Coleglabra sentaniensis ( Benthem Jutting, 1963 )

Ponder, Winston F., Fukuda, Hiroshi & Hallan, Anders, 2014, A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea), Zootaxa 3872 (2), pp. 101-153 : 147

Coleglabra sentaniensis ( Benthem Jutting, 1963)

Figure 28

Clenchiella sentaniensis Benthem Jutting, 1963: 438 , fig. 5a, b.

Types and type locality. Holotype, NE shore of Lake Sentani, near ‘Meerzicht’ [a restaurant on the lake shore], 0–1m deep amongst water plants and tree roots. 16 Oct. 1954. Coll. L. D. Brongersma (ZMA 1206).

Distribution. Known only from the type locality, near Jayapura, NE Irian Jaya. It is a freshwater lake 73 m above sea level, containing at least three endemic species of freshwater fishes ( Polhemus et al. 2004).

Material examined. Holotype.

Shell. Minute (2.0 mm in maximum diameter; Table 3), spire slightly raised ( Fig. 28 G–I). Protoconch of about 1.4 whorls, surface details not known, although apparently smooth under light microscope; terminated by indistinct thin varix. Teleoconch of about 1.7 convex whorls, sculptured with few (4–5) distinct, weak spiral lirae with near linear interspaces on the outer dorsal and dorso-lateral surface; details of any other dorsal sculpture not discernable. Periphery evenly convex, spiral threads apparently absent on mid-peripheral area. Base evenly convex, with 6 distinct spiral lirae with near linear interspaces in middle part; umbilicus about half width of base, spiral sculpture not discernable within (surface not clean and sculpture may be obscured). Sutures impressed. Aperture near circular, with simple, slightly thickened peristome, with narrow, weak external varix. Colour brown to dark brown (imparted by thin deposits on thin periostracum).

Head-foot, radula and anatomy unknown.

Remarks. This species was described from a single specimen. Co. sentaniensis and Co. nordaustralis are the only known strictly freshwater clenchiellids. The shell of Co. sentaniensis is similar to that of Coleglabra nordaustralis but differs from that species in having a narrow, weak external varix and, notably, much stronger spiral threads both dorsally and ventrally. In addition, the apertural edge, viewed dorsally, is less distinctly convex. This species is included in Coleglabra because of the general similarity of its shell to that of C. nordaustralis , but this placement requires anatomical confirmation.

Figures

FIGURE 28. Holotypes of Colenuda n. gen. and Coleglabra n. gen. (from left towards right: dorsal, lateral and ventral view respectively). A – C, Colenuda kessneri n. sp. (NTM P. 53500; shell diameter 1.79 mm); D – F, Coleglabra nordaustralis n. sp. (NTM P. 53502; shell diameter 1.82 mm); G – I, Coleglabra sentaniensis (ZMA 1206; shell diameter 1.1 mm).