Laoennea carychioides 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 : 2

Laoennea carychioides Páll-Gergely, A. Reischütz & Maassen , new species

( Figs. 1A, B , 6A )

Type material. Holotype (1 shell, H: 2.37 mm, D: 1.13 mm; Fig. 1A ) ( NHMW 113107 ), Laos, Vientiane Province, Tham Pou Kham Cave , W of Vang Vieng, 265 m a.s.l., 18°55.601′N, 102°23.711′E, at the base of limestone rocks near the cave entrance, coll. A. Reischütz, March 2010; 1 paratype (RE/1, H: 2.27 mm, D: 1.19 mm; Fig. 1B ), same data as holotype.

Diagnosis. Shell minute, elongate with wide penultimate and conspicuously narrow last whorl. Swelling behind peristome absent, parietal lamella nearly continuous, long. Palatal wall with a single pointed lablar denticle.

Description. Shell minute, whitish, transparent when fresh. Shell elongate with wide penultimate and conspicuously narrow last whorl, entire shell with 6.75 whorls. It is nearly impossible to determine the boundary between protoconch and teleoconch. Teleoconch and protoconch glossy, extremely finely pitted, with some indication of weak radial growth lines that develop to thin ribs behind peristome. Aperture suboval, parietal callus rounded, extends to more than a half of preceding whorl, strongly thinned, “smeared” onto the preceding whorl. Apertural dentition three-fold, weak. Parietal lamella nearly straight from apertural view, continuous without changing direction or bending, although the “turning point” is identifiable, situated close to the outer end of the lamella. Sinulus relatively wide, rounded, opening shifted slightly laterally. There is a single, palatal (lablar) denticle, pointing in the direction of parietal lamella. Columellar lamella low, situated close to peristome. Peristome expanded and slightly reflected. Umbilicus slit-like, situated behind the columellar peristome, showing only last whorl.

Differential diagnosis. This species can be distinguished from all tiny Sinoennea species at first sight by the wide penultimate and narrow last whorl. Laoennea carychioides , new species, is superficially similar to members of the genus Carychium O.F. Müller, 1773 , due to the tiny, elongate shell. However, Carychium shells have a more pointed apex, their parietal callus does not climb on the preceding whorl that much, and their parietal lamella is oblique, and situated closer to the columella on the parietal wall.

Etymology. The specific epithet indicates that this new species is similar in size, shape, and colour to the genus Carychium O.F. Müller, 1773 .

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.