Gymnomenia Odhner, 1921

Type species. -- Gymnomenia pellucida Odhner, 1921, by monotypy.

Distribution. -- Off Namibia (G. virgulata ) and in a Norwegian fjord (G. pellucida ) at depths less than 800 m.

Slender, elongate, translucent, midgut sacculations visible externally; less than 5 mm long, body ventrally flattened, anterior end truncate, with distinct mouth-fold when pharynx is everted, pedal pit often everted, posterior end broadly pointed; most spicules adpressed, ovate, rimmed; with paired groups of 2 or more copulatory spicules; paired seminal receptacles large, lobate, ventral; lower gametoducts muscular, ending in large, unpaired genital cone; mantle cavity ventral, shallow, without gill folds; presence of dorsoterminal sense organ not determined.

Remarks. -- Epidermal spicules had obviously dissolved on the two specimens of G. pellucida available to Odhner, who described the cuticle as a meshwork marked by cuticular 'lists,' or sharp ridges (Odhner, 1921). Such ridges are formed by the cuticle that lies between spicules and are seen in histologic sections after spicules have been dissolved. Although the morphology of the spicules in G. pellucida is not known, other morphologies that are similar in G. pellucida and G. virgulata make it likely that spicule morphology in the two species is also similar. Thus, the spicules of G. virgulata is considered typical for the genus. The radula of G. pellucida was apparently destroyed by a sagittal cut before sections were made and was considered lacking (see also Salvini-Plawen, 1997, for a similar situation withWirenia Odhner /Aesthoherpia Salvini-Plawen).

Gymnomenia minuta Scheltema in press
Gymnomenia pellucida Odhner, 1921
Gymnomenia virgulata Scheltema 1999

From Ophelia 51 (1): 1-28 (1999).