Coryphaenoides biobtusus, Lin & Brzobohatý & Nolf & Girone, 2017

Lin, Chien-Hsiang, Brzobohatý, Rostislav, Nolf, Dirk & Girone, Angela, 2017, Tortonian teleost otoliths from northern Italy: taxonomic synthesis and stratigraphic significance, European Journal of Taxonomy 322, pp. 1-44 : 5-10

Coryphaenoides biobtusus sp. nov.

urn:lsid:zoobank.org:act:58E20EDF-1778-4704-924E-886C4028B5A1

Fig. 8 E–F

Diagnosis

This species is characterised by nearly rectangular and thickset otoliths. The anterior rim of the otoliths is blunt, which makes the highest part of the otolith at the anterior portion. The dorsal rim undulates, with the middle part being concave, while both the anterior and posterior parts are higher and angular. The posterior rim is rounded, smaller than the anterior one. The sulcus is filled with two large elongate collicula.

Etymology

The species epithet is derived from the Latin ‘ biobtusus , a, um ’, which means obtuse (or blunt) on both sides, alluding to the blunt anterior and posterior rims of the otoliths.

Type material examined

Holotype

ITALY: a left otolith ( IRSNB P 9684 , Fig. 8 E ).

Paratype

ITALY: 1 specimen ( IRSNB P 9685, Fig. 8F ).

Type locality and horizon

ITALY: Tortonian Clay at Alba, Tanaro River (massive clays, 5 m upstream of reference sandstone ledge).

Dimensions of the holotype

Length = 4.95 mm, height = 3.05 mm, thickness = 1.35 mm.

Description

The otoliths are very thick. The inner face is slightly convex; the outer face is markedly convex in all directions, but with the strongest convexity in the antero-posterior direction ( Fig. 8E 1 ). The anterior rim of the otolith is oblique, bears a blunt rostrum, and slightly protrudes in its ventral part; the posterior rim is blunt and shorter than the anterior one. The ventral rim is smooth, curving gently upwards in its posterior portion. The sulcus is pince-nez-shaped (pince-nez is a kind of glasses without ear branches that are worn by pinching the nose), rather shallow, and with unclear ends at both the anterior and the posterior ends. The cristae are well-marked. The collicula are large, highly elevated, nearly rectangular in shape, and lie symmetrical to the junction between ostium and cauda. The dorsal area is narrower than the ventral one. A deep ventral furrow running along the ventral rim is especially evident in the paratype.

Remarks

These two well-preserved otoliths represent adult specimens of this species, which allow a reasonable assignment to the genus Coryphaenoides Gunnerus, 1765 . In some Recent species, for example in C. armatus (Hector, 1875) (see Nolf 2013: pl. 92), the general outline of the otolith and the sulcus configuration are comparable to that of this fossil species.

Figures

Fig. 8. Tortonian fish otoliths from northern Italy. A. Coelorinchus caelorhincus (Risso, 1810), Montegibbio (IRSNB P 9772). B. Coryphaenoides contortus (Bassoli, 1906), Sant’Alosio (IRSNB P 9773). C–D. “Merluccius” rattazzii sp. nov., Sant’Alosio (IRSNB P 9686 (holotype)–P 9687). E–F. Coryphaenoides biobtusus sp. nov., Alba, Tanaro (5 m) (IRSNB P 9684 (holotype)–P 9685). G–H. Nezumia aff. sclerorhynchus (Valenciennes, 1838), Alba, Tanaro (5 m) (IRSNB P 9774–P 9775). I–J. Moridae indet., Sant’Agata Fossili (IRSNB P 9776–P 9777). K. Nezumia ornata (Bassoli, 1906), Montegibbio (IRSNB P 9778). L–M. Coelorinchus robustus (Robba, 1970); L. Stazzano, M. Sant’Alosio (IRSNB P 9779–P 9780). N. Gadiculus labiatus (Schubert, 1905), Torrente Stirone (IRSNB P 9781). O–P. Melanonus paralyconus Schwarzhans, 1986, Mondovi, Madonna della Neve (IRSNB P 9782– P 9783). Q–R. Melanonus triangulus (Robba, 1970), Costa Vescovato (IRSNB P 9784–P 9785). S. Gadiculus argenteus Guichenot, 1850, Torrente Stirone (IRSNB P 9786). 1 = ventral view; 2 = inner view. Scale bars = 1 mm.

Fig. 1. Map showing the sampling sites.