Ampheristus brevicaudatus Lin & Steurbaut & Nolf 2024, sp. nov.
Creators: name: Lin, Chien-Hsiang
name: Steurbaut, Etienne
name: Nolf, Dirk
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Ophidiiformes
Ophidiidae
Ampheristus
Ampheristus brevicaudatus

description: 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.
Stratigraphic and geographic distribution
Ypresian: Bashi Formation, Alabama; Potapaco Member, Virginia; Woodstock Member, Maryland.
description: Published as part of Lin, Chien-Hsiang, Steurbaut, Etienne & Nolf, Dirk, 2024, Early Eocene fish otoliths from the eastern and southern USA, pp. 203-240 in European Journal of Taxonomy 935 on pages 217-219, DOI: 10.5852/ejt.2024.935.2557, http://zenodo.org/record/11526096