Holosteus, AGASSIZ, 1835

† HOLOSTEUS AGASSIZ, 1835

Type species: † H. esocinus Agassiz, 1835 .

Diagnosis: Holosteine paralepidid with very elongated body and fineness ratio of 15.0–16.0; head is of about five to six times SL; upper jaw terminating below the ventral margin of the orbit; prominent, non-ossified and horizontally directed projection forming the anterior tip of the lower jaw; articular–quadrate joint located below the posterior margin of the orbit; eight branchiostegal rays; small recurved teeth on premaxilla; large, thin and pointed teeth on palate and lower jaw without corrugate pattern or serrate margins; epineurals and epipleurals extending throughout the vertebral column, being thicker and more ossified in the caudal region; most epineurals bifid or trifid proximally; 106–112 vertebrae of which about 30% are caudal; dorsal fin with 18–20 rays; about 19–22 anal-fin rays; about 10–12 pelvic-fin rays; caudal fin with 19–20 principal rays and about 10–12 dorsal and ventral procurrent rays; five or six autogenous hypurals, of which the first two appear to be partially fused; proximal ends of the epaxial caudal-fin rays that extensively overlap the associated hypurals; bony fulcral scales just in front of the upper and ventral caudal-fin lobes; body completely naked, with a broad, uniform, mid-dorsal brown-pigmented band along the back.

Remarks: † Holosteus esocinus was created by Agassiz (1835) based on a nearly complete specimen in the collection of the MNHN, Paris (F.Bol175). Recently, Prokofiev (2005) provided a re-examination of the lower Oligocene paralepidids from the Caucasus and Carpathians. Following the taxonomic interpretations of Daniltshenko (1960), Gorbach (1961) and Constantin (2001), Prokofiev (2005) assigned to the genus † Holosteus , the Oligocene barracudina species † Pavlovichthys mariae Menner, 1948 , also providing a diagnosis of the genus. This Oligocene species differs from † H. esocinus by having the articular–quadrate joint located in front of the anterior margin of the orbit, large fang-like teeth with corrugate pattern on lower jaw, more than eight branchiostegal rays, first and second hypurals not fused and anal and pelvic fins with about 25 rays. Our observations clearly indicate that the generic diagnosis provided by Prokofiev (2005) for the genus Holosteus must be restricted to the Oligocene taxon, which, as a consequence, should be referred to a separate genus (see above). The Oligocene species †‘ Holosteus ’ mariae is therefore reassigned to the genus † Pavlovichthys , following the principle of priority of the International Commission on Zoological Nomenclature ( ICZN, 1999). In his analysis, Prokofiev (2005) indicated the generic name † Xiphopterus , erected by Agassiz (1833 –1844) for † Esox falcatus Volta, 1796 , from the Eocene of Monte Bolca as a probable synonym of † Holosteus . The examination of the holotype of † Xiphopterus falcatus housed in the MNHN, Paris (F.Bol544) allows us to exclude such a hypothesis, considering that except for the similar elongated body, none of the diagnostic characters of the Paralepididae can be recognized in this fish.