New articulated asteroids (Echinodermata, Asteroidea) and ophiuroids (Echinodermata, Ophiuroidea) from the Late Jurassic (Volgian / Tithonian) of central Spitsbergen

Authors: Julie Rousseau 1,*, Andrew Scott Gale 2 & Ben Thuy 3

1 1111 Belle Pre Way, Apt. 537, Alexandria, VA, 22314, United States of America
2 School of Earth & Environmental Sciences, University of Portsmouth, United Kingdom
3 Department of Palaeontology, Natural History Museum Luxembourg, Luxembourg-City, Luxembourg.

Source: Rousseau J., Gale A.S. & Thuy B. 2018. New articulated asteroids (Echinodermata, Asteroidea) and ophiuroids (Echinodermata, Ophiuroidea) from the Late Jurassic (Volgian/Tithonian) of central Spitsbergen. European Journal of Taxonomy 411: 1–26. https://doi.org/10.5852/ejt.2018.411

Abstract: The Late Jurassic–Early Cretaceous Slottsmøya Member of the Agardhfjellet Formation in central Spitsbergen has yielded two new species of asteroids and two species of ophiuroids, one of which is described as new. Polarasterias janusensis Rousseau & Gale gen. et sp. nov. is a forcipulatid neoasteroid with elongated arms, small disc and very broad ambulacral grooves with narrow adambulacrals. Savignaster septemtrionalis Rousseau & Gale sp. nov. is a pterasterid with welldeveloped interradial chevrons. The Spitsbergen specimens are the first described articulated material of Savignaster and reveal the overall arrangement of the ambulacral groove ossicles. Ophiogaleus sp. is an ophiacanthid with relatively long jaws and lateral arm plates, with a coarsely reticulate outer surface. Here again, we report the first articulated skeletons of this genus, providing unprecedented insights into the disc morphology. Ophioculina hoybergia Rousseau & Thuy gen. et sp. nov. is an ophiopyrgid with a well-developed arm comb and tentacle pores reduced to within-plate perforations starting at median arm segments. These new finds are important additions to the asterozoan fossil record with regard to their good degree of articulation and the high latitudinal position of the localities. They significantly add to the set of exhaustively known fossil asterozoan taxa which play a key role in the phylogenetic analysis and reconstruction of evolutionary history.

Ophioculina hoybergia Rousseau & Thuy gen. et sp. nov., holotype PMO 217.930. A. Specimen preserving the ventral side of about half of the disc area and the proximal section of three arms. B. Drawing detail of the oral region, from D. C. Detail view of the base of an arm showing the arm comb. D. Detail view of the oral region. Abbreviations: abgp = abradial genital plate; adgp = adradial genital plate; aopa = apical oral papilla; as = arm spine; gpa = genital papilla; lap = lateral arm plate; lopa = lateral oral papilla; op = oral plate; os = oral shield; v = vertebra; 2opa = papilla of the second oral tentacle pore.

Ophioculina hoybergia Rousseau & Thuy gen. et sp. nov., holotype PMO 217.930. A. Specimen preserving the ventral side of about half of the disc area and the proximal section of three arms. B. Drawing detail of the oral region, from D. C. Detail view of the base of an arm showing the arm comb. D. Detail view of the oral region. Abbreviations: abgp = abradial genital plate; adgp = adradial genital plate; aopa = apical oral papilla; as = arm spine; gpa = genital papilla; lap = lateral arm plate; lopa = lateral oral papilla; op = oral plate; os = oral shield; v = vertebra; 2opa = papilla of the second oral tentacle pore.

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