Angustopila halongensis 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 halongensis Pall-Gergely & Vermeulen sp. nov.

Figs 15 , 16

Type material.

Holotype: Vietnam • 1 empty shell (H: 0.96 mm, D: 0.89 mm); Quang Ninh Province, Halong Bay, Cap La Cave, soil deposited 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.; HNHM 103473.

Paratypes: Vietnam • 1094 shells; same data as for the holotype; JJV 17631 • 10 shells; same data as for the holotype; coll. HA • 33 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; 2 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6263 • 3 shells; Quang Ninh Province, Halong-Campha area, limestone hill S of Halong, mainly regrowth and bamboo thickets; 20°57.00'N, 107°04.72'E; 28 Sep. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6246 • 2 shells; Quang Ninh Province, Halong Bay area, unnamed small island east of Cong Do Island, sparsely-vegetated limestone rocks; 20°51.84'N, 107°13.19'E; 4 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6249 • 2 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; JJV 16611 • 1 shell; Haiphong Province, Cat Ba Island, Cave Qua Vang, around cave entrance, rocky limestone slope with low, 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 16612 • 3 shells (one of them is figured); Haiphong Province, Cat Ba Island, lake Ao Ek, high and damp primary forest (locality code: Vietnam 06); 20°48.05'N, 107°01.33'E; 26 Sep. 1998; W.J.M. Maassen leg.; RMNH.5006719 • 3 shells; Haiphong Province, Cat Ba Island, Cave Trung Trang, around cave entrance, steep limestone cliffs with vegetated ledges; 20°47.30'N, 106°59.84'E; 50 m a.s.l.; 6 Jun. 2017; J.J. Vermeulen & K. Anker leg.; JJV 16617 • 193 adult + 2 j/b shells; Haiphong Province, Cat Ba Island, Cave Minh Chou, inside cave, cave with freshwater stream flowing into the sea, much disturbed by water extraction and concrete paths; 20°45.21'N, 107°0.75'E; 50 m a.s.l.; 5 Jun. 2017; J.J. Vermeulen & K. Anker leg.; JJV 16610 • 1 shell; Quang Ninh Province, Halong Bay area, Hang Tai Island, southern end, beach drift sample; 20°46.24'N, 107°07.77'E; 4 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6250.

Diagnosis.

A small to medium-sized, conical, or concave-conical species of variable shell height with a relatively large, ovate-oblong, toothless aperture, and strong spiral striation.

Description.

Shell small to medium-sized for the genus, higher than wide or very rarely wider than high; pale grey, conical or rarely concave-conical with regularly increasing whorls (sometimes except for the last one), shell height variable, last whorl widest from standard apertural view; protoconch consists of 1.5 whorls, with strong spiral striae; teleoconch with some fine, weak, irregular radial growth lines and much stronger, elevated, irregularly spaced spiral striae of variable density (ca. 16-20 on body whorl in standard apertural view); whorls 4-4.5, rounded; aperture moderately oblique to shell axis from lateral view; umbilicus relatively narrow; aperture relatively wide, ovate-oblong with straight parietal part; peristome expanded, not reflected; parietal callus not detached from penultimate whorl; aperture toothless.

Measurements (in mm).

H = 0.79-0.94, D = 0.81-0.95, H/D*100 = 98.8-120.7 (n = 12), RUD = 21.0-25.6 (n = 5).

Differential diagnosis.

Similar to A. elevata , but has a comparatively larger aperture and more regular conical shell shape and denser spiral striation on the body whorl. Angustopila werneri sp. nov. is larger with narrower aperture and wider umbilicus.

Etymology.

The specific epithet refers to the wide distribution of this new species in the Halong Bay Area, northern Vietnam.

Distribution.

This species is known only from the Halong Bay Area, Vietnam (Fig. 17 ).

Figures

Figure 15. Angustopila halongensis Pall-Gergely & Vermeulen, sp. nov., (holotype, HNHM 103473). Apertural (A), lateral (B), ventral (C) and apical (D) sides of the shell; sculpture on the protoconch (E), ventral (F) and frontal (G) surface of the body whorl.

Figure 16. Variability of Angustopila halongensis Pall-Gergely & Vermeulen, sp. nov., (JJV 17631) A holotype B-D paratypes.

Figure 17. Distribution of Angustopila halongensis Pall-Gergely & Vermeulen, sp. nov.