Angustopila erawanica Pall-Gergely & Dumrongrojwattana, 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 erawanica Pall-Gergely & Dumrongrojwattana sp. nov.

Figs 37 , 38 , 39

Type material.

Holotype: Thailand • 1 empty shell (H: 1.11 mm, D: 0.97 mm); Phrae Province, Long District, Tham Erawan (cave) near Maharat Rock Garden; 18°09.21'N, 99°59.24'E; 18 Jun. 2016; P. Dumrongrojwattana, P. Juangsantad, K. Khwantong, N. Namisa & P. Panthong leg.; CUMZ 7437.

Paratypes: Thailand • 2 figured shells; same data as for holotype; HNHM 103474 • 2 dissected paratypes in ethanol; same data as for holotype; HNHM 103472 • 2 shells; same data as for holotype; NMBE 551275 • 7 specimens in ethanol; same data as for holotype; coll. PGB • 8 specimens in ethanol; same data as for holotype; coll. PD • 10 shells; same data as for holotype; coll. PD • 2 shells; same data as for holotype; coll. HA • 34 shells; same data as for holotype; coll. PGB.

Additional material.

Thailand • 18 j/b shells; same data as for holotype; coll. PD.

Diagnosis.

A medium-sized to large Angustopila species with a narrow umbilicus and an elliptical or ovoid, slightly protruding aperture with wide sinulus and impressed at the position of the strong parietal tooth.

Description.

Shell medium- to large-sized for the genus, slightly higher than wide or slightly wider than high; pale grey, conical-ovoid, last or penultimate whorl widest from standard apertural view; protoconch consists of 1.25 whorls, with very slight indication of spiral striae preceding the first teleoconch whorl; teleoconch sculpture overall weak; teleoconch finely ornamented with irregularly spaced radial growth lines crossed by fine rows of regularly spaced spiral striae (ca. 16-18 spiral striae on body whorl in apertural view, the denser striation on the holotype is probably due to duplication of spiral striation, other shells have fewer striae); on both frontal and ventral surfaces of body whorl spiral lines dominant; whorls 4.5, slightly shouldered; aperture strongly oblique to shell axis from lateral view; umbilicus very narrow, less than 1/4 of shell width; aperture slightly protruding (visible from ventral and lateral views); aperture elliptical or ovoid, impressed at position of parietal tooth, sinulus wide; peristome slightly expanded, not reflected; parietal callus strongly elevated, sharp, detached from penultimate whorl; parietal tooth strongly developed; parietal side and parietal tooth align at an angle less than 90 degrees.

Measurements (in mm).

H = 0.94-1.11; D = 0.97-1.05, H/D*100 = 95.9-114.4 (n = 4), RUD = 20.4-22.4 (n = 3).

Differential diagnosis.

The aperture shape, in combination with the large size and narrow umbilicus, distinguishes this species from its congeners. Angustopila erawanica sp. nov. is most similar to A. bidentata sp. nov. by its narrow umbilical form and the shape of the aperture, but that species has a strong palatal tooth, a less protruding and more oblique aperture, and stronger spiral striation on the protoconch. Angustopila dominikae also possesses a strong palatal tooth and has a more globular shell. Angustopila concava has a wider body whorl, a wider umbilicus, and a more oblique aperture. See also under A. huoyani .

Anatomy.

Two specimens were dissected. Due to the small size of the animals, some traits could not be examined in detail. The traits of the distal genitalia could be relatively clearly seen, but proximal to the vagina, the animals consisted of a very soft, gelatinous material. No bursa copulatrix or any other female glands found, but this can be due to the difficulties to separate these organs. Penis well-developed but short, with triangular, thick penial caecum; retractor muscle inserts at end of caecum; epiphallus starts from base of caecum, thickened at its proximal end; vas deferens slender, but could not be followed (got torn just after its distal end); the lumen of the penis is visible under light microscope as a whiter (= less translucent) area, this can be followed from the distal penis throughout the penial caecum to the proximal end of epiphallus; vagina thick, longer than penis, although its proximal end could not be identified, inside vagina was a thick whiter area.

Etymology.

The new species is named after its type locality (Erawan cave). Specific epithet is used as a noun in apposition. Erawan is the Thai form of the mythical three- or thirty-three-headed, white elephant ridden by Indra (Sanskrit), the diety of rain, thunder, weather, and river flows.

Distribution.

This species is known from the type locality only (Fig. 31 ).

Figures

Figure 31. Distribution of Angustopila species.

Figure 37. Angustopila erawanica Pall-Gergely & Dumrongrojwattana, sp. nov. (holotype, CUMZ 7437). Apertural (A), ventral (B), lateral (C) and apical (D) sides of the shell; aperture (F); sculpture of the protoconch (E), ventral (G) and frontal (H) surface of the body whorl.

Figure 38. Conchological variability of Angustopila erawanica Pall-Gergely & Dumrongrojwattana, sp. nov. A and C paratypes [HNHM 103474] B holotype [CUMZ 7437].

Figure 39. Anatomy of Angustopila erawanica Pall-Gergely & Dumrongrojwattana, sp. nov. (HNHM 103472) A photo of the left lateral side of the body for which the genitalia are dissected out and specified in B B distal genitalia. Abbreviations: a: atrium; e: epiphallus; g: gut; h: head; p: penis; pc: penial caecum; rm: retractor muscle; s: sole; v: vagina; vd: vas deferens. White areas in B indicate parts of the genitalia that were lighter in colour (i. e., less translucent). Scale bars: 200 μm.