Two new cyclophoroid species from Hubei, China, with proposal of a new genus (Gastropoda, Caenogastropoda, Diplommatinidae and Alycaeidae)

Abstract Two new species, Sinoarinia feii Chen, gen. et sp. nov. and Pincerna vallis Chen & Wu, sp. nov., are described from western Hubei, China. The new genus Sinoarinia Chen & Wu, gen. nov. is established based on the strongly constricted penultimate whorl and the ascending last whorl. The Vietnamese species Pincerna costulosa (Bavay & Dautzenberg) is newly reported from Yunnan, China. For comparison, photographs of the shells of closely related species are provided. A key to the known species of Sinoariniagen. nov. is included.


Introduction
The malacofauna of western Hubei has usually been studied at some well-known localities along the Yangtze River, for example in Badong and Changyang (Heude 1882, 1885, 1890Yen 1939). In the region farther south, which encompasses vast areas of limestone mountains, the land snail fauna is still poorly known. During a short faunal survey in Wufeng (Tujiazu Autonomous County) in summer 2019, we found two cyclophoroid species new to science, namely Sinoarinia feii Chen gen. et sp. nov. (Diplommatinidae) and Pincerna vallis Chen & Wu, sp. nov. (Alycaeidae).

Methods
Photographs of the shells and the habitats were taken using a Canon 5D Mark IV camera. The shells were measured with digital vernier calipers to the nearest 0.1 mm. Whorls were counted as described by Kerney and Cameron (1979). The terminology to describe alycaeid shells (Regions 1-3) follows Páll-Gergely et al. (2017).
Abbreviations: a.s.l. -above sea level; D -shell breadth; H -shell height; HBUMM -mollusc collection of the Museum of Hebei University, Baoding, China; MNHN -Muséum National d'Histoire Naturelle, Paris, France; R1 (Region 1) -from the beginning of the teleoconch to the beginning of the differently ribbed region along the suture; R2 (Region 2) -the differently ribbed area before the constriction; R3 (Region 3) -from the constriction to the peristome.
Diagnosis. Shell minute, dextral, thin, translucent, cylindrical. Penultimate whorl strongly constricted. Last whorl strongly ascending, covering part of penultimate whorl. Protoconch oblique. Apical whorls depressed, with strong or weak ribs. Aperture rounded; peristome double, expanded but not reflected. Columellar lamella not visible from aperture but internally present; one parietal lamella and one palatal plica extending inwards from last whorl to penultimate whorl (in type species). Palatal plica visible through semitransparent parietal wall. Constriction absent or very weak where lamellae and plica terminate. Umbilicus closed, forming a chink.
Etymology. This name honors the herpetologist, Prof. Liang Fei, who encouraged the first author to carry out the research work.