Laval development of the Megabalanine Balanomorph Austromegabalanus nigrescens (Lamarck) (Cirripedia, Balanidae)

Abstract

The presence of embryos in the mantle cavity of A. nigrescens was monitored over a 2-year period. A, nigrescens maintains some breeding individuals throughout the year but shows peak breeding during the late autumn, winter and early spring in the vicinity of Sydney, New South Wales, Australia.

The larval stages of A. nigrescens are described from larvae reared in the laboratory. A. nigrescens larvae can be easily distinguished from other nauplii described from balanomorphs of New South Wales by their distinctive marginal spines and paired dorsal shield spines. The duration of larval development in A. nigrescens, 13-23 days, is similar to that of other Australian balanids and does not appear to accord with the concept that the distribution of Austromegabalanus species has involved long-range epiplanktonic dispersal.

The separation of Austromegabaianus, Notomegabalanus and Megabalanus is supported by larva! differences.