Contributions to the Runcinidae. I. Six new species of the genus Runcina (Opisthobranchia cephalaspidea) in the Mediterranean

Six new species of Runcina Forbes & Hanley, 1853, are described in this fir st part of a bipartite article on the Runcinidae, three more will follow in the second part (in press). All but one species are described with live co loration, radula and jaws examined by SEM. Five Runcina in this report are from Posidonia/ Zostera of Banyuls-sur-Mer, France, one from the sand inter sticium of Naples, Italy. Runcina langei n. sp. is greenish with fine dark green specks, the notum with six paired dark marginal marks and few deep bl ack blotches, a white cross-band behind the eyes and a white rear. R. kress ae n. sp. is yellowish with three black spotted cross lines, a white cross- band behind the eyes and a white notum rear. R. hansbechi n. sp. is covered densely with large, variably shaped, amoeboid black blotches, interspersed with white spots, on a yellowish ground colour. R. nivale n. sp. out of th e mesopsammnon is transparent whitish with very large eyes and gills. R. ba nyulensis n. sp., with exceptionally large eyes, is light beige with small black spots, the notum broadly bordered with white, interspersed with red a nd brown spots, and bearing a pure white 'T'. R. avellana n. sp. is chocola te brown with a lighter foot sole, one blackish brown mark on the clear tai l, and clear head sides and front. A morphological introduction to the Runc inidae with emphasis on jaws and radula is given. Dental metamorphosis is o bserved and reanalysed.