Asteracmea illibrata (Verco, 1906)
Description: Shell minute, translucent when fresh, opaque when aged. Very variable in height, apex slightly in front of centre, posterior slope concave, anterior slope straight or convex. Exterior surface smooth apart from concentric growth lines. Margin smooth. Interior with margin and spatula clearly delineated. Colour white, fawn or pink, sometimes with up to 10 white rays.
Size: Up to 4 mm in length
Distribution: Endemic to Australia: NSW to south-western WA, including Tasmania.
Habitat: In SA, reported from 20-100 fathoms. In NSW, known mainly from empty shells sorted from beach grit, plus a few specimens dredged from around 40 m; occasionally seen alive in intertidal algae washings. Uncommon in collections, but probably common in occurrence.
Comparison: This is the smallest limpet occurring in NSW, but is difficult to distinguish from juveniles of other species.
Synonymy; Shells from Sydney beaches were assigned the subspecific name Parvacmea illibrata mellila Iredale, 1924, but it is an unnecessary separation.
Remarks; The exact habitat of this species is not known, but it has been suggested that it lives on the encrusting coralline algae Lithothamnion sp. at low tide level and below (W. Ponder, pers. comm.).
Fig. 1 Off Sussex Inlet, NSW, in 37 m (C.022423)
Copyright Des Beechey 2005