Coelorinchus nordenskjoeldi, 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 : 157-158

Coelorinchus nordenskjoeldi sp. nov.

( Figs 4N—R , 6J—L )

Material. Holotype: NRM-PZ P.15978 ( Figs 4N—P , 6J—L ) . Paratypes: eight specimens, NRM-PZ P.15979—15980 ( Fig. 4Q, R ). Other material: 11 eroded or fragmentary specimens, NRM-PZ P.15981—15982.

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 Dr Otto Nordenskjold, leader of the Swedish South Polar Expedition 1901—1903.

Diagnosis. OL:OH = 1.9—2.0. Dorsal rim with broad predorsal angle. Ventral rim rather shallow, deepest anteriorly, sometimes flattened at deepest point. CCL: OCL = 1.3; CaL:OsL = 1.3—1.45. Collum narrow, ventrally indented, without pseudocolliculum.

Description. Moderately elongate and moderately thin otoliths of up to at least 6 mm in length (holotype 5.7 mm long). OH:OT = 2.6—3.0. Dorsal rim highest anteriorly above ostial collum with broad predorsal angle, rim somewhat undulating, posteriorly regularly declining with very broad, indistinct postdorsal angle near end of cauda. Ventral rim moderately shallow, deepest below ostium and deepest area flattened in large specimens. Anterior rim with obtuse angular tip at level of ostium; posterior rim tapering, somewhat projecting, rounded, with tip at level of cauda.

Inner face slightly convex with distinctly supramedian, moderately narrow and shallow sulcus. Ostium distinctly shorter than cauda. Ostial and caudal colliculi well marked, with narrow, ventrally indented collum; no pseudocolliculum. Dorsal depression narrow, indistinct; ventral furrow feeble, close to ventral rim of otolith; few radial furrows along rims, diminishing in large specimens. Outer face almost flat, with many radial furrows coalescing at centre of outer face without umbo.

Remarks. Coelorinchus nordenskjoeldi was the most common species at the collection site. Yet it shows little variability, being mainly restricted to the expression of the ornamentation of the otolith rims and the outer face.

Coelorinchus nordenskjoeldi is readily distinguished from the co-occurring C. balushkini through its more elongate shape (OL:OH = 1.9—2.0 vs. 1.7) and narrow, indented collum without pseudocolliculum (vs. moderately wide collum and with pseudocolliculum). There are no comparable species from other Eocene locations of the Southern Ocean.

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.