Neobythites longesulcatus, Lin & Steurbaut & Nolf, 2024

Lin, Chien-Hsiang, Steurbaut, Etienne & Nolf, Dirk, 2024, Early Eocene fish otoliths from the eastern and southern USA, European Journal of Taxonomy 935, pp. 203-240 : 220-222

Neobythites longesulcatus sp. nov.

urn:lsid:zoobank.org:act:E7434385-3EEF-4F21-B545-519B63B9EA49

Fig. 8A–C

Diagnosis

OL/OH = 1.8–1.9, OsL/CaL = 2.5–2.8. Fusiform otoliths with angled posterior rim. Rounded antero-dorsal bulge on dorsal rim. Anterior rim largely blunt. Sulcus very wide and elongate. Ostium markedly elongate, very slightly narrower than rectanglar cauda.

Etymology

‘ Longesulcatus, a, um ’ = ‘provided with a long sulcus’. Refers to the notably elongate sulcus of the species.

Type material examined

Holotype UNITED STATES OF AMERICA • Left otolith; Virginia, Pamunkey River, Hanovertown , Potapaco Member ; Fig. 8A ; IRSNB P 10745 .

Paratypes (3 in total) UNITED STATES OF AMERICA • 3 otoliths of which two are figured: Fig. 8B–C ; Maryland, Loyola Retreat House, N of Popes Creek, Woodstock Member ; IRSNB P 10746 , P 10747 .

Type locality and horizon

United States of America, Pamunkey River, Hanovertown (Virginia), Potapaco Member.

Dimensions of the holotype

Length = 4.99 mm; height = 2.81 mm; thickness = 1.50 mm.

Description

The species is identifiable by its fusiform otoliths, which have a largely blunt anterior rim and a well-marked posterior angle. The dorsal rim is elevated and possesses a blunt antero-dorsal bulge, forming the highest point of the otoliths. The ventral rim is gently curved, and all margins are smooth. The otoliths are thick and possess convex inner and outer faces ( Fig. 8A 1 ). A straight, wide, and well-divided sulcus occupies nearly the entire length of the inner face in the central region of the otoliths. The sulcus does not open to the margins. The ostium is notably elongate and extends over one-third of the sulcus length, and it is very slightly narrower than the short, rectanglar cauda. Above the crista superior, there is a shallow, elongate dorsal depression.

Remarks

The massive, robust otoliths of this new species share many characters with those of “ Neobythites ” auribatianus Lin et al., 2017, from the Lutetian of the Aquitaine Basin ( Lin et al. 2017b: fig. 9a–g), indicating a possible close relationship. Nevertheless, the American species is distinguished by its less pronounced blunt antero-dorsal bulge, more rounded anterior rim, less tapered posterior rim, and somewhat broader sulcus. Moreover, the high resemblance of the sulcus shape and proportions (e.g. OL/ sulcus length, OsL/CaL) and the overall configuration with otoliths of Neobythites allow us to assign this new species to this extant genus (see Lin & Chang 2012: pl. 81).

Stratigraphic and geographic distribution

Ypresian: Potapaco Member, Virginia; Woodstock Member, Maryland.

Figures

Fig. 8. Fish otoliths from the US lower Eocene formations. A–C. Neobythites longesulcatus sp. nov. A. Pamunkey River, Hanovertown, Potapaco Member, Virginia, holotype (IRSNB P 10745).B–C. Loyola Retreat House, N of Popes Creek, Woodstock M., Maryland, paratypes (IRSNB P 10746, P 10747). D–E. “Neobythites” stringeri sp. nov., Hatchetigbee Bluff, Hatchetigbee Fm., Alabama. D. Paratype (IRSNB P 10748). E. Holotype (IRSNB P 10749). 1 = ventral view; 2 = inner view. Scale bars = 1 mm.

Fig. 1. Maps showing the sampling sites on the US Gulf Coastal Plain (Texas, Mississippi, and Alabama) and Atlantic Coastal Plain (A = Virginia and Maryland). 1. Ridge Creek. 2–4. Taylor’s Branch of Two Mile Creek, samples 1–3. 5. Meridian, Gallagher Creek. 6. Meridian, Red Hot Truck Stop. 7. Hatchetigbee Bluff. 8. Cave Branch. 9. Elba Dam on Pea River. 10. Ozark. 11. Pamunkey River, E of Hanover School for boys. 12. Pamunkey River, Hanovertown. 13. Pamunkey River, 1 km W of Hunters Club. 14. Pamunkey River, Hunters Club. 15. Rappahannock River. 16. Loyola Retreat House, N of Popes Creek. 17. Popes Creek, South. 18. Piscataway Creek, Thrift Road ravine.