Genus-level revision of the Alycaeidae (Gastropoda, Cyclophoroidea), with an annotated species catalogue

Abstract

412 species-group names (including 11 replacement names), and 14 genus-group names of the Alycaeidae have been introduced to date. Type materials of 85% (336) of the known species and subspecies were examined, a further 5% (19) of the taxa were studied using available non-type material, and for another 6% (22) the original descriptions were sufficiently detailed to evaluate their taxonomic status. Only 3% of the taxa (12) could not be examined. Special attention was paid to the sculpture of the embryonic whorls and the sutural tube-microtunnel system in order to provide a novel classification for this group. In this study 363 taxa (320 species or 43 subspecies) are accepted within the family Alycaeidae. Of these, 22 have been described by the lead author and his coauthors in previous publications. In addition, there are 18 species that were formerly classified in Cycloryx and now belong to Pincerna due to its synonymy with Cycloryx. Among the remaining 323 species, 209 (65%) are transferred here to another genus, whilst 114 (35%) have remained in their original genus. Seven genera are accepted. While some questions (e.g., the distinction between Pincerna and Alycaeus) remained unanswered, this revision made three main achievements: (1) The Dicharax species were identified based on the absence of spiral striation on the entire shell; (2) the Metalycaeus species were identified based on the spiral striation of the protoconch; (3) and Stomacosmethis was separated from Alycaeus based on the extremely short sutural tube. Five nominal species are being synonymised with other species, and eight species are now treated as subspecies. The following replacement names are proposed: Dioryx urnula niosiensis Páll-Gergely, nom. nov. for Alycaeus urnula var. daflaensis Godwin-Austen, 1914; Dioryx urnula rotundus Páll-Gergely, nom. nov. for Alycaeus urnula var. globosus Godwin-Austen, 1914; Pincerna crenilabris juttingae Páll-Gergely, nom. nov. for Alycaeus crenilabris laevis van Benthem Jutting, 1959; Pincerna crenilabris korintjiensis Páll-Gergely, nom. nov. for Alycaeus crenilabris latecostatus van Benthem Jutting, 1959; Dicharax conicus jatingaensis Páll-Gergely, nom. nov. for Alycaeus conicus var. nanus Godwin-Austen, 1914; Metalycaeus godwinausteni Páll-Gergely, nom. nov. for Alycaeus neglectus Godwin-Austen, 1914; and finally Metalycaeus suhajdai Páll-Gergely, nom. nov. for Alycaeus varius Godwin-Austen, 1914.

The operculate micro land snail genus Dicharax Kobelt & Möllendorff, 1900 (Caenogastropoda, Alycaeidae) in Thailand, with description of new species

“…Dicharax species inhabiting China, Laos and Vietnam have been revised recently by . Several other species have been included in Dicharax in a recent family-wise revision without examining species-level taxonomy (Páll-Gergely et al 2020b). Here we report a total of ten Dicharax species from Thailand, six out of ten species being recorded from their type localities only, and the remaining species with additional occurrences within the vicinity of the type locality which ranges wider within Thailand or both Thailand and Myanmar.…”

“…The alycaeid shell is complicated mostly due to the three clearly distinguishable regions of the teleoconch (R1, R2, R3) having their own characteristics of sculpture (the most important is the rib density), length and morphology. Previous revisions , 2020b, Páll-Gergely and Auffenberg 2019 showed that most populations are recognizable, i.e. possess unique combinations of characters that distinguish them from other conspecific populations.…”

“…This family ranges from western India to Japan, including Indonesia in the south. This group is known to be particularly diverse in three regions, (1) the southeastern Himalaya, (2) Peninsular Malaysia and Sumatra, and (3) northern Vietnam, northern Laos and southern China , 2020b, Aravind and Páll-Gergely 2018, Páll-Gergely 2019, Sajan et al 2020. In Southeast Asia, alycaeid taxa from Laos, Vietnam, and Peninsular Malaysia have received attention in the past few years (Foon andLiew 2017, Páll-Gergely et al 2017), whereas the taxa from Thailand have remained poorly studied.…”

“…Dicharax Kobelt & Möllendorff, 1900 (replacement name for Charax Benson, 1859, non Charax Scopoli, 1777) is one of the seven genera of the Alycaeidae (Páll-Gergely et al 2020b). It was originally described as a subgenus of Alycaeus, and was diagnosed as follows:…”

Figure 1 from: Jirapatrasilp P, Páll-Gergely B, Sutcharit C, Tongkerd P (2021) The operculate micro land snail genus Dicharax Kobelt & Möllendorff, 1900 (Caenogastropoda, Alycaeidae) in Thailand, with description of new species. Zoosystematics and Evolution 97(1): 1-20. https://doi.org/10.3897/zse.97.59143

“…Dicharax caudapiscis Páll-Gergely & Hunyadi, 2018 and D. stuparum Páll-Gergely & Hunyadi, 2018 were described from Northern Thailand subsequently (Páll-Gergely and Hunyadi 2018). Following the genus definition of , as many as 164 nominal species were assigned to Dicharax, including three Alycaeus species that were formerly recorded from Thailand or "Siam", namely A. davisi Godwin-Austen, 1914, A. omissus Godwin-Austen, 1914, and A. pratatensis Panha & Burch, 1997(Páll-Gergely et al 2020b.…”