Anauchen evanidus Gojsina & Pall-Gergely 2025, sp. nov.

Anauchen evanidus Gojšina & Páll-Gergely sp. nov. Figs 10 E, 16, 17, 37 Type material. Holotype. Thailand • 1 shell (SH: 2.57 mm, SW: 2.23 mm); Chanthaburi Province, 3.0 km W of Na Yai Am; 12.738°N, 101.881°E; 23 Apr. 1987; F. G. Thompson leg.; UF 530655. Paratypes. Thailand • 2 shells; same data as for holotype; CUMZ 14431 • 33 shells; same data as for holotype; UF 591355. Additional material examined. Thailand • 2 shells (1 damaged and 1 juvenile, not paratypes); same data as for holotype; UF 583732. Type locality. Thailand, Chanthaburi Province, 3.0 km W of Na Yai Am; 12.738°N, 101.881°E. Diagnosis. Anauchen with very slightly keeled last whorl (below the centre of the periphery) which is also detached from the penultimate. Teleoconch finely dimpled, pasty sculptured, with no spiral striae. Five or six apertural barriers present (parietal, infraparietal, upper palatal, lower palatal, basal and columellar), all strongly spiniferous. Description. Shell conical, brown, consisting of 4.5–5 convex whorls separated by a deep suture. Protoconch similar in colour as the rest of the shell, finely pitted, showing no spiralling pattern or spiral striae and consisting of 1.25–1.5 whorls. Teleoconch surface sculpture fine, pasty, without spiral striae and with several irregularly spaced whitish radial streaks which are most prominent on the last whorl. Last whorl convex but weakly keeled below the centre of the periphery, slightly detached from the penultimate near the aperture and very slightly ascending (below 5 ° compared to the shell axis). Peristome dirty white, expanded but not reflected. Aperture rounded, equally as wide as high. It is equipped with five or six simple apertural barriers (parietal, infraparietal, upper palatal, lower palatal, basal and columellar). Parietal lamella high and moderately strong, not reaching the expanding peristome. Upper and lower palatal plicae equally strong but the lower palatal is usually slightly higher. Basal plica present as a very weak, dot-like swelling situated halfway between the lower palatal plica and columellar lamella. The latter is sometimes almost as wide as long, provoking a rounded shape. The columellar wall of the aperture is weakly swollen around the columellar lamella. Infraparietal lamella present as a small swelling or completely absent. None of the apertural barriers are reaching the peristome (although the parietal lamella is the closest) and all are roughly spiniferous as well as the apertural surface. Sinulus wide and not strongly isolated from the rest of the aperture due to the relatively weak upper palatal plica. Umbilicus very narrow, measuring ~ 1 / 10 of the shell width. The umbilical groove is present running alongside it. This groove is the broadest near the peristome and regularly tapering towards the umbilicus, ending as a narrow canal at the last ~ ¼ of the body whorl. Differential diagnosis. This species is the most similar to A. picasso sp. nov. and for differences, see under that species. The new species also bears some resemblance to Aulacospira pluangtong Panha & Burch, 2004, but the latter has less rounded whorls, more elongated umbilicus, smooth apertural barriers (not spiniferous) and it lacks the basal plica. Measurements (in mm, n = 5). SW = 2.10–2.58; SH = 2.39–2.82; AH = 1.10–1.22; AW = 1.09–1.28. Etymology. The Latin word evanidus means vanishing, which refers to the quarrying of the type locality of this species. Distribution. This species is known only from the type locality. Remarks. Unlike congeners (except for A. kozari), this species has rough, spiniferous surface of the apertural barriers. It is retained in Anauchen because of the similar barrier arrangement to other species (e. g., A. angthongensis, A. crassus sp. nov., A. huaykhakang, A. obesus sp. nov.) and a single lamella on the parietal side.