Amphidromus (Amphidromus) cambojiensis ( Reeve, 1860 )

Sutcharit, Chirasak, Naggs, Fred, Ablett, Jonathan D., Sang, Pham Van, Van Hao, Luong & Panha, Somsak, 2021, Anatomical note on a tree snail Amphidromus (Amphidromus) cambojiensis (Reeve, 1860) from Vietnam (Eupulmonata: Camaenidae), Journal of Natural History 55 (17 - 18), pp. 1059-1069 : 1060-1065

Amphidromus (Amphidromus) cambojiensis ( Reeve, 1860) Figures 1–3

Bulimus cambojiensis Reeve, 1860 : Type locality: Cambodia. Pfeiffer 1862: 11, 12. Pfeiffer 1868: 16. Bulimus cambogiensis [sic!] – Pfeiffer 1877: 23. Amphidromus cambojiensis – Fischer 1891: 114. Fulton 1896: 91, pl. 7, fig. 7. Pilsbry 1900: 177, 178, pl. 59, fig. 32. Laidlaw and Solem 1961: 529, 607. Richardson 1985: 10. Abbott 1989: 160, text figure. Sutcharit et al. 2015: 62, fig. 4f, g. Thach 2017: figs 459, 462. Thach 2018: figs 607, 608. Páll-Gergely et al. 2020: 51. Bulimus perversus var. cambodjiensis [sic!] – Morelet 1875: 260, 261. Amphidromus lamdongensis Thach & Huber in Thach 2016: 67, figs 32, 339–342. Type locality: Dambri area of Lam Dong Province (Central Vietnam) . Amphidromus schileykoi Thach, 2016: 68 , figs 39, 381–383. Type locality: Ha Tien , Kien Giang Province (Southwest Vietnam) . Amphidropmus montesdeocai Thach & Huber in Thach 2017: 43, figs 454–458 . Type locality: Dinh Quan District along National road no . 20, Dong Nai Province, South Vietnam .

Material examined. Lectotype of Bulimus cambojiensis NHMUK 19601468/1 (1S; Figure 1 (a)), paralectotypes NHMUK 19601468 /2–3 (1S+1D) . Holotype of A. schileykoi, NHMUK 20160297 (1S; Figure 1 (e)). CAMBODIA: NHMUK 19601467 (1D juvenile shell), NHMW Rusnov ex Rolle coll. (1S shell). VIETNAM: Cochin China: ZMA. MOLL.395799, leg. Wright (1D shell). Lodge gardens, Cat Tien National Park, Vietnam (11°25ʹ24”N, 107°25ʹ43” E): NHMUK 20130819 (2S+1D in ethanol; Figure 1 (b,c), 2). Thac Dambri Waterfall, Dambri, Bao Loc, Lam Dong, Vietnam (11°38ʹ26.7”N, 107°44ʹ33.6”E): NHMUK 20210004 (1S in ethanol; Figures 1 (d), 3). Forest trail, Nam Cat Tien National Park , Dong Nai, Vietnam : ZRC.MOL.03 (1D in ethanol; Figure 3 ) .

Shell. Shell large (height up to 75 mm), dextral or sinistral, solid, and ovate conic. Apex acute with white or dark colour; spire long, conical with white or pale rose-pink colour. Shell surface generally smooth; 6 to 7 convex whorls; suture wide and depressed. Last whorl ovate; one or two dark varices generally present on penultimate or last whorl. Periostracum thin, corneous or with oblique brownish radial streaks; shell with irregular brown to dark-brown radial streaks. Aperture broadly ovate; inner surface of outer wall with bright purplish-pink or violet colour. Peristome whitish; lip thickened, expanded, and reflexed, but not attached to last whorl. Parietal callus thickened and white. Columella white, straight, or little twisted; umbilicus imperforate.

Living specimen. Animals with pale brown body covered with reticulated skin. Foot broad and long with uniform pale brownish colour to posterior tail. Head with bright orange patch covering tentacles and mouthparts. Upper tentacles drumstick shaped, orange-brown to dark, with dark eyespots on tentacular tips; lower tentacles short and orange in colour ( Figure 3 ).

Genital system. Atrium relatively long. Penis slender, conical, and short (about half of vagina length). Penial retractor muscle thickened and inserted on epiphallus near penis. Epiphallus long, slender tube, coiled and twisted upon itself. Flagellum long, extending from epiphallus and terminating in slightly enlarged folded coil. Appendix small, longer than flagellum and about same length as epiphallus. Vas deferens small tube passing from free oviduct and terminating at epiphallus-flagellum junction ( Figure 2 (a)). Internal wall of penis corrugated, exhibiting series of thickened and swollen longitudinal penial pilasters (pp) forming fringe around penial wall, and with nearly smooth to weak folds around base of penial verge. Penial verge (pv) short conic with nearly smooth surface ( Figure 2 (b)).

Vagina (v) slender, long, cylindrical, and about two times longer than penis length. Gametolytic duct (gd) enlarged cylindrical tube abruptly tapering to a small tube terminally and connected to elongate gametolytic sac (gs). Free oviduct (fo) short; oviduct enlarged to form lobule alveoli. Albumen gland (ag) slightly small and lingulate. Hermaphroditic gland (hg) composed of numerous small lobules; narrow and convoluted hermaphroditic duct (hd) connects gland and middle of talon ( Figure 2 (a)). Internal wall of vagina possesses corrugated ridges near genital orifice, ridges become thinner and smooth longitudinal vaginal pilasters (vp), and swollen with irregularly shaped and deep crenellations near free oviduct opening ( Figure 2 (b)).

Distribution. The published records and museum specimens of A. (A.) cambojiensis are quite vague and only ‘Cambodia’ is given as the collection locality. Originally, it was published together with the now endangered species, Bertia cambojiensis ( Reeve, 1860) , which has the same type locality. The type specimens were received from the famous French naturalist Henri Mouhot ( Reeve 1860). For over 160 years after Reeve’s description of ‘ Bulimus cambojiensis ’, there were no specific distribution records, and it was thought to be a ‘lost species’ ( Abbott 1989). Fortunately, the re-description works on Bertia cambojiensis clarified its type locality, which was probably in the vicinity of ‘Brelum’, Vietnam, and neighbouring areas in Cambodia (see Sutcharit et al. (2019) for more detail).

This recent collection has revealed that the range of this species includes the south of Vietnam, and it probably also occurs in Cambodia ( Figure 3 ). However, more precise locality records of this species in Cambodia will require intensive surveys.

Remarks. Based solely on shell morphology, A. (A.) cambojiensis is superficially like A. (A.) schomburgki ( Pfeiffer, 1860) and A. laosianus Bavay, 1898 . However, the relatively large shell size (height> 60 mm), white apertural lip, and purplish-pink colour on the inside of the aperture are clear differences from these two other species. In contrast, A. (A.) schomburgki has a greenish periostracum, white or purplish ground shell, and dark purple apertural lip and callus; A. laosianus possesses an elongate shell with brown radial streaks, and rose-pink lip, callus and inside aperture ( Pfeiffer 1860; Bavay 1898; Sutcharit and Panha 2006b; Sutcharit et al. 2015; Inkhavilay et al. 2019). The genitalia of A. (A.) schomburgki have a series of protuberances arranged on penial pilasters, and smooth vaginal pilasters located near the genital orifice covering about half of the chamber, while A. (A). cambojiensis has smooth penial pilasters, and vaginal pilasters with deep crenellations near the genital orifice and near the free oviduct, but smooth in middle ( Sutcharit and Panha 2006b).

Laidlaw and Solem (1961) noted that A. (A.) cambojiensis was probably closely related to A. placostylus M ӧllendorff, 1900a and A. ingens M ӧllendorff, 1900b from Vietnam. They were placed together into an intermediate species-group that could not be appropriately assigned to any subgenera ( Laidlaw and Solem 1961). From this study, the genitalia characteristics of a long epiphallus, flagellum, and appendix suggest it is a member of the nominotypical subgenus ( Schileyko 2003; Sutcharit and Panha 2006b). The shell characters distinguishing A. (A.) cambojiensis from A. placostylus and A. ingens are the white apertural lip and callus, and purplish-pink colour inside the aperture ( Pilsbry 1900; Möllendorff 1900a, 1900b; Zilch 1953). In contrast, A. ingens ( Figure 1 (g)) has a monochrome whitish shell, last whorl large ovate, with two spiral indentations (one below suture and one on periphery) and flattened whorls; A. placostylus ( Figure 1 (f)) has a slightly larger shell (height 75 mm), ovate last whorl, brownish-streaked shell, and dark brown colour on the lower half of the last whorl. Unfortunately, these two species are known only from dry shells and A. placostylus is known only from the holotype. Hence, the current relationship and subgeneric assignment of the two species needs further revision, and future attempts should consider including more information on reproductive anatomy and distribution ranges to improve the taxonomy of Amphidromus in general.

Figures

Figure 1. (a-e). Shell of A. (A.) cambojiensis. (a) Lectotype NHMUK 19601468/1, (b,c) Specimen NHMUK 20130819 from Cat Tien National Park, (d) specimen NHMUK 20210004 from Thac Dambri Waterfall, and (e) holotype of A. schileykoi, NHMUK 20160297. (f). Holotype of Amphidromus placostylus, SMF 7593 from Phuc-Son, Annam. (g) Lectotype of Amphidromus ingens, SMF 7565 from Berg ‘Mutter und Kind’, Annam.

Figure 2. (a,b) Genitalia of A. (A.) cambojiensis, specimen NHMUK-20130819 from Cat Tien National Park. (a) Overview of the genital system and (b) interior structures of the penis and vaginal chambers.

Figure 3. Distribution of A. (A.) cambojiensis in southern Vietnam. 1. Thac Dambri Waterfall, Lam Dong Province (approximate type locality of ‘A. lamdongensis’) with living specimen NHMUK 20210004 (shell height about 65 mm, photo by H Taylor (NHM)). 2. Cat Tien National Park, Dong Nai Province, and specimen from ZRC.MOL.03 (shell height about 65 mm). 3. Dinh Quan, Dong Nai Province (approximate type locality of ‘A. montesdeocai’). 4. Ha Tien, Kien Giang Province (approximate type locality of ‘A. schileykoi’).