Sarika limbata ( Moellendorff , 1894)

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 limbata ( Moellendorff, 1894) Figs 1 , 7 , 9F , 17A-C , 18A, B , 19 , 30D

Macrochlamys limbata Möllendorff 1894: 148, pl. 16, figs 6, 7. Type locality: "Samui Islands, Gulf of Siam" [Samui Islands, Ko Samui District, Surat Thani Province, Thailand]; Panha 1996: 34; Hemmen and Hemmen 2001: 44.

Nanina (Macrochlamys) limbata : Fischer and Dautzenberg 1904: 395.

Sarika limbata : Tomlin 1929: 16.

Type material.

Syntypes SMF 227100 (Fig. 17A ) from Insel Samui, Gulf der Siam [Samui Island, Surat Thani, Thailand], SMF 90854/2 (two shells), 90855/4 (four shells), 227101/3 (three shells; Fig. 17B ), 227102/1 (one shell).

Other material examined.

Thailand-Southern. Insel Samui, Gulf der Siam [Samui Island, Gulf of Thailand], 9°28'02.9"N, 99°58'43.8"E: SMF 298596/2. Tham Chang Phuek Bureau of Monks, Mueang, Chumphon, 10°26'47.0"N, 99°02'06.0"E: CUMZ 7637, 7647, 7654. Tham Krating Thong Bureau of Monks, Mueang, Chumphon, 10°27'20.6"N, 99°06'20.6"E: CUMZ 7638. Tham Sing, Mueang, Chumphon, 10°25'45.7"N, 99°02'52.7"E: CUMZ 7640. Wat Tham Sanook, Mueang, Chumphon, 10°28'52.3"N, 99°04'31.3"E: CUMZ 7644, 7646. Wat Uthaitham, Mueang, Chumphon, 10°30'24.1"N, 99°07'50.4"E: CUMZ 7658. Pla Cave, Thung Tako, Chumphon, 10°07'58.3"N, 99°08'08.1"E: CUMZ 7639. Wat Phut Sadi Phupharam, Thung Tako, Chumphon, 10°05'37.0"N, 99°04'39.3"E: CUMZ 7652 (Fig. 17C ). Tham Pisadan Bureau of Monks, Tha Sae, Chumphon, 10°45'36.7"N, 99°13'45.8"E: CUMZ 7655, 7657. Nang Thong Cave, Pathio, Chumphon, 10°40'14.3"N, 99°17'35.9"E: CUMZ 7641. Wat Tham Khao Plu, Pathio, Chumphon, 10°43'49.6"N, 99°19'19.7"E: CUMZ 7660. Wat Tham Khao Bang Siap, Pathio, Chumphon, 10°40'06.7"N, 99°17'37.9"E: CUMZ 7661. Wat Rat Burana, Lang Suan, Chumphon, 9°56'20.6"N, 99°02'25.7"E: CUMZ 7645. Tham Khao Kriap, Lang Suan, Chumphon, 9°49'03.0"N, 99°02'18.0"E: CUMZ 7649, 7659, 7662, 7663. Tham Khao Lak Bureau of Monks, Sawi, Chumphon, 10°19'39.7"N, 98°58'39.3"E: CUMZ 7642. Tham Nam Lod Thepnimit Bureau of Monks, Sawi, Chumphon, 10°22'36.9"N, 99°00'42.2"E: CUMZ 7643. Cholkhiri Bureau of Monks, Sawi, Chumphon, 10°22'20.1"N, 99°03'29.7"E: CUMZ 7648. Wat Nam Cha, Sawi, Chumphon, 10°17'50.9"N, 99°01'57.4"E: CUMZ 7650. Limestone outcrop in Sawi, Sawi, Chumphon, 10°15'05.0"N, 99°10'25.6"E: CUMZ 7651. Wat Tham Khao Lan, Sawi, Chumphon, 10°15'47.7"N, 99°10'18.1"E: CUMZ 7653. Wat Tham Khwan Mueang, Sawi, Chumphon, 10°14'18.2"N, 99°06'43.3"E: CUMZ 7656.

Diagnosis.

Shell large, depressed and well-rounded body whorl. Animal with pale to dark grey body and five mantle lobes. Genitalia with straight epiphallic caecum and inner penial sculpture with small reticulated pilasters in proximal part and small cuboidal pilasters in distal end. Spermatophore: head filament with irregularly plate-like sculpture; tail filament near sperm sac with three spines and terminal part more than ca. one-third of its length with series of several branching spines.

Description.

Shell. Shell depressed, large size (shell width up to 27.0 mm, shell height up to 13.7 mm) and rather thin. Shell surface smooth, shiny; shell colour pale yellowish brown to pale brown. Whorls 6- 6½, increasing regularly; body whorl large and well-rounded. Spire elevated; suture impressed. Aperture crescent-shaped and obliquely opened. Peristome simple. Columellar margin simple and slightly reflected near umbilicus. Umbilicus narrowly opened (Fig. 17A-C ).

Genital organs. Atrium short. Penis cylindrical with thin penial sheath covering proximal penis. Inner sculpture of penis proximally more than ca. one-fifth of penial chamber covered with very fine longitudinal penial pilasters, changing to small and thin reticulated pilasters around two-fifth of chamber, and transformed to small cuboidal pilasters at distal end near epiphallus. Epiphallus cylindrical, approximately two times total penis length, and smaller diameter than penis. Epiphallic caecum short, straight, similar diameter as proximal epiphallus, and located near middle of epiphallus. Penial retractor muscle thin and attached at tip of epiphallic caecum. Flagellum very slender, and approximately same length as penis. Vas deferens thin tube connecting distal epiphallus and free oviduct (Fig. 18A, B ).

Vagina cylindrical and ca. two-thirds penis length. Dart apparatus large, long, cylindrical, and located on atrium of vagina and penis junction. Gametolytic sac enlarged and bulbous; gametolytic duct long and cylindrical. Free oviduct cylindrical, approximately same length with penis, and proximal end encircled with thick tissue (Fig. 18A ).

Spermatophore long and needle-shaped. Sperm sac enlarged and elongate-oval. Head filament gourd shape; region close to sperm sac with irregularly plate-like sculpture then transformed to irregularly acute-serrate longitudinal ridges. Tail filament very long tube; region near sperm sac with three spines. Spine I very reduced to small knob. Spine II was broken but slightly large at base. Spine III (partially broken) with branching into small spines and spinules. Region furthest away smooth and without spine; terminal part (more than ca. one-third of its length) with series of short to long and complicated branching spines, arranged in a row or opposite rows near tail filament tip (Fig. 19 ).

Radula . Teeth with half row formula: 1-(16-17)-69. Central tooth symmetrical tricuspid; lateral teeth asymmetrical tricuspid; marginal teeth elongate bicuspid. Marginal teeth starting at approximately row number 16 or 17 (Fig. 30D ).

External features. Animal with reticulated skin and pale to dark grey body, pale grey foot sole, and dark grey caudal horn. Mantle edge well developed and same colour as body (Fig. 9F ).

Distribution.

Sarika limbata occurs eastwards of the Tenasserim Range to the Phuket Range and is common in Chumphon Province (Fig. 7 ).

COI analysis.

The ML and BI analyses revealed that the samples of S. limbata (n = 4) formed a monophyletic group with very strong support (Fig. 1 ; BS = 100%, PP = 1), and sister to S. lactospira sp. nov. with only BI support (Fig. 1 ; PP = 0.99). The mean intraspecific genetic distance of S. limbata was 1.2% (Table 2 ).

Sarika limbata , S. kawtaoensis , and S. lactospira sp. nov. are phylogenetically closely related, yet only with BI support (Fig. 1 ). The average interspecific sequence divergences were 7.2% ( S. limbata and S. kawtaoensis ), 7.5% ( S. limbata and S. lactospira sp. nov.), and 6.9% ( S. kawtaoensis and S. lactospira sp. nov.) (Table 2 ).

Remarks.

The shell morphology of S. limbata is similar to that of S. kawtaoensis . The main distinguishing characters of S. limbata are the reticulated and cuboidal penial pilasters, and the plate-like and acute-serrate longitudinal ridges on the head filament of the spermatophore. In contrast, S. kawtaoensis has reticulated and irregular large folded penial pilasters and acute-serrate longitudinal ridges on the head filament of the spermatophore.

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 9. Living snails of group I: Sarika resplendens group. A Sarika resplendens specimen CUMZ 7843 showing left shell lobe lobes (lsl) B S. resplendens specimen CUMZ 7827 C mating pairs of S. resplendens CUMZ 7876 D S. dohrniana specimen CUMZ 7611 E S. obesior specimen CUMZ 7673 F S. limbata specimen CUMZ 7652. All not to scale.

Figure 17. Shells of group I: Sarika resplendens group. A-C Sarika limbata A syntype SMF 227100, B syntype SMF 227101, and C specimen CUMZ 7652 D-F S. heptagyra D syntype SMF 227096 E syntype SMF 227097, and F specimen CUMZ 7231.

Figure 18. Genitalia. A, B Sarika limbata specimen CUMZ 7652 A general view of the genital system and B internal structure of penis C, D S. heptagyra specimen CUMZ 7279 C general view of the genital system and D internal structure of penis. White arrowheads indicate the ends of the penes.

Figure 19. Spermatophore of Sarika limbata specimen CUMZ 7652 A general view of spermatophore, B head filament C-E tail filament showing C three spines located close to the sperm sac D region with and without branching spines, and E branching spines on the tip region. Yellow arrowheads indicate the ends of spines from the tip.

Figure 30. Representative SEM images of the radula. A Sarika resplendens specimen CUMZ 7851 B S. dohrniana specimen CUMZ 7633 C S. obesior specimen CUMZ 7673 D S. limbata specimen CUMZ 7652 E S. heptagyra specimen CUMZ 7279. Central tooth indicated by ' C'; yellow colour indicates lateral teeth in the transition to marginal teeth.