Early Eocene fish otoliths from the eastern and southern USA Author Lin, Chien-Hsiang 50EBAA8C-3EE0-4655-A0BB-694D9A8F49BA Biodiversity Research Center, Academia Sinica, 128 Academia Road, Seca 2, Nankang, Taipei 11529, Taiwan. chlin.otolith@gmail.com Author Steurbaut, Etienne 9A884B23-5D05-4D6C-92B8-08B321D16845 Royal Belgian Institute of Natural Sciences, 29 Vautier Street, 1000 Brussels, Belgium. & Department of Earth and Environmental Sciences, KU Leuven, Celestijnenlaan 200 E, 3001 Leuven, Belgium. etienne.steurbaut@naturalsciences.be Author Nolf, Dirk 6BCC71A0-1BEE-4BC0-BDFC-D070609DEFAB Royal Belgian Institute of Natural Sciences, 29 Vautier Street, 1000 Brussels, Belgium. dirk.nolf@scarlet.be text European Journal of Taxonomy 2024 2024-06-04 935 203 240 https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2557/11559 journal article 298344 10.5852/ejt.2024.935.2557 b9f405d9-04c7-4cfe-9f28-b6edc3416cb0 2118-9773 11526096 6C66A1E4-7EA4-45B7-B261-5D3ED749568E 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. 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. 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 .