The status of some southern African nominal species of Cucumaria (s.e.) referable to a new genus and their ecological isolation

Abstract

A full history of four nominal species of southern African dendrochirotid holothurians, namely Cucumaria jageri Lampert, Semperia (= Cueumaria) sykion Lampert, C. insolens Theel and C. sinorbis Cherbonnier, is given and the confusion in their taxonomic status discussed. Morphological differences and habitat selection indicate that the latter three are valid sister species. C. jageri is relegated to the synonymy of C. sykion, a well-established name which it threatens. Since none of the three species is referable to the genus in which it is currently classified, a new genus Pseudocnella is erected to accommodate them. It is suggested that the Mediterranean Oenus syraeusanus (Grube) be also classified in the new genus. A key to the three southern African species is given, their synonymy detailed, additional notes provided, and the geographic distributions mapped. Although P. sykion and P. sinorbis have an identical geographical range it is demonstrated that the two species are ecologically isolated and thus prevented from any interspecific competition. P. insolens is sympatric with P. sinorbis over a wide area, often occupying the same habitat in a single locality. However, morphological and other evidence points to subtle niche differences between them. A provisional cladogram is proposed to show the possible relationships of the four species included in the new genus.

S.Afr.J.ZooL 1987.22(4)