Angustopila majuscula Pall-Gergely & Hunyadi, 2023

Pall-Gergely, Barna, Hunyadi, Andras, Vermeulen, Jaap J., Grego, Jozef, Sutcharit, Chirasak, Reischuetz, Alexander, Dumrongrojwattana, Pongrat, Botta-Dukat, Zoltan, Oerstan, Aydin, Fekete, Judit & Jochum, Adrienne, 2023, Five times over: 42 new Angustopila species highlight Southeast Asia's rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae), ZooKeys 1147, pp. 1-177 : 1

Angustopila majuscula Pall-Gergely & Hunyadi sp. nov.

Figs 68 , 69

Type material.

Holotype: Thailand • 1 empty shell (H: 1.21 mm, D: 1.24 mm); Chiang Rai Province, 6 km S of Chiang Khian, toward Pa Ngae, Wat Phra That Charui (locality code: 2015/20); 19°34.41'N, 99°59.19'E; 420 m a.s.l.; 13 Feb. 2015; A. Hunyadi leg.; CUMZ 7438.

Paratypes: Thailand • 4 shells; same data as for holotype; coll. HA.

Additional material.

Thailand • 3 j/b shells; same data as for holotype; coll. HA • 1 imaged shell; Chiang Rai Province, Wat Doi Khong Khao Meditation Centre , 8 km NW of Chiang Rai, clay at the entrance of the cave (locality code: Th.6); 19°54.75'N, 99°46.60'E (approximate GPS coordinates); Nov. 2007; A. Reischütz leg.; HNHM 103482 • 4 shells + 13 j/b shells; same data as for preceding; coll. RE .

Diagnosis.

A large, conical Angustopila species with a wide umbilicus, a prominent palatal and a highly placed parietal tooth pointing towards the palatal.

Description.

Shell large for the genus, higher than wide, or rarely slightly wider than high; off-white, conical; body whorl widest from apertural view; protoconch consists of 1.5 whorls, with very slight indication of spiral striation preceding the first teleoconch whorl; teleoconch with fine, dense, irregularly spaced radial growth lines and somewhat stronger, equidistantly and sparsely-arranged spiral lines (ca. 12-17 on body whorl from standard apertural view); whorls 5, rounded or slightly shouldered; aperture oblique to shell axis from lateral view; umbilicus wide; aperture pear-shaped with distinct sinulus caused by the parietal and palatal teeth; peristome expanded, not reflected; parietal callus protruding, detached from penultimate whorl; parietal tooth oblique to parietal callus, strong but short, almost reaching peristome edge; upper palatal tooth points in direction of parietal tooth, blunter and wider than parietal tooth.

Measurements (in mm).

H = 1.21-1.31, D = 1.13-1.24, H/D*100 = 97.6-114.2 (n = 6), RUD = 33.3-36.3 (n = 4).

Differential diagnosis.

Angustopila majuscula sp. nov. mostly resembles species classified as Hypselostoma (e.g., H. socialis , H. lacrima , etc.) by the relatively large shell, the parietal and palatal teeth that point towards each other, and the wide umbilicus. However, those " Hypselostoma " species possess much denser spiral striation and their apertural dentition is more developed. Angustopila majuscula sp. nov. can be easily distinguished from its congeners by the arrangement of the teeth, the larger size, and the wide umbilicus. Angustopila concava lacks a palatal tooth, has a smaller parietal tooth, a concave-conical shell and a much more oblique aperture than Angustopila majuscula sp. nov. See also under A. akrodon sp. nov., A. parallela sp. nov., and A. tamlod .

Etymology.

The name Angustopila majuscula (somewhat larger in Latin) refers to the size of this species, which is the largest amongst all its congeners, but still a tiny land snail species.

Distribution.

This species is known from two nearby localities in Thailand’s Chiang Rai Province (Fig. 48 ).

Remarks.

The shells of sample Th.6 agree with those of the type series considering the most important characters (exactly conical shell, wide umbilicus, presence of two teeth). However, the parietal tooth of the former samples is much weaker than that in the typical shells. Therefore, we do not designate them as paratypes, but consider them conspecific.

This is the largest Angustopila species. At first sight it seemed to be a member of Hypselostoma , but that genus is characterised by denser spiral striation and an oblong-ovate apertural form.

Figures

Figure 48. Distribution of Angustopila species.

Figure 68. Angustopila majuscula Pall-Gergely & Hunyadi, sp. nov. (holotype, CUMZ 7438). Ventral (A), apertural (B), lateral (C), and apical (D) sides of the shell; sculpture on the protoconch (E), aperture (F); ventral (G) and frontal (H) surface of the body whorl.

Figure 69. Angustopila majuscula Pall-Gergely & Hunyadi, sp. nov., Th. 6 (HNHM 103482). Apertural (A), ventral (B), apical (C) and lateral (D), sides of the shell; aperture (E); sculpture on the protoconch (F); ventral (G) and frontal (H) surface of the body whorl.