Discartemon epipedis Siriboon & Panha

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 : 70-72

16. Discartemon epipedis Siriboon & Panha sp. n. Figs 3A, 7C, D, 14A, B, 19 F–I, 23, Table 2

Type material.

Holotype CUMZ 6250 (Fig. 7C). Measurement: shell height 4.6 mm, shell width 8.7 mm, and with 6 whorls. Paratypes: CUMZ 6020 (15 shells), 6215 (5 specimens in ethanol; Figs 3A, 14A, B, 19 F–I), NHMUK 20130678 (2 shells), and SMF (2 shells) from the type locality.

Type locality.

Gua Matu Madu, Gua Musang, Kelantan, Malaysia, 4°50'13.4"N, 101°56'56.3"E.

Diagnosis.

Discartemon epipedis sp. n. differs from Discartemon plussensis and Discartemon leptoglyphus in having a higher spire, a nearly smooth shell surface, a semi-ovate aperture, and four apertural lamellae. Compared with Discartemon flavacandida sp. n., Discartemon epipedis sp. n. has a smaller shell, lacks longitudinal furrows, has the last whorl rounded and regularly coiled, and has four apertural lamellae. The genitalia of Discartemon epipedis sp. n. differ from those of Discartemon flavacandida sp. n. in having a very short and swollen penial appendix, a long and enlarged vagina, short free oviduct, low conical penial hooks, penial papillae present, and in lacking vaginal pores. Discartemon epipedis sp. n. differs from Discartemon roebeleni in having a depressed-heliciform shell, a nearly smooth shell surface, and a semi-ovate aperture. The genitalia have a very short and swollen penial appendix, long and enlarged vagina, long and slender free oviduct, dark brown penial hooks located on conical penial papillae, and a vaginal wall with smooth surface.

Description.

Shell. Shell depressed-heliciform, white and translucent; whorls 6, spire only slightly convex with distinct suture. Shell surface glossy, nearly smooth with few transverse ridges near peristome; varices present. Embryonic shell large, about 2½ whorls. with a smooth surface; following whorls regularly coiled. Last whorl shouldered or rarely rounded, regularly expanded; umbilicus widely open and deep. Aperture semi-ovate; peristome discontinuous, thickened, expanded and reflected. Apertural dentition with a strong parietal lamella and one palatal, one basal and one columellar lamella (Fig. 7C).

Genital organs. Atrium (at) very short. Proximal penis (p) very short penial appendix (pa) swollen in middle, and distal penis slender. Penial sheath (ps) thin, extending about two-thirds of penis length; penial sheath retractor muscle (psr) very thin, originating at genital orifice wall and inserting distally on penial sheath (Fig. 14A). Vas deferens (vd) passes through about one-seventh of penial sheath length before entering into penis distally (Fig. 14B). Penial retractor muscle (pr) thin and very long, inserting at penis and vas deferens junction.

Internal wall of atrium generally smooth with sparse atrial pores (Fig. 19F); penial wall with scattered dark brown penial hooks, about 2 hooks/200 µm 2 (Fig. 19G). Hooks located on conical penial papillae (pp) separated by thin reticulated folds. Penial hooks small (<0.03 mm in length), low conical, expanded at base, tips pointed (Fig. 17H).

Vagina (v) long, enlarged, about half of penis length. Gametolytic duct (gd) expanded at base and tapering to long and tube extending as far as albumin gland; gametolytic sac (gs) ovate. Free oviduct (fo) a long and narrow tube; oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short and club shaped. Hermaphroditic duct (hd) bearing long seminal vesicle (sv) about three times longer than the length from talon to branching point of seminal vesicle (Fig. 14A).

Vaginal wall with smooth surface of strong recticulate vaginal folds (Fig. 17I).

Etymology.

The specific epithet “epipedis” is derived from the Greek “epipedos” meaning “flat” It refers to the flattened- or depressed-heliciform shell.

Distribution.

This species is known only from the type locality.

Remarks.

Apparently rare and only extensive searching yielded living animals.