Gymnomenia Odhner, 1921
Type species. -- Gymnomenia pellucida Odhner, 1921, by
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
|Gymnomenia minuta||Scheltema in press|
|Gymnomenia pellucida||Odhner, 1921|
|Gymnomenia virgulata||Scheltema 1999|
From Ophelia 51 (1): 1-28 (1999).