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)

Kimberleytrachia Köhler, 2011 is a genus of camaenid land snail endemic to the Western Australian Kimberley region. It comprises 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 variation in shell and genital anatomy as well as the differentiation in the mitochondrial markers 16S and COI, we assess the monophyly of Kimberleytrachia with respect to other camaenid genera from north-western Australia. In addition, we newly 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. silvaepluvialis n. sp.) based on comparative morphology and mitochondrial DNA differentiation. We found that a rather smooth, weakly elevated shell and, in particular, the complex penial anatomy are key morphological characteristics of Kimberleytrachia. Its constituent species are differentiated by a combination of shell and genital features and their morphological disparity appears to be more pronounced when species occur in sympatry. While island species are usually narrowly endemic to one or a few islands, the mainland species have much larger distributional ranges. One new species from the Maret and Berthier Islands, Bonaparte Archipelago, is phylogenetically and morphologically so distinct from Kimberleytrachia that it is recognized as a new monotypic genus, Succochlea n. gen.