Morphological descriptions of the eggcases of skates (Rajidae) from the central‑Western Mediterranean, with notes on their distribution

Eggcases of eight rajiform skates (Dipturus nidarosiensis, D. oxyrinchus, Leucoraja melitensis, Raja asterias, R. brachyura, R. clavata, R. miraletus and R. polystigma) present in the central-western Mediterranean are described, based on specimens obtained from fishery surveys. Eggcase features such...

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Bibliographic Details
Published in:Helgoland Marine Research
Main Authors: Porcu, Cristina, Marongiu, Martina Francesca, Bellodi, Andrea, Cannas, Rita, Cau, Alessandro, Melis, Riccardo, Mulas, Antonello, Soldovilla, Giuditta, Vacca, Laura, Follesa, Maria Cristina
Format: Article in Journal/Newspaper
Language:English
Published: 2017
Subjects:
Distribution
Eggcase
Identification key
Mediterranean Sea
Rajidae
Oceanography
Aquatic Science
Dipturus nidarosiensis
Online Access:http://hdl.handle.net/11388/204164
https://doi.org/10.1186/s10152-017-0490-2
Description
Summary:Eggcases of eight rajiform skates (Dipturus nidarosiensis, D. oxyrinchus, Leucoraja melitensis, Raja asterias, R. brachyura, R. clavata, R. miraletus and R. polystigma) present in the central-western Mediterranean are described, based on specimens obtained from fishery surveys. Eggcase features such as dimensions, horns and apron lengths, and presence/ absence of lateral keels were crucial to discriminate the eggcases of the various species. Morphological and morphometric data, confirmed by the multivariate analysis, indicated that the eggcase of R. miraletus and L. melitensis were distinct from those of the other species for being unkeeled. Within the species having keeled eggcases, those of the genus Dipturus and R. brachyura were discriminated from the remaining group by having the largest dimensions and aprons. Sandy bottoms (<100-150 m depth) were identified as egg-laying sites (i.e. sites with females bearing eggcases in uteri) for many species belonging to genus Raja Raja asterias, R. brachyura, R. miraletus and R. polystigma). The finding of R. asterias and R. miraletus carrying eggcases yearly on the same sites, seems to confirm the theory that many rajid species demonstrate site fidelity, returning to the same depositional area on an annual basis. Some remarks on reproductive biology of these skates are also provided. The eggcase identification key reported here represents the first for the Mediterranean and may be useful, in the future, to identify egg-laying grounds of skates with a nonlethal method.

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