Opisthoporus lubricus Dautzenberg & Fischer, 1908

Sang, Do Duc, Chinh, Bui Thi & Nhuong, Do Van, 2020, The land snail genus Opisthoporus Benson in L. Pfeiffer, 1851 (Gastropoda: Caenogastropoda: Cyclophoridae) from Vietnam, with description of a new species, Raffles Bulletin of Zoology 68, pp. 103-111 : 105-107

Opisthoporus lubricus Dautzenberg & Fischer, 1908

( Figs. 1 , 2 E–G, 3B, E, H; Table 1, 2)

Opisthoporus lubricus Dautzenberg & Fischer, 1908: 201 , pl. 7 figs. 5–8 (type locality: Quang-Huyen, Vietnam).

Cyclotus (Opisthoporus) lubricus – Kobelt, 1913: 836, pl. 124 figs. 5–8.

Material examined. 5 shells ( ZMHU), 2 figured shells (figs. 2E, 3B, E, H), Vietnam, Lang Son Province, Trang Dinh District, Tri Phuong Commune, Bo Village , Limestone karst forest, 429 m a.s.l., 22°19′28″N, 106°29′15″E, coll. D.S. Do, 10 July 2018 ; 4 shells ( ZMHU), Vietnam, Lang Son Province, Trang Dinh District, Chi Minh Commune, Lung Phay Village , Limestone karst forest, 482 m a.s.l., 22°20′09″N, 106°27′02″E, coll. D.S. Do, 10 July 2018 ; 27 shells ( ZMHU), Vietnam, Lang Son Province, Bac Son District, Nga Hai Village, Limestone mountain with depleted primary forest, 397 m a.s.l., 21°47′41″N, 106°09′13″E, coll. D.S. Do, 9 July 2018 ; 6 shells ( ZMHU), Vietnam, Lang Son Province, Huu Lung District, Quyet Thang Commune, Bong Village , Limestone karst forest, 627 m a.s.l., 21°38′40″N, 106°14′06″E, coll. C.N. Duong, 20 December 2018 ; 5 shells ( ZMHU), Vietnam, Thai Nguyen Province, Vo Nhai District, Than Sa-Phuong Hoang Nature Reserve, Densely vegetated limestone hill, 260 m a.s.l., 21°50′51″N, 105°53′19″E, coll. D.S. Do & T.B. Nguyen, 14 May 2017 .

Diagnosis. Shell yellow to yellowish brown with a short and stout breathing tube directed toward aperture.

Distribution. Opisthoporus lubricus is known from its type locality in northeastern Vietnam (Cao Bang, Lang Son and Thai Nguyen Provinces) ( Dautzenberg & Fischer, 1908; this study).

Remarks. Opisthoporus lubricus has a thick shell, with thin corneous periostracum. The shell colour is usually rather uniform yellow to yellowish brown, with a darker brown spiral band below the periphery. This species differs mainly from Opisthoporus beddomei by its larger shell with darker colouration, somewhat higher spire, slightly different aperture morphology, and breathing tube structure (see also Remarks for that species).

Figures

Fig. 1. Approximate localities of Opisthoporus spp. in Vietnam. (1): Opisthoporus beddomei; (2): Opisthoporus lubricus; (3): Opisthoporus thuathienhuensis, new species. The numbered locality names are detailed in Table 1.

Fig. 2. Shell (apertural view, dorsal view, ventral view, and side view) and operculum (outer surface, inner surface, and side view) of Opisthoporus spp. in Vietnam. A–D, Opisthoporus beddomei Dautzenberg & Fischer, 1908; A, B, ZMHU/5; C, from Dautzenberg & Fischer, 1908; D, from Kobelt, 1913. E–G, Opisthoporus lubricus Dautzenberg & Fischer, 1908; E, ZMHU/4; F, from Kobelt, 1913; G, from Dautzenberg & Fischer, 1908. H–K, Opisthoporus thuathienhuensis, new species; H, I, holotype VNMN_IZ 000.000.176; J, K, paratypes ZRC.MOL. 15631. Photographs by D.S. Do and T.S. Nguyen.