Paraconger wechesensis, Lin & Nolf & Steurbaut, 2022

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 : 39-40

Paraconger wechesensis sp. nov.

urn:lsid:zoobank.org:act:5369716F-FDB7-4926-90F4-B28096D37553

Fig. 11E–F

Diagnosis

OL/OH = 1.17–1.25. Elliptic otoliths with protruding dorsal area in the middle. Sulcus wide, long, but not divided into ostium and cauda. Narrow ostial channel present at antero-dorsal corner.

Etymology

The species is named after the formation from which it was collected.

Material examined

Holotype UNITED STATES OF AMERICA • Left otolith; Texas, Wall Farm 1; Weches Formation ; Fig. 11E ; IRSNB P 9997 .

Paratypes UNITED STATES OF AMERICA • 100 otoliths of which one is figured, Fig. 11F ; same collection data as for holotype; IRSNB P 9998 .

Type locality and horizon

United States of America, Wall Farm 1 (Texas), Weches Formation.

Dimensions of the holotype

Length = 4.33 mm; height = 3.24 mm; thickness = 1.22 mm.

Description

The species is characterized by massive, more or less elliptic otoliths that are high in the center, with a protruding dorsal rim. This protruding dorsal part of the otoliths is sharply raised, making its anterior rim and particularly the posterior one steep and angled. The anterior and the ventral rims are, overall, smoothly curved. The posterior rim of the otolith is extended and its shape varies; it is angled in the holotype ( Fig. 11E ) but tapering upwards in many of the smaller specimens ( Fig. 11F ). The inner face is convex and the outer face is slightly concave but swollen in the center. The sulcus is wide, nearly straight and not distinctively divided into ostium and cauda; it opens very restrictedly to the anterodorsal rim of the otolith. A single large elevated colliculum fills the entire sulcus. A marked constriction in the posterior part of the crista inferior is followed by a broad ventrally extended posterior end of the cauda.

Remarks

The otoliths of this species are readily distinguished from those of the co-occurring related species, Paraconger brazosensis (Dante & Frizzell, 1965) , P. sector ( Koken, 1888) , and P. yazooensis Nolf & Stringer, 2003 , by their more compact outline and wider and rounded ventral area. They have a slightly more extended posterior part than those of P. solidus ( Fig. 38C ) from the Piney Point Formation of Virginia. Paraconger wechesensis sp. nov. is currently confined to the Weches Formation; however, the available specimens are not always perfectly preserved; many of them are somewhat worn and surface abraded.

Stratigraphic and geographic distribution

Lutetian: Weches Formation, Texas.

Figures

Fig. 11. Fish otoliths from the US middle and upper Eocene. A–D. Ariosoma nonsector Nolf & Stringer, 2003. A–C. Wheelock M., Little Brazos River, Stenzel loc., Texas (IRSNB P 9993–9995).D. “Stone City beds”, Stone City Bluff, Brazos River, sample 5 from bed S, Texas (IRSNB P 9996). E–F. Paraconger wechesensis sp. nov., Weches F., Wall Farm 1, Texas. E. Holotype (IRSNB P 9997). F. Paratype (IRSNB P 9998). G–L. Paraconger brazosensis (Dante & Frizzell, 1965), “Stone City beds”, Stone City Bluff, Brazos River, sample 2 from bed P, Texas (IRSNB P 9999–10004). 1 = ventral view; 2 = inner view. Scale bars = 1 mm.

Fig. 38 (opposite page). Fish otoliths from the US middle and upper Eocene. A. “Ophichthus” brevior (Koken, 1888), holotype (ZMB Ot. 26), “Jackson Beds”, Mississippi (?). B. Gnathophis dissimilis (Frizzell & Lamber, 1962), Moodys Branch F., Town Creek, Jackson, Mississippi (IRSNB P 9038). C. Paraconger solidus Müller, 1999, holotype (coll. Institut für Geowissenschaften, University of Leipzig, Nr. 10/P67), Piney Point F., loc. 24 (Horseshoe) of Müller, 1999, Virginia. D–G. Paraconger yazooensis Nolf & Stringer, 2003, Yazoo Clay, Tullos M., Copenhagen, Louisiana. D. Holotype (IRSNB P 6962). E–G. Paratypes (IRSNB P 6963–6965). H. Muraenanguilla aff. thevenini (Priem, 1906), Yazoo Clay, Copenhagen, Louisiana (IRSNB P 6966). I. Signata nicoli Dante & Frizzell, 1965, Weches F., Pleasanto, Atascosa County, Texas, holotype (USNM 23370). J. Xenosirembo decipiens (Koken, 1888), lectotype (ZMB Ot. 135), middle Eocene, “Clayborne Group”, southern USA. K. Brotula aquitanica Nolf, 1980, Yazoo Clay, Tullos M., Copenhagen, Louisiana (IRSNB P 7419). L–O. Aequalobythites aequaloides (Nolf & Stringer, 2003), Yazoo Clay, Copenhagen, Louisiana.L. Holotype (IRSNB P 6977). M–O. Paratypes (IRSNB P 6978–6980). 1 = ventral view; 2 = inner view. Scale bars = 1 mm.