Bensonella spelaea Gojšina, Grego & Páll-Gergely sp. nov.

Type material.

Holotype. Myanmar • 1 shell (SH: 3.3 mm, SW: 2.4 mm); Kayah State, Hpruso district, Maw Thi Do Village, entrance of Phruno river cave; 19°22.744'N, 97°2.570'E; 12 Feb. 2019; J. Grego leg.; CUMZ 14444. Paratypes. Myanmar • 7 shells; same data as for holotype; coll. JG • 1 shell; same data as for holotype; coll. HA.

Type locality.

Myanmar, Kayah State, Hpruso district, Maw Thi Do Village, entrance of Phruno river cave; 19°22.744'N, 97°2.570'E.

Diagnosis.

Bensonella species with 7–9 apertural barriers, most peculiar of these is the transversal plica (strong, high but with a concave frontal surface resembling a cave entrance).

Description.

Shell triangular, conical-ovoid, brownish, consisting of 5–5.5 convex, regularly increasing, rounded whorls separated by a deep suture. Boundary between the protoconch and the teleoconch is only clearly visible after SEM imaging because of the delicate sculpture and somehow weathered type series. Protoconch is spirally striated, probably ~ 1.75 whorls). Teleoconch of fine, pasty sculpture with dense but fine radial growth lines and without signs of spiral striation. Last whorl rounded, adnate to the penultimate. Aperture profile sinuated in its upper portion (concave) but convex in its middle and lower sections. Peristome expanded, especially at the parietal side where it leans on the penultimate whorl in form of a strong callus but not reflected. There is a moderate cervical crest located a short distance behind the peristome. Aperture equipped with relatively small number of barriers, seven to nine. Angular, parietal, upper palatal, transversal, palatal tubercle, columellar and infraparietal are always present, while basal and supracolumellar only sometimes. Parietal lamella heart-shaped in profile due to the sinuation located in its middle part (this makes the middle part of the lamella lower than outer and inner parts). Angular lamella also appears curvy, and it is curved to the palatal side. Upper palatal plica relatively weak and low. Transversal plica large (the largest in the aperture), high but with a strongly concave frontal surface (this gives the appearance of the transversal plica as an entrance to a cave). Basal very short and low when present. Columellar lamella very strong and thick (roughly the same as the parietal lamella). Supracolumellar lamella weak, dot like (sometimes absent). Infraparietal lamella present but much weaker than both the parietal and the columellar. Surface of all apertural barriers is granulated to almost spiniferous. Sinulus small and distinctly separated from the rest of the aperture due to the strong and closely positioned angular lamella and palatal tubercle. Umbilicus initially narrow and the widening at the last whorl, elongated, measuring ~ 1 / 6–1 / 7 of the shell width.

Differential diagnosis.

This species is the largest one with a transversal plica. This plica shows the peculiar appearance with the strongly concave frontal surface resembling a cave entrance.

Measurements

(in mm, n = 5). SH = 2.48–3.38; SW = 1.98–2.4; AH = 1.08–1.30; AW = 0.95–1.12.

Etymology.

Named after the cave-like transversal plica.

Distribution.

This species is known only from the type locality.