Nassarius jonasii (Dunker, 1846)
Description: Shell with rounded whorls with axial folds that form nodules at the sutures, with a constriction below; folds on the dorsal surface of the body whorl restricted to upper half of the whorl. Body whorl with widely spaced spiral ribs on the base, extending to the centre of the whorl, and sometimes with spiral grooves between the axial folds on the upper half of the whorl. Outer lip reflected outwards, either smooth or with 8-10 teeth internally. Columella callus expanded, usually extending above the body whorl; columella smooth. Columella callus white, exterior fawn or brown, with a dark band below the suture.
Size: Length up to 16 mm.
Distribution: Endemic to Australia; Noosa Heads, Qld, to SA.
Habitat: On sand and mud flats in estuaries and lagoons, intertidal down to 100 m. Abundant.
Comparison: N. jonasii may be distinguished from N. burchardi by several characters. In jonasii there is frequently spiral grooves between the axial folds on the upper half of the body whorl, but they are absent in burchardi. The callus is larger and thicker in jonasii than in burchardi and usually extends beyond the body whorl, while this is rarely so for burchardi. The most consistent feature is that jonasi has a smooth columella, but teeth are always present on the lower half, even if weak, in burchardi.
Synonyms: Austronassaria simplex C. & J. Laseron, 1956; Nassa mangelioides Reeve, 1853Figs. 1,2: Tuross Head, NSW (DLB4960)
Copyright Des Beechey 2000