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 Ampheristus brevicaudatus sp. nov. urn:lsid:zoobank.org:act: 4ACB919D-6809-44FF-AE33-560D58E9276B Fig. 6D–G Diagnosis OL/OH = 1.8–2.1, OsL/CaL = 2.0–3.1. Otoliths with notable pointed or protruding posterior rim. Sulcus straight, elongate, well-divided into ostium and cauda, both filled with colliculum. Cauda short, oblong, ventrally oriented posteriorly. Etymology ‘ Brevicaudatus , a , um ’ = ‘having a short cauda’. Refers to the very small and short cauda. Type material examined Holotype UNITED STATES OF AMERICA • Left otolith ; Virginia , Rappahannock River , Potapaco Member; Fig. 6D ; IRSNB P 10734 . Paratypes ( 14 in total) UNITED STATES OF AMERICA • 12 otoliths of which three are figured: Fig. 6E–G ; same collection data as for holotype; IRSNB P 10735 to P 10737 • 1 otolith ; Alabama , Cave Branch , Bashi Formation ; IRSNB • 1 otolith ; Maryland , Loyola Retreat House , N of Popes Creek , Woodstock Member; IRSNB . Type locality and horizon United States of America , Rappahannock River ( Virginia ), Potapaco Member. Dimensions of the holotype Length = 3.85 mm ; height = 1.84 mm ; thickness = 0.79 mm . Description This species has fusiform otoliths with a postero-ventral angle that is extended. While the holotype has a pointed angle ( Fig. 6D ), it is typically blunt in other specimens (probably a result of abrasion). The margins are smooth, but may be slightly lobated in some specimens along the anterior and postero-dorsal rims ( Fig. 6F ). The antero-dorsal rim is slightly elevated, but not protruding dorsally, while the anterior rim forms a large, obtuse rostrum. The inner face is slightly convex; the outer face is concave posteriorly, but may be slightly convex anteriorly. The sulcus is well-divided into an elongate ostium and a very short, much narrower cauda that points downwards. Both the ostium and cauda are filled with a colliculum each. The ventral area is of similar size to the dorsal area. There is a shallow, elongate dorsal depression above the crista superior. Remarks Otoliths of Ampheristus are mainly known from Paleogene European deposits ( Nolf 2013 ), with two species from the Lutetian of New Zealand ( Schwarzhans 2019 ). The first record of the genus from the New World region is Ampheristus americanus Schwarzhans & Stringer, 2020 , a recently described Maastrichtian–Danian species from the southern USA ( Schwarzhans & Stringer 2020 ; Stringer & Schwarzhans 2021 ). The cauda of A. brevicaudatus sp. nov. is much shorter than that of A. americanus . The posterior rim of A. brevicaudatus also appears to be more pointed than the truncated rim of A. americanus . The occurrences of the new species and A. americanus indicate a much wider geographic distribution and longer stratigraphic range of Ampheristus . Fig. 6. Fish otoliths from the US lower Eocene formations. A . Bauzaia gibbosa sp. nov. , Loyola Retreat House, N of Popes Creek, Woodstock M., Maryland (IRSNB P 10731). B–C . Bauzaia mucronata (Koken, 1891) , Taylor’s Branch of Two Mile Creek, Reklaw Fm., Texas (IRSNB P 10732, P 10733). D–G . Ampheristus brevicaudatus sp. nov. , Rappahannock River, Potapaco Member, Virginia. D . Holotype (IRSNB P 10734). E–G . Paratypes (IRSNB P 10735 to P 10737). 1 = ventral view; 2 = inner view. Scale bars = 1 mm. Stratigraphic and geographic distribution Ypresian: Bashi Formation, Alabama ; Potapaco Member, Virginia ; Woodstock Member, Maryland .