Bauzaia gibbosa, 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 : 216-217

Bauzaia gibbosa sp. nov.

urn:lsid:zoobank.org:act:6C930371-0974-49BC-B693-778E70E26798

Fig. 6A

Diagnosis

OL/OH = 1.5, OsL/CaL = 2.8. Large, oval otoliths with salient and pointed posterodorsal angle. Straight, wide, well-divided sulcus; ostium large, elongate; cauda short, rectangular. Ventral area markedly large.

Etymology

‘ Gibbosus, a, um ’ = ‘hump bearing’. Alludes to the very convex inner face of the otoltihs.

Type material examined

Holotype UNITED STATES OF AMERICA • Right otolith; Maryland, Loyola Retreat House, N of Popes Creek, Woodstock Member; Fig. 6A ; IRSNB P 10731 .

Paratypes (2 in total) UNITED STATES OF AMERICA • 2 otoliths very badly preserved, not figured; Maryland, Loyola Retreat House, N of Popes Creek, Woodstock Member ; IRSNB .

Type locality and horizon

United States of America, Loyola Retreat House, N of Popes Creek (Maryland), Woodstock Member.

Dimensions of the holotype

Length = 3.77 mm; height = 2.56 mm; thickness = 1.00 mm.

Description

The otoliths are thick and rounded, with a salient, pointed posterior end. The inner face is convex and the outer face is strongly concave. The margins are smooth. The sulcus is straight, broad, and reaching, but not opening, to the margins of both anterior and posterior rims. It is divided into an elongate ostium and a very short cauda, which is rectangular and slightly pointing downwards. The ventral area is markedly large, semicircular and forming the general shape of the otoliths.

Remarks

The otolith characters of the new species, Bauzaia gibbosa sp. nov., display a mix of those seen in the other two congeneric species, B. mucronata (Koken, 1891) , and B. lamberi Dante & Frizzell, 1965 , but differ from them by lacking the notable antero-dorsal bulging expansion of the dorsal rim. The appearance and shape of the otoliths of B. gibbosa are most similar to those of B. lamberi , but the former has a sulcus type resembling that of B. mucronata , especially the rectangular shape of the cauda. The new species is very rare and only known from the type locality.

Stratigraphic and geographic distribution

Ypresian: Woodstock Member, Maryland.

Figures

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.