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Présence du genre Lepidocottus Sauvage, 1875 (Teleostei, Gobioidei) dans l’Oligocène inférieur des environs de Céreste (Alpes-de-Haute-Provence, France)

Jean GAUDANT

fr Geodiversitas 37 (2) - Pages 229-235

Published on 26 June 2015

Occurrence of the genus Lepidocottus Sauvage (Teleostean fishes, Gobioidei) in the lower Oligocene of the Céreste vicinity (Alpes-de-Haute-Provence, France)

Although they are rather scarce, articulated skeletons of gobioid fishes were found by private collectors when excavating in the vicinity of Céreste (Alpes-de-Haute-Provence, France) fossiliferous localities that have yielded numberless skeletons of Dapalis macrurus (Agassiz, 1836). The studied specimens were collected at two different outcrops of the lower Oligocene (Stampian) Campagne-Calavon Formation: near Viens and at Pichovet, near Vachères, a locality that has also yielded an almost complete skeleton of a primitive ruminant, Bachitherium sp.

Anatomical description
These gobioids are rather small fishes having a standard length which does not significantly exceed 100 mm. One of them, which is kept at Apt (Vaucluse), in the Museum of the Luberon Regional Nature Park (PNRL-MER-7) shows a palatine lacking the postero-dorsal process, like that of the Recent eleotrids and butids. The vertebral column consists of ten abdominal and 15 or 16 postabdominal vertebrae having elongate centra. The caudal fin, which is paddle shaped, is composed of 13 principal rays, both articulated and furcated, and about ten dorsal and ventral marginal rays. The caudal axial skeleton comprises three components: the posterior uro-terminal complex, which is fused with the triangular upper hypural plate (Hy 3+4), and articulates both with the parhypural (PHy) and the triangular lower hypural plate (Hy 1+2). Dorsally, the triangular upper hypural plate is surmonted by a narrow hypural (Hy 5). Two epurals are present in front of it. The anterior dorsal fin comprises six slender spines that are supported by six pterygiophores. The first of them is inserted behind the neurapophyse borne by the fourth abdominal centrum. The other ones are disposed according to the formula 2-2-1-1. The posterior dorsal fin consists of one slender spine and eight rays that are supported by nine pterygiophores. An interneural gap is present between the last pterygiophore of the anterior dorsal fin and the first pterygiophore of the posterior dorsal fin. The anal fin, which is opposed to the posterior dorsal fin, begins slightly behind it. It is composed of one slender spine and seven rays and is supported by seven pterygiophores. There are at least 13 rays in the pectoral fins. The pelvic fins, which are inserted slightly in front of the base of the pectoral rays, consists of a slender spine and five rays. The body is covered with poorly preserved scales. There is no lateral line.

Relationships
The gobioid fishes described precedently share with the recent eleotrids and butids a significant character: a palatine lacking a postero-dorsal process, like in the upper Oligocene species from Aix-en-Provence Lepidocottus aries (Agassiz, 1839) (Gierl et al. 2013). A comparison with this species shows that the two specimens from the lower Oligocene of Haute-Provence differ mainly from it by the possession of slightly smaller posterior dorsal and anal fins that consist respectively of one spine and eight rays – against one spine and 9-10 rays in Lepidocottus aries (Agassiz, 1839) – and one spine and seven rays (instead of one spine and nine rays). For this reason, they are here described as Lepidocottus cf. aries (Agassiz, 1839).

Keywords :

Lower Oligocene (Rupelian/Stampian), Fishes, Teleostei, Gobioidei, Lepidocottus, Alpes de Haute-Provence

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