Atherina debilis, (Koken, 1888)

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 : 64

“ Atherina ” debilis ( Koken, 1888)

Fig. 22A–C

Otolithus (Mugilidarum) debilis Koken, 1888: 288 , pl. 17 fig. 8.

“genus? Mugilidarum ” debilis – Nolf 1985: 124.

“genus Atherinidarum” debilis – Nolf & Stringer 2003: pl. 3 figs 20–21. — Nolf 2003: 5, pl. 1 fig. 10.

“ Atherinida ” debilis – Nolf 2013: 73, pl. 150.

Remarks

Otoliths of “ A. ” debilis have a cauda with a very long anterior portion and a restricted ostium. They show some plesiomorphic features that make both allocations, either to Atherinidae or Mugilidae , plausible. The close relationship of both families is supported by a number of features ( Stiassny 1993; Datovo et al. 2014). However, the inner face showing only a weak convexity and the deeper ventral area seem to be more typical of atherinid otoliths. The New Zealandian middle Eocene (Bortonian) species Thoroatherina toroa Schwarzhans, 2019 shows some similarity to “ A. “ debilis , especially in the morphology of the cauda, and was placed in the same genus in the original description of Schwarzhans (2019a: 61). However, we prefer not to include the American species in the same genus because otoliths of T. toroa have a much deeper ventral portion, and a very considerable convexity and thickness.

Stratigraphic and geographic distribution

Lutetian: “Stone City beds”, Texas. Bartonian: Moodys Branch Formation, Louisiana, Mississippi and Alabama. Priabonian: Yazoo Clay, Louisiana.

Figures

Fig. 22. Fish otoliths from the US middle and upper Eocene. A–C. “Atherina” debilis (Koken, 1888). A. “Stone City beds”, Stone City Bluff, Brazos River, sample 6 from bed U, Texas (IRSNB P 10122). B–C. Moodys Branch F., Jackson, Riverside Park, Mississippi (IRSNB P 10123–10124). D–E. Mene garviei sp. nov., Landrum M., Pin Oak Creek, Texas. D. Holotype (IRSNB P 10125). E. Paratype (IRSNB P 10126). F–G. Psettodes trapeziformis Müller, 1999, Piney Point F., Virginia. F. Pamunkey River, 1 km E of Eanes property (IRSNB P 10127). G. Pamunkey River, Devil’s Hole (IRSNB P 10128). H–I. Carangidae indet. H. Wheelock M., Little Brazos River, Stenzel loc., Texas (IRSNB P 10129). I. “Stone City beds”, Stone City Bluff, Brazos River, sample 2 from bed P, Texas (IRSNB P 10130). 1 = ventral view; 2 = inner view; 3 = anterior view. Scale bars = 1 mm.