Bioluminescent Australian Earthworms II. Taxonomy and Preliminary Report of Bioluminescence in the General Spenceriella, Fletcherodrilus and Pontodrilus (Megascolecidae:Oligochaeta).

Abstract

Bioluminescence is demonstrated in four species of Spenceriella, in Fletcherodrilus fasciatus and F. unicus, all being megascolecines from eastern Australia, and in the circummundane megascolecine Pontodrilus bermudensis, and is compared with that of the North American acanthodrile Diplocardia longa. The four Spenceriella species are placed in a new cormieri species-group in the subgenus Spenceriella. Of these, S.(S.) cormieri, S.(S.) curtisi and S.(S.) noctiluca are new species and S.(S.) minor (Spencer) is redescribed. The subgenus Spenceriella is redefined to include species lacking calciferous glands, and the subgenus S. (Austroscolex) is distinguished in lacking buccopharyngeal or other tufted nephridia anteriorly. Fletcherodrilus is redefined and a key to its four species provided. The synonymy and world distribution of Pontodrilus bermudensis Beddard is given. On electrical or tactile stimulation the seven described species, in Spenceriella, Fletcherodrilus and Pontodrilus, all exhibit spontaneous luminescence which is enhanced by addition of peroxide and which cross-reacts with Diplocardia longa luciferase and, usually luciferin. It is suggested that the luminescent system resides in the free chloragogen cells (elecocytes) in the coelomic fluid, in all except P. bermudensis in which luminescence is not cell-bound. Five species studied in the megascolecine genera Heteroporodrilus, Spenceriella (Austroscolex) and Digaster, and the glossoscolecid Pontoscolex corethrurus, are non-luminescent. Possible functions of luminescence are discussed.