Land snail genus Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from Cambodia, with description of three new species

Taxonomic work on the land snail genus Sarika Godwin-Austen, 1907 in Cambodia is scarce. A total of three species were recognized from Cambodia prior to this study. However, their taxonomic descriptions were based mainly on shell morphology, with limited genital data. To address this knowledge gap, we opportunistically surveyed for land snails in Cambodia. Our inventory yielded four species of Sarika – one recognized species, Sarika bocourti (Morelet, 1875), from Battambang Province and three new species, Sarika khmeriana Pholyotha & Panha sp. nov., Sarika lactoconcha Pholyotha & Panha sp. nov. and Sarika nana Pholyotha & Panha sp. nov. from Kampot and Takeo Provinces in southern Cambodia. Our discovery involves the first species of Sarika to be described from Cambodia in more than a century highlights the extent to which the diversity of Cambodian land snails remains to be discovered. The status of two species, Sarika benoiti (Crosse & Fischer, 1863) and Sarika resplendens (Philippi, 1846), is at present ambiguous because no material identifiable as these species was found in recent extensive surveys. Although S. bocourti was recently collected from Cambodia, European Journal of Taxonomy 674: 1–21 (2020) 2 its taxonomic position remained unclear due to a lack of living specimens. Detailed descriptions and illustrations of living animals, shell morphology and reproductive anatomy are provided, and a map showing their distributions is given.

Recent field collections from karstic and non-karstic habitats in southern Cambodia have yielded a number of ariophantid snails that could be classified into the genus Sarika. They are all clearly distinct from all other known members of the species complex of Sarika-Macrochlamys from Myanmar, Thailand, Laos and Vietnam. Therefore, we describe three new species of Sarika herein based on shell, external morphology, radula, genitalia and spermatophore characters. Additionally, the diagnostic characters of three previously recorded species in Cambodia, S. resplendens, S. benoiti and S. bocourti are also provided. This information further supports the growing knowledge of the diverse terrestrial snail fauna in Cambodia.

Material and methods
We collected snail samples from karstic and non-karstic habitats in southern Cambodia (Fig. 1). Photographs of living snails were taken using a Nikon camera (DSLR D850) with a macro lens.
Samples were euthanized by a two-step method following the AVMA Guidelines for the Euthanasia of Animals (American Veterinary Medical Association 2020) and fixed in 70% (v/v) ethanol for anatomical examination. Species identification followed original descriptions and comparison with the relevant type specimens. Each species (3-10 specimens) was dissected and examined under an Olympus SZX2-TR30 stereoscopic light microscope and then imaged by Nikon camera. Inner sculpture of genitalia was imaged by a stereo microscope with Cell'D Imaging Software. Shells were imaged by digital camera. Shell whorls were counted and measured using a vernier caliper. Radulae were extracted, soaked in 10%

Abbreviations for morphological terms
In the species descriptions, the term 'proximal' refers to the region closest to the genital opening, whereas 'distal' refers to the region furthest away from the genital opening. The following abbreviations are used in the descriptions of anatomy as described in Pholyotha et al. (2018Pholyotha et al. ( , 2020

Diagnosis
Shell depressed, large (shell width 22.1 mm, shell height 10.5 mm), rather thin, semi-translucent and pale yellowish brown. Shell surface smooth and glossy; more glossy below the periphery; suture impressed; spire slightly elevated. Entire shell consisting of 6½ regularly increasing whorls. Periphery of body whorl rounded. Aperture obliquely oval-lunate shaped; peristome simple. Columellar margin simple and slightly reflected near umbilicus. Umbilicus narrowly opened and deep.

Remarks
Sarika resplendens is a widely distributed species and has been recorded throughout mainland Southeast Asia (Collinge 1903;Fischer 1973;Schileyko 2011;Inkhavilay et al. 2019). This species is found commonly in Thailand (Pholyotha personal observation) and Laos (Inkhavilay et al. 2019). Godwin-Austen (1883: 110, pl. 26, fig. 2) first reported this species from Cambodia without a precise location. The description of this shell morphology agrees well with the typical S. resplendens from Myanmar (see Pholyotha et al. 2020 for comparison), and we provide a brief description herein based on this specimen. Later, Fischer & Dautzenberg (1904: 395) mentioned the specimen identified as S. resplendens from "Kébal-Roméas, Cambodge (Pavie)", without illustration. We have visited this limestone outcrop, Phnom Kbal Romeas, and found one Sarika species that clearly differs from S. resplendens s.s. and is described herein as a new species (for further comparison with this species see under S. lactoconcha Pholyotha & Panha sp. nov.).  (Crosse & Fischer, 1863)

Diagnosis
Shell sub-depressed, medium-sized (shell width 16.0 mm, shell height 9.0 mm), rather thin, semitranslucent and brownish. Shell surface smooth and glossy; more glossy below the periphery; suture impressed; spire slightly elevated; apex rather obtuse. Entire shell consisting of 6 whorls and increasing regularly. Last whorl rounded on the periphery. Aperture obliquely oval-lunate shaped; peristome simple. Umbilicus narrowly opened and deep.

Remarks
Sarika benoiti can be found in Thailand, Laos, Vietnam and Cambodia (Ancey 1898;Fischer & Dautzenberg 1904;Saurin 1953;Fischer 1973;Schileyko 2011;Inkhavilay et al. 2019). In Cambodia, it had been listed among the land snail fauna by Fischer (1891Fischer ( , 1973 and Fischer & Dautzenberg (1904), but with no description or illustration. No examples of this species were found in our survey but, in keeping with earlier records, we provisionally retain this species in the Cambodian land snail fauna. (Morelet, 1875)

Remarks
The distribution of S. bocourti is currently known only from the type locality in Battambang, Cambodia (Fig. 1). In this survey, no living specimens have been collected from the type locality.
Sarika bocourti differs from S. resplendens (specimen NHMUK 1903.7.1.112 from Cambodia) with the last whorl obtusely angulated on the periphery, while the shell in S. resplendens has a rounded periphery. Diagnosis Sarika lactoconcha sp. nov. is characterized by a large, depressed and whitish shell, rounded on the periphery. Animal with dark grey body and five mantle lobes. Genitalia with rather long epiphallic caecum and triangular prism-shaped penial pilasters on inner penial sculpture.

Etymology
The specific epithet 'lactoconcha' is derived from the Latin word 'lactis' meaning 'milk, milky' and the Latin word 'concha' meaning 'snail' or 'shell'. It refers to the milky colour of the shell.

Description
Shell (Fig. 2C-D). Depressed, large (shell width up to 23.7 mm, shell height up to 12.1 mm), rather thin, semitransparent. Shell surface generally smooth, glossy; more glossy below periphery; shell colour monochrome pale milky or whitish colour. 6-6½ whorls, increasing regularly, slightly convex, separated by rather shallow and wide suture. Spire slightly elevated; last whorl broadly rounded. Aperture oval- lunate shaped, open obliquely. Peristome simple, very slightly thickened, not expanded. Parietal callus thin, transparent; columellar margin simple, slightly reflected near umbilicus. Umbilicus narrow, deep. external featureS (Fig. 3A). Living animals have dark grey body; dorsally with darker colour than below, foot sole. Caudal foss present; caudal horn raised, rather large. Mantle and lung scattered with dark pigment or spots or blotches. Mantle edge well-developed, dark grey to paler in colour, with three dorsal lobes, two shell lobes (see Pholyotha et al. 2018: fig. 1). Dorsal lobes large, broad; right dorsal lobe larger than both anterior and posterior left dorsal lobes. Shell lobes large, long; right shell lobe larger, longer than left shell lobe.

Distribution
This new species is currently known from Phnom Chhngok Cave (the type locality), an undisturbed small karst outcrop, which is about 1 km long and surrounded by rice fields. Another locality is Phnom Kbal Romeas, a small limestone outcrop. This outcrop (Fig. 1) is situated about 4 km southwest of the type locality, surrounded by housing areas and an inactive old quarry, and now has become a tourist attraction.

Remarks
Sarika lactoconcha sp. nov. differs from S. benoiti, S. bocourti and S. resplendens with whitish shell, while the three latter species have brownish shells. Moreover, S. lactoconcha sp. nov. has a rounded last whorl, while S. bocourti has an obtusely angulated last whorl. Unfortunately, no genital information of S. resplendens from Cambodia is available for further comparison. However, the genitalia of S. resplendens from Myanmar possess a large penial retractor muscle with about the same diameter as the epiphallic caecum, and short flagellum compared with penis (see Godwin-Austen 1907: 179-181, pl. 111, figs 3, 3a for comparison), while this new species has a small and thin penial retractor muscle and long flagellum.
Compared to species of Sarika-Macrochlamys having a whitish shell, S. lactoconcha sp. nov. has a wider last whorl (loosely coiled), apertural lip simple and genitalia without penial verge. Meanwhile, S. consepta (Benson, 1860) from Myanmar has a narrow last whorl (densely coiled), apertural lip slightly expanded and rather thickened inside, and genitalia with large penial verge (see Pholyotha et al. 2020 for comparison). Another species, Macrochlamys psyche Vermeulen et al., 2019 was recently described from southern Vietnam. This Macrochlamys species has a flattened to slightly concaved spire, whereas S. lactoconcha sp. nov. has an elevated spire. Unfortunately, the genital anatomy of M. psyche is not available for comparison, therefore, its generic placement is still provisional.

Description
Shell (Fig. 4A-B). Depressed, large (shell width up to 24.2 mm, shell height up to 12.3 mm), rather thin, semi-translucent. Shell colour dark brownish on upper surface and at periphery; below periphery surrounding umbilicus pale to very pale brownish. Shell surface smooth, glossy; more glossy below periphery; suture rather shallow with narrow, whitish subsutural band. Spire slightly elevated; whorls 6-6½, increasing regularly; last whorl broadly rounded on periphery. Aperture obliquely crescentshaped; peristome simple. Columellar margin simple, slightly reflected near umbilicus. Umbilicus somewhat narrow and deep. external featureS (Fig. 5A). Living animals have monochrome dark grey body with pale grey foot sole. Caudal foss present; caudal horn elevated and large. Mantle edge well developed with three dorsal lobes and one shell lobe (see Pholyotha et al. 2018: fig. 1). Shape and size of dorsal lobes and right shell lobe (left shell lobe absent) similar to previous species. Genitalia (Fig. 5B-C). Atrium (at) enlarged, very short. Penis (p) cylindrical, with thin penial sheath covering proximal penis. Inner sculpture of penis very finely folded to nearly smooth then gradually transformed to triangular prism (rhombic base and acute angle on top) penial pilasters (pp) near epiphallus. Epiphallus (e) cylindrical, elongate, about two times penis length. Epiphallic caecum (ec) large, similar diameter as penis, straight and located near middle of epiphallus. Penial retractor muscle (prm) thin, attached at tip of epiphallic caecum. Flagellum (fl) slender, somewhat long, about 1.5 times epiphallus length. Vas deferens (vd) a thin tube. Vagina (v) cylindrical, similar length as penis. Dart apparatus (da) cylindrical, rather large, long, attached to atrium at penis and vagina junction. Gametolytic sac (gs) enlarged, bulbous (spermatophore inside); gametolytic duct (gd) long, cylindrical. Free oviduct (fo) cylindrical, longer than vagina, proximal end encircled with thickened tissue. Oviduct large lobules; prostate gland running alongside oviduct. Spermatophore (Fig. 6A-F). Sperm sac (ss) enlarged, elongate-oval. Head filament (hf) enlarged (most was missing) with irregularly serrated longitudinal folds. Tail filament (tf) very long tube, region close to sperm sac bearing two spines. Spine I simple, short; spine II with complicated branching into small, numerous spinules. Spines on tail filament starting just after spine II, with complicated branching into spinules, arranged alternate (Fig. 7D) or opposite (Fig. 7F). radula (Fig. 5D). Teeth arranged in wide-angle U-shape with half row formula: 1-(13-14)-55 teeth. Central tooth symmetrical tricuspid with triangular-shaped mesocone; ectocones very small. Lateral teeth asymmetrical tricuspid; mesocone large, pointed cusp; endocone small, located near the tip; ectocone larger than endocone, pointed cusp, located in middle of tooth. Marginal teeth occurring around tooth numbers 13-14, obliquely bicuspid; endocone elongate, pointed cusp; ectocone small, pointed cusp. Outermost teeth gradually reduced in size as cusps to small teeth.

Distribution
This new species is known from two locations very close to each other, on limestone outcrops. Totong Mountain (type locality) is a small karst with an old quarry, surrounded by housing areas and is adjacent to paddy fields (Fig. 1). The second locality, Prasat Phnom Totong, about 500 m south of the type locality, is a very large and active mining site of a cement factory.

Remarks
Sarika khmeriana sp. nov. is quite similar in terms of shell shape with S. lactoconcha sp. nov., but this species is distinct in possessing dark brown shell on upper surface and pale brownish (to whitish) surrounding umbilicus, and left shell lobe absent (four mantle lobes); whereas S. lactoconcha sp. nov. has a monochrome pale milky shell, and well-developed left shell lobe (five mantle lobes).
This new species differs from S. resplendens in having a thin penial retractor muscle and the entire tail filament of spermatophore has branching spines, whereas the genitalia of S. resplendens (see Godwin-Austen 1907: fig. 3) have a large and thickened penial retractor muscle, and the tail filament of spermatophore is without a branching spine. Compared with other species of Sarika from Cambodia, S. khmeriana sp. nov. is rounded on the periphery while S. bocourti is obtusely angulated on the periphery, and this new species has a larger shell diameter than S. benoiti. Sarika khmeriana sp. nov. also differs from M. despecta (Mabille, 1887) from northern Vietnam in having an elevated spire and narrower umbilical opening. Pholyotha & Panha sp. nov. urn:lsid:zoobank.org:act:48DF9AB1-369C-4930-A006-9E57AE9DBACB Table 1; Figs 4C-D, 6G-J, 7

Sarika nana
Diagnosis Sarika nana sp. nov. can be characterized by medium shell size, globosely depressed, pale yellowishbrown shell, and well-rounded periphery. Animal has dark grey body and five mantle lobes. Genitalia have a rather long epiphallic caecum, short penial caecum, rather large penial verge and oval-shaped penial pilasters. Spermatophore has smooth head filament and tail filament near sperm sac bearing two spines, and terminal one-third of tail filament contains a series of short branching spines.

Etymology
The specific epithet 'nana' is from the Latin word 'nanus' meaning "dwarf" and refers to the small-sized species in this genus.
Paratypes CAMBODIA • 24 alcohol-preserved specimens; same collection data as for holotype; CUMZ 7908 • 2 shells; same collection data as for preceding; NHMUK • 2 shells; same collection data as for preceding; ZRC.
external featureS (Fig. 7A). Living animals having monochrome pale grey body, foot sole. Caudal foss, large caudal horn present. Mantle edge well developed, dark colour, with three dorsal lobes and two shell lobes (see Pholyotha et al. 2018: fig. 1). Dorsal lobes and shell lobes similar to those of S. lactoconcha sp. nov.

Distribution
This new species is known only from the conglomerate mountain Phnom Bayang (type locality; Fig. 1). The habitat at the collection site is an evergreen forest mixed with fruit orchards and with outcroppings of large granite boulders. This location is surrounded by villages and is adjacent to paddy fields.

Remarks
Sarika nana sp. nov., a medium-sized species, can be distinguished from all species of Sarika recorded from mainland Indochina by having a penial verge. Compared to medium-sized species of Macrochlamys, body whorl of S. nana sp. nov. is relatively broader and more well-rounded on the periphery, umbilicus is relatively wider and aperture opening is less convex than M. excepta (Mabille, 1887) (Fig. 4E) and M. zero (Mabille, 1887) (Fig. 4F). The type locality of the new species is about 1000 km from the two species described from Northern Vietnam. The Thai species M. brunnea Möllendorff, 1902 has much narrower umbilical opening than this new species (see Pholyotha et al. 2018: fig. 8a). Unfortunately, the anatomical data of M. brunnea, M. excepta and M. zero is unavailable for further comparison.

Discussion
Cambodian terrestrial gastropods are poorly known with most literature dating from the late 18 th to the early 20 th century. New land snail species, mostly Ariophantidae but excluding Sarika, have recently been published from Vietnam and Cambodia (Vermeulen et al. 2007(Vermeulen et al. , 2019. The three species of Sarika recorded from Cambodia have remained unchanged for more than a century (Crosse & Fischer 1863;Fischer 1891;Fischer & Dautzenberg 1904). The three new species discovered in this study, S. lactoconcha sp. nov., S. khmeriana sp. nov. and S. nana sp. nov. are the first land snails in the genus Sarika to be described from Cambodia in almost 145 years.
Interestingly, all new species had a high degree of endemism and were found in association with karst formations and mountainous areas on the west flank of the Mekong River delta in Cambodia. The vast alluvial plain of the Mekong delta area from Cambodia to Vietnam has a group of several scattered limestone outcrops and hosts an exclusive concentration of endemic taxa including snails (Vermeulen et al. 2019), insects (Bayarsaikhan et al. 2019) and geckos (Nguyen et al. 2018). Indeed, the Mekong delta limestone hills are recognized as possessing habitat island faunas with relatively few species but high rates of endemism. Study of the Cambodian land snail fauna is in its infancy (Vermeulen et al. 2007(Vermeulen et al. , 2019. Land snails of the genus Macrochlamys sensu stricto were not found in Cambodia during our field collections. The distribution ranges and records of the genus in Cambodia are still questionable, in contrast to Thailand and Myanmar, where many species of Macrochlamys were recently reported (Pholyotha et al. 2018(Pholyotha et al. , 2020. Although the reproductive anatomy of M. psyche has not yet been examined, it was recently described from southern Vietnam (Vermeulen et al. 2019). So far, most of the species of Sarika-Macrochlamys in Indochina, especially Cambodia, Laos and Vietnam have only been described based on shell characters, and the investigation of genitalia is still sorely needed. In addition to the need for anatomical descriptions, the systematics of the group of Macrochlamys/ Sarika can only be resolved by a species diverse molecular phylogeny.
collections, the type material database and photographs. Special thanks go to the Inland Fisheries Research and Development Institute (IFReDI) of the Cambodia Fisheries Administration for the preparation of permission documents and data collection in Cambodia. The work was funded by TRF Strategic Basic Research DBG 6080011 (2017-2019), The Thailand Research Fund (TRF-DPG628001), and Center of Excellence on Biodiversity (BDC-PG2-160012). Additionally, this project was supported by a grant from the Human Resource Development in Science Project (Science Achievement Scholarship of Thailand) to AP. We thank Thor-Seng Liew and Fred Naggs for useful comments which improved this paper.