Hypselostoma populare Gojšina, Hunyadi & Páll-Gergely, 2025

Gojšina, Vukašin, Hunyadi, András, Sutcharit, Chirasak, Tongkerd, Piyoros, Auffenberg, Kurt, Grego, Jozef, Vermeulen, Jaap J., Reischütz, Alexander & Páll-Gergely, Barna, 2025, A new start? Revision of the genera Anauchen, Bensonella, Gyliotrachela and Hypselostoma (Gastropoda, Eupulmonata, Hypselostomatidae) of Southeast Asia with description of 46 new species, ZooKeys 1235, pp. 1-338 : 1-338

Hypselostoma populare Gojšina, Hunyadi & Páll-Gergely sp. nov.

Type material.

Holotype. Thailand • 1 shell (SH: 1.4 mm; SW: 2.2 mm); Krabi Province, 9.2 km northwest from Krabi towards Phang Nga, right side of the road ; 08°07.305'N, 98°52.231'E; 40 m a. s. l.; 21 Feb. 2015, A. Hunyadi leg.; CUMZ 14455 . Paratypes. Thailand • 5 shells; same data as for holotype; coll. HA • 1 shell; Chumphon Province, Pathio, 500 m from the junction Ban Tham Tong - Thung Yang Beach , large rock; 10°54.328'N, 99°29.903'E; 20 m a. s. l.; 23 Feb. 2015; A. Hunyadi leg.; coll. HA • 10 shells; Ranong Province, south of Kra Buri, Tham Phra Kayang , southeastern part of the rock, 10°19.480'N, 98°45.933'E; 22 Feb. 2015; A. Hunyadi leg.; coll. HA • 17 shells; Chumphon Province, 2.5 km northeast from Pathio, Tham Khao Phlu , 10°43.851'N, 99°19.242'E; 30 m a. s. l.; 23 Feb. 2015; A. Hunyadi leg.; coll. HA • 2 shells; Krabi Province, Railay (= Rai Leh) Beach West , Railay Highlands , at the base of limestone rocks; 8°0.865'N, 98°50.219'E; 30 m a. s. l.; Sep. 2007; A. Reischütz leg.; coll. REI • 3 shells; Krabi Province, N of Krabi, Tiger Cave Temple (= Wat Tham Suea), along the ~ 200 steps to the cave , at the base of limestone rocks; 8°7.603'N, 98°55.466'E; 90 m a. s. l.; Sep. 2007; A. Reischütz leg.; coll. REI .

Additional material examined.

Thailand • 8 shells (damaged / juveniles, not paratypes); Chumphon Province, 2.5 km northeast from Pathio, Tham Khao Phlu , 10°43.851'N, 99°19.242'E; 30 m a. s. l.; 23 Feb. 2015; A. Hunyadi leg.; coll. HA • 5 shells (damaged / juveniles, not paratypes); Ranong Province, south of Kra Buri, Tham Phra Kayang , southeastern part of the rock, 10°19.480'N, 98°45.933'E; 22 Feb. 2015; A. Hunyadi leg.; coll. HA .

Type locality.

Krabi Province, 9.2 km northwest from Krabi towards Phang Nga, right side of the road; 08°07.305'N, 98°52.231'E; 40 m a. s. l.

Diagnosis.

Shell depressed, concave-conical, last whorl strongly detached from the penultimate and ascending at nearly 60–70 ° angle. Teleoconch strongly spirally striated. Aperture equipped with four blunt barriers (angulo-parietal, upper palatal, lower palatal, and columellar). Umbilicus very wide.

Description.

Shell depressed, concave-conical (due to the strongly enlarged last whorl), consisting of 3.75–4.25 whorls separated by a very deep suture. Colouration yellowish or very pale brownish, opaque. Protoconch initially almost smooth and then finely pitted, showing spiralling pattern and consisting of 1.25–1.5 whorls. Boundary between the protoconch and teleoconch clearly visible due to the change of microsculpture. Teleoconch strongly and regularly spirally striated, spiral striae thread-like raised. Space between two spiral striae measuring approximately the width of two to four spiral striae. There are ~ 30 spiral striae on the last whorl in standard view. Weaker, irregularly spaced radial growth lines are also visible crossing the spiral striae. Some irregularly spaced radial white streaks are occasionally present. Last whorl shouldered, strongly detached from the penultimate and ascending strongly near the aperture (~ 60–70 ° compared to the shell axis). Peristome lighter than the rest of the shell, fragile, expanded and not reflected. Aperture equipped with four moderately strong barriers (angulo-parietal, upper palatal, lower palatal, and columellar). Angulo-parietal lamella is the strongest in the aperture, consisting of two parts corresponding to angular and parietal lamellae in the former Gyliotrachela . The angular part of the angulo-parietal lamella is very small and pointy, leaning towards the palatal wall. The parietal part of the angulo-parietal lamella is much stronger and positioned deeper in the aperture, leaned towards the columellar lamella. Both palatal plicae and a columellar lamella are developed to similar level, relatively short and blunt. Upper palatal plica nearly fully rectangular in shape, lower palatal plica and columellar lamella more rounded and positioned even deeper in the aperture than the upper palatal plica. The apertural barriers are not very variable. None of these barriers reach the peristome. Surface of all apertural barriers is finely granulated. Sinulus rounded and well separated from the rest of the aperture. Umbilicus open, very wide, measuring ~ 1 / 3 of the shell width and showing all previous whorls.

Differential diagnosis.

This species is nearly identical in external appearance to Hypselostoma erawan . However, H. erawan clearly differs in the appearance of the apertural barriers. Hypselostoma erawan has more barriers than the new species and palatal plicae are hooked (neither of the barriers in H. populare sp. nov. are hooked). Acinolaemus colpodon F. G. Thompson & Upatham, 1997 is smaller and also has hooked barriers. Hypselostoma cucumense has the same appearance of the apertural barriers but the last whorl in H. populare sp. nov. is without a keel. The umbilicus is also initially narrow in H. cucumense and then widening at the last whorl, but it is wide even in its initial parts in H. populare sp. nov.

Measurements

(in mm, n = 5). SH = 1.33–1.41; SW = 2.13–2.22; AH = 0.79–0.86; AW = 0.7–0.87.

Etymology.

Named after the fact that many sampling sites of this species are popular touristic destinations.

Distribution.

This species is known from Krabi, Chumphon and Ranong provinces in Thailand.

Remarks.

This species is not very variable in terms of shell size and apertural dentition but in some specimens the spire is more depressed conical than in others.