A new subfamily of ulmarid scyphomedusae, the Santjordiinae, with a description of Santjordia pagesi gen. et sp. nov. (Cnidaria: Scyphozoa: Discomedusae: Semaeostomeae: Ulmaridae) from the Sumisu Caldera, Ogasawara Islands, Japan.

An undescribed species of ulmarid medusa was observed in situ and captured at 812 m depth within the Sumisu Caldera, Ogasawara Islands, Japan. Morphological and molecular evidence points to it being distinct from other ulmarid medusae and a new species (pagesi), genus (Santjordia) and subfamily (Santjordiinae) are herein erected to contain it. This new subfamily of semaeostome ulmarid medusae has both marginal and subumbrellar rhopalia, making it unique within the order Semaeostomeae. Although the combination of subumbrellar tentacles and the lack of branched canals should warrant the erection of a new family within the Semaeostomeae, a lack of information on the gonad structure and poor bootstrap support in the molecular phylogenetic tree cause us to relegate it to the catch-all family Ulmaridae, until greater taxon sampling and phylogenetic analyses are carried out for the Semaeostomeae.

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A new species of clausophyid calycophoran siphonophore (Cnidaria: Hydrozoa), Kephyes hiulcus sp. nov., widely distributed throughout the world's oceans.

A new species of clausophyid siphonophore, Kephyes hiulcus sp. nov. is described. It can most easily be differentiated from its congener Kephyes ovata by the shape of the hydroecium in the anterior nectophore of the polygastric stage. This is open over the entire height of the nectophore in K. hiulcus sp. nov., and it is this character from which its specific name is derived. This species was found in the eastern and western Pacific Ocean, as well as the Celebes and Mediterranean Seas, indicating that this species is both relatively common and geographically widespread.