Revision of sinistral land snails of the genus Camaena (Stylommatophora, Camaenidae) from China based on morphological and molecular data, with description of a new species from Guangxi, China.

Weichuan Zhou,Chungchi Hwang,Hong-Mu Ai,Pei Wang,Jun-Hong Lin,Zhou-Xin Qian,Hong-Li Ding

doi:10.3897/zookeys.584.7173

Abstract

The camaenid land snail genus Camaena is widely distributed throughout Southeast Asia. Thirteen species are found in China alone. Among these, Camaena cicatricosa (Müller, 1774) is the most widely distributed species, including four subspecies, Camaena cicatricosa ducalis (Ancey, 1885), Camaena cicatricosa inflata (Möllendorff, 1885), Camaena cicatricosa obtecta (Fischer, 1898) and Camaena cicatricosa connectens (Dautzenberg & Fischer, 1906). The systematics of these taxa is revised herein based on comparative shell morphology and anatomy as well as analyses of DNA sequences of two mitochondrial genes (COI, 16S rRNA) and one nuclear marker, ITS2. We found that all subspecies form well-supported clades in a molecular phylogeny and are well-differentiated from each other by genetic distances that are consistent with amounts of interspecific differentiation. In addition, they clearly differ from each other in reproductive features. Based on these observations, we elevate all four subspecies to the rank of full species. Moreover, based on morphological and mitochdondrial differentiation, we describe a new species, Camaena poyuensis sp. n. from Guangxi, China. The new species conspicuously differs from its sibling species Camaena cicatricosa in having a larger and more depressed shell, a completely covered umbilicus, more or less purplish peristome, an obtuse angle at the junction of the basal and columellar lip, longer pedunculus of the bursa copulatrix, thicker epiphallus and penis, and short conic verge. Previous named species are also redescribed on their shell and anatomical characters, because the original descriptions are uninformative.

Highlights

The genus Camaena Albers, 1850, with the type species Helix cicatricosa Müller, 1774, is distributed throughout Southeast Asia where it occurs in southern China, IndoChina, Eastern India, the Philippines and Sulawesi (Zilch 1959–1960)
The present study aims to resolve the phylogenetic relationships of C. cicatricosa, to correctly delimit its closely related allies and to describe a putatively new species based on comparative analyses of morphological and molecular characters
Separate models determined by jModeltest for the three genes revealed the GTR model with gamma distribution and proportions of invariable sites (GTR+G+I) as the best-fit substitution model for c oxidase subunit 1 (COI), TPM2uf with gamma distribution (TPM2uf+G) for 16S rRNA gene (16S), and HKY model with gamma distribution (HKY+G) for internal transcribed spacer 2 (ITS2)

Summary

Introduction

The genus Camaena Albers, 1850, with the type species Helix cicatricosa Müller, 1774, is distributed throughout Southeast Asia where it occurs in southern China, IndoChina, Eastern India, the Philippines and Sulawesi (Zilch 1959–1960). The type locality of the second sinistral species, Camaena cicatricosa cicatricosa (Müller, 1774) is unknown, but specimens exhibiting typical features, such as a sinistral, umbilicated, subcarinated, depressed-globular, yellowish shell with numerous chestnut coloured bands, are widely distributed throughout southern China (Möllendorff 1885, Pilsbry 1891). They can be found in Guangdong, Guangxi, Yunnan, Guizhou, Hunan and Hong Kong (Yen 1939, Chen and Gao 1987, Zhang 2008, Wang et al 2014)

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