Orthacanthus lintonensis, Babcock, 2024

Babcock, Loren E., 2024, Replacement names for two species of Orthacanthus Agassiz, 1843 (Chondrichthyes, Xenacanthiformes), and discussion of Giebelodus Whitley, 1940, replacement name for Chilodus Giebel, 1848 (Chondrichthyes, Xenacanthiformes), preoccupied by Chilodus Mueller & Troschel, 1844 (Actinopterygii, Characiformes), ZooKeys 1188, pp. 219-226 : 219

Orthacanthus lintonensis nom. nov.

Fig. 1B

Diplodus gracilis Newberry, 1857: 99.

Diplodus gracilis : Newberry 1873: 334-336.

Diplodus gracilis : Newberry 1874: 330-331.

Diplodus gracilis : Newberry 1875a: 45, pl. LVIII, figs 3, 3a.

Diplodus gracilis : Newberry 1875b: 45, pl. LVIII, figs 3, 3a.

Xenacanthus gracilis (Newberry, 1857): Olson 1946: 290-291.

Xenacanthus compressus (Newberry, 1857): Hotton 1952: 496, 499.

Orthacanthus compressus (Newberry, 1857): Hook and Baird 1986: table 2.

Orthacanthus gracilis (Newberry, 1857): Hampe 1988: 292.

Orthacanthus compressus : Hook and Baird 1988: table 1.

Orthacanthus gracilis : Hampe 1994: 63.

Orthacanthus compressus : Johnson 1999: 243-245.

Orthacanthus gracilis : Hampe 2003: 209-210.

Syntypes.

Teeth, repository unknown, previously illustrated by Newberry (1875a: 45, pl. LVIII, figs 3, 3a; 1875b:45, pl. LVIII, figs 3, 3a).

Type locality.

Upper Freeport Coal (Carboniferous), from the Diamond Coal Mine, Linton, Jefferson County, Ohio, USA.

Etymology.

The species refers to Linton, Ohio, the type locality.

Remarks.

The new species-group name Orthacanthus lintonensis nom. nov. replaces Diplodus gracilis Newberry, 1857, which after recombination as Orthacanthus gracilis (Newberry, 1857) is a junior secondary homonym of Orthacanthus gracilis (Giebel, 1848).

Detailed study of xenacanthiform materials from the Linton Lagerstätte is needed, and the type specimens need to be re-examined. Much of the systematic work on fish taxa described from Linton after 1900 has involved non-type specimens. Indeed, most published illustrations of Linton fish types are line-art drawings (e.g. Newberry 1873, 1874, 1875a, 1875b; herein, Fig. 1B, C ), often with generous “restoration;” few of the types, even the ones whose repositories are known, have been photographically illustrated. Pending restudy of the type specimens of xenacanthiform sharks from the Linton Lagerstätte, O. lintonensis nom. nov. is proposed here as an available name that can compete in priority with other names, not as a junior synonym of any other species (compare Hotton 1952; Hook and Baird 1986; Johnson 1999).

Figures

Figure 1. Original 19 th century figures of Carboniferous-age xenacanthiform shark fossils from Saxony-Anhalt, Germany, and Ohio, USA A Orthacanthus gracilis (Giebel, 1848), tooth, holotype (Geiseltalmuseum Halle, GTM 1095), two views; reproduced from Giebel (1849: pl. XXIX, fig. 2 a, b), 7.7 mm long. Wettin-Schichten, Wettin / Saalegebiet, Saxony-Anhalt, Germany B Orthacanthus lintonensis nom. nov., replacement name for Diplodus gracilis Newberry, 1857 a, two teeth, syntypes (repository unknown); reproduced from Newberry (1875 a: pl. LVIII, figs. 3, 3 a), ca 5 and 13 mm long. Upper Freeport Coal, Allegheny Group, Diamond Coal Mine, Linton, Ohio, USA C Orthacanthus adamas nom. nov., replacement name for Orthacanthus gracilis Newberry, 1875 a, dorsal spine, illustration is a composite based on syntypes (Orton Geological Museum, OSU 4467 A, 4467 B); reproduced from Newberry (1875 a, pl. LIX, fig. 7), ca 71 mm long. Upper Freeport Coal, Allegheny Group, Diamond Coal Mine, Linton, Ohio, USA D Orthacanthus carbonarius (Germar, 1844), two teeth, syntypes (repository unknown) of Chilodus tuberosus Giebel, 1848; reproduction of Giebel (1849: pl. XXIX, figs. 1, 1 a, 1 b as), length unknown. Wettin-Loebejun, Saxony-Anhalt, Germany E Orthacanthus carbonarius (Germar, 1844), tooth, syntype (repository unknown) of Lamna carbonaria Germar, 1844; reproduced from Germar (1844: pl. 1, fig. 1), ca 20 mm long. Presumably from Saxony-Anhalt, Germany.