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| Santjordia pagesi Lindsay, Grossmann, Montenegro & Morandini, 2023 |
Abstract
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.
Key words: Coelenterata, deep sea, medusa, new species, new genus, submarine caldera
Systematics
Class Scyphozoa Goette, 1887
Order Semaeostomeae L. Agassiz, 1862
Family Ulmaridae Haeckel, 1880
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| Santjordia pagesi gen. et sp. nov. Holotype. a: photograph of lateral view of living specimen in the gate sampler; b: photograph of aboral view of living specimen in the gate sampler; c: sketch of lateral view of living specimen; d: sketch of aboral view of living specimen; e: sketch of portion of oral view of preserved specimen; f: close-up of adradial rhopalium of preserved specimen, showing exumbrella with cleft, statocyst and rhopaliar canal; g: close-up of oral arm of living specimen in the onboard aquarium, showing marginal papillae. Scale bar = 2 cm except f: scale bar = 1 mm. |
Subfamily Santjordiinae subfam. nov.
Genus Santjordia gen. nov.
Etymology: The genus name Santjordia refers to the red cross of Saint George (Catalan: Sant Jordi)—the shape and colour of which correspond well to the distinctive stomach base in this genus and species. Saint George is also the patron saint of Catalonia, where the first author began the present work while on sabbatical in the laboratory of a Catalan taxonomist.
Santjordia pagesi sp. nov.
Etymology: The species name is in honour of Dr. Francesc Pagès, who hosted the first author during his sabbatical in Barcelona and introduced him to the intricacies of cnidarian taxonomy.
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| In situ images of the holotype of Santjordia pagesi gen. et sp. nov. Top left: aboral-lateral view; top right: lateral view; bottom left: oral-lateral view; bottom right: lateral view within the gate valve sampler on the ROV Hyper-Dolphin. Specimen size = 100 mm diameter. |
Dhugal John Lindsay, Mary Matilda Grossmann, Javier Montenegro and André Carrara Morandini. 2023. 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. Zootaxa. 5374(4); 533-551. DOI: 10.11646/zootaxa.5374.4.5
