Bensonella perfecta Gojšina & Páll-Gergely, 2025

Bensonella perfecta Gojšina & Páll-Gergely sp. nov.

Figs 39 X View Figure 39 , 84 View Figure 84 , 85 View Figure 85 , 95 View Figure 95

Type material.

Holotype. Laos • 1 shell (SH: 2.9 mm; SW: 2.1 mm); Central Laos, Xieng Khouang Province, ca 30 km WNW of Phonsavan, ca 47 km ENE of Phou Khoun , limestone, black soil in limestone pockets, clay, under rocks in old secondary forest at base of cliff; 19°32.019'N, 102°51.901'E; 1131 m a. s. l.; 15 Nov. 2006; A. Abdou, I. V. Muratov leg.; MNHN -IM-2000-39829 . GoogleMaps

Paratypes. Laos • 2 shells; same data as for holotype; CUMZ 14442 View Materials ; 174 shells GoogleMaps ; same data as for holotype; MNHN -IM-2000-39830 GoogleMaps .

Additional material examined.

Laos • 94 shells (damaged and juveniles, not paratypes); same data as for holotype; MNHN -IM-2012-25390 GoogleMaps .

Type locality.

Central Laos, Xieng Khouang Province, ca 30 km WNW of Phonsavan, ca 47 km ENE of Phou Khoun, limestone, black soil in limestone pockets, clay, under rocks in old secondary forest at base of cliff; 19°32.019'N, 102°51.901'E; 1131 m a. s. l.

Diagnosis.

Bensonella species with a conical, brownish shell that is not spirally striated. Apertural barriers numerous: five plicae (4 palatals and one basal), all weak and low. Palatal tubercle strong.

Description.

Shell conical, pale brown, consisting of 5–5.5 regularly increasing, rounded whorls. Protoconch consisting of 1.75 whorls, same colour as the rest of the shell, finely pitted and spirally striated. Teleoconch with fine pasty like surface sculpture and coarse radial growth lines which are irregularly spaced. Rarely, these radial lines appear as stronger, whitish streaks. A spiralling pattern is very slightly visible on the last whorl (only under SEM) although there are no spiral striae. Last whorl rounded, adnate to the penultimate and slightly descending near the aperture (~ 5–10 ° compared to the shell axis). Apertural profile slightly prosocline to the shell axis. Peristome of same colour as the rest of the shell, expanded but not reflected. There is a weak cervical crest just behind the peristome. Aperture equipped with numerous barriers. Parietal lamella strong and blade-like, not reaching the peristome. Angular lamella closer to the peristome but appears discontinuous as its outer and inner parts are separated by a distinct sinuation. These two parts are roughly equally strong. There are one or two barriers inside the sinulus. Four palatal plicae (upper palatal, interpalatal, lower palatal and infrapalatal). Upper, inter and lower palatal are moderately long and high, equally developed and equally distanced. Sometimes, upper palatal is weak and lower palatal is stronger than others. Infrapalatal plica is much weaker (lower and shorter). Palatal tubercle is strong, sitting on the palatal lip of the peristome just below the line of upper palatal plica. Basal plica situated close to the infrapalatal and equally developed or sometimes weaker. Columellar lamella stronger than in most of the congeners (quite broad and high), almost horizontal, sometimes appears slightly wavy. Infraparietal lamella moderate, weaker than other lamellae but stronger than all the plicae. Surface of all apertural barriers is finely granulated. Additionally, plicae in the palatal and basal areas as well as the infraparietal and angular lamellae are equipped with isolated but strong spines which are positioned medially. Sinulus small and distinctly separated from the rest of the aperture. Umbilicus narrow, slightly elongated, measuring ~ 1 / 5–1 / 6 of the shell width.

Differential diagnosis.

See under H. frequens .

Measurements

(in mm, n = 5). SH = 2.91–3.09; SW = 2.08–2.23; AH = 1.15–1.30; AW = 1.2–1.37.

Etymology.

This species is named for the exceptionally fine surface sculpture.

Distribution.

This species is known only from the type locality.