Sinoennea infantilis Páll-Gergely & Grego, 2020

Páll-Gergely, Barna, Reischütz, Alexander, Maassen, Wim J. M., Grego, Jozef & Hunyadi, András, 2020, New taxa of Diapheridae Panha & Naggs in Sutcharit et al., 2010 from Laos and Thailand (Gastropoda: Eupulmonata: Stylommatophora), Raffles Bulletin of Zoology 68, pp. 1-13 : 5

Sinoennea infantilis Páll-Gergely & Grego , new species

( Figs. 1C , 6B )

Type material. Holotype (1 shell, H: 1.88 mm, D: 0.99 mm; Fig. 1C ) ( HNHM 103485 ), south-central Laos, Khammouan

Province , Tham Don Cave, earthquake Dome, sand sediments at bank of cave river, 17°33.815′N, 104°52.298′E, alt. 160 m a.s.l., locality code: JG2 B, coll. J. Grego, 11 February 2017 .

Diagnosis. A minute species with ovoid, smooth shell, very narrow umbilicus, and very weak apertural barriers comprising a short parietal lamella, two tiny palatal denticles, and a columellar denticle.

Description. Shell greyish white, somewhat translucent, ovoid. Body whorl and penultimate whorls are widest from standard apertural view. Entire shell with 4.75 whorls. Due to the obscure boundary between protoconch and teleoconch, size of protoconch could not be determined. Protoconch and teleoconch of similar sculpture, not glossy, practically smooth, with the exception of some thread-like ribs behind peristome. Whorls moderately bulging, suture not very deep. Aperture suboval, deformed heart-shaped. Parietal callus rounded, does not reach half of preceding whorl, relatively thin, “smeared” onto preceding whorl. Apertural dentition four-fold. Parietal lamella weak, almost straight, short, outer portion very slightly bent into palatal direction, inner portion bent in columellar direction. Sinulus relatively wide, not isolated well (i.e., tips of parietal and palatal denticles are far from each other). Palatal denticles minute, pointed, situated on a ridge. Upper one situated closer to peristome. Columellar tooth relatively close to peristome, small, pointed, not elongated. Peristome slightly thickened, expanded, and reflected. Basal swelling very slight, situated just behind peristome. Depression anterior to basal swelling not visible. Umbilicus very slightly open, teardrop-shaped.

Differential diagnosis. This new species can be distinguished from all other known Sinoennea species based on the combination of the smooth, pupoid shell and weakly developed apertural barriers. At first sight this species resembles the pupilloid genera Gastrocopta Wollaston, 1878 , and Nesopupa Pilsbry, 1900 . However, the apertural barriers of S. infantilis , new species, are typical of Sinoennea .

Sinoennea variabilis Páll-Gergely & Grego , new species, has a ribbed shell, deeper suture, and often rather conical shell instead of pupoid.

Etymology. The species name “ infantilis ” refers to the weak apertural denticles of this species, reminiscent of juvenile shells of species with stronger dentition.

Figures

Fig. 1. New species of Diapheridae from Laos. A, Laoennea carychioides Páll-Gergely, A. Reischütz & Maassen, new species (holotype); B, L. carychioides (paratype); C, Sinoennea infantilis Páll-Gergely & Grego, new species (holotype). Scale bar represents 1 mm.

Fig. 6. Synoptic view of Sinoennea and Laoennea, new genus, species of Laos (all species shown) and northern Thailand. A, Laoennea carychioides Páll-Gergely, A. Reischütz & Maassen, new species; B, Sinoennea infantilis Páll-Gergely & Grego, new species; C–E, Sinoennea variabilis Páll-Gergely & Grego, new species; F, Sinoennea sutchariti Páll-Gergely & Hunyadi, new species; G, Sinoennea panhai Páll-Gergely & Hunyadi, new species; H, Sinoennea euryomphala Inkhavilay & Panha, 2016; I, Sinoennea ljudmilena Páll-Gergely, new species; J, Sinoennea lizae Maassen, 2008; K, Sinoennea otostoma Páll-Gergely, A. Reischütz & Maassen, new species; L, Sinoennea angustistoma Páll-Gergely, A. Reischütz & Maassen, new species. Scale bar represents 1 mm.