Sarika bocourti (Morelet, 1875)

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 bocourti (Morelet, 1875) Figs 1 , 32 , 33A, C , 34D-F , 35C, D , 37 , 43B

Helix bocourti Morelet, 1875: 249. Type locality: "Ľespece provient de Battambang, dans le Cambodje" [Battambang Province, Cambodia]; Breure et al. 2018: 222, 223, figs 135, 136.

Nanina (Macrochlamys) aff. boucourti [sic]: Tryon 1886: 89, pl. 29, figs 43-45.

Ariophanta (Xesta) bocourti : Fischer 1891: 20.

Nanina (Xesta) bocourti : Fischer and Dautzenberg 1904: 394.

Sarika bocourti : Pholyotha et al. 2020a: 7, 8, fig. 2b; Sutcharit et al. 2020: 27.

Type material.

Syntype NHMUK 1893.2.4.1076-1077 (two shells; Fig. 34D ) from Battambang [Battambang Province, Cambodia].

Other material examined.

Cambodia. Samov Mountain, Phnom Sampov, Banan, Battambang, 13°01'33.6"N, 103°06'03.6"E: CUMZ 7900. Thailand-Eastern. Wat Trok Nong Lang, Khlung, Chanthaburi, 12°32'16.3"N, 102°16'33.8"E: CUMZ 7578. Trok Nong Waterfall, Khlung, Chanthaburi, 12°32'39.4"N, 102°14'13.5"E: CUMZ 7580, 7582, 7583, 7585, 7590 (Fig. 34E ), 7591, 7596, 7608. Khao Kaeo Priest’s camp site, Khlung, Chanthaburi, 12°29'26.8"N, 102°18'49.6"E: CUMZ 7598. Khlong Narai Waterfall, Mueang, Chanthaburi, 12°34'53.4"N, 102°10'34.2"E: CUMZ 7597, 7601, 7610. Wat Khao Banchob, Makham, Chanthaburi, 12°51'09.1"N, 102°12'12.7"E: CUMZ 7581. Khao Soi Dao, Soi Dao, Chanthaburi, 13°06'31.0"N, 102°12'01.5"E: CUMZ 7579, 7584, 7586, 7609. Mountain area near Khao Soi Dao, Soi Dao, Chanthaburi, 13°07'49.3"N, 102°10'57.2"E: CUMZ 7600. Mountain area near Wat Ban Wang Ka Prae, Pong Nam Ron, Chanthaburi, 12°58'10.9"N, 102°16'20.6"E: CUMZ 7594. Thailand-Southern. Mountain area near Khao Sok Nature Resort, Phanom, Surat Thani, 8°54'22.6"N, 98°31'45.1"E: CUMZ 7587. Mountain area near Khao Sok Evergreen House, Phanom, Surat Thani, 8°54'38.1"N, 98°31'47.2"E: CUMZ 7592 (Fig. 34F ), 7606. Mountain area near Anurak Community Lodge, Phanom, Surat Thani, 8°53'16.2"N, 98°40'52.9"E: CUMZ 7593, 7603. Wat Tham Wararam, Phanom, Surat Thani, 8°53'03.3"N, 98°40'02.5"E: CUMZ 7604. Wat Tham Phanthurat, Phanom, Surat Thani, 8°54'36.9"N, 98°31'28.3"E: CUMZ 7595. Mountain area near Ban Ya Plong, Phanom, Surat Thani, 8°54'33.0"N, 98°34'51.6"E: CUMZ 7605. Lot cave, Nopphitam, Nakhon Si Thammarat, 8°44'10.0"N, 99°38'06.5"E: CUMZ 7602. Limestone outcrop in Tham Nam Phut, Mueang, Phang-nga, 8°27'49.7"N, 98°32'37.0"E: CUMZ 7607. Mountain area near Ban Pak Khlong, Kapong, Phang-nga, 8°47'54.8"N, 98°30'40.6"E: CUMZ 7588.

Diagnosis.

Shell large, depressed, obtusely angulated body whorl and higher shell spire. Animal with pale to dark grey body and four mantle lobes. Genitalia with a large and straight epiphallic caecum, and triangular prism shaped penial pilasters. Spermatophore with irregularly acute-serrate longitudinal ridges on the head filament, tail filament with two spines and more than ca. two-thirds of its length with series of short branching spines.

Description.

Shell. Shell depressed, large to very large size (shell width up to 33.1 mm, shell height up to 16.1 mm) and rather thin. Shell surface smooth and polished; shell colour pale yellowish brown to brown. Whorls 6-7, increasing regularly; body whorl large and obtusely angulated. 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. 34D-F ).

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, slightly longer than penis, and approximately same diameter as penis. Epiphallic caecum short, straight, approximately similar diameter with penis, and located 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. 35C, D ).

Vagina cylindrical and approximately as long as penis. Dart apparatus enlarged, long cylindrical, and located on atrium at vagina and penis junction. Gametolytic sac enlarged and bulbous (with spermatophore inside); gametolytic duct cylindrical. Free oviduct cylindrical, nearly two times of vagina length, and proximal end encircled with thick tissue (Fig. 35C ).

Spermatophore long and needle-shaped. Sperm sac enlarged and elongate-oval. Head filament gourd shape with irregularly acute-serrate longitudinal ridges. Tail filament very long tube; region near sperm sac with two spines. Spine I simple and rather short. Spine II very large at base and divided in two spines and then each one branching into many spinules near the tip. Region furthest away smooth without spine; terminal part (more than ca. two-thirds of its length) with series of short branching spines arranged in a row and transformed to long serrate-like spines arranged in opposite rows near the tail filament tip (Fig. 37 ).

Radula . Teeth with half row formula: 1-(12-13)-61. Central tooth symmetrical tricuspid with large mesocone and very small to nearly absent ectocone; lateral teeth asymmetrical tricuspid with large mesocone and very small to nearly absent endocone and ectocone; marginal teeth elongate bicuspid. Marginal teeth starting at approximately row number 12 or 13 (Fig. 43B ).

External features. Animal with reticulated skin, pale to dark grey body and darker than foot sole, and dark grey caudal horn. Mantle edge well developed and pale grey colour. Shell lobes and dorsal lobes shape and structure like S. hainesi (Fig. 33A, C ).

Distribution.

This species is known from several localities in Chanthaburi Province, eastern Thailand and Surat Thani, Nakhon Si Thammarat and Phang-nga provinces, southern Thailand (Fig. 32 ), and Battambang Province, Cambodia ( Morelet 1875; Pholyotha et al. 2020a). Sarika bocourti is common in both human-influenced habitats, such as plantations or gardens, and natural habitats.

COI analysis.

The ML and BI analyses showed that the four specimens of S. bocourti represent a single haplotype, sister group to S. inferospira sp. nov. + S. melanospira sp. nov. with strong support (Fig. 1 ; BS = 99%, PP = 1).

Remarks.

Specimens from Chanthaburi Province, eastern Thailand were identical with the syntype of S. bocourti that was described from Battambang Province, Cambodia. Both the shell morphology and genital anatomy of the disjunct populations from southern Thailand agree well with the populations from eastern Thailand. From the COI gene phylogeny, all specimens from southern Thailand are retrieved as monophyletic with S. bocourti from eastern Thailand and with no variation in the COI sequences (Table 2 ). The eastern and southern populations of S. bocourti are possibly shaping up by sea level fluctuation in the last glacial periods recorded in tree-dwelling snails and centipedes ( Prasankok et al. 2007; Siriwut et al. 2015). Further investigation by adding more samples and genetic markers would help elucidate the phylogeographical history of this species.

Although shell morphology of S. bocourti and S. hainesi is quite similar, the genitalia and spermatophore are clearly distinct. Sarika bocourti has larger epiphallic caecum, and a spermatophore with a head filament with acute-serrate ridges, and the tail filament has fewer branching spines. Sarika hainesi has a smaller epiphallic caecum, and a spermatophore with a head filament with a sponge-like appearance and the tail filament has more branching spines. In addition, the genetic distance between these two species is rather high (7.0%).

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 34. Shells of Group II: Sarika hainesi group. A-C Sarika hainesi A syntype NHMUK 20200290 and B, C specimen CUMZ 7237 D-F S. bocourti D syntype NHMUK 1893.2.4.1076 - 1077 E specimen CUMZ 7590, and F specimen CUMZ 7592.

Figure 35. Genitalia. A, B Sarika hainesi specimen CUMZ 7237 A general view of the genital system and B internal structure of the penis. C, D Sarika bocourti specimen CUMZ 7591 C general view of the genital system and D internal structure of the penis. White arrowheads indicate the ends of the penes.

Figure 37. Spermatophore of Sarika bocourti specimen CUMZ 7591 A general view of the spermatophore B head filament, and C-E tail filament showing C two spines located close to the sperm sac D branching spines on middle region E branching spines on the tip region. Yellow arrowhead indicates the end of the spines from the tip.

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.