Two species of Porosoma (Echinoidea) in the Eocene and Oligocene of north-eastern Italy
Borghi, E.; Morra, L.E.; Bottazzi, A.; Caporiondo, F. (2025). Two species of Porosoma (Echinoidea) in the Eocene and Oligocene of north-eastern Italy. Notiziario SRSN 2025: 125-144
In: Notiziario della Società Reggiana di Scienze Naturali. Società Reggiana di Scienze Naturali. , more
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| Author keywords |
Porosoma, cladistics, systematics |
| Authors | | Top |
- Borghi, E.
- Morra, L.E.
- Bottazzi, A.
- Caporiondo, F.
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| Abstract |
The taxonomy of Porosoma Cotteau, 1856 has long remained uncertain, owing to reliance on morphological traits subject to considerable variability. To address this issue, well-preserved specimens from the Eocene and Oligocene of the Veneto Region (Northeastern Italy) were examined. An extensive sample from the type horizon, the Calcareniti di Castelgomberto formation (Rupelian), confirms the diagnosis of the type species, Porosoma cribrum (Agassiz in Agassiz & Desor, 1846), including the distinctive composition of polygeminate ambulacral plates in echinid style. The study of topotypic specimens from the Priabonian of the Colli Berici further supports the reassignment of Cyphosoma pulchrum Laube, 1868 to Porosoma. The diagnostic characters of Porosoma should include the composition of the ambulacral plates as in the type species. Based on this criterion, only three additional species are retained within Porosoma: P. haimei (Desor, 1856), P. vidali (Lambert, 1902) and P. montserratense Lambert, 1927. Phylogenetic analysis recovers Porosoma in an unresolved polytomy with Phymosoma and Gauthieria, thereby corroborating its placement within the family Phymosomatidae Pomel, 1883. |
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