“…The subgenus Cathorops, within which the species described here are included, can be diagnosed from the subgenus Precathorops and from other ariid genera by possessing a lateral ethmoid and frontal limiting a wide conspicuous fenestra, visible under the skin (vs. moderately developed in Precathorops, Amphiarius, Aspistor, Bagre, Galeichthys, Notarius, and Potamarius or reduced or absent in Genidens, Sciades, and Occidentarius), mesethmoid, lateral ethmoid and frontal lacking bony spinulations (vs. bony spinulations present in Precathorops), posterior cranial fontanel very reduced (vs. moderately developed, long and narrow in Precathorops, Notarius, and Potamarius, large and long in Amphiarius and Aspistor, or absent in Sciades), vomerine tooth plates absent (vs. present in Precathorops, Aspistor, Bagre, Galeichthys, Notarius, Occidentarius, and Sciades), accessory tooth plates bearing molariform teeth (vs. conical in Precathorops, and in other ariid genera except Aspistor), posterior cleithral process short (vs. moderate length in Precathorops and other ariid genera), and Key to the species of Cathorops from the Mesoamerica and Caribbean Sea distinguished from A. fissus by having a shorter head, larger teeth and larger accessory tooth plates. The characters used to diagnose A. arenatus are typical of females, whereas the condition found in A. fissus is characteristic of males (Marceniuk, 2007b). The latter species is currently considered junior a synonym of the former.…”