Discartemon leptoglyphus Benthem Jutting, 1954

Siriboon, Thanit, Sutcharit, Chirasak, Naggs, Fred, Rowson, Ben & Panha, Somsak, 2014, Revision of the carnivorous snail genus Discartemon Pfeiffer, 1856, with description of twelve new species (Pulmonata, Streptaxidae), ZooKeys 401, pp. 45-107 : 65-67

13. Discartemon leptoglyphus Benthem Jutting, 1954 Figs 2C, 6E, F, 13A, B, 18 F–L, 23, Table 2

Discartemon leptoglyphus Benthem Jutting, 1954: 90-92, fig. 7. Type locality: Gunong Rapat, near Ipoh, Perak, Malaysia. Benthem Jutting 1959: 168. Maassen 2001: 87.

Material examined.

Holotype ZMA 3.54.019 (Fig. 6E). Paratypes NHMUK 1954.4.3.3 (1 shell), ZMA 3.54.020 (1 shell), ZMA 3.54.021 (5 shells). Ampang Baru, Ipoh, Perak, Malaysia, 6°29'36.2"N, 100°15'53.2"E, CUMZ 6010 (3 shells; Fig. 6F). Lost World, Tanjung Rambutan, Ipoh, Perak, Malaysia: CUMZ 6007 (9 specimens in ethanol; Figs 2C, 13A, B, 18 F–L), 6260 (4 shells).

Description.

Shell. Shell depressed-heliciform, white and semi-transparent; whorls 5 –5½, spire only slightly convex with distinct suture. Shell surface glossy with transverse ridges and varices present. Whorls regularly coiled; last whorl angular, regularly expanded, ultimate part expanded; umbilicus very wide, deep and showing all preceding whorls. Aperture triangular, sometimes semi-ovate; peristome discontinuous, expanded and little reflected. Apertural dentition of one parietal and one small palatal lamella (Fig. 6E).

Genital organs. Atrium (at) short. Penis (p) long, swollen at middle and with a long and slender penial appendix (pa) about half of penis length. Penial sheath (ps) thin, extending about one-third of penis length; penial sheath retractor muscle (psr) very thin, originating at genital orifice wall and inserting distally on penial sheath (Fig. 13A). Vas deferens (vd) passes through entire length of penial sheath before entering into penis distally (Fig. 13B). Penial retractor muscle (pr) thin and very long, inserting at penis and vas deferens junction.

Internal wall of atrium with smooth surface (Fig. 18F). Penial wall with translucent penial hooks densely scattered, about 18 hooks/200 µm 2 (Fig. 18G). Hooks located on ovate penial papillae (pp). Penial hooks small (<0.04 mm in length), tips obtuse and curved towards genital orifice (Fig. 18 H–K).

Vagina (v) short, about one-third of penis length. Proximal gametolytic duct (gd) enlarged, stout; distally a long tube extending as far as albumin gland; gametolytic sac (gs) ovate. Proximal free oviduct (fo) enlarged then tapering to smaller tube distally. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small and club shaped. Hermaphroditic duct (hd) bearing long and thick seminal vesicle (sv) about one and half times longer than the length from talon to branching point of seminal vesicle (Fig. 13A).

Vaginal wall generally smooth (Fig. 18L).

Distribution.

This species is known from the limestone mountains around the type locality in Perak, Malaysia.

Remarks.

Compared with Discartemon platymorphus , this species differs in having a smaller shell, with transverse ridges appearing on the entire shell and a more inflated last whorl. Discartemon leptoglyphus can be distinguished from Discartemon stenostomus by having a depressed-heliciform shell with lower spire, transverse ridges on the entire shell, the last whorl angular, and apertural dentition of one straight parietal lamella. In addition, the penial appendix in Discartemon leptoglyphus is relatively much longer than that shown for Discartemon stenostomus (see Berry 1965).