Heroina isonycterina, a new species of cichlid fish from Western Amazonia, with comments on cichlasomine systematics

" Heroina isonycterina, new genus and species, is distributed in a narrow band crossing the Caqueta (Colombia), Napo (Ecuador), Corrientes, Tigre and Pastaza (Peru) river drainages in the extreme western Amazonian lowlands. The largest specimen examined is 101.9 mm SL. Distinguishing characters shared with Caquetaia, Parachromis, and Petenia include the shift of the palatopalatine ligament to insert on the lateral ethmoid bone immediately posterior to the ethmopalatine articulation instead of on the palatine bone; and a narrow palatine bone leaving a portion of the median palatovomerine ligament exposed to lateral view. Heroina is distinguished on its own by characters in combination, including shortjaws, well scaled dorsal and anal fin bases, short caudal peduncle, and a colour pattern dominated by dark vertical bars. Nomenclatural changes and revised diagnoses are proposed for the cichlasomine group of cichlids, recognising two major assemblages. One group, the cichlasomines in the strict sense, is characterised by uniserial and triserial predorsal squamation and the tight circular pattern in which eggs are laid. The other group, here informally named heroines and including Heroina, is characterised by having the palatine caudolaterally displaced from the vomer and, with exceptions, bicuspid anterior teeth and more than four anal fin spines. "