Pebasciaena amazonensis, Schwarzhans & Aguilera & Scheyer & Carrillo-Briceño, 2022

Schwarzhans, Werner W., Aguilera, Orangel A., Scheyer, Torsten M. & Carrillo-Briceño, Jorge D., 2022, Fish otoliths from the middle Miocene Pebas Formation of the Peruvian Amazon, Swiss Journal of Palaeontology (2) 141 (1), pp. 1-15 : 9

publication ID	https://doi.org/10.1186/s13358-022-00243-5
persistent identifier	https://treatment.plazi.org/id/03DA87A9-FF93-5914-FF65-5B87FD00886A
treatment provided by	Felipe
scientific name	Pebasciaena amazonensis
status	sp. nov.

Treatment

Pebasciaena amazonensis n. sp.

Figure 4A–E View Fig

Holotype. PIMUZ A/I 5006, Pebas Fm., middle Miocene, Iquitos (layer VI), Peru.

Etymology. Named for its type location in the Amazon Basin.

Diagnosis. Same as genus (monospecific genus).

Description. A single, large, well-preserved specimen of 10.4 mm in length. OH:OT = 2.1. Dorsal rim shallow, nearly flat, slightly undulating, with faint predorsal expansion. Ventral rim moderately deep, with distinct angle slightly in front of its middle, smooth. Anterior rim broadly rounded; posterior rim with obtuse angle at joint with dorsal rim and rounded angular tip at about level of central otolith axis.

Inner face distinctly convex, particularly in horizontal direction, with large, sciaenid-type sulcus extending over much of the space. Ostium very wide, shallow, convex, with distinct postostial lobe and predorsal depressions slightly bent downwards anteriorly. Cauda joining ostium near upper margin of latter and is long, narrow, somewhat deepened, steeply curving, extending beyond lower limit of ostium and bent forward in its lower third, with tapering tip. Dorsal and posterior fields very narrow, without distinct depressions; ventral field entirely smooth. Outer face thickset but without umbo; instead, somewhat depressed and coarsely and irregularly ornamented central region.

Discussion. See above to discussion of genus. Pebasciaena amazonensis is thought to represent an endemic freshwater genus and species that occurred in the Pebas Wetland System during the middle Miocene and has no direct derivatives in the contemporary freshwater (or marine) sciaenid assemblage of the Americas.