A Genus of Land Snail Endemic to the Coastal Kimberley, Western Australia with Description of New Taxa (Gastropoda, Camaenidae)
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Contributions to Zoology, 83 (4) 245-267 (2014) Molecular phylogenetics and comparative anatomy of Kimberleytrachia Köhler, 2011 – a genus of land snail endemic to the coastal Kimberley, Western Australia with description of new taxa (Gastropoda, Camaenidae) Francesco Criscione1, Frank Köhler1, 2 1 Australian Museum, 6 College Street, Sydney NSW 2010, Australia 2 E-mail: [email protected] Key words: genetic distances, Helicoidea, mitochondrial DNA, new species, Stylommatophora Abstract Acknowledgements ...................................................................... 256 Kimberleytrachia Köhler, 2011 is a genus of camaenid land snail References ...................................................................................... 256 endemic to the Western Australian Kimberley region. It com- Appendix ........................................................................................ 259 prises twelve previously recognised species, all of which occur within the high precipitation zone along the north-western coast between the Admiralty Gulf and King Sound and within less than about 50 km distance from the coast. By evaluating the Introduction variation in shell and genital anatomy as well as the differentia- tion in the mitochondrial markers 16S and COI, we assess the The Kimberley Region, a comparatively pristine region monophyly of Kimberleytrachia with respect to other camaenid in Western Australia has yet widely escaped the impacts genera from north-western Australia. In addition, we newly of urban, industrial and agricultural development due describe six species (K. jacksonensis n. sp., K. leopardus n. sp., K. nelsonensis n. sp., K. serrata n. sp., K. setosa n. sp. and K. to its remoteness and rugged terrain. As a result, the silvaepluvialis n. sp.) based on comparative morphology and Kimberley is an area of high significance for natural mitochondrial DNA differentiation. We found that a rather heritage conservation across terrestrial and marine smooth, weakly elevated shell and, in particular, the complex environments. The inaccessibility of vast parts of the penial anatomy are key morphological characteristics of Kim- Kimberley has also hampered the scientific exploration berleytrachia. Its constituent species are differentiated by a combination of shell and genital features and their morphologi- of its biodiversity, rendering current knowledge of the cal disparity appears to be more pronounced when species occur Kimberley’s fauna and flora patchy. However, several in sympatry. While island species are usually narrowly en- large surveys conducted during the past four decades demic to one or a few islands, the mainland species have much have improved the documentation of biotic patterns larger distributional ranges. One new species from the Maret and throughout the Kimberley highlighting this region as Berthier Islands, Bonaparte Archipelago, is phylogenetically and morphologically so distinct from Kimberleytrachia that it is one of Australia’ s biodiversity hotspots (McKenzie, recognized as a new monotypic genus, Succochlea n. gen. 1991; Gibson and McKenzie, 2012). Thanks to the hallmark works of Alan Solem, the Kimberley is known to support an exceptionally diverse Contents fauna of camaenid land snails. Solem (1979, 1981a, b, 1984, 1985, 1988, 1997) revised the entire camaenid Introduction ................................................................................... 245 fauna known at the time and described many new taxa, Material and methods .................................................................. 247 bringing the count of described species from about 30 Material .................................................................................... 247 to 120. However, this number was still based on rather Molecular methods ................................................................ 247 patchy collections undertaken mostly at readily acces- Morphological examinations .............................................. 248 Delimitation of species ......................................................... 248 sible locations along major roads and the coast. Thus, Abbreviations .......................................................................... 248 there had been little doubt that future surveys in yet Results ............................................................................................. 248 un-sampled areas would unearth many additional spe- Molecular analyses ................................................................ 248 cies. Our on-going revisionary work, which has mostly Comparative morphology .................................................... 252 been based on newly collected materials from more Discussion ...................................................................................... 253 Phylogenetic relationships of Kimberleytrachia ............ 253 remote locations, has since doubled the number of Species delimitation ............................................................... 253 known camaenid species from the Kimberley to about Patterns of diversification and distribution .................... 254 260 (e.g. Köhler, 2010a, b, 2011a, b, c; Criscione et al., 246 Criscione & Köhler - Kimberleytrachia land snails from Western Australia 2012; Köhler and Johnson, 2012; Köhler and Shea, 2012; inhabit more open woodland and rocky habitats. Since Köhler and Criscione, 2013; Criscione and Köhler, these habitats are more widespread and less fragmented, 2013a, b, c, 2014a, b). inland species tend to have much wider ranges. How- The patterns of distribution and diversity of land snail ever, the species richness of more xeric regions is much communities throughout the Kimberley are governed by lower than this of the sub-humid parts of the Kimberley. rainfall, topography, soil and vegetation types (Solem The richest land snail communities are found in vine and McKenzie, 1991; Gibson and Köhler, 2012; Köhler thicket patches in the high precipitation zone of the et al., 2012), and predominantly characterised by narrow north-western coastal region between the Admiralty range endemism and allopatry. Previous studies of Gulf to the north and the Camden Sound to the south camaenids from the Kimberley mainland and from (Solem and McKenzie, 1991). Altogether fifteen cama- offshore islands have shown that on average species enid genera are represented in this region, some of which ranges are restricted to a diameter of about 20 km or have recently been revised based on comparative analy- even less (Solem, 1991; Cameron, 1992; Köhler, 2011b). ses of morphological and mitochondrial DNA differen- The same works have revealed a correlation between tiation, such as Baudinella Thiele, 1931 and Retroterra preferred habitat and the extent of species distributions. Solem, 1985 (Criscione and Köhler, 2014a) as well as Along the coasts, many camaenids occur in rainforest Setobaudina Iredale, 1933 (Criscione and Köhler, 2013b). habitats (i.e., vine thickets) but not in the surrounding, The present study is dedicated to yet another genus more open wood- and bushland. Because rainforest occurring in the high precipitation zone, Kimberleytra- vegetation is restricted to small protected pockets, such chia Köhler, 2011. This genus comprises twelve pres- rainforest species are often narrowly endemic to one or ently recognised species. Almost all species occupy few rainforest patches (Solem, 1991; Köhler, 2010b, vine thickets between the Montague Sound and Collier 2011b, c). Further inland, however, where rainforest Bay and within less than 50 km distance from the coast patches are sparse or entirely lacking, camaenid snails (Fig. 1). Fig. 1. Distribution of Kimberleytrachia species in the Kimberley, Western Aus- tralia. White dots = new records, black dots = records from Solem (1979, 1985) and Köhler (2011). Scale bar = 50 km. Dashed lines indicate isohyets of average annual rainfall (in mm). Contributions to Zoology, 83 (4) – 2014 247 Available data indicate that Kimberleytrachia species species are those dissected specimens, which were used are patchily distributed and narrowly endemic (Köhler, to produce the anatomical illustrations figured herein. 2011b). As in most camaenids from the Kimberley, congeneric species are predominantly allopatric. Excep- Molecular methods tionally three species occur in sympatry on Boongaree Island and two on Augustus Island (Köhler, 2011b). DNA was extracted from small pieces of foot muscle Species now placed within Kimberleytrachia were from up to four specimens per lot by use of a QIAGEN originally affiliated with Torresitrachia Iredale, 1939 DNA extraction kit for animal tissue following the (Solem, 1979, 1985), another genus with superficially standard procedure of the manual. Fragments of the similar species having a moderately large and weakly mitochondrial 16S rRNA (16S) and cytochrome c oxi- elevated shell with wide aperture, an expanded and dase subunit 1 (COI) genes were amplified by PCR somewhat reflected lip and a saucer-shaped umbilicus. using the primer pairs 16Scs1 (Chiba, 1999) and 16Sbd1 However, Kimberleytrachia and Torresitrachia can (Sutcharit et al., 2007) and L1490 and H2198 (Folmer clearly be differentiated by features of their genitalia as et al., 1994), respectively. Reactions were performed well as their microscopic shell sculpture. In particular, with annealing temperatures / elongation times of 55°C the inner penial wall of Kimberleytrachia species does / 90 s for 16S and 50°C / 60 s for COI, respectively.