13) Trinectes fluviatilis (Meek & Hildebrand 1928);

Achiridae .

Freshwater Sole; Lenguado Redondo Fluvial, Suela Fluvial (Fig. 3G).

Diagnosis: This species differs from the other species of the family occurring in freshwaters of the country (Pacific side) by the following combination of characters: absence of interbranchial foramen (vs. present in Achirus spp.); pectoral fin usually absent [vs. usually present in Trinectes fonsecensis (Günther, 1862)]; lateral line scales 90–98 (vs. 73–76 in T. fonsecensis); caudal vertebrae 21 (vs. 19–20 in T. fonsecensis); anal fin rays 43–46 [vs. 35–38 in Trinectes fimbriatus (Günther, 1862)]; and coloration pattern (see Krupp 1995, Robertson & Allen 2015).

Basis of the record: Three specimens were captured in the Barranca and Coto River basins. One in the río Lagarto, near Punta Morales, Chomes, Puntarenas (10.08569, -84.92540), at 28 m. a.s.l., on January 25, 2021, by Arturo Angulo (UCR 3318-001). Another specimen was captured in río Sábalo, 2.5 Km E of Playa Zancudo (Coto River basin), on the Sabalos-Playa Zancudo road, Puntarenas (8.49517, -83.10448), at 15 m. a.s.l., on March 28, 2021. The third specimen was captured in the quebrada Cocal Amarillo (Coto River basin), 5 Km N of Pavones, on the Puerto Pilón-Pavones road, Puntarenas (8.43643, -83.09660), at 26 m. a.s.l., on March 30, 2021; both by Arturo Angulo, Jorge San Gil, Alejandro Oviedo and Juan Ignacio Abarca.

Remarks: This species inhabits estuarine areas and coastal environs; it could be considered as an opportunistic visitor of freshwater ecosystems (Robertson & Allen 2015).