Proparrella, Schwarzhans & Aguilera, 2024

Genus Proparrella n. gen.

Type species Proparrella darienensis n. sp.

Etymology Combination of pro (Latin) for before and the genus name Parrella , indicating its presumed plesiomorphic position as compared to Parrella .

Diagnosis A fossil otolith-based genus of the Gobiosomatini , Microgobius Group, Akko clade with the following combination of characters. Small otoliths to about 2 mm in length and nearly quadratic otolith shape with slightly elevated postdorsal region; OL:OH = 1.0–1.1. Postdorsal rim with conspicuous narrow concavity behind postdorsal angle and before blunt, short postdorsal projection. Sulcus long, narrow, with low ostial lobe and long, narrow, straight, sometimes tapering cauda; OL:SuL very variable, ranging from 1.5 to 2.2; sulcus inclination angle 12–18°. Subcaudal iugum moderately long, relatively narrow. Dorsal depression shifted dorsally with straight lower margin and broad crista superior. Ventral furrow distinct, close to ventral rim of otolith.

Discussion Proparrella is best recognized by the characteristic shape of the postdorsal region with the narrow concavity in front of a short, blunt postdorsal projection and the, at first perhaps, inconspicuous shape of the cauda. Proparrella resembles otoliths of Akko as well as Parrella and is therefore considered to represent a fossil genus related to these taxa. It differs from Akko in the shape of the cauda, the broad crista superior, and the relatively long sulcus (except a few tentatively assigned specimens; see below), which it shares with the most plesiomorphic species in that genus, Akko lobata . Proparrella differs from Parrella in being more compressed and in the shape of the dorsal rim and the broad crista superior. It appears plausible that Proparrella represented an extinct branch as a sister taxon to Akko .

Species At least two species: the widespread Proparrella darienensis n. sp., known from the Tortonian to Zanclean and distributed from Ecuador to Trinidad; and P. pusilla n. sp., known from the Tortonian and Messinian of Panama.