As Atrina dumosa:
Wedge-shaped, thin, somewhat convex, margins rounded (not angulate), radiately ribbed; about seven rows of eight or nine erect subtubular scales on the ventral limb; colour dull olive, clouded with purple, apex livid. Length 60 mm., height 124 mm. Type locality: Tapley Shoal, Gulf St. Vincent. Smaller than Atrina tasmanica Tenison Woods, from Tasmania, and much more thorny. The two species A. tasmanica and A. dumosa may belong to the subgenus Servatrina Iredale 1939, type species Pinna assimilis Reeve 1858. N. H. Ludbrook 1955 could not decide whether the Pliocene species Pinna semicostata Tate 1886 belonged to Pinna or Atrina. Subgenerically it could be placed in Servatrina Iredale 1939. The "subspecies" Atrina tasmanica dumosa was described by Hedley from Australian Museum specimens and if a holotype were chosen it should be there.
Loc.: Rare, at low tide mark, Outer Harbour, Largs, Port Willunga; dredged Investigator Straits, 15 fathoms off Black Point; Yankalilla Bay, deep water. S.W.A., S.A.

Shell length lo 240 mm; fragile; dorsal margin straight; posterior margin usually broadly rounded; ventral margin convex posteriorly, concave anteriorly, moderately inflated. Sculpture: 10-14 prominent ribs on the posterior slope, which bear strong semi-tubular spines. Colour: shell horn coloured, translucent, spines white. Habitat: littoral sand or mud. Distribution: New South Wales, Victoria and Tasmania.