Janbinmorpha sculpticarina ( Martens, 1883 ) Pholyotha & Sutcharit & Panha & Tongkerd, 2024

Pholyotha, Arthit, Sutcharit, Chirasak, Panha, Somsak & Tongkerd, Piyoros, 2024, Reassessment and phylogenetic position of the overlooked limacoid land snail Trochomorpha sculpticarina Martens, 1883 (Eupulmonata, Ariophantidae), with the description of a new genus, Zoosystematics and Evolution 100 (3), pp. 1135-1154 : 1135-1154

Janbinmorpha sculpticarina ( Martens, 1883) comb. nov.

Figs 1 , 2 , 3 , 4 , 5 , 6 A

Trochomorpha sculpticarina Martens, 1883: 136, pl. 25, figs 13–16. Type locality: “ insulam Salanga ” [Phuket Province, Thailand].

Videna sculpticarina – Basch and Solem 1971: 95. Maassen 2001: 116.

Type material examined.

Syntype ZMB / Moll 58132 (1 shell; Fig. 2 A ) ex. Paetel collection from Salanga [Phuket Province, Thailand] . Syntypes ZMB / Moll 34164 (2 shells; Fig. 2 B ) ex. Weber collection from Salanga [Phuket Province, Thailand] .

Other material examined.

Myanmar-Southern. Buddha Cave , Lenya City, Tanintharyi Region, 11 ° 13 ' 46.2 " N, 99 ° 10 ' 34.3 " E: CUMZ 15254 (1 preserved specimen) . Thailand. Salanga [Phuket Province, Thailand]: ZMB / Moll 75765 (1 shell) ex. Webb collection, ZMB / Moll 88249 (1 shell) ex. Kammaun collection, SMF 179828 / 2 (2 shells; Fig. 2 C ), SMF 179829 / 2 (2 shells) ex. Möllendorff collection, NHMUK 1883.3 . 27.4 (1 shell) . Phuket: Bang Pae Waterfall , Thalang District, 8 ° 02 ' 21.9 " N, 98 ° 23 ' 27.8 " E: CUMZ 15077 (4 shells and 4 preserved specimens; Fig. 2 D ), 15161 (3 shells) . Chumphon: Tham Nam Lod Thepnimit Bureau of Monks , Sawi District, 10 ° 22 ' 37.8 " N, 99 ° 00 ' 41.2 " E: CUMZ 15157 (2 shells) . Wat Tham Sanook , Mueang District, 10 ° 28 ' 51.4 " N, 99 ° 04 ' 28.3 " E: CUMZ 15156 (1 shell) . Area in Pak Song , Phato District, 9 ° 46 ' 10.8 " N, 98 ° 40 ' 42.9 " E: CUMZ 15255 (1 preserved specimen) . Ranong: Near Wat Pa Thung Rong , Kapoe District, 9 ° 37 ' 00.2 " N, 98 ° 37 ' 52.3 " E: CUMZ 15256 (2 preserved specimens) . Phang-nga: Wat Khiriwong (Tham Kob), Thap Put District, 8 ° 31 ' 55.9 " N, 98 ° 34 ' 38.4 " E: CUMZ 15163 (1 shell) . Wat Pa Dok Daeng , Takua Pa District, 8 ° 44 ' 28.6 " N, 98 ° 18 ' 24.3 " E: CUMZ 15151 (3 shells and 3 preserved specimens; Fig. 2 F ) . Ton Phrai Waterfall , Thai Mueang District, 8 ° 26 ' 10.4 " N, 98 ° 18 ' 33.3 " E: CUMZ 15150 (1 shell and 2 preserved specimens) . Nature study route 1 in Ko Surin Nuea , Khura Buri District, 9 ° 27 ' 01.1 " N, 97 ° 52 ' 39.1 " E: CUMZ 15164 (1 shell) . Nature study route 4 in Ko Surin Nuea , Khura Buri District, 9 ° 25 ' 46.3 " N, 97 ° 52 ' 14.0 " E: CUMZ 15152 (2 preserved specimens) . Nature study route 3 in Ko Surin Tai , Khura Buri District, 9 ° 23 ' 48.2 " N, 97 ° 52 ' 02.8 " E: CUMZ 15162 (2 shells) . Surat Thani: Nature trail at Ratchaprapha Dam , Ban Ta Khun District, 8 ° 58 ' 19.1 " N, 98 ° 48 ' 16.7 " E: CUMZ 15154 (29 shells) . Area in Khiri Rat Nikhom District , 9 ° 04 ' 13.1 " N, 98 ° 59 ' 45.6 " E: CUMZ 15153 (8 shells; Fig. 2 E ) . Area near Anurak Community Lodge , Klong Sok, Phanom District, 8 ° 53 ' 05.6 " N, 98 ° 41 ' 12.6 " E: CUMZ 15076 (2 preserved specimens) . Nakhon Si Thammarat: Area in Khao Noi , Sichon District, 8 ° 56 ' 17.3 " N, 99 ° 48 ' 54.7 " E: CUMZ 15155 (1 shell) . Krabi: Toh Chong Toh Yuan Shrine , Ao Luek District, 8 ° 22 ' 25.5 " N, 98 ° 44 ' 09.7 " E: CUMZ 15160 (1 shell) . Trang: Khao Ting Cave , Palian District, 7 ° 09 ' 32.3 " N, 99 ° 48 ' 10.3 " E: CUMZ 15158 (1 shell) .

Diagnosis. Shell depressed and lenticular; body whorl keeled on periphery; surface with prominent radial ribs and reticulated microsculptures; whorls 6 and increasing regularly; aperture obliquely crescent-shaped with simple peristome; umbilicus open and funnel shaped. Animal dark gray with pigmentation of yellow to orange dots or patches; one stripe at middle of body running from anterior to posterior; three dorsal lobes present; foot tripartite; caudal foss present; caudal horn very reduced. Genitalia having very short flagellum; two bundles of penial retractor muscle; epiphallic sheath thickened and entirely covering proximal epiphallus; gametolytic duct absent; gametolytic sac having two lobes; dart apparatus present.

Description.

Shell (Figs 2 , 3 A – D ). Shell dextral, depressed, lenticular, medium-sized (shell width up to 19.8 mm, shell height up to 9.3 mm), thickened, rather opaque, yellowish brown to dark brownish. Embryonic shell about 2 ½ whorls, with raised growth lines forming riblet-like textures (Fig. 3 A, B ). Whorls 6, convex, regularly increasing, separated by shallow suture. Later whorls distinct, regular, curved radial ribs, with fine, widely regularly spaced radial ribs, with reticulated microsculptures; and 4–5 distinct spiral threads close to the periphery, positioned above the radial ribs (Fig. 3 C, D ). Last whorl distinctly angular, compressed at periphery, and moderately convex below periphery. Spire rather elevated. Aperture obliquely crescent-shaped; peristome simple; columellar margin simple and slightly reflected near umbilicus. Umbilicus opened, deep, slightly less than one-third the width of the last whorl from the bottom view of the shell.

Genitalia (Fig. 4 ). Atrium (at) enlarged and short. Penis (p) enlarged and short cylindrical. Inner wall sculptured with small, curly and closely packed oblique penial pilasters extending through entire penis chamber; penial verge absent; junction between penis and epiphallus thickened (Fig. 4 B ). Epiphallus (e) long cylindrical tube: proximal epiphallus longer than penis and vagina, and encircled with thickened epiphallic sheath (es); distal epiphallus smaller diameter than proximal part. Epiphallic caecum (ec) large, straight, and located near middle of epiphallus. Penial retractor muscle (prm) rather thickened and divided into two bundles: one bundle attached to tip of epiphallic caecum and another bundle attached to distal end of epiphallic sheath (Fig. 4 A ). Flagellum (f) very short or nearly absent. Vas deferens (vd) small tube continuing from free oviduct to near distal tip of epiphallus.

Vagina (v) long cylindrical tube, about two times penis length. Dart apparatus slender, long and located on mid-vaginal length. Gametolytic organ with undistinguished duct; gametolytic sac (gs) divided into two lobes separated at base: one large and bulbous shape, and another small and long-slender tube (Fig. 4 A, C, D ). Free oviduct (fo) long cylindrical, approximately as long as vagina length. Oviduct enlarged with lobules; prostate gland bound to oviduct.

Radula (Fig. 3 E ). Teeth arranged in a wide-angle U-shape with half-row formula: 1 – (11–15) – 56. Central tooth relatively symmetrical tricuspid; mesocone large and triangular shape with pointed cusp; ectocones very small with dull cusp. Lateral teeth unicuspid or asymmetrical bicuspid with mesocone large with pointed cusp and ectocone nearly wanting with dull cusp. Lateral teeth larger than marginal teeth. Marginal teeth starting at approximately row number 11 to 15 with obliquely elongate unicuspid form; outermost teeth narrower and shorter than inner teeth.

External features (Figs 1 , 5 , 6 A ). Living snails with dark gray body and more or less distinct pale milky or yellow to orange stripe running from head to caudal horn; entire animal with pigmentation of yellow to orange dots or patches. Eye stalks long and pale blackish; lower tentacles shorter and paler in colour. Mantle lobes or mantle extensions well developed, crescent-shaped, yellow to orange, divided into three dorsal lobes, and somewhat thickened near their margins. Right dorsal lobe prominent, broadly crescent-shaped, and larger than both anterior and posterior left dorsal lobes. Anterior left dorsal lobe broadly crescent-shaped; posterior left dorsal lobe relatively long crescent-shaped. Sole evenly tripartite, pedal groove very strong. Foot margin yellow to orange. Caudal foss cup-shaped; caudal horn very reduced, short, not overhung, and yellow to orange.

Distribution.

(Fig. 5 ). This species is apparently restricted to the southern peninsula of Thailand. Major populations of J. sculpticarina comb. nov. occur in the Phuket Range, while a few populations can be found in Nakhon Si Thammarat and the southern part of the Tenasserim ranges. This species was also recorded from the Pulau Aur Island, Malaysia ( Basch and Solem 1971), but this record needs to be confirmed with the newly collected specimens.

Remarks.

According to the limacoid snails with a depressed trochiform shell from Thailand and the Malay Peninsula, Janbinmorpha sculpticarina comb. nov. (Fig. 6 A ) is conchologically similar to some helicarionoidean species, for example Hemiplecta cymatium (Pfeiffer, 1856) (Fig. 6 B ) and Holkeion anceps (Gould, 1843) (Fig. 6 C ), and is also similar to some trochomorphoidean species, such as Siamoconus geotrochoides Pholyotha in Pholyotha et al. 2023 a (Fig. 6 D ), Trochomorpha sp. 2 (Fig. 6 E ), and Pseudoplecta bijuga (Stoliczka, 1873) (Fig. 6 F ). However, J. sculpticarina comb. nov. can be distinguished by its genitalia in having two lobes of the gametolytic sac, no gametolytic duct, and a penial retractor muscle attached to the epiphallic caecum and epiphallic sheath. In comparison, Hemiplecta cymatium possesses a bulbous gametolytic sac, no gametolytic duct, and a penial retractor muscle attached to epiphallic caecum only (Sutcharit and Panha, unpublished data), while Holkeion anceps has an elongate gametolytic duct and a penial retractor muscle attached to the epiphallic caecum ( Pholyotha et al. 2023 b). The trochomorphoideans, S. geotrochoides and Trochomorpha sp. 2 differ by having a long gametolytic duct and a penial retractor muscle attached to the epiphallus ( Pholyotha et al. 2023 a; Pholyotha and Panha, unpublished data). In addition, P. bijuga possesses a gametolytic organ located on the amatorial organ and a penial retractor muscle attached to the epiphallus ( Jirapatrasilp et al. 2021).

Compared with other taxa having a depressed trochiform shell, and regardless of genitalia data, J. sculpticarina comb. nov. differs from Trochomorpha species and Videna species recorded from mainland Southeast Asia by a combination of no spiral band, larger shell size, relatively narrower umbilicus, and strong radial striations with reticulated microsculptures ( Möllendorff 1902; Preece et al. 2022; Inkhavilay et al. 2023).

Trochomorpha benigna (Pfeiffer, 1863) , T. vinhensis Thach, 2018 and T. buotia Inkhavilay et al., 2023 are very similar to J. sculpticarina comb. nov. in terms of shell shape and size. For comparison, J. sculpticarina comb. nov. has a narrower funnel-shaped umbilicus, while T. benigna and T. vinhensis have a wider funnel-shaped umbilicus and showing all preceding whorls ( Inkhavilay et al. 2023). Compared with T. buotia , J. sculpticarina comb. nov. has radial striations and reticulated microsculptures on shell surface, depressed shell, a strong peripheral keel, and last whorl convex below periphery, while T. buotia has radial and spiral striations on the shell surface, a dome-shaped shell, distinctly sharpened peripheral keel, and last whorl flattened below periphery ( Inkhavilay et al. 2023).

Figures

Figure 1. Maximum likelihood phylogram based on analyses of concatenated COI, 16 S, and 28 S sequences. Numbers on branches indicate nodal support by ML bootstrap (BS) and Bayesian posterior probabilities (PP) analyses. Asterisk indicates the type species of its corresponding genus. The sample code in front of species name indicates voucher samples as shown in Table 1. Living specimen of Janbinmorpha sculpticarina (Martens, 1883), comb. nov. from Phang-nga Province, not to scale.

Figure 2. Shell of Janbinmorpha sculpticarina (Martens, 1883), comb. nov. A. Syntype from Salanga [Phuket Province]: ZMB / Moll 58132; B. Syntypes from Salanga [Phuket Province]: ZMB / Moll 34164; C. Specimen from Salanga I., Malaysia [Phuket Island, Phuket Province, Thailand]: NHMUK 1888.3. 27.4; D. Specimen from Phuket Province: CUMZ 15077; E. Specimen from Surat Thani Province: CUMZ 15153; F. Specimen from Phang-nga Province: CUMZ 15151 using for SEM imaging.

Figure 3. Scanning electron microscope (SEM) images of shell surface and radula of Janbinmorpha sculpticarina (Martens, 1883), comb. nov. A – D. Specimen CUMZ 15151, showing shell surface; A. Protoconch viewed from above; B. Zoomed-in view of protoconch; C. Body whorl viewed from above; D. Zoomed-in view of body whorl; E. Specimen CUMZ 15077, showing radula; central tooth indicated by ‘ C’.

Figure 4. Genitalia of Janbinmorpha sculpticarina (Martens, 1883), comb. nov. A. Specimen from Surat Thani Province: CUMZ 15076, showing general view of genital system; B. Specimen from Phang-nga Province: CUMZ 15150, showing internal structure of penis and epiphallus; C. Specimen from Phuket Province: CUMZ 15077, showing gametolytic organ; D. Specimen from Phang-nga Province: CUMZ 15150, showing gametolytic organ. White arrowhead indicates the end of the penis.

Figure 5. Map of the Malay Peninsula in southern Thailand and the southernmost tip of Myanmar showing the sampling sites. Localities where the living specimens were collected are indicated by numbers on map, not to scale.

Figure 6. Representative living limacoid snails with a depressed trochiform shell from Thailand and the Malay Peninsula. A. Janbinmorpha sculpticarina (Martens, 1883), comb. nov. in the Ariophantidae; B. Hemiplecta cymatium (Pfeiffer, 1856) in the Ariophantidae; C. Holkeion anceps (Gould, 1843) in the Ariophantidae; D. Siamoconus geotrochoides Pholyotha, 2023 in the Euconulidae; E. Trochomorpha sp. 2 in the Trochomorphidae; F. Pseudoplecta bijuga (Stoliczka, 1873) in the Dyakiidae.