Revision of the Alycaeidae of China, Laos and Vietnam (Gastropoda: Cyclophoroidea) I: The genera Dicharax and Metalycaeus

Abstract

This is the first part of the revision of the Alycaeidae of China, Laos and Vietnam. Here we revise the species hitherto classified in Chamalycaeus Möllendorff, 1897 (genera Dicharax and Metalycaeus in this study). We show that no Chamalycaeus live in the region, and the alycaeid species of the investigated region can be classified into five genera: Alycaeus Baird, 1850, Dicharax Kobelt & Möllendorff, 1900, Dioryx Benson, 1859, Metalycaeus Pilsbry, 1900 and Pincerna Preston, 1907. We propose Dioryx dautzenbergi Páll-Gergely nom. nov. as a replacement name for Alycaeus (Dioryx) major Bavay & Dautzenberg, 1900, non Alycæus (Dioryx) granum var. major Godwin-Austen, 1893. Alycaeus anceyi Mabille, 1887, A. eydouxi Venmans, 1956, A. mouhoti L. Pfeiffer, 1862, A. rolfbrandti Maassen, 2006 and A. vanbuensis Bavay & Dautzenberg, 1900 are retained in Alycaeus. Alycaeus costulosa Bavay & Dautzenberg, 1912 and A. maolanensis Luo, Zhang & Zhuo 2009 were transferred to Pincerna. We examined newly collected specimens and the type specimens of all species with the exception of the following: A. elevatus Heude, 1886, A. expansus Heude, 1890, A. neglectus Heude, 1885, Chamalycaeus libonensis Chen, Li & Luo 2003, C. panshiensis Chen, 1989, C. tangmaiensis Chen & Zhang, 2001, C. zayuensis Zhang, Chen & Zhou, 2008. Fifteen new species are described as follows: Dicharax (?) abdoui Páll-Gergely, n. sp., Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp., Dicharax (?) ellipticus Páll-Gergely n. sp., Dicharax (?) immaculatus Páll-Gergely n. sp., Dicharax bison Páll-Gergely & Hunyadi n. sp., Dicharax draco Páll-Gergely & Hunyadi n. sp., Dicharax imitator Páll-Gergely & Hunyadi n. sp., Dicharax microcostatus Páll-Gergely n. sp., Dicharax micropolitus Páll-Gergely & Hunyadi n. sp., Dicharax robustus Páll-Gergely & Hunyadi, n. sp., Metalycaeus (?) awalycaeoides Páll-Gergely & Hunyadi n. sp., Metalycaeus (?) ibex Páll-Gergely & Hunyadi n. sp., Metalycaeus laosensis Páll-Gergely n. sp., Metalycaeus oharai Páll-Gergely & Hunyadi n. sp., Metalycaeus (?) okuboi Páll-Gergely & Hunyadi, n. sp. A total of twelve names are synonymised with valid species. In this revision we payed special attention to conchological characters hitherto neglected, such as the fine sculpture of the embryonic whorls and the fine structure of the microtunnels along the breathing tube. We described the radula and penis morphology of five Dicharax species.

Revision of Chondrocyclus s.l. (Mollusca: Cyclophoridae), with description of a new genus and twelve new species

“…Several characters closely resembled those features described in other cyclophorids or species in related families in Africa, Asia and New Zealand (e.g., Morton 1952;Bruggen 1983Bruggen , 1985Bruggen , 1986Emberton 2003;Marshall & Barker 2007;Lee et al 2008a;Rowson et al 2010b;Páll-Gergely et al 2017b). These include multiple spiral rows of hairs on the periostracum, taenioglossate radula and numbers of cusps on teeth, mammillation of the protoconch, and penis position and shape.…”

First record of subterranean rissoidean gastropod assemblages in Southeast Asia (Mollusca, Gastropoda, Pomatiopsidae)

“…Bole and Velkovrh (1986) mentioned only one subterranean species from South Asia that was recorded in Sri Lanka (Srilankiella horanae Bole & Velkovrh, 1986, nomen nudum according Kabat and Hershler 1993) and 12 probable pomatiopsid taxa from Japan belonging to the genera Akiyoshia Kuroda & Habe, 1954, Cochliopopsis Mori, 1938 and Moria Kuroda & Habe, 1958. Despite the recent increased interest in South and East Asian terrestrial micromolluscs (Maassen 2008, Culver 2012, Páll-Gergely 2014, Páll-Gergely et al 2015, Inkhavilay et al 2016, Páll-Gergely et al 2016, Páll-Gergely et al 2017, our knowledge of the stygobiont gastropod fauna of the region has not advanced significantly since 1986. Despite the extraordinary high radiation of surface freshwater Pomatiopsidae Bourguignat, 1863, species of the tribe Triculini Annandale, 1924 in the Mekong tributary (Deshayes and Jullien 1876;Crosse and Fischer 1879;Annandale 1919;Brandt 1968Brandt , 1970Brandt , 1974Davis 1979, Temcharoen 1971Brandt and Temcharoen 1974;Strong et al 2007), the troglobiont and stygobiont species of the area remained unknown.…”

Annotated checklist of the terrestrial molluscs from Laos (Mollusca, Gastropoda)

“…Type locality: limestone hills 20 km E. of Takek, Laos [Thakhek District, Khammouan Province, Laos]. Páll-Gergely et al 2017b: 10, fig. 3b.…”

“…Another fifty years later, Panha et al (2002), Lehmann and Maassen (2004) and Maassen (2008) studied a range of land snails from various parts of Laos, recording five new taxa. The most recent treatments on Laotian land snails are from Inkhavilay et al (2016a, b, 2017) and Páll-Gergely et al (2016, 2017b).…”