Haploptychius porrectus (Pfeiffer, 1863)

Inkhavilay, Khamla, Siriboon, Thanit, Sutcharit, Chirasak, Rowson, Ben & Panha, Somsak, 2016, The first revision of the carnivorous land snail family Streptaxidae in Laos, with description of three new species (Pulmonata, Stylommatophora, Streptaxidae), ZooKeys 589, pp. 23-53 : 30-32

Taxon classification Animalia Pulmonata Streptaxidae

Haploptychius porrectus (Pfeiffer, 1863) Figs 1, 2B, 3 D–F, 7C, D, 9 G–M, 10H; Table 1

Streptaxis porrecta Pfeiffer 1863 [1862]: 273. Type locality: Lao Mountains, Camboja [Cambodia]. Martens 1867: 85. Pfeiffer 1868: 442. Tryon 1885: 74. Fischer 1891: 18. Gude 1903: 217. Gude 1903: 275, 322, 325, pl. 12, figs 20-22.

Haploptychius porrectus - Kobelt 1906: 133, pl. 61, figs 24-26. Richardson 1988: 219.

Material examined.

This species was described from the H. Cuming collection. The number of specimens was not indicated, but only one set of measurements was given in the original description. The NHM collection contains two specimens from the Cuming collection that has Pfeiffer’s handwritten label stating the species name and collection locality. In order to stabilize the name, a specimen matching with the measurements given in the original description is designated here as lectotype NHMUK 20140750.1 (Fig. 3D; H = 8.0, W = 9.0). The other specimen from the same lot becomes a paralectotype NHMUK 20140750.2 (1 shell; Fig. 3E; H = 8.0, W = 8.2).

Laos: NHMUK 1906.1.1.770 (4 shells), NHMUK MacAndrew coll. (2 shells). Ban Nong Tang, Phoukood, Xieng Khuang, Laos: CUMZ 6273 (18 shells; Fig. 3F), 6274 (1 specimen in ethanol; Figs 2B, 7C, D). Tam Pew, Kham, Xieng Khuang, Laos: CUMZ 6275 (4 specimens in ethanol; Figs 9 G–M, 10H).

Description.

Shell. Shell oblique-heliciform, white and translucent. Whorls 6½, spire conical, suture distinct. Shell surface glossy, with transverse ridges that diminish below the periphery. Embryonic shell smooth with 2½ whorls; following whorls regularly coiled. Penultimate whorl rounded; last whorls rounded and axially deflected. Aperture subcircular; peristome thickened and reflected. Aperture dentition with one parietal lamella. Umbilicus open and deep (Fig. 3 D–F).

Radula. Each row consists of 46-58 teeth with formula (23-29)-1-(23-29). Central tooth very small and triangular, with a pointed cusp. Lateral and marginal teeth undifferentiated, lanceolate, unicuspid. Latero-marginal teeth gradually reduce in size, with outermost teeth much smaller and shorter than inner teeth (Fig. 10H).

Genital organs. Atrium (at) short. Proximal penis (p) stout about one-fifth of penis length; distal penis slender. Penial sheath (ps) thin, extending about two thirds of penis length; penial sheath retractor muscle (psr) very thin, originating at atrium and inserting distally on penial sheath (Fig. 7C). Vas deferens (vd) passes through about a quarter of the penial sheath length before entering into penis apically (Fig. 7D). Penial retractor muscle (pr) thick, short and connected with penis apically.

Internal wall of atrium generally smooth (Fig. 9G). Proximal penial wall densely covered with brownish penial hooks, about 10 hooks/200 μm 2. Hooks located on low conical penial papillae, separated by very thin reticulated folds. Proximal penial hooks small and short (<0.04 mm in length), slightly expanded at base, tip sharp and directed towards genital orifice (Fig. 9H, I). Distal penial wall less densely scattered with brownish penial hooks, about 4 hooks/200 μm 2; penial papillae absent. Distal hooks very large, long and slender (<0.5 mm in length), expanded at base, tip obtuse and directed towards genital orifice (Fig. 9J, K).

Vagina (v) short, about half of penis length. Gametolytic duct (gd) long tube extending as far as albumin gland; gametolytic sac (gs) small. Free oviduct (fo) short with almost the same diameter as vagina. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small and club shape. Hermaphroditic duct (hd) bearing very long and enlarged seminal vesicle (sv) about ten times longer than the length from talon to branching point of seminal vesicle (Fig. 7C).

Vaginal wall generally corrugated with irregular vaginal papillae (Fig. 9L, M). Vaginal hooks absent.

Distribution.

This species is known from the limestone outcrops in northeastern and central parts of Laos. The animals can be found at altitudes from 150-300 meters above mean sea level.

Remarks.

This species can be distinguished from Haploptychius dorri (Dautzenberg, 1894) and Haploptychius blaisei (Dautzenberg & Fischer, 1905) in having a less depressed shell and less deviated last whorl. In addition, Haploptychius blaisei possesses a solid shell with an angular penultimate whorl, and Haploptychius dorri has a smaller and smooth shell with an angular penultimate whorl. Haploptychius anceyi (Mabille, 1887) is similar to Haploptychius porrectus , however it differs in its smaller shell, circular aperture, and nearly smooth shell surface.