A new genus,
Cryptassiminea, is introduced for the taxon previously known as
Assiminea buccinoides (Quoy & Gaimard). These small gastropods are abundant in mangrove and salt marsh habitats in south-eastern and subtropical eastern Australia. Seven species (five new) are recognised using morphological characters in the complex previously treated as a single species. Five taxa have rather narrow ranges while the other two are widespread and often sympatric. Two groups of species are recognised. One contains
Cryptassiminea buccinoides, widespread in south-east and east Australia, and two closely related allopatric taxa from South Australia and south-eastern Tasmania (
C. adelaidensis, sp. nov. and
C. kershawi, sp. nov.). A second group of species is typified by
Cryptassiminea tasmanica (Tenison-Woods), also widespread in east and south-east Australia and often sympatric with
C. buccinoides. Allied to
C. tasmanica, are two closely related taxa from western Victoria:
C. glenelgensis, sp. nov. from the Glenelg River estuary and
C. surryensis, sp. nov. from the Surry River estuary and Western Port, in the vicinity of Geelong. A distinctive species,
Cryptassiminea insolata, sp. nov. from the east coast of Queensland, also has similarities with
C. tasmanica. A cladistic analysis using morphological characters of the
Cryptassiminea taxa and three other genera of Assimininae, with an omphalotropidine as the outgroup, resulted in a single tree. The new genus has rather poor support, possibly because many of its characters appear to be plesiomorphic within Assimineinae.
Cryptassiminea is defined by a unique combination of characters but lacks any obvious synapomorphy. Two clades within
Cryptassiminea are well supported, each containing the species-groups referred to above.