Luxuriant fertile colonies. Stems to 5 mm long internode length 0.30-0.38 mm; diameter at node 0.03-0.06 mm. Hydrotheca 0.19-0.28 mm long. Tubular nematothecae present in the base of proximal infrathecal chamber.
Colour: light brown.
Bale recognized 3 varieties of A. minima in southern Australian waters: the largest, var. pumiloides Bale, 1884 (from Queenscliff, Vic.), a "typical" form from Port Phillip Bay and New Zealand waters, and var. intermedia Bale, 1915, from the Nuyts Archipelago in the Great Australian Bight. It is possible that these are ecological variants or closely-related separate species.
Var. pumiloides is a robust form, conforming to Bale's (1884) description. The hydrothecae are almost entirely adnate, and the typical wedge of perisarc between hydrotheca and internode is well developed. The gonothecae are variable in shape, round to elongate in lateral view; those with a raised apertural collar do not have a ring of internal submarginal denticles.
The var. intermedia, not figured by Bale, is much smaller, with shorter internodes, and rectilinear hydrothecae. Nematothecae, varying from short cylindrical tubules to mere breaks in the perisarc, are present on all stems, but are confined to the infrathecal chamber of the proximal hydrothecae. Gonothecae are round to ovate.
Southern Australia: South Australia, Tasmania, Victoria, Western Australia.
Subtidal, epiphytic on algae and epizoic on sponges and other benthic fauna.