Sarika lactoconcha Pholyotha & Panha, 2020

Pholyotha, Arthit, Sutcharit, Chirasak, Thach, Phanara, Chhuoy, Samol, Ngor, Peng Bun & Panha, Somsak, 2020, Land snail genus Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from Cambodia, with description of three new species, European Journal of Taxonomy 674 (674), pp. 1-21 : 8-10

Sarika lactoconcha Pholyotha & Panha sp. nov.

urn:lsid:zoobank.org:act:0E48F6FB-6775-4470-BF85-345C3D43112A

Table 1 ; Figs 2 C–D, 3

Diagnosis

Sarika lactoconcha sp. nov. is characterized by a large, depressed and whitish shell, rounded on the periphery. Animal with dark grey body and five mantle lobes. Genitalia with rather long epiphallic caecum and triangular prism-shaped penial pilasters on inner penial sculpture.

Etymology

The specific epithet ‘ lactoconcha ’ is derived from the Latin word ‘ lactis ’ meaning ‘milk, milky’ and the Latin word ‘ concha ’ meaning ’snail’ or ’shell’. It refers to the milky colour of the shell.

Material examined

Holotype

CAMBODIA • 1 shell (width 23.6 mm, height 12.1 mm); Kampot Province, Tuek Chhou District, limestone outcrops at Phnom Chhngok Cave Temple, locality code C046; 10°38′33.8″ N, 104°16′08.3″ E; CUMZ 7901 .

Paratypes

CAMBODIA • 1 shell, 3 alcohol-preserved specimens; same collection data as for holotype; CUMZ 7902 • 1 shell; same collection data as for preceding; NHM • 1 shell; same collection data as for preceding; ZRC .

Other material

CAMBODIA • 2 shells; Kampot Province, Tuek Chhou District, limestone outcrops at Phnom Kbal Romeas, locality code C045; 10°36′59.6″ N, 104°14′37.8″ E; CUMZ 7903 .

Description

SHELL ( Fig. 2 C–D). Depressed, large (shell width up to 23.7 mm, shell height up to 12.1 mm), rather thin, semitransparent. Shell surface generally smooth, glossy; more glossy below periphery; shell colour monochrome pale milky or whitish colour. 6–6½ whorls, increasing regularly, slightly convex, separated by rather shallow and wide suture. Spire slightly elevated; last whorl broadly rounded. Aperture oval- lunate shaped, open obliquely. Peristome simple, very slightly thickened, not expanded. Parietal callus thin, transparent; columellar margin simple, slightly reflected near umbilicus. Umbilicus narrow, deep.

EXTERNAL FEATURES ( Fig. 3A ). Living animals have dark grey body; dorsally with darker colour than below, foot sole. Caudal foss present; caudal horn raised, rather large. Mantle and lung scattered with dark pigment or spots or blotches. Mantle edge well-developed, dark grey to paler in colour, with three dorsal lobes, two shell lobes (see Pholyotha et al. 2018: fig. 1). Dorsal lobes large, broad; right dorsal lobe larger than both anterior and posterior left dorsal lobes. Shell lobes large, long; right shell lobe larger, longer than left shell lobe.

GENITALIA ( Fig. 3 B–C). Atrium (at) enlarged, very short. Penis (p) cylindrical, with thin penial sheath covering proximal penis. Inner sculpture of penis very finely folded to nearly smooth surface close to atrium then gradually transforming to triangular prism (rhombic base, acute angle on top) penial pilaster (pp) near epiphallus. Epiphallus (e) cylindrical, elongate, about two times penis length. Epiphallic caecum (ec) similar diameter as epiphallus, straight, located near middle of epiphallus. Penial retractor muscle (prm) thin, attached at tip of epiphallic caecum. Flagellum (fl) slender, rather long, nearly 1.5 times epiphallus length. Vas deferens (vd) thin tube. Vagina (v) cylindrical, about half of penis length. Dart apparatus (da) cylindrical, rather large and long, joined to atrium at vagina and penis junction. Gametolytic sac (gs) elongate bulbous; gametolytic duct (gd) enlarged cylindrical. Free oviduct (fo) enlarged cylindrical, approximately two times vagina length, proximally encircled with brownish tissue. Oviduct large lobules; prostate gland running alongside oviduct.

RADULA ( Fig. 3D ). Teeth arranged in wide-angle U-shape with half row formula: 1–(15–16)–65 teeth. Central tooth symmetrical tricuspid with pointed cusps; mesocone large lanceolate, dull cusp; ectocones very small. Lateral teeth asymmetrical tricuspid; mesocone large with pointed cusp; endocone very small, located near tip; ectocone larger than endocone, located in middle of tooth. Marginal teeth starting around tooth numbers 15–16, obliquely bicuspid; endocone large, pointed cusp; ectocone small. Outermost teeth gradually reduced in size from elongate, narrow teeth to very short teeth.

Distribution

This new species is currently known from Phnom Chhngok Cave (the type locality), an undisturbed small karst outcrop, which is about 1 km long and surrounded by rice fields. Another locality is Phnom Kbal Romeas, a small limestone outcrop. This outcrop ( Fig. 1 ) is situated about 4 km southwest of the type locality, surrounded by housing areas and an inactive old quarry, and now has become a tourist attraction.

Remarks

Sarika lactoconcha sp. nov. differs from S. benoiti , S. bocourti and S. resplendens with whitish shell, while the three latter species have brownish shells. Moreover, S. lactoconcha sp. nov. has a rounded last whorl, while S. bocourti has an obtusely angulated last whorl. Unfortunately, no genital information of S. resplendens from Cambodia is available for further comparison. However, the genitalia of S. resplendens from Myanmar possess a large penial retractor muscle with about the same diameter as the epiphallic caecum, and short flagellum compared with penis (see Godwin-Austen 1907: 179–181, pl. 111, figs 3, 3a for comparison), while this new species has a small and thin penial retractor muscle and long flagellum.

Compared to species of Sarika - Macrochlamys having a whitish shell, S. lactoconcha sp. nov. has a wider last whorl (loosely coiled), apertural lip simple and genitalia without penial verge. Meanwhile, S. consepta (Benson, 1860) from Myanmar has a narrow last whorl (densely coiled), apertural lip slightly expanded and rather thickened inside, and genitalia with large penial verge (see Pholyotha et al. 2020 for comparison). Another species, Macrochlamys psyche Vermeulen et al., 2019 was recently described from southern Vietnam. This Macrochlamys species has a flattened to slightly concaved spire, whereas S. lactoconcha sp. nov. has an elevated spire. Unfortunately, the genital anatomy of M. psyche is not available for comparison, therefore, its generic placement is still provisional.

Figures

Fig. 2. Shells of Sarika spp. A. Sarika resplendens (Philippi, 1846) (NHMUK 1903.7.1.112). B. S. bocourti (Morelet, 1875) (CUMZ 7900). C. S. lactoconcha Pholyotha & Panha sp. nov., holotype (CUMZ 7901). D. S. lactoconcha Pholyotha & Panha sp. nov., paratype (CUMZ 7902).

Fig. 3. Sarika lactoconcha Pholyotha & Panha sp. nov., paratype (CUMZ 7902). A. Living snail. B. General view of genital system. C. Internal structure of penis. D. Representative SEM image of the radula. Central tooth indicated by ‘C’; yellow arrow heads indicate lateral teeth with the transition to marginal teeth; white arrow heads indicate the end of penis.

Fig. 1. Geographic distribution of Sarika spp. in Cambodia based on new specimens examined herein. (modified from GinkgoMaps-project http://www.ginkgomaps.com).