Amphidromus (Syndromus) areolatus (Pfeiffer, 1861)

Inkhavilay, Khamla, Sutcharit, Chirasak & Panha, Somsak, 2017, Taxonomic review of the tree snail genus Amphidromus Albers, 1850 (Pulmonata: Camaenidae) in Laos, with the description of two new species, European Journal of Taxonomy 330, pp. 1-40 : 20-24

Amphidromus (Syndromus) areolatus (Pfeiffer, 1861)

Figs 1 , 7 G−I, 9A, 10A−C, 11A–B; Table 1

Bulimus areolatus Pfeiffer, 1861a: 194 . Type locality: Siam [ Thailand]. Pfeiffer 1861b: 172, pl. 46, figs 11–12.

Amphidromus areolatus – Fulton 1896: 81. — Pilsbry 1900: 198–199, pl. 63, figs 85–86. — Laidlaw & Solem 1961: 564. — Solem 1965: 624–625, pl. 1, figs 4–7. — Sutcharit et al. 2015: 58 , fig. 3j–k.

Material examined

Type material

THAILAND: Lectotype NHMUK 19601430 ( Sutcharit et al. 2015: fig. 3j); paralectotype NHMUK 19601431 (1 shell).

Other material

LAOS: 20 shells ( Fig. 10 A−C, CUMZ 7022), 17 specimens in freezer ( Figs 7 G−I, 9 A, 11A–B, CUMZ 7023), Thad Fek, Sammakeexay District, Attapeu; 8 shells, Thad Phasoam, Paksong District, Champasak ( CUMZ 7024).

Description

Shell sinistral, elongate conical, rather small, thin and glossy. Spire conical; apex acute, with black spot on tip. Whorls 5 to 6 slightly convex; suture depressed; last whorl rounded. Periostracum transparent to thin corneous. Last whorl process, with yellow to absent Band 1; Bands 2 to 4 (sometimes Bands 2 to 5) usually merge and become brownish slanted blotches with flame shape; Band 6 yellowish or roseate. Parietal callus thin and transparent. Aperture auriform; peristome expanded to weakly expanded; lip white to transparent. Columella straight and white. Umbilicus narrowly opened.

Radula

Teeth arranged in V-shaped rows, each row contains about 126 (62-(13-9)-1-(9-13)-63) teeth. Central tooth tricuspid, with triangular shaped mesocone, ectocones very small, with pointed cusp. Lateral teeth bicuspid, endocone small, with curved cusp; ectocone large, with truncate or curved cusps, gradually transformed to tricuspid marginal teeth. Tricuspid marginal teeth start around tooth number 9 to 13 outwards; endocone curve shaped; mesocone of largest size, with long and obtuse cusp; ectocone smallest, with pointed cusp. Outermost teeth with small serrated endocone and extocone; mesocone large, with curved cusps ( Fig. 7 G–I).

Genital organs

Atrium (at) rather long (n = 10). Penis (p) long, cylindrical and enlarged. Epiphallus (e) short, of about same length as penis; flagellum (fl) short and terminated in pointed tip. Appendix absent. Penial retractor muscle (pr) thin and relatively long. Vas deferens (vd) narrow tube connecting epiphallus and free oviduct ( Fig. 11A ).

Internal penial wall nearly smooth and corrugated into thin penial pilasters, which form fringe around penial verge. Penial verge rather small, conical, with smooth surface ( Fig. 11B ).

Vagina cylindrical, of about same length as penis. Gametolytic duct long, proximal to genital orifice, of larger diameter than vagina and coiled; distal to genital orifice tapering to small tube of about same length as proximal part and connected to gametolytic sac. Oviduct and albumin gland very small ( Fig. 11A ).

Internal wall of vagina shows longitudinal vaginal pilasters (vp); proximal to genital orifice with nearly smooth surface for about half of its length, distally pilasters become corrugated ridges ( Fig. 11B ).

Distribution

The species is known from southern Laos, where the specimens were collected at Thad Fek, Sammakeexay District, Attapue and Thad Phasoam, Paksong District, Champasak in a dry dipterocarp forest.

Remarks

This species can be distinguished from A. zebrinus (Pfeiffer, 1861) and A. begini (Morlet, 1886) by its having a smooth shell surface and brownish spiral Bands 4 and 5 present, with white lip. In contrast, A. zebrinus (see Sutcharit et al. 2015: fig. 15k) has an elongate conical shell shape, Band 1 absent, Bands 2 to 5 merged and developing slanted radial streaks, as well as a reddish band between Bands 5 and 6. Amphidromus begini exhibits strong radial ridges, Bands 2 to 6 merged and developing slanted brownish radial streaks, and brownish ribs ( Fig. 10D , syntype MNHN-IM-2000-1832).

Figures

Fig. 1. Distribution map of Amphidromus spp. in Laos recognized in this study.

Fig. 7. SEM images of the radula. A–C. Amphidromus roseolabiatus Fulton, 1896 from Ban Phavong, Khammouan, Laos (CUMZ 7012). D–F. Amphidromus syndromoideus sp. nov., holotype (CUMZ 7019). G–I. Amphidromus areolatus (Pfeiffer, 1861) from Thad Fek, Attapue, Laos (CUMZ 7023). A, D, G = central tooth with the first to fifth to eighth lateral teeth; B, E, H = lateral teeth with the tricuspid marginal teeth transition; C, F, I = outermost marginal teeth. Numbers indicate the order of the lateral and marginal teeth. Central tooth indicated by ‘C’.

Fig. 10. Shells of Amphidromus (Syndromus) spp. A−C. Amphidromus areolatus (Pfeiffer, 1861) from Thad Fek, Attapeu, Laos (CUMZ 7022). D. Amphidromus begini (Morlet, 1886), syntype from Strung- Trang, Cambodia (MNHN-IM-2000-1832). E-G. Amphidromus flavus (Pfeiffer, 1861) from Tam Pou Kham, Vientiane, Laos (CUMZ 7029). H. Amphidromus flavus var. “indistinctus” Pilsbry, 1900, holotype (ANSP 31486). I–K. Amphidromus flavus var. “tryoni” Pilsbry, 1900. I. Lectotype (ANSP 31488). J. Paralectotype (ANSP 252745). K. Specimen from Ban Na Deauy, Luang Phrabang, Laos (CUMZ 7026). L–M. Amphidromus semitessellatus (Morlet, 1884). L. Lectotype (MNHN-IM-2000-1985). M. Specimen from Cambodia (NHMUK).

Fig. 11. Genitalia of Amphidromus (Syndromus) spp. A–B. Amphidromus areolatus (Pfeiffer, 1861) from Thad Fek, Attapeu, Laos showing the reproductive system and interior structures of the penis and vaginal chamber (CUMZ 7023). C–D. Amphidromus flavus (Pfeiffer, 1861) from Ban Na Deauy, Luang Phrabang, Laos showing the general characteristics of the genital system and the interior structures of the penis, atrium and vagina chamber (CUMZ 7027).