Acinolaemus cryptidentatus Changlom, Chan-ard & Dumrongrojwattana, 2019

Tongkerd, Piyoros, Janjai, Teerangkul, Pholyotha, Arthit, Gojšina, Vukašin, Panha, Somsak & Sutcharit, Chirasak, 2025, The microsnail genera Clostophis and Acinolaemus (Eupulmonata, Pupilloidea, Hypselostomatidae) from central Thailand, with description of three new species, ZooKeys 1258, pp. 35-71 : 35-71

Acinolaemus cryptidentatus Changlom, Chan-ard & Dumrongrojwattana, 2019

Fig. 10 , Table 4

Acinolaemus cryptidentatus Changlom, Chan-ard & Dumrongrojwattana, 2019: 158, 159, fig. 2. Type locality: Tham Wua (Wua Cave), Mueang District, Mae Hong Son Province, Thailand. Tongkerd et al. 2024: 164, figs 1 b, 2 b.

Material examined.

Thailand • 3 shells (Fig. 10 A, B ); Mae La Na Cave , Pang Mapha District, Mae Hong Son Province; 19°34'30.8"N, 98°12'56.3"E; S. Panha leg.; CUMZ 15362 .

Diagnosis.

Shell concave-conical, peristome weakly expanded, rectangular reticulated sculpture present on shell surface. Apertural dentitions nine: three on parietal wall, three on palatal wall, one basal, and two on columellar wall. Palatal tubercle prominent and located between upper- and inter-palatal plicae.

Re-description.

Shell weakly concave-conical, colourless; spire high and growing regularly; last whorl expanded. Shell height 1.6–1.8 mm and shell width 1.5–1.6 mm. Apex blunt; protoconch ~ 2 whorls with conspicuous spiral striae. Whorls ~ 4–5, bluntly shouldered, and convex; suture wide, well impressed, and deep. Shell surface sculptured with equidistantly spaced spiral striae, crossed with discontinuous and irregular radial ridge-like growth lines making rectangular reticulated sculpture throughout shell. Penultimate whorl regularly coiled to slightly sunken into last whorl. Last whorl rounded to weakly shouldered and flattened below periphery. Aperture subovate; peristome weakly expanded. Aperture with eight dentitions. Parietal wall with three lamellae: parietal lamella large, outer part low and reaching peristome edge, inner part strongly developed with long tall ridge located deeper inside aperture; infraparietal lamella prominent with a high ridge; angular lamella slightly curved, reaching peristome edge, a strong, tall ridge, long deeper inside aperture and with deep incision medially. Palatal tubercle strong, triangular, and situated on peristome edge between upper- and inter-palatal plicae. Three tiny and low plicae present in sinulus. Palatal wall with three plicae: upper-, inter-, and lower-palatal plicae with tall ridges and situated slightly inside aperture. Lower palatal plica tall and more prominent than upper- and inter-palatal plicae. Basal plica prominent with tall ridge. Columellar wall with two lamellae: columellar lamella is a very tall and distinct ridge; subcolumellar lamella a strong ridge and almost same size as basal plica. Umbilicus widely perforated, ~ ⅓ of shell width, rounded and deep.

Distribution.

Acinolaemus cryptidentatus is known from the type locality at Tham Wua Cave, Mae Hong Son Province in northern Thailand ( Changlom et al. 2019), and subsequently reported from Shan State, Myanmar ( Tongkerd et al. 2024).

Remarks.

The specimens from Mae La Na Cave in Pang Mapha District, which is ca 15 km east of the type locality are almost identical to the type specimen in shell shape, sculpture, and most of the apertural dentitions. However, these specimens have a prominent subcolumellar lamella, which was probably overlooked in the original description.

Figures

Figure 10. Acinolaemus cryptidentatus from Mae Hong Son Province. A. Specimen CUMZ 15362 with enlarged aperture from three different angles; B. Protoconch and earlier whorl sculptures. An asterisk (*) indicates small lamella and plica situated in posterior chamber.