Sarika megalogyne 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 megalogyne Pholyotha & Panha sp. nov. Figs 1 , 7 , 10E , 25C, D , 26C, D , 27 , 31D

Type material.

Holotype CUMZ 7521 (Fig. 25C , width 19.5 mm, height 9.8 mm). Paratypes CUMZ 7522 (23 shells and 34 specimens preserved in ethanol; Fig. 25D , width 19.5 mm, height 10.0 mm), CUMZ 7238 (10 specimens preserved in ethanol), CUMZ 7529 (12 shells and 78 specimens preserved in ethanol), CUMZ 7530 (24 shells), CUMZ 7536 (16 specimens preserved in ethanol), CUMZ 7537 (three specimens preserved in ethanol), NHMUK 20200283 (two shells), SMF (two shells), ZRC.MOL.017028 (two shells).

Other material examined.

Thailand-Western. Khao Pho Cave, Bang Saphan Noi, Prachuap Khiri Khan, 10°59'25.2"N, 99°21'32.8"E: CUMZ 7540. Thailand-Southern. Pla Cave, Thung Tako, Chumphon, 10°07'58.4"N, 99°08'14.5"E: CUMZ 7523. Tham Sing, Mueang, Chumphon, 10°25'45.9"N, 99°03'11.3"E: CUMZ 7527. Wat Bonphot Phisai, Lang Suan, Chumphon, 9°56'23.8"N, 99°08'51.4"E: CUMZ 7528. Tham Pisadan Bureau of Monks, Tha Sae, Chumphon, 10°45'36.7"N, 99°13'45.8"E: CUMZ 7538. Limestone outcrop in Saphli, Pathio, Chumphon, 10°33'12.0"N, 99°16'34.5"E: CUMZ 7524, 7532. Malagor Cave, Pathio, Chumphon, 10°52'42.9"N, 99°30'30.3"E: CUMZ 7525. Nang Thong Cave, Pathio, Chumphon, 10°40'14.3"N, 99°17'35.9"E: CUMZ 7526. Wat Tham Khao Plu, Pathio, Chumphon, 10°43'49.6"N, 99°19'19.7"E: CUMZ 7539. Wat Tham Khao Bang Siap, Pathio, Chumphon, 10°40'06.7"N, 99°17'37.9"E: CUMZ 7534. Ko Wiang, Pathio, Chumphon, 10°50'43.3"N, 99°28'46.5"E: CUMZ 7909. Cholkhiri Bureau of Monks, Sawi, Chumphon, 10°22'23.9"N, 99°03'38.1"E: CUMZ 7531. Limestone outcrop in Sawi, Sawi, Chumphon, 10°15'16.9"N, 99°10'01.2"E: CUMZ 7533. Wat Tham Khao Lan, Sawi, Chumphon, 10°15'47.0"N, 99°10'28.1"E: CUMZ 7535.

Type locality.

Limestone outcrop at Khao Ma Rong Cave, Bang Saphan, Prachuap Khiri Khan, Thailand, 11°12'09.2"N, 99°29'48.7"E.

Diagnosis.

Shell medium to large, depressed and very pale brown with well-rounded to slightly shouldered body whorl. Animal with grey body and five mantle lobes. Genitalia with a straight epiphallic caecum, very large free oviduct and triangular prism-shaped pilasters on inner penial sculpture. Spermatophore: tail filament near sperm sac with three spines and terminal part more than ca. three-quarters of its length with series of several branching spines.

Description.

Shell. Shell depressed, medium to large size (shell width up to 21.2 mm, shell height up to 11.3 mm), and thin. Surface smooth and glossy; shell colour very pale brown. Whorls 6- 6½, increasing regularly; body whorl slightly well rounded to slightly shouldered. Spire moderately to very much elevated; suture impressed. Aperture crescent-shaped and obliquely opened. Peristome simple. Columellar margin simple and slightly reflected near umbilicus. Umbilicus narrowly opened (Fig. 25C, D ).

Genital organs. Atrium short. Penis cylindrical with thin penial sheath covering proximal penis. Inner sculpture of penis proximally more than ca. one-third of penial chamber with very finely longitudinal penial pilasters to nearly smooth surface, and then gradually modified from small to large rhomboid pilasters with acute angle on top (triangular prism). Epiphallus cylindrical, slightly longer than penis length. Epiphallic caecum large, straight, diameter slightly larger than epiphallus, and located proximally near middle of epiphallus. Penial retractor muscle thin and attached at tip of epiphallic caecum. Flagellum long slender and slightly longer than epiphallus. Vas deferens thin tube connecting distal epiphallus and free oviduct (Fig. 26C, D ).

Vagina cylindrical, enlarged and slightly shorter than penis. Dart apparatus large, long cylindrical, and located on atrium at vagina and penis junction. Gametolytic sac enlarged and bulbous; gametolytic duct long and cylindrical. Free oviduct enlarged cylindrical, extremely long, approximately three times of vagina length (Fig. 26C ).

Spermatophore long and needle-shaped. Sperm sac and head filament were missing. Tail filament long tube; region near sperm sac with three spines. Spine I simple and short. Spine II large, long, and with complicated branching spines into spinules near the tip. Spine III smaller than spine II and with complicated branching spines into spinules. Region furthest away smooth and without spine; terminal part (approximately three-quarters of its length) with series of long complicated branching spines into spinules arranged in a row, and then transformed to very long serrate-like spines arranged in opposite rows near the tail filament tip (Fig. 27 ).

Radula . Teeth with half row formula: 1-(13-14)-55. Central tooth symmetrical tricuspid; lateral teeth asymmetrical tricuspid; marginal teeth elongate bicuspid. Marginal teeth starting at approximately row number 13 or 14 (Fig. 31D ).

External features. Animal with reticulated skin and body darker grey above and paler grey near foot sole. Caudal foss and caudal horn present. Five mantle lobes well developed and pale grey in colour (Fig. 10E ).

Etymology.

The specific name megalogyne is derived from the Greek word megale meaning large and the Greek gyne meaning female. It refers to the female part of genital organs with a very large free oviduct, which characterises this species.

Distribution.

Sarika megalogyne sp. nov. is common in Prachuap Khiri Khan and Chumphon provinces (Fig. 7 ). This species is often found under leaves of small trees and shrubs on limestones.

COI analysis.

The ML and BI analyses of S. megalogyne sp. nov. revealed that all samples (n = 3) formed a clade with very strong support (Fig. 1 ; BS = 100%, PP = 1). The mean intraspecific genetic distance of S. megalogyne sp. nov. was 1.4% (Table 2 ).

Remarks.

Sarika megalogyne sp. nov. and S. caligina sp. nov. have similar genitalia and penial sculpture. However, S. megalogyne sp. nov. has a much longer free oviduct and flagellum than S. caligina sp. nov. In addition, the spermatophore of S. megalogyne sp. nov. with more than ca. three-quarters of the tail filament contains branching spines, whereas the spermatophore of S. caligina sp. nov. with more than ca. only half of the tail filament contains branching spines. Furthermore, the genetic distance between these two species is high (7.4%).

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 7. Geographic distribution of Sarika limbata and S. megalogyne sp. nov. based on the specimens examined herein.

Figure 10. Living snails of group I: Sarika resplendens group. A Sarika heptagyra specimen CUMZ 7279 B S. kawtaoensis specimen CUMZ 7738 C S. caligina sp. nov. paratype CUMZ 7245 D S. lactospira sp. nov. paratype CUMZ 7287 E S. megalogyne sp. nov. paratype CUMZ 7522 and F S. subheptagyra sp. nov. paratype CUMZ 7507. All not to scale.

Figure 25. Shells of group I: Sarika resplendens group. A, B Sarika lactospira sp. nov. A holotype CUMZ 7286 and B paratype CUMZ 7287 C, D S. megalogyne sp. nov. C holotype CUMZ 7521 and D paratype CUMZ 7522 E, F S. subheptagyra sp. nov. E holotype CUMZ 7506 and F paratype CUMZ 7507.

Figure 26. Genitalia. A, B Sarika lactospira sp. nov. specimen CUMZ 7291 A general view of genital system B internal structure of penis C, D S. megalogyne sp. nov. paratype CUMZ 7522 C general view of genital system D internal structure of penis. White arrowheads indicate the ends of the penes.

Figure 27. Spermatophore of Sarika megalogyne sp. nov. paratype CUMZ 7522 A general view of the spermatophore and B-D tail filament showing B three spines located close to the sperm sac C region with and without branching spines, and D branching spines on the tip region. Yellow arrowheads indicate the end of the spines from the tip.

Figure 31. Representative SEM images of the radula. A Sarika kawtaoensis specimen CUMZ B S. caligina sp. nov. paratype CUMZ 7245 C S. lactospira sp. nov. specimen CUMZ 7291 D S. megalogyne sp. nov. specimen CUMZ 7531, and E S. subheptagyra sp. nov. paratype CUMZ 7507. Central tooth indicated by ' C'; yellow colour indicates lateral teeth in the transition to marginal teeth.