Maeotichthys salebrosus, Schwarzhans & Bratishko & Vernyhorova, 2023

Schwarzhans, Werner W., Bratishko, Andriy & Vernyhorova, Yuliia V., 2023, Approaching the Khersonian Crisis: Fish otoliths from the upper Bessarabian (middle Sarmatian s. l.; Late Miocene) of Jurkine (Kerch Peninsula, Crimea), Palaeontologia Electronica (a 31) 26 (2), pp. 1-15 : 6

Maeotichthys salebrosus n. sp.

Figure 3F–Q

zoobank.org/ 02CD4720-EAEB-4F55-91B3-B8506A333089

?1968 Otolithus (Clupea) fimbriosus – Suzin, 1968, plate 18, figure 4 [name not available according to ICZN article 13.1.1].

Holotype. Figure 3I–K , NMNH ГКН 5960 079, Jurkine, Kerch Peninsula, Crimea, microfauna sample #21, lower Dnipropetrovskian , Bessarabian , middle Sarmatian s.l.

Paratypes. Four specimens, SMF PO 101.339 , Jurkine, Kerch Peninsula, Crimea, microfauna sample #20, upper Vasylivkian , Bessarabian , middle Sarmatian s.l .

Name. From salebrosus (Latin) = rugged, referring to the rugged appearance of the otoliths.

Diagnosis. Robust, thick otoliths with long rostrum (18–25% of OL). OL:OH = 1.65–1.8; OH:OT = 1.6– 2.0. Ventral rim relatively shallow, irregular, rugged. Inner face flat with marked crista superior and inferior and bulged area behind sulcus.

Description. The otoliths of M. salebrosus are small, reach 1.25 mm in length (holotype 1.15 mm), and are relatively thick and robust. The rostrum is long and variably pointed or rounded; an antirostrum is not clearly developed, and the excisura is wide and not deep, more like a broad concavity. The dorsal rim is low, irregularly curved, and can be smooth ( Figure 3F, I ) or coarsely undulating ( Figure 3L ). The ventral rim likewise is irregularly curved and relatively shallow; only rarely is the postventral region somewhat expanded ( Figure 3L ).

The inner face is almost flat in the horizontal direction but slightly curved in the vertical direction. It bears a moderately long and distinctly deepened sulcus that shows equally long and wide ostium and cauda, which are indistinctly marked by a variable indentation of the dorsal sulcus margin or a deepening of the ostium toward the cauda; OL:SuL = 1.3–1.4; OsL:CaL = 1.3. The crista superior and inferior are well developed, ridge-like (best seen on anterior views in Figure 3J, M, P ), and the area behind the caudal tip is more or less strongly bulged. The dorsal depression is distinct and relatively large; a ventral depression or furrow underlies most of the crista inferior. The outer face is variably convex and relatively smooth. The otolith rims are thick, contributing to the overall thick appearance of the otoliths.

Discussion. Maeotichthys salebrosus differs from M. wilhelmi in the more robust, rugged appearance and the relatively shallow ventral rim (vs. ventral rim expanded along the postventral rim and recessed below the rostrum). A specimen figured by Suzin (1968) as Clupea fimbriosus from the middle Sarmatian of the Crimea may represent the same species based on the rather shallow ventral rim and not M. wilhelmi as suggested by Bratishko et al. (2023); nevertheless, the name is not available according to the regulations of the ICZN. Maeotichthys salebrosus occurs in parallel in the late Vasylivkian but not in earlier, restricted marine sediments. We therefore assume that M. salebrosus was probably adapted to a more brackish marine environment, based, however, on a limited number of specimens.

Figures

FIGURE 3. Otoliths. A–D Ophichthidae indet. juv., SMF PO 101.337, microfauna sample #20, A = anterior view, B = inner face, C = dorsal view, D = ventral view. E Maeotichthys wilhelmi (Djafarova, 2006), SMF PO 101.338, microfauna sample #20, inner face (reversed), digitally composed from three broken segments. F–Q Maeotichthys salebrosus n. sp., F, I, L, O = inner faces, G, J, M, P = anterior views, H, K, N, Q = ventral views, I–K holotype, NMNH ГКН 5960 079 (reversed), microfauna sample #21, F–H, L–Q paratypes, SMF PO 101.339, microfauna sample #20. R–Y Scythogobius spissus n. gen., n. sp., R, V, W = inner faces, S = dorsal view, Y = ventral view, T, U = posterior views, X = anterior view, R–T holotype, NMNH ГКН 5960 080 (reversed), microfauna sample #20, U–Y paratypes (U–V reversed), SMF PO 101.340, microfauna sample #20. Z–AB Anatirostrum profundorum (Berg, 1927), Recent, Caspian Sea, Gilan, Iran, CMNFI 1999-0023.1, Z = inner face, AA = dorsal view, AB = posterior view.