Angustopila babel Pall-Gergely & Vermeulen, 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 babel Pall-Gergely & Vermeulen sp. nov.

Figs 28 , 29C-E

Type material.

Holotype: Vietnam • 1 empty shell (H: 1.07 mm, D: 0.97 mm); Quang Ninh Province, Halong Bay area, unnamed island in Dau Moi Temple area (locality code: WMVT.0328); 20°55.69'N, 107°09.40'E; 13 Sep. 2003; W.J.M. Maassen leg.; RMNH 347765.

Paratypes: Vietnam • 12 shells; same data as for holotype; RMNH 347766 • 491 shells; Quang Ninh Province, Halong Bay, Cap La Cave, deposit of soil fallen in through roof in pristine cave, vegetation outside cave tall and woody; 20°51.79'N, 107°13.54'E; 7 Mar. 2018; J.J. Vermeulen & K. Anker leg.; JJV 17632 • 10 shells; same data as for preceding; coll. HA • 20 shells; Quang Ninh Province, Halong Bay area, Dao Bo Hon, Song Sot Cave, drift material washed together over sinkhole in cave; 20°50.83'N, 107°05.67'E; J.J. Vermeulen & A.J. Whitten leg.; 2 Oct. 1998; JJV 6220 • 12 shells; Quang Ninh Province, Halong Bay area, Dao Bo Hon, Song Sot Cave, guano enriched sediments in cave; 20°50.83'N, 107°05.67'E; 2 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6221 • 1 shell; Haiphong Province, Cat Ba Island, Cave Qua Vang, around cave entrance, rocky limestone slope with low, somewhat mature forest; 20°48.64'N, 107°04.64'E; 100 m a.s.l.; 6 Jun. 2017; J.J. Vermeulen & K. Anker leg.; JJV 17657 (ex JJV 16612) • 20 shells; Haiphong Province, Cat Ba Archipelago, Dao Dau Be, rocks and small soil deposits bordering beach; 20°45.68'N, 107°07.47'E; 10 m a.s.l.; 8 Jun. 2017; J.J. Vermeulen & K. Anker leg.; JJV 16591 • 73 shells; Haiphong Province, Cat Ba Island, Cave Qua Vang, inside cave, large, ecologically intact active cave with speleothems; 20°48.64'N, 107°04.64'E; 60 m a.s.l.; 6 Jun. 2017; J.J. Vermeulen & K. Anker leg.; JJV 16590 • 1 shell; Quang Ninh Province, Halong Bay area, May Den Island, Tam Cung Cave, densely-vegetated limestone hill, near cave; approx. GPS coordinates: 20°52.33'N, 107°07.09'E; 3 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6248 • 2 shells; Quang Ninh Province, Halong-Campha area, 2.5 km SW Quang Hanh, foot of limestone cliff with degraded regrowth, near gardens; 20°59.750'N, 107°12.750'E; 29 Sep. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6218.

Diagnosis.

A medium-sized to large Angustopila species with a conical shell, regularly growing whorls, a strong parietal fold reaching the peristome and a narrow umbilicus.

Description.

Shell medium-sized to large-sized for the genus, higher than wide, very rarely slightly wider than high; conical, body whorl widest in standard apertural view; protoconch consists of 1.25 whorls with weak spiral striae preceding the first teleoconch whorl; teleoconch with very fine irregularly spaced, weak radial growth lines crossed with equally strong, rather regularly and sparsely-spaced spiral striae (ca. 12 on body whorl from apertural view); on both ventral and dorsal surfaces of body whorl spiral lines dominant or some radial lines are of comparable strength; sculpture overall weaker than in most other Angustopila species; whorls ca. 3.25-4, rounded or very slightly shouldered; aperture oblique to shell axis from lateral view; umbilicus narrow; aperture ovate-oblong, parietal callus straight; sinulus very wide, weakly isolated due to the rather low parietal tooth; peristome expanded, not reflected; parietal callus only very slightly detached from penultimate whorl, not smeared onto it; parietal tooth moderately elevated, of normal length, reaches parietal callus (in some, probably subadult shells it does not), perpendicular to parietal wall.

Measurements (in mm).

H = 0.94-1.17, D = 0.92-1.16, H/D*100 = 89.0-121.7 (n = 18), RUD = 22.1-25.2 (n = 8).

Differential diagnosis.

Shells of A. fabella lots in the Halong Bay area differ from A. babel sp. nov. by having a concave-conical shell (instead of the conical shape of A. babel sp. nov.), a wider umbilicus and a more deeply set parietal tooth.

From A. fabella populations living outside of the Halong Bay area, A. babel sp. nov. can be distinguished by the following traits: Angustopila babel sp. nov. is usually larger, has a less pointed (rather blunt) apex, and a comparatively larger aperture, a narrower umbilicus, and the parietal tooth reaches the parietal callus. Some A. fabella populations are, however, strikingly similar in shape. For example, sample 2020/58, which is smaller and has a more deeply situated parietal tooth, and sample 2020/32, which is also smaller, and has a more pointed apex and a smaller aperture. See also under A. fratermajor sp. nov.

Etymology.

Named after the conical shape, resembling the Tower of Babel as depicted by Pieter Breughel the Elder (ca. 1563). To be used as a noun in apposition.

Distribution.

Known from several populations in the Halong Bay area only (Fig. 11 ).

Remarks.

Conical or concave-conical shells with a single parietal tooth belong to two distinct morphological groups in the Halong Bay Area. Both types would otherwise fit the morphological continuum of the widespread and variable Angustopila fabella . However, since the two types are clearly distinct within such a small area, only one of them is identified A. fabella , and the other one must be a distinct species. There are three populations in the Halong Bay area with concave-conical shells bearing a single parietal tooth. Individuals from these populations are identified here as A. fabella . Conversely, the other populations of morphospecies that are conical, have a blunt apex, and possess a single parietal tooth are described as A. babel sp. nov.

Figures

Figure 11. Distribution of Angustopila apiostoma Pall-Gergely & Vermeulen, sp. nov. and Angustopila babel Pall-Gergely & Vermeulen, sp. nov.

Figure 28. Angustopila babel Pall-Gergely & Vermeulen, sp. nov. (holotype, RMNH 347765). Apertural (A), ventral (B), lateral (C) and apical (D) sides of the shell; microstructure of the protoconch (E), ventral (F) and frontal (G) surface of the body whorl.

Figure 29. Variability of Angustopila fabella Pall-Gergely & Hunyadi, 2015 in the Halong Bay A JJV 6217 B WMVT. 0338 and Angustopila babel Pall-Gergely & Vermeulen, sp. nov. C JJV 16590 D JJV 17634, Specimen 1 E JJV 17634, Specimen 2.