Bensonella fracta Gojšina, Hunyadi & Páll-Gergely, 2025

Bensonella fracta Gojšina, Hunyadi & Páll-Gergely sp. nov.

Figs 101 B View Figure 101 , 103 View Figure 103 , 104 View Figure 104 , 107 View Figure 107

Type material.

Holotype. Thailand • 1 shell (SH: 2.08 mm; SW: 2.09 mm); Loei Province, Nong Hin district, 20.3 km southwest from centre of Nong Hin towards Pha Wai , left side of road no. 3029; 17°2.471'N, 101°43.655'E; 705 m a. s. l.; 28 Feb. 2023; A. Hunyadi & J. U. Otani leg.; CUMZ 14448 View Materials . GoogleMaps

Paratypes. Thailand • 5 shells; same data as for holotype; coll. HA GoogleMaps .

Type locality.

Thailand, Loei Province, Nong Hin district, 20.3 km southwest from centre of Nong Hin, Pha Wai; left side of road no. 3029; 17°2.471'N, 101°43.655'E; 705 m a. s. l.

Diagnosis.

Bensonella species with spirally striated teleoconch and strongly convex whorls separated by a deep suture. Last whorl narrow, slightly detached, rounded. Apertural barriers usually 7. Upper palatal plica bipartite, consisting of anterior and posterior bulge.

Description.

Shell conical, light yellowish-brownish, opaque. It is consisting of ~ 5 regularly increasing, strongly convex whorls separated by a deeply impressed suture. Protoconch finely pitted, showing a spiralling pattern (which is stronger terminally) and consisting of ~ 1.5 whorls, coloured as the rest of the shell. Teleoconch with sculpture consisting of fine, raised, and innumerable spiral striae which are occasionally crossed by much weaker radial growth lines (rarely present as strong white streaks). The sculpture of the teleoconch gets more prominent as the whorls are increasing, thus being most noticeable on the last two whorls. Last whorl relatively narrow (low), slightly detached from the penultimate, and slightly ascending near the aperture (~ 5–10 ° compared to the shell axis). It is completely rounded and strongly convex. Peristome the same colour as the rest of the shell, strongly expanded with finely pitted surface, not reflected. Aperture equipped with five main barriers (angular, parietal, upper palatal, lower palatal, and columellar). Angular lamella short and thick, directed towards the lower palatal plica. Parietal lamella longer than the angular, leaned towards the upper palatal plica. Upper palatal plica usually bipartite, consisting of anterior and posterior bulge. Anterior bulge is closer to the peristome, smaller and lower. Posterior bulge is longer, higher, and stronger, positioned behind the anterior (deeper in the aperture). Origin of the anterior bulge is not known but it may be homologous with the palatal tubercle usually found in many typical Bensonella species. Columellar lamella developed to the similar extent as the palatal plicae. In front of the columellar lamella, there is sometimes a small swelling on the peristome. Apart from these main barriers, there is usually an additional smaller basal plica and one even smaller knob-like lamella in the columello-parietal embayment. Only the angular lamella and anterior bulge of the upper palatal plica are reaching t peristome. Surface of all apertural barriers is finely granulated. Sinulus small, well separated from the rest of the shell due to the closely situated angular lamella and upper palatal plica. Umbilicus moderately wide (1 / 5–1 / 6 of the shell width), showing only the penultimate whorl. Umbilical groove absent.

Differential diagnosis.

Bensonella fracta sp. nov. is much larger than all other representatives of Bensonella wangviangensis group. See also under B. wangviangensis .

Measurements

(in mm, n = 4). SW 1 = 2.09–2.18; SW 2 = 1.31–1.48; SH = 1.9–2.08; AH = 0.81–1.1; AW = 0.89–1.23.

Etymology.

The first examined specimen of this species had a crack on the apical whorls, which gave the specific epithet fracta.

Distribution.

This species is known only from the type locality.

Remarks.

This species is not a typical representative of this group since the angular lamella is quite small and not almost enclosing the sinulus. However, it is placed here because of the high morphological similarity with mostly B. wangviangensis . A tubercle-like swelling in the columellar-parietal embayment was found to be missing in one specimen. Otherwise, this species does not seem to be much variable regarding apertural barriers.