Coliracemata

Ponder, Winston F., Fukuda, Hiroshi & Hallan, Anders, 2014, A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea), Zootaxa 3872 (2), pp. 101-153 : 140

Coliracemata ? innocens ( Preston, 1915)

Figure 27

Cyclostrema (Tubiola) innocens Preston, 1915: 296 , figs 9, 9a–b.

Types and type locality. Holotype: Serua Nadi, Lake Chilka (=Chilika Lake) (eastern India), 5–9 ft. (1.5–2.7 m) depth (Indian Museum, Calcutta, Preston, 1915: 289 (type material apparently lost).

Distribution. Known only from the type locality, a large brackish-water lake.

Material examined. None.

Description (based on Preston 1914: 296, figs 9a–c).

Shell. Minute (2.0 mm in diameter; Table 3), spire low ( Fig. 27 C–E). Protoconch not elevated above line of spire, details unknown. Teleoconch of about 3 convex whorls, surface smooth except for growth lines. Periphery evenly convex. Base evenly convex, umbilicus moderately wide (slightly more than half width of base). Sutures impressed. Aperture near circular, prosocline, with simple, slightly thickened peristome, no obvious external varix. Colour milk white.

Operculum, head-foot and anatomy unknown.

Remarks. Preston’s Cyclostrema (Tubiola) innocens was compared with Co. microscopica by Annandale and Kemp (1916: 347) with the comment that it “clearly belongs to the same genus” and “appears to differ from that species in its smaller size, reddish colour and in the sculpture on its surface; but the type of Preston’s species is bleached and perhaps somewhat eroded.” Preston’s description stated that his specimen (from Serua Nadi, Lake Chilka, a brackish water locality) is smooth. He gives a size of 2.0 mm maximum diameter, whereas microscopica is, according to Nevill’s original description, 1.5 mm in diameter. Annandale later (1924: 858) stated a slightly different opinion - “Dr Kemp and I were inclined to think [that innocens ] is a small denuded shell of Nevill’s species”. These authors are the only ones who had access to the type material of both and that have published an opinion on these taxa. Abbott (1949) was uncertain regarding the synonymy of these two species. Because, on the available evidence, Co.? innocens differs from Co.? microscopica in its larger size, apparent lack of spiral sculpture and slightly wider umbilicus, we tentatively treat both as separate species pending the discovery of new topotypic material. Co.? innocens could also conceivably be a species of Coleglabra n. gen.

Figures

FIGURE 27. Coliracemata? microscopica (A, B) modified from the original illustrations by Annandale and Kemp (1916, fig. 3) and Coliracemata? innocens (C – E) modified from the original illustrations by Preston (1915, fig. 9 a – c). Scale bars: 500 µm.