Museum, Rhodes University affiliated Research Institute, Somerset Street, Grahamstown, 9139, South Africa. E-mail: [email protected] (Mlambo) 3Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140, South Africa 4Kansas Biological Survey, and The Biodiversity Institute, The University of Kansas, Higuchi Hall, 2101 Constant Avenue, Lawrence, KS 66047-3759, USA. E-mail: [email protected] (Rogers) Received 27 November 2019 / Accepted 15 January 2020 / Published 5 August 2020 Special issue (articles 32-46) communicated by Thomas A. Hegna and D. Christopher Rogers The ephemeral waterbodies of southern Africa are regarded a global hotspot for large Branchiopod diversity. Although the distributions and systematics of Anostraca and Notostraca have been fairly well defined, clam shrimps have received much less attention. So far, 18 clam shrimp species are known from the sub-region, but none of the available published literature defines their distribution in South Africa. Furthermore, most of the recent studies were concentrated in the mesic provinces, while very little information is available from the Northern Cape, where most ephemeral waterbodies in the country occur. This study reviews the distribution of clam shrimps in South Africa by reviewing published distribution records and contributing novel data from surveys in the Northern Cape. We found that 13 of the 18 species from the sub-region occur in South Africa, of which four are restricted to their respective provinces. We further clarify the current state of endemism patterns in South Africa and provide novel findings from the Northern Cape, including three new range extensions. The Northern Cape hosts the highest species richness, with nine species, followed by the Eastern Cape, where seven species have been recorded so far. Most other provinces have low species richness and endemism, while no species records have been published from the Limpopo province yet. Surveys over large geographical scales are important, and more research is needed on clam shrimp systematics in South Africa. Key words: Wetlands, Ephemeral, Endemism, Richness, Branchiopoda. BACKGROUND in research and conservation efforts (Herremans 1999). Ephemeral wetlands are particularly vulnerable to Ephemeral water bodies include a diverse array of alterations in land use patterns, because any hydrological intermittently inundated wetland systems that support modifications in the neighbouring landscape ultimately unique and specially adapted aquatic invertebrates affect their ecological functioning (Calhoun et al. 2017). (Calhoun et al. 2017). They are especially conspicuous However, during their desiccated phases, which can in semi-arid and arid landscapes (Atashbar et al. 2014), last for years (Brendonck et al. 2008), these systems but their sporadic nature causes them to be neglected are often either completely overlooked or regarded as Citation: Meyer-Milne E, Mlambo MC, Rogers DC. 2020. Distribution of clam shrimps (Crustacea: Laevicaudata and Spinicaudata) in South Africa, with new records from the Northern Cape Province. Zool Stud 59:39. doi:10.6620/ZS.2020.59-39. © 2020 Academia Sinica, Taiwan 1 Zoological Studies 59:39 (2020) page 2 of 9 lifeless and unimportant. This state of ignorance causes We aim to depict the known geographical distribution, anthropogenic disturbances and changes to continuously richness and endemism patterns of clam shrimps in pressure the unique biodiversity of these temporary South Africa and highlight opportunities for future waterbodies and renders their associated species research focus. vulnerable to decline and extinction (De Roeck et al. 2007; Amis et al. 2009; Atashbar et al. 2014; Dalu et al. 2017). MATERIALS AND METHODS Large Branchiopods are the flagship aquatic invertebrates of ephemeral waterbodies globally We examined the peer reviewed published (Brendonck et al. 2008). The orders Notostraca (tadpole literature for clam shrimp records from South Africa, shrimps) and Anostraca (fairy shrimps) are the two most and also include additional data from our own surveys well-known branchiopod crustacean groups and have across the Northern Cape Province (Fig. 1). Our surveys been fairly well studied (Bird et al. 2019). The order were conducted during 2017 and 2018 in 18 wet Diplostraca with suborders Laevicaudata, Spinicaudata locations, using a square frame 500-µm aquatic sweep and Cyclestherida, make up the third major group of net (30 cm wide), of which 13 sites produced clam large Branchiopods, colloquially known as clam shrimps shrimps. Hatching experiments were conducted in 2018 (Bird et al. 2019). Collectively, clam shrimps consist of from sediment collected from 98 desiccated locations five extant families, 19 genera and ~155 species; and during 2017, of which clam shrimp species from 15 even though they are widespread and abundant globally, locations were successfully reared for identification. This they have not been well studied (Brendonck et al. 2008; entailed inundating the sediment in 2L plastic containers Bird et al. 2019). and allowing species to hatch and grow over a 28 days The ephemeral waterbodies of southern Africa period (Henri et al. 2014) from nutrients that naturally are regarded a global hotspot for large Branchiopod occur in the sediment. Hatching was performed in diversity (Bird et al. 2019) and yet these systems have a semi-controlled environment using a temperature been neglected, especially in terms of their associated exposure that simulates the average temperature for the species (Martens and De Moor 1995; Mlambo et al. region (26–28°C) and a 24 hour photoperiod. All Triops 2011). Clam shrimps have received much less attention were removed to prevent predation. Identifications were than other associated fauna in the region (Bird et al. made by direct comparison with the primary taxonomic 2019). Eighteen clam shrimp species are known from literature, existing keys (Barnard 1929; Brendonck the sub-region (Brendonck 1999; Bird et al. 2019), but 1999), and previously identified reference material. All none of the available published literature defines the species currently considered valid from South Africa distribution of clam shrimps in South Africa. Brendonck were included in the species richness and endemism (1999) provided an authoritative summation on the clam analysis. The undetermined Eulimnadia spp. were shrimps in Southern Africa, but a number of faunistic excluded from these counts. Species richness is defined inventories pre-dating his analysis (Hamer and Appleton as the number of species that have been recorded in a 1991; Seaman et al. 1995; Hamer and Martens 1998) given province, while endemic species include those were not included. Furthermore, most of the recent known only from South Africa or a specific province. studies (De Roeck et al. 2007; Vanschoenwinkel et al. Species are considered to have restricted distributions 2008; Ferreira et al. 2012; Mabidi et al. 2016), were if they are known from only one of the nine provinces, concentrated in mesic regions. These include areas in even though they are not endemic to South Africa. Western Cape, Free State, Mpumalanga and Eastern Cape, which receive average anual rainfall of 400 - 1000 mm. Conversely, the Northern Cape is the largest, RESULTS most arid (MAP < 350 mm) province in South Africa, with the most pronounced occurrence of ephemeral The specific results are presented in table 1. A total waterbodies, but very little information is available on of 13 clam shrimp species including five endemics are these systems or their associated biodiversity (Meyer- recognised from South Africa to date, all of which are Milne and Mlambo 2019). This limits our understanding from the suborders Laevicaudata and Spinicaudata. No on the richness patterns and conservation status of clam species of Cyclestherida have been recorded in South shrimps in the country, which in turn causes concerns Africa yet and only Spinicaudata species have so far regarding land use management. Therefore, we review been recorded in the Northern Cape. The Northern Cape the distribution of clam shrimps in South Africa, by has the highest species richness and endemism, hosting providing an overview of published distribution records nine species of which three are restricted- and one is and contributing novel data from the Northern Cape. endemic to the province. No species records have so © 2020 Academia Sinica, Taiwan Zoological Studies 59:39 (2020) page 3 of 9 far been published from Limpopo Province. Ozestheria respective provinces. australis (Loven, 1847) is the most widespread species Five species were found during our surveys with a distribution across eight of the nine provinces, (Table 1), all of which belong to Spinicaudata. Of followed by Leptestheria rubidgei (Baird, 1862) these, Leptestheria striatoconcha Barnard, 1924 was which occurs across six provinces. Four species have recorded for the first