Lesueurigobius stironensis, 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 : 12-13

Lesueurigobius stironensis sp. nov.

urn:lsid:zoobank.org:act:CCEB6FA7-DA02-47B3-8A38-D7CA369E9E79

Fig. 11 F–I

Diagnosis

This species is characterised by high, pentagonal otoliths. The shape of the dorsal rim is very characteristic in bearing 4–6 large lobes, with the highest one located at the middle and lowering towards both ends. The other rims are nearly straight and perpendicular to each other. The sulcus is deep and ventrally directed at the anterior.

Etymology

The species is named after its type locality, the Torrente Stirone.

Type material examined

Holotype

ITALY: a left otolith ( IRSNB P 9689 , Fig. 11F ).

Paratypes

ITALY: 21 specimens of which 3 are figured ( IRSNB P 9690– P 9692, Fig. 11 G–I).

Type locality and horizon

ITALY: Tortonian Clay exposed in the Torrente Stirone.

Dimensions of the holotype

Length = 1.75 mm, height = 1.80 mm, thickness = 0.55 mm.

Description

The otoliths are tall and pentagonal. The dorsal rim bears 4–6 large lobes; the largest and highest lobe and highest lobe is located in the middle and marks the highest point of the otolith. The anterior and posterior rims are almost straight, and the ventral rim is straight in the holotype but very slightly curved in some of the paratypes (e.g., Fig. 11I ). In some specimens, however, the anterior rim is crenulated at the lower part and a small concavity is observed in the middle part of the posterior rim (e.g., Fig. 11G ). The inner face is more or less flat; the outer face is convex. The sulcus is deep, clearly delimited, and well-divided into ostium and cauda; the anterior part of the ostium is directed ventrally. The cristae are well-developed. The ostium is large and expanded ventrally, with a concavity at the antero-dorsal margin. The cauda is rod-like and rounded at the posterior end. There is a marked swollen collicular crest just below the cauda.

Remarks

The otoliths of this new species are easily recognised and the shape of the dorsal rim is consistent regardless of size among the available material. The sulcus shape and a slightly asymmetric dorsal rim of the otoliths are the main reasons for attributing this new species to the genus Lesueurigobius . Several Lesueurigobius otoliths have been reported from the Miocene of the Mediterranean (e.g., Reichenbacher & Cappetta 1999: pl. 3, figs 1–5, L. vicinalis (Koken, 1891) ; Hoedemakers & Batllori 2005: pl. 11, figs 9–13, Lesueurigobius sp.), but none of them present the characteristic morphology of the dorsal rim as our new species.

Figures

Fig. 11. Tortonian fish otoliths from northern Italy. A. “Sparus” doderleini (Bassoli & Schubert, 1906), Sant’Agata Fossili (IRSNB P 9821). B. Lesueurigobius aff. friesii (Malm, 1874), Torrente Stirone (IRSNB P 9822). C. Lesueurigobius aff. suerii (Risso, 1810), Torrente Stirone (IRSNB P 9823). D. Deltentosteus aff. quadrimaculatus (Valenciennes, 1837), Torrente Stirone (IRSNB P 9824). E. Gobius aff. guerini Chaine & Duvergier, 1931, Montegibbio (IRSNB P 9825). F–I. Lesueurigobius stironensis sp. nov., Torrente Stirone (IRSNB P 9689 (holotype)–P 9692). J–L. Deltentosteus sp., Torrente Stirone (IRSNB P 9826–P 9828). M. Antigonia capros Lowe, 1843, Montegibbio (IRSNB P 9829). N. “Gobius” aff. weileri Bauza Rullan, 1955, Torrente Stirone (IRSNB P 9830). O. “Gobius” brioche (Lin, Girone & Nolf, 2015), Montegibbio (IRSNB P 9831). P–Q. Brachydeuterus speronatus (Bassoli, 1906), Montegibbio (IRSNB P 9832–P 9833). R–S. Gobius aff. paganellus Linnaeus, 1758; R. Torrente Stirone, S. Montegibbio (IRSNB P 9834–P 9835). 1 = ventral view; 2 = inner view. Scale bars = 1 mm.