Sinoennea angustistoma Páll-Gergely, A. Reischütz & Maassen, 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 : 4-5

Sinoennea angustistoma Páll-Gergely, A. Reischütz & Maassen , new species

( Figs. 2B , 6L )

Type material. Holotype (1 shell, H: 2.91 mm, D: 1.68 mm; Fig. 2B ) ( NHMW 113108 ), Laos, Khammouane Province, limestone hill in the rice paddies E of road 1E about 300 m SE of Gnommalat , NE of Thakhek, 175 m a.s.l., 17°35.004′N, 105°10.443′E, at the base of limestone

rocks, coll. A. Reischütz, March 2010; 1 paratype (RE/1, H: 3.02 mm, 1.72 mm), same data as holotype .

Diagnosis. Shell ovoid with a conspicuously narrowed, elongate aperture and a deep, wide, internally grooved umbilicus. Aperture with short parietal lamella, and three denticles each on both palatal and columellar sides.

Description. Shell chalk white, probably slightly transparent when fresh. Shell ovoid with strongly sideways flattened aperture. Last and penultimate whorls are the widest from standard apertural view. Entire shell with 5.25–5.5 whorls. Protoconch consisting of two whorls, moderately glossy, very finely pitted. Teleoconch regularly ribbed. Ribs of upper whorls curved or slightly S-shaped for last whorl. Aperture elongate ovate, strongly compressed from both sides. Parietal callus is smeared onto preceding whorl. Apertural dentition seven-fold. Parietal lamella elevated, very short, rather straight, its outer end slightly turning to the palatal side, and its inner end slightly bent in direction of the columella. Sinulus relatively small, teardrop-shaped, opens slightly upwards. Palatal wall with three denticles, uppermost one small, pointed, facing parietal lamella, middle one slightly elongate inside, somewhat larger than first one, third one also slightly elongate obliquely in basal direction. Columellar wall also with three denticles, uppermost tiny, blunt, situated at the middle of parietal lamella, lower two ones situated along an inwards running ridge, lower one situated closer to the peristome edge. Both denticles slightly elongated inside. Outer side of body whorl slightly impressed in the position of the innermost palatal denticle, no swelling visible behind peristome. Umbilicus wide, rounded, showing all whorls, periumbilical keel prominent, sharp. Inner side of body whorl (i.e., inside umbilicus) with a conspicuous groove.

Differential diagnosis. Sinoennea angustistoma , new species, is similar to Sinoennea guiyangensis T.-C. Luo, D.-N. Chen & G.-Q. Zhang, 1998, from Guizhou Province of China, but has a more rounded shell, denser ribs, narrower aperture, and an additional columellar denticle on the peristome. Furthermore, the umbilicus of the new species is probably wider than that of S. guiyangensis, but it is not illustrated in the original description of that species. Sinoennea maolanensis T.-C. Luo, W.-C. Zhou & D.-N. Chen, 2004, also from Guizhou, has a less rounded shell, a narrower umbilicus, and more widely-spaced ribs.

Etymology. The specific epithet refers to the narrow aperture of this new species.

Figures

Fig. 2. New Sinoennea Kobelt, 1904, species from Laos. A, Sinoennea otostoma Páll-Gergely, A. Reischütz & Maassen, new species (holotype); B, Sinoennea angustistoma Páll-Gergely, A. Reischütz & Maassen, 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.