Orthacanthus adamas, 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 adamas nom. nov.

Fig. 1C

Orthacanthus gracilis Newberry, 1875a: 56-57, pl. LIX, fig. 7.

Orthacanthus gracilis : Newberry 1875b: 56-57, pl. LIX, fig. 7.

Orthacanthus gracilis : Cope 1881: 163.

Pleuracanthus (Orthacanthus) gracilis : Case 1900: 701, pl. I, fig. 4.

Orthacanthus gracilis : Morningstar 1924: 53.

Xenacanthus gracilis (Newberry, 1875a): Olson 1946: 287.

Xenacanthus gracilis : Hook and Baird 1986: 179, table 2.

Xenacanthus gracilis : Hook and Baird 1988: table 1.

Orthacanthus gracilis : Hampe 2004: 209.

Syntypes.

Two dorsal spines, Orton Geological Museum, The Ohio State University, Columbus, Ohio, USA (OSU) 4467A, 4467B, previously illustrated as a composite by Newberry (1875a: pl. LIX, fig. 7; 1875b: pl. LIX, fig. 7).

Type locality.

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

Etymology.

Adamas (Latin, diamond), in allusion to the Diamond Coal Mine, where the species was first collected.

Remarks.

The new species-group name Orthacanthus adamas nom. nov. replaces Orthacanthus gracilis Newberry, 1875a, which is a junior homonym of Orthacanthus gracilis (Giebel, 1848). Newberry (1875a: pl. LIX, fig. 7; 1875b: pl. LIX, fig. 7) illustrated this species with a composite figure based on syntypic dorsal spines. This species should not be confused with the other xenacanthiform species from Linton bearing the species epithet Orthacanthus gracilis , based on teeth, and also referred to Orthacanthus , as discussed above. Replacement names for both taxa will reduce potential confusion. Cope (1881) and Case (1900) extended the stratigraphic range of this species into the Permian.

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.