Sarika melanospira Pholyotha & Panha, 2020

Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2020, Integrative taxonomic revision of the land snail genus Sarika Godwin-Austen, 1907 in Thailand, with descriptions of nine new species (Eupulmonata, Ariophantidae), ZooKeys 976, pp. 1-100 : 1

Sarika melanospira Pholyotha & Panha sp. nov. Figs 1 , 32 , 33E , 38C, D , 39C, D , 43D

Type material.

Holotype CUMZ 7258 (Fig. 38C , width 28.3 mm, height 13.3 mm). Paratypes CUMZ 7243 (ten shells and 44 preserved specimens in ethanol; Fig. 38D , width 26.5 mm, height 11.7 mm) CUMZ 7244 (four shells and two preserved specimens in ethanol), NHMUK 20200286 (two shells), SMF (two shells), ZRC.MOL.017029 (two shells).

Type locality.

Wat Tham Suwan Phu Pha, Khao Chamao, Rayong, Thailand, 12°59'24.1"N, 101°39'28.8"E.

Diagnosis.

Shell large, dextral, depressed and pale brown with rounded to weak shouldered body whorl. Animal with blackish body, four mantle lobes and mantle covered by spiral black band below the suture at the body whorl. Genitalia with a large straight epiphallic caecum and triangular prism pilasters on inner penial sculpture.

Description.

Shell. Shell depressed, large size (shell width up to 29.3 mm, shell height up to 13.3 mm) and thin. Surface smooth and polished; shell colour pale brown. Whorls 6- 6½, increasing regularly; body whorl large, rounded to weak shouldered. Spire slightly to moderately elevated; suture impressed. Aperture crescent-shaped and obliquely opened. Peristome simple. Columellar margin simple and slightly reflected near umbilicus. Umbilicus narrowly opened (Fig. 38C, D ).

Genital organs. Atrium short. Penis cylindrical with thin penial sheath covering proximal penis. Inner sculpture of penis proximally more than ca. half of penial chamber with very finely longitudinal penial pilasters to nearly smooth surface, and then gradually transformed from small to large rhomboid pilasters with acute angle on top (triangular prism). Epiphallus cylindrical and nearly two times penis length. Epiphallic caecum short, straight, slightly larger than epiphallus and located near middle of epiphallus. Penial retractor muscle thin and attached at tip of epiphallic caecum. Flagellum slender, narrower than epiphallus and approximately as long as penis. Vas deferens thin tube connecting distal epiphallus and free oviduct (Fig. 39C, D ).

Vagina long cylindrical and approximately as long as penis. Dart apparatus large, long cylindrical, and located on atrium at vagina and penis junction. Gametolytic sac enlarged and bulbous; gametolytic duct long cylindrical. Free oviduct cylindrical, nearly as long as vagina (Fig. 39C ).

Radula . Teeth with half row formula: 1-(17-18)-59. Central tooth symmetrical tricuspid; lateral teeth asymmetrical tricuspid; marginal teeth elongate bicuspid. Teeth shape is similar to that of S. resplendens . Marginal teeth starting at approximately row number 17 or 18 (Fig. 43D ).

External features. Animal with reticulated skin and blackish body. Mantle with conspicuous blackish spiral band at the body whorl below the suture. Creamy-grey foot sole and blackish caudal horn. Four mantle lobes well developed and blackish. Left shell lobe absent (Fig. 33E ).

Etymology.

The specific epithet melanospira is derived from the Greek word melanos meaning black or dark, and the Latin word spira meaning coil. It refers to the mantle being covered by a spiral black band at the body whorl.

Distribution.

Sarika melanospira sp. nov. is only known from the limestone habitats at the type locality (Fig. 32 ).

COI analysis.

The ML and BI analyses showed that the individuals of S. melanospira sp. nov. (n = 3) formed a monophyletic group with very strong support (Fig. 1 ; BS = 100%, PP = 1). The mean intraspecific genetic distance of S. melanospira sp. nov. was 0.5% (Table 2 ).

Remarks.

Among the Sarika hainesi group, this new species differs from S. hainesi , S. bocourti , and S. inferospira sp. nov. in having a rounded to very weak shouldered body whorl. Sarika hainesi and S. bocourti have an obtusely angulated body whorl and S. inferospira sp. nov. has a shouldered body whorl.

Figures

Figure 1. Maximum likelihood tree showing the relationships among species of Sarika based on the mitochondrial COI gene sequences. Numbers by the nodes are the ML bootstrap values (left) and Bayesian posterior probabilities (right); shown only for the nodes supported by ML or BI (≥ 70 % and ≥ 0.95). Each clade colour refers to a genus.

Figure 32. Geographic distribution of Sarika bocourti, S. hainesi, S. inferospira sp. nov., S. melanospira sp. nov. and S. pellosa sp. nov. based on examined specimens herein.

Figure 33. Living snails of group II: Sarika hainesi group. A Sarika bocourti specimen CUMZ 7591 showing no left shell lobe (yellow arrow) B S. hainesi specimen CUMZ 7237 C S. bocourti specimen CUMZ 7591 D S. inferospira sp. nov. specimen CUMZ 7257 E S. melanospira sp. nov. paratype CUMZ 7243, and F S. pellosa sp. nov. paratype CUMZ 7517. Not to scale.

Figure 38. Shells of Group II: Sarika hainesi group. A, B Sarika inferospira sp. nov. A holotype CUMZ 7254 and B paratype CUMZ 7255 C, D S. melanospira sp. nov. C holotype CUMZ 7258 and D paratype CUMZ 7243 E, F S. pellosa sp. nov. E holotype CUMZ 7249 and F paratype CUMZ 7517.

Figure 39. Genitalia. A, B Sarika inferospira sp. nov. specimen CUMZ 7257 A general view of the genital system and B internal structure of the penis C, D S. melanospira sp. nov. paratype CUMZ 7243 C general view of the genital system and D internal structure of the penis. White arrowheads indicate the ends of the penes.

Figure 43. Representative SEM images of the radula. A Sarika hainesi specimen CUMZ 7237 B S. bocourti specimen CUMZ 7597 C S. inferospira sp. nov. paratype CUMZ 7255 D S. melanospira sp. nov. paratype CUMZ 7243, and E S. pellosa sp. nov. specimen CUMZ 7251. Central tooth indicated by ' C'; Yellow colour indicates lateral teeth with the transition to marginal teeth.