Amphidromus ingens Moellendorff , 1900

Jirapatrasilp, Parin, Huang, Chih-Wei, Sutcharit, Chirasak & Lee, Chi-Tse, 2024, The arboreal snail genus Amphidromus Albers, 1850 (Eupulmonata, Camaenidae) of Southeast Asia: 1. Molecular systematics of some Vietnamese species and related species from Cambodia, Indonesia, and Laos, ZooKeys 1196, pp. 15-78 : 15

publication ID	https://dx.doi.org/10.3897/zookeys.1196.112146
publication LSID	lsid:zoobank.org:pub:7954DFBF-803A-48F5-B791-42DD09FE5D01
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scientific name	Amphidromus ingens Moellendorff , 1900
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Treatment

Amphidromus ingens Moellendorff, 1900 View in CoL

Figs 3 View Figure 3 , 4A View Figure 4 , 5A-C View Figure 5 , 6A-C View Figure 6 , 7 View Figure 7

Amphidromus ingens Möllendorff, 1900b: 23-24. Type locality: Berg "Mutter und Kind", Annam [Vietnam]. Pilsbry 1900: 175-176. Fischer and Dautzenberg 1904: 406. Laidlaw and Solem 1961: 529, 629. Richardson 1985: 21. Thach 2005: 235, pl. 73, fig. 22. Schileyko 2011: 50. Sutcharit et al. 2021: fig. 1g.

Amphidromus Amphidromus (Amphidromus) ingens . Zilch 1953: 135, pl. 23, fig. 25.

Amphidromus naggsi Thach & Huber, 2014: 35-37, figs 1-13, 15. Type locality: Don Duong district, Lam Dong Province, South Vietnam. Páll-Gergely et al. 2020: 53. Thach et al. 2020: 185, 187, pl. 1, fig. 6a. Thach 2020a: 70, fig. 881 left. Thach 2021: 70. syn. nov.

Material examined.

Vietnam: Dextral , lectotype of " Amphidromus ingens ", SMF 7565/1 (Fig. 3A View Figure 3 ); 2D + 2S, paralectotypes of " Amphidromus ingens ", SMF 7566/4 (Fig. 3B View Figure 3 ). Vietnam: Dextral, holotype of " Amphidromus naggsi ", RMNH.5003908 (Fig. 3C View Figure 3 ) .

Other material examined.

Vietnam: 4D + 1S specimens, M’drak District, Dak Lak Province, NMNS-8764-082- NMNS-8764-086 (Fig. 3D, E View Figure 3 ); 1D specimen, Ea M’doal ward, M’drak District, Dak Lak Province, NMNS-8764-087 (Fig. 3F View Figure 3 ); 4D + 1S specimens, Krong A ward, M’drak District, Dak Lak Province, NMNS-8764-088- NMNS-8764-092 (Fig. 3G View Figure 3 ); 7D + 5S specimens, Ea Sup District , Dak Lak Province, NMNS-8764-093- NMNS-8764-104 (Fig. 3H, I View Figure 3 ) .

Diagnosis.

Shell large conical and chirally dimorphic (sinistral and dextral coiling). Shell surface with coarse growth lines; last whorl with subsutural depression area and more or less prominent keel on periphery. Genitalia with appendix.

Differential diagnosis.

Amphidromus ingens is unique among all reported Vietnamese species ( Schileyko 2011) in having a last whorl with subsutural depression area and more or less prominent keel on periphery. Amphidromus bozhii is similar in most of the shell form and sculpture, but the shell sculpture of A. bozhii has a very weak spiral depression area and sometimes with or without keel, and the shell colour is generally rose-pink to dark colour, with last whorl stained with dark brown colour below periphery and ~ 1/2 of upper periphery. On the other hand, A. ingens has a monochrome (whitish, yellowish, tinted pink) shell, often stained with dark brown to blackish below periphery. Amphidromus ingens is also recognised by a distinct clade in the molecular phylogeny (Fig. 2 View Figure 2 ), with the closest p -distance to A. ingensoides sp. nov. in COI (10.2%) and A. bozhii in 16S (2.76%) (Table 2 View Table 2 ).

Description.

Shell large (height 62.3-74.6 mm, width 38.5-42.5 mm), chirally dimorphic, solid, and ovate conical shape. Spire long conical to elongate conical, apex acute without black spot on tip. Whorls 5-7 convex; suture wide and depressed; last whorl rounded to slightly angulated. Periostracum brownish to thin corneous; varix usually absent. Shell surface generally with irregular and coarse growth lines; below sutural with broad subsutural depression area, and with blunt or low to prominent keel on periphery. Shell colour highly variable: monochrome (whitish, yellowish, tinted pink) to stained with dark brown to blackish below periphery. Parietal callus thickened and white, dilated at umbilical area. Aperture broadly ovate; inner side of outer wall with white, yellow or dark brown to blackish colour. Peristome thickened, expanded, and reflexed but not attached to last whorl; lip whitish. Columella white, straight, or little twisted. Umbilicus imperforate.

Radula. Teeth arranged in anteriorly pointed V-shaped rows. Central tooth monocuspid and spatulate with truncated cusp. Lateral teeth bicuspid; endocone small, slightly curved, with wide notch and dull cusp; ectocone large with truncated to slightly curved cusp. Lateral teeth gradually transformed to asymmetric tricuspid marginal teeth (Fig. 4A View Figure 4 ).

Genital organs. Atrium relatively short. Penis slender, conical, and short ~ 1/3 of vaginal length. Penial retractor muscle thickened and inserting on epiphallus close to penis. Epiphallus long, slender tube, slightly narrower than penis. Flagellum short ~ 1/2 of epiphallus and terminating in slightly enlarged folded coil. Appendix short, slender tube, approximately as long as epiphallus, and ~ 2 × longer than flagellum. Vas deferens slender tube passing from free oviduct and terminating at epiphallus-flagellum junction (Fig. 5A View Figure 5 ). Internal wall of penis corrugated, exhibiting series of thickened and swollen longitudinal penial pilasters forming fringe around penial wall, and with nearly smooth to weak folds around base of penial verge. Penial verge short conical with nearly smooth surface, and with opening on the tip (Fig. 5B View Figure 5 ).

Vagina slender, long cylindrical, and ~ 3 × longer than penis. Gametolytic duct enlarged cylindrical tube then abruptly tapering to slender tube terminally and connected to gametolytic sac (missing during dissecting). Free oviduct short; oviduct compact and enlarged to form lobule alveoli (Fig. 5A View Figure 5 ). Internal wall of vagina possessing corrugated ridges near genital orifice; ridges becoming thinner and smooth surfaced longitudinal vaginal pilasters, swollen with irregularly shaped and deep crenelations close to free oviduct opening. Spermatophore (in part) dark brown stuck inside gametolytic duct (Fig. 5C View Figure 5 ).

Living specimens generally with pale brown to yellowish body covered with reticulated skin. Foot broad and long with uniform pale brownish to yellowish colour to posterior tail. Dorsal side of anterior body usually with stripe of darkly reticulated skin; head area at base and just behind upper tentacle with orange patch. Upper tentacles drumstick shaped, orange to paler and with dark eyespots on tentacular tips; lower tentacles short and pale orange in colour (Fig. 6A-C View Figure 6 ).

Haplotype network.

There was a total of 12 COI haplotypes (Fig. 7A View Figure 7 ) and nine 16S haplotypes (Fig. 7B View Figure 7 ) of A. ingens in this study, and the highest numbers of mutational steps in the COI and 16S minimum spanning networks are 13 and three, respectively.

Distribution.

The distribution range of the species covers Dak Lak and Lam Dong provinces, Vietnam.

Remarks.

Thach and Huber (2014) introduced A. naggsi , which is described to differ from A. ingens in its wrinkled outer surface, the presence of 2-3 broad spiral channels on the body whorl, the more prominent sculpture on the penultimate whorl, and a more elongate aperture. However, upon examining the type specimens of both A. ingens and A. naggsi , these diagnostic characters were also present in the lectotype and paralectotypes of A. ingens , and the holotype of A. naggsi agrees well with all the type specimens of A. ingens in terms of shell shape, shell surface sculpture, peristome, and apertural shape. Thus, A. naggsi is regarded herein as a junior subjective synonym of A. ingens .

The shell colour generally varies from whitish (typical) to yellowish to rose-pink colour (Fig. 3 View Figure 3 ). In our examined specimens, many are stained with dark brown colour below periphery and some are stained nearly entirely on the last and penultimate whorl. The shell sculpture generally has two depression areas, one upper periphery and one below suture, and the conspicuous keel to weak keel is generally present on periphery.