Suspected neoplasms in deep-sea corals (Scleractinia:Oculinidae:Madrepora spp.) reinterpreted as galls caused by Petrarca madreporae n. sp. (Crustacea:Ascothoracida:Petrarcidae)

Abstract

Hypertrophied corallites with irregular septal patterns in the Hawaiian deep-water coral Madrepora kauaiensis Vaughan were interpreted 30 yr ago as possible neoplasms, and this idea has persisted in comparative oncological literature. Many colonies of Madrepora oculata L, with similarly modified corallites are recorded herein from 233 to 604 m depth off northwestern Australia and Japan, in the Formosa Strait, and in the Banda and Arafura Seas, Indonesia. The affected corallites have a hollow space beneath the interrupted columella. Most specimens had been dried and bleached, leaving no tissue, but in some alcohol-preserved Indonesian specimens this cavity was occupied by endoparasitic petrarcid ascothoracidan crustaceans. These are described herein as Petrarca madreporae Grygier, new species, which is characterized by a posterior lobe on each carapace valve, poorly armed mouthparts, and a bifid penis with fixed rami. The validity of the diagnosis of the petrarcid genus Zibrowia Grygier, 1985 is questioned. The abnormal corallites are provisionally reinterpreted as an unusual kind of petrarcid 'internal gall.",