The genus Herdmania Lahille, 1888 (Tunicata, Ascidiacea) in Australian waters

Abstract

Revision of material from Australian waters previously assigned to Herdmania momus (Savigny, 1816) has resulted in the recognition of five species (including two new indigenous species). A tropical Indo-West Pacific range is recorded for the type species (H. momus), although it is not recorded from Western Australia. A circum-continental range for the third and largest species, H. grandis (Heller, 1878) is confirmed. Herdmania pallida (Heller, 1878), with a wide range in the western Pacific and Indian Ocean including the north-eastern and north-western coasts of Australia, is a different species from the Atlantic Ocean species (formerly thought to be conspecific). Herdmania fimbriae, a new species with a geographical range from southern to north-eastern Australia, is distinct from H. mentula, also a new species, from the north-western coast. The structure of the gonads and their ducts and accessory membranes and the arrangement and number of body wall muscles distinguish the species. Species differences are supported by the maximum size of individuals, nature of their test, number of branchial folds, number of internal longitudinal vessels on the folds and between the dorsal lamina and dorsal fold, the size and form of the dorsal tubercle and dorsal lamina, and the shape of the ciliated opening of the neural duct, although these characters are affected to some extent by growth. A variety of accessory membranes associated with both male and female gonoducal apertures are found in the majority of species in this genus.