Systematics of the family Plectopylidae in Vietnam with additional information on Chinese taxa (Gastropoda, Pulmonata, Stylommatophora)

Abstract

Vietnamese species from the family Plectopylidae are revised based on the type specimens of all known taxa, more than 600 historical non-type museum lots, and almost 200 newly-collected samples. Altogether more than 7000 specimens were investigated. The revision has revealed that species diversity of the Vietnamese Plectopylidae was previously overestimated. Overall, thirteen species names (anterides Gude, 1909, bavayi Gude, 1901, congesta Gude, 1898, fallax Gude, 1909, gouldingi Gude, 1909, hirsuta Möllendorff, 1901, jovia Mabille, 1887, moellendorffi Gude, 1901, persimilis Gude, 1901, pilsbryana Gude, 1901, soror Gude, 1908, tenuis Gude, 1901, verecunda Gude, 1909) were synonymised with other species. In addition to these, Gudeodiscus hemmeni sp. n. and Gudeodiscus messageri raheemi ssp. n. are described from north-western Vietnam. Sixteen species and two subspecies are recognized from Vietnam. The reproductive anatomy of eight taxa is described. Based on anatomical information, Halongella gen. n. is erected to include Plectopylis schlumbergeri and Plectopylis fruhstorferi. Additionally, the genus Gudeodiscus is subdivided into two subgenera (Gudeodiscus and Veludiscus subgen. n.) on the basis of the morphology of the reproductive anatomy and the radula. The Chinese Gudeodiscus phlyarius werneri Páll-Gergely, 2013 is moved to synonymy of Gudeodiscus phlyarius. A spermatophore was found in the organ situated next to the gametolytic sac in one specimen. This suggests that this organ in the Plectopylidae is a diverticulum. Statistically significant evidence is presented for the presence of calcareous hook-like granules inside the penis being associated with the absence of embryos in the uterus in four genera. This suggests that these probably play a role in mating periods before disappearing when embryos develop. Sicradiscus mansuyi is reported from China for the first time.

A new species of Gudeodiscus Páll-Gergely, 2013 from China, with extraordinary conchological and anatomical features (Gastropoda, Pulmonata, Plectopylidae)

“…In some examples the caecum was absent (Páll-Gergely and Asami 2014, Páll-Gergely et al 2015a). Assuming that the penial and caecal calcareous hooks have similar functions, this suggests that whatever function the hooks might have (stimulation, mucus injection, mechanical holdfast, see Páll-Gergely et al 2015a), the penis makes a larger contribution than the penial caecum. The penial pockets of Gudeodiscus longiplica sp.…”

“…More than half of the recorded 24 species of Gudeodiscus are known from only empty shells at this time (Páll-Gergely and Hunyadi 2013, Páll-Gergely and Asami 2014, Páll-Gergely et al 2015a), including Gudeodiscus soosi Páll-Gergely, 2013 reported from three nearby localities in northern Guangxi. After Gudeodiscus soosi was described, we had the opportunity to examine four additional specimens (shells and ethanol-preserved bodies), from the original sample.…”

“…In addition to these peculiar conchological features, unique traits in the anatomy of Plectopylidae have been reported, i.e. “disposable” calcareous, hook-like granules inside the penis lumen which are probably spent during mating (Páll-Gergely and Hunyadi 2013, Páll-Gergely et al 2015a). …”

Systematic revision of the Plectopylinae (Gastropoda, Pulmonata, Plectopylidae)

“…For example, the genus Halongella is known to possess calcareous thorns on the inner surface of the vagina. Furthermore, several species of Gudeodiscus, Sinicola and Sicradiscus are known to have disposable calcareous crystals of usually claw-like shape in pockets formed by the penial wall (Páll-Gergely et al 2015b). The diverticulum of plectopylids is unique in terms of its position.…”

“…With this paper all members of the Plectopylidae are revised and figured (Páll-Gergely & Hunyadi 2013;Páll-Gergely & Asami 2014Páll-Gergely et al 2015b, 2015cPáll-Gergely 2018), with the exception of the Taiwanese Sicradiscus ishizakii (Kuroda, 1941) and the Japanese S. hirasei (Pilsbry, 1904). The large amount of morphological and unpublished molecular phylogenetic information made the subdivision of the family into two subfamilies possible.…”