Hypselostoma aquila Gojšina, Hunyadi & Páll-Gergely, 2025

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

Figs 111 D View Figure 111 , 117 View Figure 117 , 118 View Figure 118 , 177 View Figure 177

Type material.

Holotype. Cambodia • 1 shell (SH: 1.98 mm; SW 1: 2.39 mm); Steung Treng Province, 55.7 km northwest + 2 km north from Stung Treng Mekong Bridge, Chap Phleung Mt. ( Neak Khiev Mt. ); 13°47.821'N, 105°36.205'E; 135 m a. s. l.; 26 Oct. 2023, A. Hunyadi & J. U. Otani leg.; CUMZ 14461 View Materials GoogleMaps . Paratypes. Cambodia • 107 shells; same data as for holotype; coll. HA GoogleMaps • 1 shell; same data as for holotype; coll. VG GoogleMaps • 229 shells; Steung Treng Province, Stung Treng Mekong Bridge, 36.3 km NWN + 5 km N, Phnom Chhnok ; 13°46.573'N, 105°44.878'E; 120 m a. s. l.; 25 Oct. 2023; A. Hunyadi & J. U. Otani leg.; coll. HA GoogleMaps .

Additional material examined.

Cambodia • 4 shells (juveniles / damaged, not paratypes); Steung Treng Province, Stung Treng Mekong Bridge, 36.3 km NWN + 5 km N, Phnom Chhnok ; 13°46.573'N, 105°44.878'E; 120 m a. s. l.; 25 Oct. 2023; A. Hunyadi & J. U. Otani leg.; coll. HA GoogleMaps .

Type locality.

Cambodia, Steung Treng Province, 55.7 km northwest + 2 km north from Stung Treng Mekong Bridge, Chap Phleung Mt. (Neak Khiev Mt.); 13°47.821'N, 105°36.205'E; 135 m a. s. l.

Diagnosis.

A Hypselostoma species with a slender, concave-conical shell, bluntly and strongly keeled last whorl (and a deep groove above it), raised spiral striation, hooked apertural barriers (upper palatal, and lower palatal) and a wide umbilicus which is initially narrow.

Description.

Shell concave-conical, light-brown, consisting of 4.5–5 whorls separated by a deep suture. Protoconch nearly white, consisting of ~ 1.25 coarsely spirally striated whorls. There are ~ 12 weak spiral striae on the protoconch. Protoconch and initial teleoconch whorls rounded, penultimate weakly convex. Last whorl with strong but blunt keel positioned at the centre of the periphery. Above the keel there is a deep groove on the last 0.75–1 whorl. All whorls densely sculptured with strong, thick spiral striae crossed by less dense radial growth lines and occasionally by a few thin, whitish radial streaks. Spacing between the spiral striae irregular and ranges from the width of two to the width of three spiral striae. Last whorl moderately detached from the penultimate and weakly ascending (≤ 10 ° compared to the shell axis). Peristome expanded, not reflected, its surface finely pitted. Aperture equipped with four strong, main barriers (angulo-parietal, upper palatal, lower palatal and columellar) and several smaller ones. Angulo-parietal lamella strong and leaned towards the palatal side, almost reaching the expanding peristome. It is consisting of main, parietal part, and a smaller, pointed angular part which are separated by a weak sinuation. Upper and lower palatal plicae roughly the same size, both divided and the inner parts are hooked (with the tip of hooks pointing outside), slender and high, while the outer parts are low and slender. A weak swelling is also observed at the palatal side (in front of the upper palatal plicae) which is probably homologous to the palatal tubercle in the majority of Bensonella species. Columellar lamella almost horizontal, approximately as high as the palatal plicae. There are four smaller barriers, two interpalatal plicae, one basal plica and one infraparietal lamella. Surface of all apertural barriers is smooth or with very weak granules. Sinulus rounded, distinctly separated from the rest of the aperture. Umbilicus initially narrow and then abruptly widening, measuring between 1 / 3 and 1 / 4 of the shell width. There is a periumbilical keel situated on the last ~ 0.75 whorl near the centre of the last whorl, but rather slightly towards the umbilicus. Along this keel there are shallow grooves on both sides.

Differential diagnosis.

See under H. benetuitum , H. sorormajor sp. nov., and H. sororminor sp. nov.

Measurements

(in mm, n = 5). SH = 1.91–2.04; SW 1 = 2.16–2.39; SW 2 = 1.35–1.42; AH = 0.80–0.86; AW = 0.69–0.82.

Etymology.

This species is named for the apertural barriers resembling claws of an eagle (aquila = eagle in Latin). To be used as a noun in apposition.

Distribution.

This species is known from two localities in Steung Treng province.

Remarks.

The largest, and still unexplored limestone hill in Steung Treng Province (13°47.941'N, 105°43.7671'E) was inaccessible during the collecting efforts in 2023 due to the works of a cement factory. Due to the proximity of this hill to the type locality of H. aquila sp. nov., it is possible that this species can be found here as well and be threatened by quarrying.