Contributions to Zoology 88 (2019) 452-497 CTOZ brill.com/ctoz The role of allopatric speciation and ancient origins of Bathynellidae (Crustacea) in the Pilbara (Western Australia): two new genera from the De Grey River catchment Giulia Perina Centre for Ecosystem Management, School of Science, Edith Cowan University, 270 Joondalup Dv, Joondalup, WA 6027, Australia Western Australian Museum, Locked Bag 49, Welshpool DC, Western Australia 6986, Australia [email protected] Ana I. Camacho Museo Nacional de Ciencias Naturales (CSIC), Dpto. Biodiversidad y Biología Evolutiva C/ José Gutiérrez Abascal 2, 28006-Madrid, Spain Joel Huey Centre for Ecosystem Management, School of Science, Edith Cowan University, 270 Joondalup Dv, Joondalup, WA 6027, Australia Western Australian Museum, Locked Bag 49, Welshpool DC, Western Australia 6986, Australia The University of Western Australia, 35 Stirling Hwy, Crawley WA 6009, Australia Pierre Horwitz Centre for Ecosystem Management, School of Science, Edith Cowan University, 270 Joondalup Dv, Joondalup, WA 6027, Australia Annette Koenders Centre for Ecosystem Management, School of Science, Edith Cowan University, 270 Joondalup Dv, Joondalup, WA 6027, Australia Abstract The stygofaunal family of Bathynellidae, is an excellent group to study the processes that shape diversity and distribution, since they have unknown surface or marine relatives, high level of endemism, and limited dispersal abilities. Recent research on Bathynellidae in Western Australia (Pilbara) has uncovered new taxa with unexpected distributions and phylogenetic relationships, but the biogeographical processes that drive their diversification on the continent are still unclear. By exploring the diversity, distribution, and © Perina et al., 2019 | doi:10.1163/18759866-20191412 This is an open access article distributed under the terms of the cc-by 4.0 License. Downloaded from Brill.com10/04/2021 08:11:12AM via free access <UN> Allopatric speciation and ancient origins 453 divergence time of Bathynellidae in a setting such as the perched and isolated aquifers of the Cleaver- ville Formation in the north of the De Grey River catchment (Pilbara), we aim to test the hypothesis that vicariance has shaped the distribution of this family, specifically if one or multiple vicariant events were involved. We analysed the specimens collected from perched water in different plateaus of the Cleaverville Formation, combining morphological and molecular data from mitochondrial and nuclear genes. We de- scribed two new species and genera (Anguillanella callawaensis gen. et sp. nov. and Muccanella cundalin- ensis gen. et sp. nov.), and two additional taxa are recognised using morphology and/or Automatic Barcode Gap Discovery and Poisson Tree Processes species delimitation methods. New genera and species result restricted to isolate perched aquifers on single plateaus and their distributions, phylogenetic relationships, and divergence time estimates support multiple vicariant events and ancient allopatric speciation. Keywords ABGD – Anguillanella gen. nov – Bathynellidae – new species – Muccanella gen. nov – PTP – stygofauna Introduction Aquatic subterranean animals (stygobi- onts) often have larger distributions than ter- Subterranean species distributions are of- restrial subterranean animals (troglobionts) ten restricted, and confined to particular ge- (Barr & Holsinger, 1985; Christman & Culver, ologies, for example isolated karst systems, 2001; Lamoreaux, 2004). This can be due to a limestone, fractured banded iron formations larger suitable continuous environment, such (BIFs), and porous hyporheic systems (Culver as the presence of groundwater in different & Pipan, 2008; Harvey, 2002; Humphreys, 2017; but adjacent geological layers, or to flood- Trontelj et al., 2009). For this reason many sub- ing events that would increase the opportu- terranean taxa are considered short-range en- nity for dispersal (Lamoreaux, 2004). Small demics (SREs; sensu Harvey, 2002). Their small stygobionts are collected not only from karst geographic ranges, and high rate of endemism areas, but also from saturated interstices in make them ideal candidates to explore histori- alluvial/colluvial deposits (Barr & Holsinger, cal climatic and geological events. For example 1985; Holsinger, 1988; Marmonier et al., 1993; ice sheet coverage during the Quaternary gla- Christman & Culver, 2001). In other cases, ciations influenced the distribution of the sub- distributions of stygofaunal species can be re- terranean amphipod species of Stygobromus in stricted to small areas (Eberhard et al., 2009). north America (Holsinger et al., 1997) and Niph- Geographically close aquifers can be isolated argus virei in France (Foulquier et al., 2008). The by impermeable or semi-impermeable mate- occurrence of the cirolanid isopod Antrolana rial such as clay, mudstone or other deposits lira in areas formerly submerged by the ocean, with very low hydraulic conductivity. Ac- confirms the role of marine transgression in cordingly, adjacent groundwater bodies can shaping cirolanid distributions (Holsinger harbour different stygofaunal species. For et al., 1994), and the presence of troglobitic sal- example, calcrete aquifers in ancient palaeo- amanders in Texan caves suggests the ancestor channels of the Yilgarn region, in the arid of this radiation migrated underground to sur- zone of Western Australia, are considered vive climate aridification (Sweet, 1982). “islands under theDownloaded desert” from and Brill.com10/04/2021 host different 08:11:12AM via free access <UN> 454 Perina et al. stygofauna communities (Cooper et al., 2002, generally fresh to brackish (Department of 2008; Guzik et al., 2008; Humphreys et al., Water, 2010) and host a highly diverse stygo- 2009; Karanovic & Cooper, 2011). fauna. Halse (2018) estimates 1329 stygofaunal To be recognised as perched, aquifers are species for the Pilbara alone, whose distribu- located above the regional water table, in the tions reflect in part the hydrogeological com- vadose zone (the unsaturated zone below the plexity of the region (Finston et al., 2009, 2007; land surface). This occurs when there are lay- Brown et al., 2015; Perina et al., 2019). ers of rocks or sediments with very low per- Bathynellidae are a common component meability such as clay, granite or mudstone, of stygofauna in different aquifers of the Pil- above the main water table but below the bara region, including perched aquifers. They land surface (Fitts, 2012). Perched aquifers represent an ideal taxon to test biogeographic commonly form in arid, semi-arid climates hypotheses as they are confined to the inter- (Sedghi, 2016), and can be occasionally con- stitial and subterranean environment, have nected to local aquifer systems, particularly no known epigean or marine relatives, and during rain seasons and flooding events have limited dispersal abilities (Schminke, (Johnson & Wright, 2001). Perched aquifers 1974; Humphreys, 2008; Coineau & Camacho, within the same area in arid regions (isolated 2013). The impediments of conservative mor- or partially isolated from regional ground- phology and poorly resolved taxonomy, often water), were probably historically connected leading to inaccurate species identifications during groundwater table fluctuations, and/or (Camacho et al., 2018), have been alleviated marine transgressions. For example, perched in recent years, by molecular tools which have aquifers in the arid zones of Western Austra- been used to integrate morphological species lia were interconnected during wetter periods studies and resolve phylogenetic relationships when large river systems were flowing and among taxa (Camacho et al., 2002; Camacho water table was higher (Van de Graaff et al., et al., 2013a, b). Understanding of the Austra- 1977; BMR Palaeogeographic Group, 1990; lian bathynellids is still limited, but a recent González-Álvarez et al., 2016). study from one of the major catchments in The Pilbara region, in the arid zone of the Pilbara, the Fortescue, revealed distantly Western Australia, exhibits many different related taxa within the same catchment and types of aquifers, sometimes with complex even within the same aquifer (Perina et al., hydrological connectivity. Groundwater can 2018, 2019), suggesting a complex and ancient be contained in unconsolidated sedimentary biogeographical history. Similar results have aquifers (alluvium and colluvium in Caino- been obtained in a study of bathynellids in zoic valley fills), chemically deposited aqui- south Queensland (Little et al., 2016). All in- fers (mainly formed by calcrete and limonite vestigations conducted so far in Australia, within alluvium and colluvium formations), though, do not clarify the biogeographical and fractured rock aquifers, comprising Pre- processes that can drive Bathynellidae diver- cambrian basement rock (like BIFs, dolomite sification on the continent. and sandstone) and distinct types of aquifers In this study we aim to test vicariance can occur in the same area (Johnson & Wright, in a setting that is apparently ideal; the 2001). Perched aquifers are also present in the perched aquifers of the Cleaverville forma- region in various geologies (Hickman et al., tion in the north of the De Grey River in the 1983; Johnson & Wright, 2001; WorleyParsons, Pilbara (fig. 1). This formation comprises 2012; Department of Water, 2016). Aquifers are ridges formed by Precambrian Banded Iron recharged by rainfall and surface water, are Formations (BIFs) Downloadedcontaining from