Revision of some Carybdeidae (Scuphozoa : Cubomedusae) including a description of the jellyfish responsible for the 'Irukandji syndrome'

Abstract

The medusa responsible for the "Irukandji syndrome" or "type A stinging" to bathers in northern Australian waters is described, as Carukia barnesi, gen. et sp. nov., from the original specimen captured by J. H. Barnes (proven experimentally as causing the syndrome) and one other specimen. The family Carybdeidae of the Cubomedusae is briefly reviewed, and revised in the light of the present study of the structure of Carukia barnesi and its comparison with other Cubomedusae. The family Carybdeidae is left with the five genera Carukia, gen. nov., Carybdea Peron & Lesueur, 1809, Manokia, gen. nov. (type species Carybdea stiasnyi Bigelow, 1938), Tamoya Muller, 1859, and Tripedalia Conant, 1897. Carukia is distinguished from the others by the absence of gastric phacellae. Carukia barnesi may be identified in the preserved state by its reasonably compact build combined with the absence of gastric phacellae, and (among Indo- Pacific Cubomedusae) by its warty exumbrella, particularly by the presence of a prominent wart externally over the centre of the velarial canals. Description of the nematocysts of Carukia barnesi is included, and some histological details of tentacle, gonad and other structures. The term "tumitele" is proposed for a class of nematocyst seen in the Carybdeidae. This is a microbasic rhopaloid in which the basis or butt enlarges only in its middle, and not at its proximal end (stenotele), or distally (eurytele). The formal name carukiosis is proposed in place of "Irukandji syndrome" or "type A stinging", based on the generic name Carukia.