Journal of Paleontology, 91(3), 2017, p. 554–565 Copyright © 2017, The Paleontological Society 0022-3360/17/0088-0906 doi: 10.1017/jpa.2017.19


A reappraisal of the Eocene priacanthid fish Pristigenys substriata (Blainville, 1818) from Monte Bolca, Italy


Giorgio Carnevale,1 G. David Johnson,2 Giuseppe Marramà,3 and Alexandre F. Bannikov4


1Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso, 35 10125 Torino, Italy ⟨giorgio.carnevale@unito.it⟩ 2Division of Fishes, Department of Vertebrate Zoology, National Museum of Natural History, MRC 0159, Smithsonian Institution, Washington,


D.C. 20013-7012 ⟨JOHNSOND@si.edu⟩ 3Department of Palaeontology, University of Vienna, Faculty of Earth Sciences, Geozentrum, UZA II, Althanstraβe 14, 1090 Vienna, Austria


⟨marramag81@univie.ac.at⟩ 4Borisyak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya 123, Moscow, 117997, Russia ⟨aban@paleo.ru⟩


Abstract.—Priacanthids are a small family of percomorph fishes comprising fewer than 20 extant species currently assigned to four genera. One of these, Pristigenys, was established by Louis Agassiz (1835) to include the Eocene species Pristigenys substriata from Monte Bolca, and is usually regarded as a subjective senior synonym of Pseudopriacanthus. Consequently, Pristigenys currently comprises five extant species plus the fossil Pristigenys substriata. The osteology of the type species of this genus, however, is poorly known, and this makes it difficult to provide an adequate comprehensive definition of the taxonomy of the whole family. Pristigenys substriata is redescribed in detail based on five well-preserved articulated skeletons. Pristigenys substriata can be easily distinguished from other priacanthids based on its unique combination of characters. Morphological analysis of the fossil specimens reveals that there is substantial evidence to justify recognition of both Pristigenys and Pseudopriacanthus as valid genera, with extant species previously assigned to Pristigenys now referred to Pseudopriacanthus. Within the Priacanthidae, Pristigenys and Pseudopriacanthus form sister taxa and this pair can be considered as the sister-group to all remaining extant priacanthid genera (Cookeolus + [Heteropriacanthus +Priacanthus]).


Introduction


Fishes of the family Priacanthidae constitute a small group of predatory percomorphs occurring circumtropically with greatest diversity in the Indo-Pacific region (Starnes, 1988). Priacanthids exhibit deep bodies, remarkably large eyes, and rough spinous scales. Because of their large eyes, cryptic habits, and night-time angling results, these fishes are usually regarded as nocturnal, even though evidence from stomach contents seems to indicate that they are also active during the day (seeHiatt and Strasburg, 1960). Larval and prejuvenile priacanthids are pelagic in the upper layers of the water column (Caldwell, 1962a, 1962b), whereas juveniles and adults (standard length >70mm; Caldwell, 1962a) are bottom dwellers with a preference for coral reefs and rocky areas. They are very secretive (Caldwell, 1962a) and usually considered solitary, although some species occasionally occur in loose and undirected aggregations around coral reefs and rock piles (Caldwell and Bullis, 1971). Some species are characterized by a sound- producingmechanism in large part based on extrinsic swimbladder muscles (Salmon andWinn, 1966). The phylogenetic position of the Priacanthidae within


percomorphs is unclear. These fishes have been traditionally aligned with the Percoidei (e.g., Johnson, 1984; Nelson, 2006), but recent large-scale molecular studies hypothesized a close affinity with the Monodactylidae and acanthuriforms


(Betancur et al., 2013), or, alternatively, with the Cepolidae, Siganidae, and Scatophagidae (Near et al., 2013). However, support for the latter hypotheses is somewhat weak and new detailed focused studies are needed to test such phylogenetic interpretations. The fossil record of the Priacanthidae is relatively rich,


documented by several Eocene, Oligocene, and Neogene articulated skeletal remains and otoliths, primarily from Europe (see Fitch and Crooke, 1984; Starnes, 1988; Bannikov, 2010; Nolf, 2013). The earliest articulated skeletal remains of the group consist of a few well-preserved specimens belonging to the species Pristigenys substriata from the lower Eocene limestone of Monte Bolca, northeastern Italy. The Eocene occurrence of priacanthids documents the remarkable increase of diversity of nocturnal feeders that took place during the earliest part of the Paleogene (see Goatley et al., 2010; Carnevale et al., 2014). Overall, the family Priacanthidae currently includes 19


extant species in four genera, Cookeolus, Heteropriacanthus, Priacanthus,and Pristigenys (Starnes, 1988; Iwatsuki et al., 2012). The nomenclatural history of Pristigenys has been controversial (e.g., White, 1936; Myers, 1958; Caldwell, 1962a; Fitch and Lavenberg, 1975; Fritzsche, 1978; Fritzsche and Johnson, 1981; Fitch and Crooke, 1984; Taverne, 1988). In his comprehensive worldwide revision of the family, Starnes (1988) allied


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