(figs. 2 C, D)
Material studied. Ormonde, stn 4: sparse polyps on cauli of some alga Zonaria tournefortii, DBUA 1521.01, Genbank accession no. KM 402032.
Remarks. The sample material was not fertile preventing an accurate identification of this species. The most similar 16 S rRNA sequence in Genbank, in relation to the sequence determined for the present material, corresponds to a medusa collected in Plymouth, identified as Amphinema dinema (Genbank accession no. EU 999223.1; Licandro et al. 2010), different in a single nucleotide position. Without doubt these sequences correspond to the same species, the Gorringe hydroids (figs. 2 E, F) exhibit morphological differences in comparison to A. dinema hydroids reared under laboratory conditions (Rees & Russell 1937). Namely the tentacles of the present colonies are in higher number (ca. 12–17, instead of four to ten), proportionally smaller and thicker, and disperse along the distal third of polyps instead of in a single whorl. Although the hydranths may have changed appearance after preservation in alcohol (Rees 1956; Schuchert 1996: 62) and/or present an abnormal/different growth form under laboratory conditions. For now, this taxon can only be identified taxonomically up to the genus level.
This species had not been reported from the Gorringe Bank previously.