Magnogobius, Schwarzhans & Aguilera, 2024

Genus Magnogobius n. gen.

Type species Magnogobius grandis n. sp.

Etymology Combination of magnus (Latin) for large and the genus name Gobius , indicating the large size of the otoliths that infers also a large size of the fishes from which they originated, and also as antagonism to the name of the putatively related genus Microgobius .

Diagnosis A fossil otolith-based genus of the Gobiosomatini , Microgobius Group, Microgobius clade with the following combination of characters. Large otoliths to about 3.3 mm in length and high-bodied with an elevated postdorsal region and a broad predorsal angle and postdorsal projection; OL:OH = 0.83–0.97. Sulcus large, with a wide ostium and a pronounced ostial lobe; cauda long, narrow, straight, slightly deepened; OL:SuL = 1.3–1.5; sulcus inclination angle 12–20°. Subcaudal iugum very long, distinct, narrow. Dorsal depression small, only above central part of sulcus. Ventral furrow distinct, anteriorly not extending beyond ostium.

Discussion Magnogobius is recognized by its large size in combination with a high-bodied shape, the large sulcus with a distinct ostial lobe, the narrow, long, and distinct subcaudal iugum, and the small dorsal depression. Te otolith size and the expression of the ostial lobe and the subcaudal iugum are the main features distinguishing Magnogobius from the otoliths of the putatively related Microgobius . Otoliths are known from all other large-growing extant American gobioid genera, and none of them resemble Magnogobius in any significant way. It cannot, however, be entirely ruled out that Magnogobius is of an exotic origin in the Miocene and Pliocene of the West Atlantic and that the genus is related to one outside of America. For instance, otoliths of the West African Porogobius schlegeli (Günther, 1861) somewhat resemble Magnogobius in the distinct and long subcaudal iugum and the distinct ostial lobe, but they have a massive postdorsal projection and a concave outer face not matched in Magnogobius otoliths. We therefore interpret Magnogobius as representing an extinct genus of the Gobiosomatini , Microgobius group, and possibly related to the genus Microgobius .

Species Two species: Magnogobius costaricensis n. sp. from the Tortonian of Panama, Darien to the Piacenzian of Atlantic Costa Rica and Panama, and Magnogobius grandis n. sp. from the Tortonian of Panama, Darien and the Tortonian to Gelasian of the Dominican Republic, Atlantic Costa Rica and Panama.