Clostophis rhynchotes Tongkerd & Panha, 2025

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

Clostophis rhynchotes Tongkerd & Panha sp. nov.

Figs 6 , 7 , Table 3

Type material.

Holotype. Thailand • height 1.3 mm (including tuba), width 1.5 mm (Fig. 6 A, B ); Wat Khao Chakkachan Wanaram , Chum Ta Bong District, Nakhon Sawan Province; 15°35'44.4"N, 99°32'39.3"E; P. Tongkerd leg.; CUMZ 14460 . Paratypes. Thailand • 1 shell (Fig. 6 C ); same data as for holotype; CUMZ 14459 . • 1 shell (Fig. 7 B ); same data as for holotype; CUMZ 14436 . • 1 shell (Fig. 7 A ); same data as for holotype; CUMZ 14437 . • 29 specimens in ethanol (Fig. 7 C ; COI accession no. PV 698339 ); same data as for holotype; CUMZ 14464 (COI accession number PV 698339 ) . • 2 shells; same data as for holotype; NHMUK 20250359 . • 2 shells; same data as for holotype; SMF .

Diagnosis.

Shell depressed concave-conical, penultimate whorl slightly sunken into last whorl, long and descending tuba, 12–14 spiral striations, peristome weakly expanded, with only parietal lamella, and wide umbilicus.

Description.

Shell depressed, concave-conical, colourless; spire growing regularly and last whorl broadly expanded. Shell height 1.3–1.4 mm (including tuba) and shell width 1.4–1.5 mm. Apex large and rounded; protoconch ~ 2 whorls, pitted and sculptured with prominent spiral striae. Whorls ~ 4–4 ¾ (excluding tuba) weakly shouldered and convex; suture wide and deep. Shell surface with strong, elevated, continuous, equidistant spiral striae (12–14 on body whorl in frontal view), and crossed with weaker and irregular radial growth lines. Growth lines on earlier whorls rather strong, making reticulated surface. Penultimate whorl slightly sunken into last whorl. Last whorl with slight indication of blunt shoulder; tuba short, <¼ whorl, strongly descending and twisted. Aperture subovate, open ventrally to subventrally; peristome thin and slightly expanded on columellar side and with weak depression on parietal side. Apertural dentition one: parietal lamella strong and tall with low ridge near peristome edge then gradually taller deep inside aperture. Umbilicus widely opened, occupies ~ ½ of shell width and showing all preceding whorls.

Differential diagnosis.

Clostophis rhynchotes sp. nov. differs from C. proboscideus , C. sankeyi , and C. yoga by having a depressed conical spire, strong parietal lamella, and 12–14 spiral striae on last whorl. In comparison, these other three species possess conical spires with 18–20 spiral striae on last whorl. In addition, C. proboscideus has a parietal lamella and a strong palatal plica, while C. sankeyi and C. yoga generally have no dentition, but parietal lamella and palatal plica may be weakly present in C. sankeyi ( Páll-Gergely et al. 2020) .

Clostophis rhynchotes sp. nov. also differs from C. udayaditinus Sutcharit & Panha, 2025 from Cambodia by having slightly concave-sided shell, penultimate whorl slightly sunken into last whorl, 12–14 spiral striae on last whorl, and only one parietal lamella, while C. udayaditinus has a strongly concave shell, the penultimate whorl sunken into last whorl, 18–24 spiral striae on last whorl, and four dentitions (hooked parietal, infraparietal, palatal, and hooked columellar) ( Sutcharit et al. 2025).

Distribution.

This new species is currently known only from the type locality. There is a small limestone outcrop ( 700 m long and 250 m wide), and a hill covered with low vegetation, surrounded by a housing area and temple, and with low disturbance.

Etymology.

The specific name rhynchotes is from the Greek word rhynchos meaning ‘ snout’ and the suffix – otes; it refers to the tuba of the last whorl, which resembles the snout of a tapir.

Remarks.

Although C. rhynchotes sp. nov. shares a depressed shell, a long descending tuba, and spirally striated protoconch with A. rhamphodontis sp. nov., it is distinguished from the latter by the prominent spiral striae crossed by less prominent growth lines without forming a rectangular pattern, and with very few dentitions. These characteristics indicate the placement of this new species within the genus Clostophis .

Figures

Figure 6. Clostophis rhynchotes sp. nov. from Nakhon Sawan Province. A, B. Holotype CUMZ 14460 with enlarged aperture: B. Protoconch and earlier whorl sculptures; C. Paratype CUMZ 14459 from the type locality.

Figure 7. Clostophis rhynchotes sp. nov. from Nakhon Sawan Province. A. Paratype CUMZ 14437 with enlarged aperture; B. Paratype CUMZ 14436 from the type locality; C. Paratype CUMZ 14464 under light microscope showing colourless and translucent shell and with enlarged aperture.