Sarika nana 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 : 15-18

Sarika nana Pholyotha & Panha sp. nov.

urn:lsid:zoobank.org:act:48DF9AB1-369C-4930-A006-9E57AE9DBACB

Table 1 ; Figs 4 C–D, 6G–J, 7

Diagnosis

Sarika nana sp. nov. can be characterized by medium shell size, globosely depressed, pale yellowishbrown shell, and well-rounded periphery. Animal has dark grey body and five mantle lobes. Genitalia have a rather long epiphallic caecum, short penial caecum, rather large penial verge and oval-shaped penial pilasters. Spermatophore has smooth head filament and tail filament near sperm sac bearing two spines, and terminal one-third of tail filament contains a series of short branching spines.

Etymology

The specific epithet ‘ nana ’ is from the Latin word ‘ nanus ’ meaning “dwarf” and refers to the small-sized species in this genus.

Material examined

Holotype

CAMBODIA • 1 shell (width 12.6 mm, height 6.8 mm); Takeo Province, Kiri Vong District, the conglomerate hills at Phnom Bayang Temple, locality code C036; 10°38′28.2″ N, 104°50′35.8″ E; CUMZ 7907 .

Paratypes

CAMBODIA • 24 alcohol-preserved specimens; same collection data as for holotype; CUMZ 7908 • 2 shells; same collection data as for preceding; NHMUK • 2 shells; same collection data as for preceding; ZRC .

Description

SHELL ( Fig. 4 C–D). Globosely depressed, medium-sized (shell width up to 12.3 mm, shell height up to 6.8 mm), thin, rather translucent. Shell surface smooth, shiny; more shiny below periphery; shell colour pale yellowish brown. Entire shell consisting of 5½–6 whorls increasing regularly, separated by shallow suture. Spire slightly elevated; last whorl broad, well-rounded. Aperture obliquely oval-lunate shaped. Peristome simple. Columellar margin simple, slightly expanded near umbilicus. Umbilicus opened, wide, deep.

EXTERNAL FEATURES ( Fig. 7A ). Living animals having monochrome pale grey body, foot sole. Caudal foss, large caudal horn present. Mantle edge well developed, dark colour, with three dorsal lobes and two shell lobes (see Pholyotha et al. 2018: fig. 1). Dorsal lobes and shell lobes similar to those of S. lactoconcha sp. nov.

GENITALIA ( Fig. 7 B–C). Atrium (at) very short. Penis (p) short, cylindrical with thin penial sheath covering proximal penis. Distal penis slightly enlarged with penial caecum (pc), corresponding to penial verge. Inner sculpture of penis proximally with smooth surface then transformed to thickened, corrugated transverse-folded penial pilasters (pp) surrounding penial verge near distal end. Penial verge (pv) large with blunt tip. Epiphallus (e) cylindrical, about twice penis length. Epiphallic caecum (ec) similar diameter as epiphallus, straight, located near proximal epiphallus. Penial retractor muscle (prm) thin, attached at tip of epiphallus. Flagellum (fl) slender, short, about half the length of epiphallus. Vas deferens (vd) thin tube. Vagina (v) cylindrical, little longer than penis. Dart apparatus (da) cylindrical, rather large and long, connected to atrium at vagina and penis junction. Gametolytic sac (gs) enlarged, bulbous (spermatophore inside); gametolytic duct (gd) cylindrical, long. Free oviduct (fo) cylindrical, same length as vagina, proximal end encircled with thickened, brownish tissue. Oviduct enlarged lobules; prostate gland running alongside oviduct.

SPERMATOPHORE ( Fig. 6 G–J). Sperm sac (ss) enlarged, elongate-oval. Head filament (hf) located subapical of sperm sac, with long, smooth surface. Tail filament (tf) about two times longer than sperm sac, region close to sperm sac bearing two spines. Spine I simple, curved, with dull tip. Spine II large, branching into spinules (antler like). Region furthest away smooth, without spine; terminal part (about one-fourth of its length) consisting of short to long branching spines arranged in row or encircling tip.

RADULA ( Fig. 7D ). Teeth arranged in wide-angle U-shape with half row formula: 1–(10–11)–46 teeth. Central tooth symmetrical tricuspid; mesocone large, lanceolate shape; ectocones small with triangular shape. Lateral teeth asymmetrical tricuspid with large, pointed cusp mesocone; endocone small, pointed cusp, located near tip; ectocone rather large, triangular-shaped, located in middle of tooth. Marginal teeth starting around tooth numbers 10–11, obliquely bicuspid; endocone elongate, pointed cusp; ectocone small, pointed cusp. Outermost teeth gradually smaller in size from lateral teeth to edge.

Distribution

This new species is known only from the conglomerate mountain Phnom Bayang (type locality; Fig. 1 ). The habitat at the collection site is an evergreen forest mixed with fruit orchards and with outcroppings of large granite boulders. This location is surrounded by villages and is adjacent to paddy fields.

Remarks

Sarika nana sp. nov., a medium-sized species, can be distinguished from all species of Sarika recorded from mainland Indochina by having a penial verge. Compared to medium-sized species of Macrochlamys , body whorl of S. nana sp. nov. is relatively broader and more well-rounded on the periphery, umbilicus is relatively wider and aperture opening is less convex than M. excepta (Mabille, 1887) ( Fig. 4E ) and M. zero (Mabille, 1887) ( Fig. 4F ). The type locality of the new species is about 1000 km from the two species described from Northern Vietnam. The Thai species M. brunnea Möllendorff, 1902 has much narrower umbilical opening than this new species (see Pholyotha et al. 2018: fig. 8a). Unfortunately, the anatomical data of M. brunnea , M. excepta and M. zero is unavailable for further comparison.

Figures

Fig. 4. Shells of Sarika spp. A. Sarika khmeriana Pholyotha & Panha sp. nov., holotype (CUMZ 7904). B. Sarika khmeriana Pholyotha & Panha sp. nov., paratype (CUMZ 7905). C. S. nana Pholyotha & Panha sp. nov., holotype (CUMZ 7907). D. S. nana Pholyotha & Panha sp. nov., paratype (CUMZ 7908). E. Macrochlamys excepta (Mabille, 1887), syntype (MNHN-IM-2000-27886). F. M. zero (Mabille, 1887), syntype (MNHN-IM-2000-27782).

Fig. 7. Sarika nana Pholyotha & Panha sp. nov., paratype (CUMZ 7908). 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. 6. SEM images of spermatophores. A–F. Sarika khmeriana Pholyotha & Panha sp. nov., paratype (CUMZ 7905). A. General view of spermatophore. B. Head filament. C–F. Detail of tail filament. G–J. S. nana Pholyotha & Panha sp. nov., paratype (CUMZ 7908). G. General view of spermatophore. H. Head filament. I–J. Detail of tail filament.

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