Pandeopsis Kramp, 1959

Schuchert, Peter & Collins, Richard, 2021, Hydromedusae observed during night dives in the Gulf Stream, Revue suisse de Zoologie 128 (2), pp. 237-356 : 249

Genus Pandeopsis Kramp, 1959

Pandeopsis Kramp, 1959b: 39 ;

type species Pandeopsis scutigera Kramp, 1959 by original designation.

Diagnosis: Pandeid medusae with wide, large manubrium and quadratic base, with long mesenteries; gonads smooth, sheet-like, covering interradial surface of manubrium, usually with a few dark spots in living or recently fixed specimens; mouth with four simple lips; up to 16 marginal tentacles and up to 24 rudimentary bulbs that may have a very short tentacle stump; tentacular cirri absent; tentacle bulbs without spur, with abaxial ocelli.

Hydroid known only from rearing; colony with common hydrorhiza giving numerous hydranths with one whorl of 3-6 filiform tentacles; medusa buds unknown.

Remarks: The only tangible difference of Pandeopsis and Merga is the more quadratic stomach base in the former. While some Pandeopsis specimens examined here indeed had a wide, quadratic stomach base ( Fig. 7C ), the difference to Merga is not always distinct and both genera could therefore be regarded as congeneric. The 16S phylogenetic tree ( Fig. 8 ) suggests that the two genera are not closely related, but this needs confirmation with additional markers.

Figures

Fig. 7. Pandeopsis ikarii. (A-C) Specimen BFLA4088, size 2.5 mm, presumable incipient oocytes are visible in the stomach wall. (D) Specimen collected 08-AUG-2018, size 5 mm, the identification is somewhat unreliable as there is no sequence data available.

Fig. 8. 16S rRNA maximum likelihood phylogenetic tree of Pandeidae species obtained with PhyML (GTR+G+I model) and based