Glyptophidium, Alcock, 1889

Lin, Chien-Hsiang & Nolf, Dirk, 2022, Middle and late Eocene fish otoliths from the eastern and southern USA, European Journal of Taxonomy 814, pp. 1-122 : 52-54

“aff. Glyptophidium ” stringeri sp. nov.

urn:lsid:zoobank.org:act:B65B9A77-A733-41EB-9AEA-61F744665C4B

Fig. 17G–N

Diagnosis

OL/OH = 1.11–1.32. Otoliths with a large protruding antero-dorsal expansion and a pointed posterior rim. Sulcus wide, oblong, and not divided into ostium and cauda; it is filled with a large colliculum.

Etymology

This species is dedicated to Gary L. Stringer (University of Louisiana at Monroe) for his many contributions to the knowledge of fossil otoliths from the Gulf Coast area.

Material examined

Holotype UNITED STATED OF AMERIA • Right otolith; Texas, Alabama Ferry; “ Stone City beds ”; Fig. 17G ; IRSNB P 10066 .

Paratypes UNITED STATES OF AMERICA • 221 otoliths, of which five are figured: Fig. 17H–L ; same collection data as for holotype; IRSNB P 10067–10071 • 543 otoliths, of which two are figured: Fig. 17M–N ; Texas, Little Brazos River, Stenzel loc.; Wheelock Member ; IRSNB P 10072–10073 • 756 otoliths; same locality as for preceding; Landrum Shale Member .

Type locality and horizon

United States of America, Alabama Ferry (Texas), “Stone City beds”.

Dimensions of the holotype

Length = 2.75 mm; height = 2.23 mm; thickness = 0.59 mm.

Description

The otoliths of this species are especially characterized by a large protruding antero-dorsal expansion, which is triangular and pointing upward, and by their acuminated posterior end. The anterior rim of the dorsal expansion can be smooth or undulated. The anterior rim of the otolith is almost vertical, forming a blunt rostrum. The posterior part of the otolith shows a triangular shape; it tapers strongly after a well-marked postero-dorsal angle. The ventral rim is smoothly curved and its deepest part is located in the middle of the otolith. This rim may be crenulate in smaller specimens ( Fig. 17L ). The inner face is slightly convex; the outer face is nearly flat, but may be slightly convex anteriorly ( Fig. 17G ). A long and wide sulcus occupies nearly the entire length of the inner face. It is located in the middle of that face, and is completely filled by a single colliculum. This sulcus is not clearly divided into ostial and caudal parts. The cristae are well-developed but not ridge-like. The dorsal and the ventral areas are almost equal in size.

Remarks

The otoliths of this new species are somewhat similar looking to those of the co-occurring Hoplobrotula melrosensis (Dante & Frizzell, 1965) and also to those of Bauzaia mucronata ( Koken, 1888) , but this similarity is only superficial and restricted to the outline of the otoliths. Firstly, the sulcus of both H. melrosensis and B. mucronata are clearly divided into an ostium and cauda, and secondly, their posterior end is much more extended and spine-like. The sulcus of “aff. G.” stringeri sp. nov. is straight, and the posterior tip is located in their lower part. Although the posterior part of the otoliths resembles that of the extant genus Glyptophidium , this genus has a sulcus type with distinct ostium and cauda. The lack of a clear division between ostium and cauda in the sulcus of “aff. G.” stringeri sp. nov. suggests affinities to Glyptophidium , but does not imply a certain attribution to that genus. Two related Eocene species with similar features are “aff. G.” biarritzense (Sulc, 1932) from the Aquitaine Basin and “aff. G.” pseudobiarritzense Nolf & Bajpai, 1992 from Java ( Nolf & Bajpai 1992: pl. 3 fig. 11).

Stratigraphic and geographic distribution

Lutetian: “Stone City beds”, Texas; Dobys Bluff Tongue of Kosciusko Formation, Mississippi. Bartonian: Landrum Member of Cook Mountain Formation, Texas; “upper” Lisbon Formation, Alabama.

Figures

Fig. 17. Fish otoliths from the US middle and upper Eocene. A–F. Signata stenzeli Dante & Frizzell, 1965, “Stone City beds”, Stone City Bluff, Brazos River, sample 2 from bed P, Texas (IRSNB P 10060– 10065). G–N. “aff.Glyptophidium” stringeri sp. nov.G–L. “Stone City beds”, Alabama Ferry, on Trinity River, North, Texas (IRSNB P 10066–10071). M–N. Wheelock M., Little Brazos River, Stenzel loc., Texas (IRSNB P 10072–10073). G. Holotype (IRSNB P 10066). H–N. Paratypes (IRSNB P 10067– 10073). 1 = ventral view; 2 = inner view. Scale bars = 1 mm.