Small snails in a big place: a radiation in the semi-arid rangelands in northern Australia (Eupulmonata, Camaenidae,Nanotrachia gen. nov.)

Abstract

Continuing the revision of the Camaenidae in the Australian Monsoon Tropics, we employed comparative analyses of morphological features (with a focus on shell and penial anatomy) and genetic markers (with a focus on mitochondrial COI and 16S sequences) to address the systematic relationships of land snails from the Victoria River District, Northern Territory, and adjacent East Kimberley (Western Australia). These analyses revealed that the species under study represented the previously undescribed genus Nanotrachia. This genus differs from all other camaenid genera known from north‐western Australia most conspicuously by its small, flat, and ribbed shell. Six species are identified as members of the new genus, four of them new species (Nanotrachia costulata sp. nov., Nanotrachia carinata sp. nov., Nanotrachia coronata sp. nov., Nanotrachia levis sp. nov.). Two further species have already been described previously but assigned to different genera. These species, Ordtrachia intermedia (as the type species of Nanotrachia) and Mouldingia orientalis, are here transferred to Nanotrachia. Like other camaenids from the Australian Monsoon Tropics, species of Nanotrachia are characterized by essentially allopatric distributions, regional endemism, and a patchy distribution across their range. © 2013 The Linnean Society of London

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)

“…Generally, the amounts of genetic differentiation between species were comparable with interspecific distances observed in other north-western Australian camaenids, such as >3% (COI and 16S) in Exiligada >4% (16S, Criscione et al, 2012), Rhagada >4% (16S) and >7% (COI) , Setobaudinia >6% (COI) and >9% (16S) (Criscione and Köhler, 2013b), Amplirhagada Iredale, 1933 >8% (COI) and >10% (16S) (Köhler and Johnson, 2012), Nanotrachia >5% (COI) and >3% (16S) (Köhler and Criscione, 2013), Baudinella, >3% (COI) and >4% (16S) Retroterra (Criscione and Köhler, 2014a). In Kimberleytrachia there has been a slight overlap between intra-and interspecific distances as was occasionally also observed in other genera.…”

“…Couper and Hoskin (2008) firstly suggested for lizards that sheltered rock habitats provide environmental conditions similar to rainforests permitting the persistence of rainforest lineages even in areas where rainforests have disappeared. Such lithorefugia have clearly been important for the persistence for several camaenid lineages in drier parts of the Kimberley and even have facilitated their radiation into semi-arid environments, such as on the limestone outcrops of the Victoria Bonaparte bioregion of the East Kimberley (Criscione et al, 2012;Köhler and Criscione, 2013). Accordingly, the survival of K. crawfordi, K. setosa and K. umbonis in inland areas may not exclusively rely on the presence of rainforests.…”

“…Our on-going revisionary work, which has mostly been based on newly collected materials from more remote locations, has since doubled the number of known camaenid species from the Kimberley to about 260 (e.g. Köhler, 2010aKöhler, , b, 2011aCriscione et al, 2012;Köhler and Johnson, 2012;Köhler and Shea, 2012;Köhler and Criscione, 2013;Criscione andKöhler, 2013a, b, c, 2014a, b).…”

Rhagadarevisited: on the taxonomy of species from the Kimberley and Dampierland, Western Australia (Pulmonata, Camaenidae)

“…Such studies have revealed that species are indeed best delineated by a combination of morphological (shell, genital anatomy) and molecular evidence (e.g., Criscione et al 2012;Köhler and Criscione 2013b). Accordingly, species have been recognised as distinct if they consistently formed phenotypically and genotypically distinct clusters (Sites and Marshall 2004).…”

Setocallosa—a new genus and species of land snail from Arnhem Land, Australia (Stylommatophora: Camaenidae)

“…In addition, this more xeric area supports lower species richness than more humid areas closer to the coast. Twenty-three genera were described from the East Kimberley and Victoria River District combined (e.g., Solem 1985;Criscione et al 2012;Köhler 2013a, 2013b;Köhler and Criscione 2013b) containing 50-60 species in total. Only three of these genera also occur in the NW Kimberley.…”