Drilonereis Claparède, 1870

Zanol, Joana & Ruta, Christine, 2015, New and previously known species of Oenonidae (Polychaeta: Annelida) from Lizard Island, Great Barrier Reef, Australia, Zootaxa 4019 (1), pp. 745-772 : 758

Genus Drilonereis Claparède, 1870

Type-species. Lumbriconereis filum Claparède, 1868

Diagnosis. Prostomium without antennae, usually triangular and dorsoventrally flat with median longitudinal furrow; eyes usually absent. Peristomium double ringed. Maxillary carriers long, two dorsal slender, strongly sclerotized and one ventral wider and shorter, moderately to poorly sclerotized. Four to five maxillary plates, shape of plates usually symmetric; MxI distally falcate, basally smooth or dentate. Mandibles reduced or absent. Notopodial cirri small papillae. Neuropodia prechaetal lobes usually shorter than postchaetal. Most chaetae limbate, ventralmost chaeta acicular spine ( Figs 7 H, 8M); ventralmost chaeta tapering to guards absent.

Remarks. Around 38 free living or endoparasitic species have been described or placed within Drilonereis . Most descriptions are incomplete, leading to a great amount of synonymisation and records of few species worldwide, consequently making it difficult to identify specimens to species level. For practical reasons, species are usually grouped based on the presence and absence of mandible and of teeth on the base of MxI, which may be inconspicuous ( Fauchald 1970). Other features used in species identification are: 1) shape of mandible, when present; 2) shape of maxillary plates; 3) relative length acicular spine chaeta in relation to postchaetal lobe. Presence of eyes is usually not considered an informative feature because it changes from juveniles to adults of the same species ( Fauchald 1970).

Two species of Drilonereis had been previously described from the Australian coast, D. australiensis and D. quadrioculata . Drilonereis australiensis is similar to one of the species analysed here, but they differ in the mandible shape. Drilonereis quadrioculata has a distinct round prostomium, four eyes in the peristomium, mandibles absent, no teeth at the base of MxI and MxII with most anterior tooth distinctly longer than the remaining. These features were not observed in the specimens examined here.

Figures

FIGURE 7. Drilonereis cf. logani Crossland, 1924. A. Whole body of live specimen in host; B. Anterior end, dorsal view; C. Anterior end, ventral view; D. Anterior end, lateral view; E. Maxillae and carriers, MxI, ventral and dorsal carriers broke during mounting, arrow at beginning of the furcula; F. Maxillae, MxI broke during mounting, G. Left parapodium 135; H. Chaeta acicular spine, left parapodium 135. A – H, AM W. 44971.