Hypselostoma fortunatum Gojšina, Hunyadi & Páll-Gergely, 2025

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

Figs 186 E View Figure 186 , 193 View Figure 193 , 194 View Figure 194 , 195 View Figure 195 , 223 View Figure 223

Type material.

Holotype. Thailand • 1 shell (SH: 1.57 mm; SW 1: 2.83 mm); Phattalung Province, Khao Ok Thalu , rock wall; 07°37.506'N 100°05.330'E; 19 Feb. 2015; A. Hunyadi leg.; CUMZ 14465 View Materials GoogleMaps . Paratypes. Thailand • 20 shells; same data as for holotype; coll. HA GoogleMaps .

Additional material examined.

Thailand • 6 shells (juveniles / damaged, not paratypes); same data as for holotype; coll. HA GoogleMaps • 11 shells; Songkhla Province, 31.3 km NW Hat Yai , 1.2 km W of Hwy. 43; 7°10'N, 100°16'E; 80 m a. s. l.; 08 Apr. 1988; K. Auffenberg leg.; locality code KA-0636 A; UF 344932 GoogleMaps • 1 shell; same locality data as previous; 08 Apr. 1988; K. Auffenberg leg.; locality code KA-0635 ; UF 591324 GoogleMaps .

Type locality.

Thailand, Phattalung Province, Khao Ok Thalu, rock wall; 07°37.506'N, 100°05.330'E.

Diagnosis.

Hypselostoma with depressed-conical shell, teleoconch with finely sandpaper-like surface and radially but not spirally striated. Aperture equipped with only four relatively weak barriers (angulo-parietal, upper palatal, lower palatal and columellar).

Description.

Shell depressed-conical, chestnut brown, glossy, not translucent. It is consisting of 3.5–4 regularly increasing, convex whorls separated by a deep suture. Protoconch of the same colour as the teleoconch, finely pitted, not showing spiralling pattern and consisting of ~ 1.25 whorls. Teleoconch sculpture finely granulated (sandpaper-like) with additional radial growth lines which are more or less regularly spaced. Last whorl bluntly keeled at the centre of the periphery, slightly to moderately detached from the penultimate whorl and strongly ascending near the aperture (usually ranging from 65 to almost 90 ° compared to the shell axis). The keel is the most prominent on the last whorl behind the peristome. Peristome brown, weakly expanded, not reflected. Aperture equipped with four main barriers (angulo-parietal, upper palatal, lower palatal and columellar), all of which are relatively weak. Angulo-parietal lamella is the strongest in the aperture, consisting of a high parietal part and weak, tubercle-like angular part which is sometimes weakly sinuated in the middle. The angular part is sometimes also more distinctly separated from the parietal. Upper palatal plica relatively weak and straight. Lower palatal plica only slightly stronger (broader and higher) than the upper palatal. Columellar lamella horizontal, developed to the same extent as the lower palatal plica. Weak basal plica and infraparietal lamella sometimes present. All barriers weaker than in the majority of the congeners, all finely spiniferous medially but indistinctly granulated to almost smoot laterally. Sinulus wide and not strongly separated from the rest of the aperture. Umbilicus moderately wide to wide, measuring ~ 1 / 3–1 / 5 of the shell width and clearly showing the penultimate whorl. A relatively shallow groove runs towards the inner side of the umbilicus, terminating at the penultimate whorl.

Differential diagnosis.

See under H. pattalungense and H. depressispira .

Measurements

(in mm, n = 5). SH = 1.46–1.58; SW 1 = 2.67–2.90; SW 2 = 1.74–1.92; AH = 1.06–1.26; AW = 1.05–1.23.

Etymology.

The shape of the aperture, between the barriers, resembles a four-leaf clover which is a common symbol of luck, hence the specific epithet which is derived from the Latin word for lucky (fortunatus).

Distribution.

This species is known from Phattalung and Songkhla provinces (S Thailand).

Remarks.

This species is present in one more distinct form superficially resembling H. depressispira . Namely, in this form the spire is much more depressed and the umbilicus is noticeably wider. We decided not to treat this form a separate species since other characters (apertural dentition, general shell shape, and its surface sculpture) are fully shared with the “ typical form ” of H. fortunatum sp. nov.