REVISION OF IONOSCOPUS PETRAROJAE (IONOSCOPIFORMES, OSTEICHTHYES) FROM THE ALBIAN OF PIETRAROJA (CAMPANIA, SOUTHERN ITALY)

The skeleton of Ionoscopus petrarojae, an ionoscopiform fish (Halecomorphi) from the marine Albian of Pietraroja (Campania, southern Italy), is studied in details. The fish exhibits all the anatomical features that characterize the family Ionoscopidae, a maxillary sensory canal, a dermosphenotic fused to the skull roof and bearing an innerorbital flange, a dermopterotic longer than the parietal, pitted infraorbitals, monospondylous vertebrae, fossae on the lateral faces of the vertebrae, more than 15 supraneurals and amioid-like scales. Ionoscopus petrarojae differs from the well known Ionoscopus cyprinoides by numerous osteological characters. The erection of a new genus for I. cyprinoides is suggested. Comparisons are done between I. petrarojae and the ionoscopid species Oshunia brevis and Quetzalichthys perrilliatae. Comments are given on the systematic position of I. petrarojae within Ionoscopidae. I. petrarojae is the plesiomorphic member of the family. It still has a large dermosphenotic that covers the autosphenitic, as in Ophiopsidae. “Ionoscopus” cyprinoides, O. brevis and Q. perrilliatae share a new derived character. The dermosphenotic is reduced. The autosphenotic is no more hidden and becomes a visible part of the skull roof.