New ascothoracid crustacean endoparasites of Scleractinia

Abstract

The ascothoracid crustacean genus Petrarca, endoparasites of scleractinian corals, is reviewed and revised. Petrarca bathyactidis, the type-species, is partly redescribed. The range of P. okadai is extended to East Africa. Three new species of Petrarca are described: P. indica in Flabellum deludens from the Indian Ocean near Ceylon; P. morula from Turbinaria sp. in the Banda Sea; P. azorica in Enallopsammia rostrata from the North Atlantic. Zibrowia auriculata gen. et sp. nov. infests Balanophyllia carinata off East Africa, and the same species appears to live in Tubastraea micranthus off East Africa and Dendrophyllia sp. at Réunion and in the Comoros. Unlike other ascothoracids, eggs and larvae are not brooded within the carapace valves, though they may be attached to them externally. Nauplii of P. okadai and Z. auriculata are described; they are generalized with familially distinct features. Adults of both genera have an overall neotenic appearance. They always occur in galls in groups of two or more, suggesting simultaneous infestation. Ahermatypic corals or their close hermatypic relatives seem to be preferred hosts, and Petrarca has a wider geographic and depth range than confamilial genera.