Coelorinchus balushkini, Schwarzhans & Mors & Engelbrecht & Reguero & Kriwet, 2017

Schwarzhans, Werner, Mors, Thomas, Engelbrecht, Andrea, Reguero, Marcelo & Kriwet, Jurgen, 2017, Before the freeze: otoliths from the Eocene of Seymour Island, Antarctica, reveal dominance of gadiform fishes (Teleostei), Journal of Systematic Palaeontology 15 (2), pp. 147-170 : 157

Coelorinchus balushkini sp. nov.

( Figs 4S—U , 6M, N )

Material. Holotype: NRM-PZ P.15976 ( Figs 4S—U , 6M, N ) . Paratypes: two specimens, NRM-PZ P.15977.

Occurrence. Telm 5 unit; ‘ Natica horizon’, Cucullea I member, La Meseta Formation, late Ypresian, early Eocene. Site IAA 1/90, Seymour Island, Antarctica.

Etymology. Named in honour of A. V. Balushkin (St Petersburg, Russia) in recognition of his contribution to the knowledge of Antarctic fishes, fossil and Recent.

Diagnosis. OL:OH = 1.7. Dorsal rim with marked predorsal angle. Ventral rim moderately deeply curved, deepest anteriorly, flattened at deepest point. CCL: OCL = 1.6; CaL:OsL = 1.45. Collum moderately wide, with faint pseudocolliculum.

Description. Moderately compressed and moderately thin otoliths of up to at least 6 mm in length (holotype 6.0 mm long). OH:OT = 2.7. Dorsal rim highest anteriorly above ostial collum with rather sharp predorsal angle, rim somewhat undulating, posteriorly regularly declining without prominent angle. Ventral rim deep, deepest below ostium and deepest area flattened. Anterior rim blunt, with obtuse angular tip at level of ostium; posterior rim tapering, rounded, with tip at level of cauda.

Inner face moderately convex with distinctly supramedian, moderately narrow and shallow sulcus. Ostium distinctly shorter than cauda and narrower. Ostial and caudal colliculi well marked, with relatively wide collum in between; ostial colliculum usually reduced towards anterior tip of otolith. Collum narrowed from ventral with short, indistinct pseudocolliculum. Dorsal depression narrow, indistinct; no ventral furrow; dorsal and ventral fields with some radial furrows from the marginal crenulation. Outer face almost flat, with many radial furrows coalescing in a shallow umbo opposing the collum of the inner face.

Remarks. A typical species of the genus Coelorinchus characterized by its rather compressed outline, the high dorsal rim and the presence of a small and short pseudocolliculum. It resembles C. buonaiutoi Schwarzhans, 1985 from the late Eocene of South Australia, but differs in the well-developed and sharp predorsal angle (vs. depressed) and the absence of a ventral furrow on the ventral field (vs. distinctly present).

Figures

Figure 4. Drawings of Eocene otoliths from Seymour Island. A, B, Tripterophycis immutatus Schwarzhans, 1980, NRM-PZ P.15969, mirror imaged; A, inner face; B, dorsal view. C—F, Macruronus eastmani sp. nov.; C—E, holotype, NRM-PZ P.15970, mirror imaged; C, inner face; D, outer face; E, ventral view; F, paratype, NRM-PZ P.15971, inner face. G—M, Palimphemus seymourensis sp. nov.; G—I, holotype, NRM-PZ P.15973, mirror imaged; G, inner face; H, ventral view; I, outer face; J, paratype, NRM-PZ P.15975, mirror imaged, inner face; K—M, paratypes, NRM-PZ P.15974; K, inner face, mirror imaged; L, ventral view; M, inner face. N—R, Coelorinchus nordenskjoeldi sp. nov.; N—P, holotype, NRM-PZ P.15978; N, inner face; O, ventral view; P, outer face; Q, R, paratype, NRM-PZ P.15979, mirror imaged; Q, inner face; R, ventral view. S—U, Coelorinchus balushkini sp. nov., holotype, NRM-PZ P.15976; S, inner face; T, ventral view; U, outer face. V, W, Coelorinchus sp., NRM-PZ P.15911; V, inner face (strongly eroded); W, ventral view.

Figure 6. Eocene otoliths from Seymour Island. A, Argentina antarctica sp. nov., holotype, NRM-PZ P.15964, mirror imaged, inner face. B, C, Diaphus? marambionis sp. nov., holotype, NRM-PZ P.15966; B, inner face; C, ventral view. D—F, Macruronus eastmani sp. nov., holotype, NRM-PZ P.15970, mirror imaged; D, inner face; E, ventral view; F, outer face. G—I, Palimphemus seymourensis sp. nov., holotype, NRM-PZ P.15973, mirror imaged; G, inner face; H, ventral view; I, outer face. J—L, Coelorinchus nordenskjoeldi sp. nov., holotype, NRM-PZ P.15978; J, inner face; K, ventral view; L, outer face. M, N, Coelorinchus balushkini sp. nov., holotype, NRM-PZ P.15976; M, inner face; N, ventral view. O, P, Hoplobrotula? antipoda sp. nov., holotype, NRM-PZ P.15984, mirror imaged; O, inner face; P, ventral view. Q, Notoberyx cionei gen. nov., sp. nov.; holotype, NRM-PZ P.15987, inner face. R, Cepola anderssoni sp. nov., holotype, NRM-PZ P.15996, mirror imaged, inner face.