Sarika obesior (Martens, 1867)

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 obesior (Martens, 1867) Figs 1 , 8 , 9E , 11E, F , 14C, D , 16 , 30C

Nanina (Orobia) resplendens var. obesior Martens 1867: 72, pl. 12, fig. 6. Type locality: "Um Petshaburi nicht selten; auch an der Ostseite des Golfs bei Bang-Pra beobachtet" [Petchaburi Province and Bang Phra, Si Racha District, Chonburi Province, Thailand].

Nanina (Macrochlamys) resplendens obesior : Tryon 1886: 91, pl. 30, fig. 76.

Sarika obesior : Solem 1966: 36-38, fig. 5b, c; Hemmen and Hemmen 2001: 45; Sutcharit and Panha 2008: 96; Pholyotha et al. 2020c: 18, 19, figs 2f, g, 7e, f, 10a, b, 13d-f.

Type material.

The type specimens could not be located and were probably missing from the Museum für Naturkunde (Berlin) collection (T. von Rintelen and C. Zorn, pers. comm., December 2018).

Other material examined.

Myanmar. Forest on Kala Island, Myeik District, Tanintharyi Division, 12°25'25.4"N, 98°29'50.6"E: CUMZ 7140, 7141. Thailand-Western. Limestone outcrop in Kaeng Krachan, Kaeng Krachan, Phetchaburi, 12°55'01.0"N, 99°37'48.0"E: CUMZ 7686. Wat Tham Rong, Ban Lat, Phetchaburi, 13°01'31.3"N, 99°55'07.9"E: CUMZ 7673 (Fig. 11F ), 7693. Wat Khao Krachiu, Tha Yang, Phetchaburi, 12°57'42.9"N, 99°54'48.8"E: CUMZ 7670. Khao Tamo, Tha Yang, Phetchaburi, 12°47'49.0"N, 99°44'40.0"E: CUMZ 7682. Wat Khiriwong, Khao Yoi, Phetchaburi, 13°20'02.2"N, 99°45'19.9"E: CUMZ 7668. Wat Puang Malai, Khao Yoi, Phetchaburi, 13°18'40.4"N, 99°47'09.2"E: CUMZ 7675 (Fig. 11E ). Khao Nang Panthurat, Cha-am, Phetchaburi, 12°50'22.2"N, 99°57'10.0"E: CUMZ 7680, 7681, 7694, 7695. Khao Na Kwang Cave Cha-am, Phetchaburi, 12°51'31.3"N, 99°56'29.3"E: CUMZ 7683, 7690. Wat Tham Jaeng, Cha-am, Phetchaburi, 12°49'39.3"N, 99°56'24.5"E: CUMZ 7667. Khao Ma Rong Cave, Bang Saphan, Prachuap Khiri Khan, 11°12'09.3"N, 99°29'39.8"E: CUMZ 7664, 7669, 7702. Wat Tham Siriwong, Bang Saphan, Prachuap Khiri Khan, 11°23'27.6"N, 99°34'55.3"E: CUMZ 7665, 7697, 7704. Wat Tham Khao Wong, Bang Saphan, Prachuap Khiri Khan, 11°17'28.0"N, 99°29'45.4"E: CUMZ 7666. Ko Thalu, Bang Saphan Noi, Prachuap Khiri Khan, 11°04'34.4"N, 99°33'37.4"E: CUMZ 7691. Khao Ta Mong Lai, Mueang, Prachuap Khiri Khan, 11°50'00.3"N, 99°49'47.2"E: CUMZ 7674. Khao Lom Muak, Mueang, Prachuap Khiri Khan, 11°47'08.5"N, 99°48'57.9"E: CUMZ 7676. Wat Ao Noi, Mueang, Prachuap Khiri Khan, 11°51'44.0"N, 99°49'20.0"E: CUMZ 7701, 7703. Tham Khao Rak Mai, Thap Sakae, Prachuap Khiri Khan, 11°25'42.1"N, 99°36'18.5"E: CUMZ 7677. Khao Kalok, Sam Roi Yot, Prachuap Khiri Khan, 12°20'13.0"N, 99°59'59.0"E: CUMZ 7678, 7698. Phraya Nakhon Cave, Sam Roi Yot, Prachuap Khiri Khan, 12°11'45.3"N, 100°00'41.8"E: CUMZ 7685. Limestone outcrop near Hat Sam Phraya, Kui Buri, Prachuap Khiri Khan, 12°09'04.0"N, 99°58'58.0"E: CUMZ 7705. Limestone outcrop in Kui Buri, Kui Buri, Prachuap Khiri Khan, 12°08'06.1"N, 99°38'41.2"E: CUMZ 7684, 7692, 7699. Wat Nong Phlap, Hua Hin, Prachuap Khiri Khan, 12°35'29.9"N, 99°43'45.8"E: CUMZ 7233. Pa La-U Waterfall, Hua Hin, Prachuap Khiri Khan, 12°32'17.2"N, 99°27'48.7"E: CUMZ 7700. Lublae Cave, Hua Hin, Prachuap Khiri Khan, 12°36'15.1"N, 99°43'20.9"E: CUMZ 7679. Thailand-Southern. Wat Bonphot Phisai, Lang Suan, Chumphon, 9°56'12.5"N, 99°08'44.2"E: CUMZ 7671. Limestone outcrop in Khlong Sok, Phanom, Surat Thani, 8°50'53.0"N, 98°44'35.3"E: CUMZ 7688. Limestone outcrop near Anurak Community Lodge, Phanom, Surat Thani, 8°53'16.3"N, 98°40'45.2"E: CUMZ 7689. Wat Tham Wararam, Phanom, Surat Thani: CUMZ 7696. Khao Kloi, Don Sak, Surat Thani, 8°52'43.9"N, 98°39'26.5"E: CUMZ 7672.

Diagnosis.

Shell medium to large, depressed and well rounded body whorl. Animal with greyish to slightly dark grey body and five mantle lobes. Genitalia with straight epiphallic caecum and triangular prism penial pilasters. Spermatophore: head filament with irregularly obtuse-serrate longitudinal ridges; 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.

The unique shell characters of S. obesior are depressed, medium to large size (shell width up to 22.1 mm; shell height up to 11.3 mm), pale brown, well-rounded body whorl, spire elevated, and impressed suture (Fig. 11E, F ).

The unique genitalia characters are straight epiphallic caecum; inner wall of penis with very fine longitudinal penial pilasters near atrium, changing to large rhomboid pilasters with acute angle on top (triangular prism shape) (Fig. 14C, D ).

Spermatophore long and needle-shaped. Sperm sac (ss) enlarged and elliptical. Head filament gourd shape with irregularly obtuse-serrate longitudinal ridges. Tail filament very long tube; region near sperm sac with three spines. Spine I located near base of spine II, simple and short. Spine II broken. Spine III large with complicated branching into small and many spinules. Region furthest away smooth and without spine; terminal part (more than ca. one-third of its length) with series of short to long branching spines arranged in a row or encircling the tail filament tip (Fig. 16 ).

Radula with half row formula: 1-(13-14)-60. The morphology of central tooth, lateral, and marginal teeth are similar to that described in Pholyotha et al. (2020c: figs 13d-f). Marginal teeth starting at approximately row number 13 or 14 (Fig. 30C ).

Living snail with monochrome greyish to slightly dark grey body. Mantle edge well developed and same colour same body (Fig. 9E ).

Distribution.

Sarika obesior occurs in western and southern Thailand (Fig. 8 ) and Tanintharyi region in Myanmar ( Pholyotha et al. 2020c).

COI analysis.

The ML and BI analyses showed that the individuals of S. obesior (n = 4) formed a monophyletic group with high support (Fig. 1 ; BS = 98%, PP = 1). The mean intraspecific genetic distance of S. obesior was 3.0% (Table 2 ).

Remarks.

This species has recently been re-described and illustrated based on the samples collected from Myeik, Myanmar by Pholyotha et al. (2020c). The topotypic specimens from Petchaburi, Thailand agree well with the previous descriptions. Solem (1966) noted that S. obesior differs from S. hainesi in having a rounded body whorl and attributed several specimens from northern and eastern Thailand to S. obesior . Yet, without the genital anatomy their identification could not be confirmed. Therefore, the specimens from northern and eastern Thailand as reported by Solem (1966) are still doubtful, and to date, the distribution of S. obesior is probably restricted to western and southern Thailand and south-eastern Myanmar.

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 8. Geographic distribution of Sarika kawtaoensis, S. lactospira sp. nov., and S. obesior 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 11. Shells of group I: Sarika resplendens group. A, B Sarika resplendens A specimen NHMUK 1898.5.18.157 and B specimen CUMZ 7815 C, D S. dohrniana C syntype NHMUK 20160046 and D specimen CUMZ 7611. E, F S. obesior E specimen CUMZ 7675 and F specimen CUMZ 7673.

Figure 14. Genitalia. A, B Sarika dohrniana specimen CUMZ 7633 A general view of the genital system and B internal structure of the penis C, D Sarika obesior specimen CUMZ 7673 C general view of the genital system and D internal structure of penis. White arrowheads indicate the ends of the penes.

Figure 16. Spermatophore of Sarika obesior specimen CUMZ 7678 A general view of the spermatophore B head filament C-E tail filament 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 arrowhead indicates the end of the 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.