Trachurus insectus, Schwarzhans, 2023

Trachurus insectus n. sp.

Figure 22b–d View Fig

Holotype SMF PO 101.283 ( Fig. 22b View Fig ), Dar bel Hamri, coquina at river level of Oued Beth, Zanclean.

Paratype 11 specimens SMF PO 101.284 , same data as holotype .

Etymology From insectus (Latin) = notched, referring to the characteristic postdorsal notch.

Diagnosis OL:OH = 1.55–1.7. Ventral rim with obtuse, rounded midventral angle; dorsal rim with broad lobe behind its middle followed by distinct notch. Rostrum relatively short, 15% OL. Ostium short, CaL:OsL = 2.9– 3.6. Curvature of caudal tip 37–45°, terminating close to postventral rim.

Description Moderately large and thin otoliths up to 6.9 mm in length (holotype). OH:OT = 4.0–4.5. Ventral rim moderately deep, anterior and posterior regions nearly straight, inclined, with rounded midventral angle, smooth or finely crenulated; dorsal rim anteriorly depressed, rising to broad lobe slightly behind middle follwed by deep and distinct notch and slightly expanded postdorsal section, irregularly undulating. Rostrum relatively short (completely preserved only in specimens of Fig. 22b, d View Fig ); antirostrum and excisura very weak. Posterior rim angular.

Inner face slightly convex with distinctly supramedian positioned, deep, relatively narrow and long sulcus. Ostium short, narrow, only slightly widened ventrally. Cauda long, straight, its tip bend downward; caudal tip not widened, terminating close to postventral otolith rim. Dorsal depression narrow, ventrally marked by crista superior, dorsal margin indistinct; ventral field with feeble ventral furrow distant from ventral rim of otolith, smooth above ventral furrow, slightly plicated below. Outer face flat to slightly concave, relatively smooth.

Discussion Tis species is recognized as a member of the genus Trachurus by the otolith shape with the midventral angle and the shape and proportions of the sulcus. It differs from the four extant congeners occurring in the eastern Atlantic in the short rostrum and the peculiar shape of the dorsal rim with the broad lobe behind the middle and the postdorsal notch. Otoliths of the parallel occurrig T. mediterraneus are further distinguished by the regularly rounded and intensely crenulated dorsal rim.