Biology of the Antarctic Seas X V32 (Other digital)

Published by the American Geophysical Union as part of the Antarctic Research Series, Volume 32.A new ascothoracican parasite of the genus Dendrogaster (herein named "D. antarcticus" n. sp.) is described from the coelomic cavity of the starfish Acodontaster conspicuus. This is the first Antarctic ascothoracican known. The appendages and external anatomy of males, females, and larvae are described in detail, and the internal anatomy to a lesser degree. The females are large (40-65 mm) and distinguishable from those of other species by the branching pattern of the mantle, which, in this case, involves numerous orders of branching, terminating with one trichotomous order or more, and by the first antennae, upon which are few sensory setae and in which the penultimate joint is shifted ventrally so that the second and fourth joints abut dorsally. Eggs are about 0.5 mm in diameter; a female produces thousands at once. Larvae hatch as bivalved ascothoracids (cyprids) with natatory appendages. They appear to undergo one molt within the female before escaping from the mantle cavity. Males are found in all females; they are quite similar to the larvae, except for a pair of long (4-9 mm) posterior mantle extensions.Aspects of affinities of "Dendrogaster antarcticus" to other species of its genus, the functional morphology, the relationship of the parasite to the host, the reproduction and development, and the biogeography are discussed.