Colenuda kessneri Ponder, Fukuda & Hallan, 2014

Diagnostic features

Shell minute (1.9 mm in diameter), with low spire and open umbilicus narrower than in other genera. Whorls with fine spiral threads, strong spiral cords or keels absent. Aperture near circular, peristome with shallow indentation dorsally, prosocline, very weak external varix usually present. Operculum simple with no peg or white smear to plate-like deposit on inner surface. Radula as for family, cusps on inner marginal teeth much larger than those on outer marginals. Head-foot with black pigment on cephalic tentacles, snout and penis. Penis wide, simple with no swellings or glands. Bursa copulatrix moderate in size; bursal duct short. Two seminal receptacles.

The shell is similar to that of Colenuda kessneri in having a few spiral threads on the dorsal surface of the shell and weaker spirals on the base, lacking spiral keels and in having a relatively narrow umbilicus and a low to moderate spire. The shell of Coleglabra differs most obviously from that of Colenuda in having a simple peristome, that of Colenuda having a wide, shallow excavation and in lacking any external varix. The head-foot is unpigmented but it is not in the other genus. The penis, like that of Colenuda, lacks distinct lobes or glands and, like Colenuda, the operculum lacks a central projection. The edge of the aperture, viewed dorsally, is convex in Coleglabra.

Classification

Colenuda kessneri Ponder, Fukuda & Hallan, 2014

Class Gastropoda

Infraclass Caenogastropoda

Order Littorinida

Suborder Rissoidina

Superfamily Truncatelloidea

Family Clenchiellidae

Genus Colenuda Ponder, Fukuda & Hallan, 2014 (Type species: Colenuda kessneri Ponder, Fukuda & Hallan, 2014)

Original nameColenuda kessneri Ponder, Fukuda & Hallan, 2014. In  Ponder, W. F, Fukuda, H. & Hallan, A. 2014. A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea). Zootaxa 3872: 101-153.

Type locality: Bamboo Creek, tributary of Daly River, near junction with main river (some estuarine influence), Northern Territory. Australia.

Biology and ecology

Colenuda kessneri is found in a narrow zone at or near the upper limit of tidal influence and is abundant where it occurs.

Distribution

This species is known only from a short section of Daly River, between Bamboo Creek and the nearby junction of Browns Creek with Daly River (Willan & Kessner, 2021).

Notes

Although this species is currently known only from the type locality, it may occur in other tidal tributaries in the same region.

Further reading

Ponder, W. F., Fukuda, H. & Hallan, A. (2014). A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea). Zootaxa 3872: 101-153.

Willan, E. C. & Kessner, V. (2021). A conspectus of the freshwater molluscs of the Daly River catchment, Northern Territory. Northern Territory Naturalist 30: 108-137.