Distinguished from most loricariines by total absence of abdominal plates, including the preanal plate. Members of Hartiella and a few species of Harttia also have the abdomen completely devoid of plates, and can be separated from species of Ixinandria by having 12 branched caudal-fin rays (vs. 10 in Ixinandria) and by the absence of postorbital notch, which is present in members of Ixinandria. Members of Crossoloricaria, Spatuloricaria, and Loricaria sometimes lack a preanal plate, but have small abdominal plates. Some species of Rineloricaria have a naked abdomen, but a preanal plate is always present, except in Rineloricaria setepovos which can be diagnosed from other loricariines by the shapes and number of premaxillary teeth. Ixinandria possesses wide and almost symmetrical tooth cusps, and up to 18 teeth in each premaxilla (vs. premaxilla with up to 13 narrow and clearly asymmetrical teeth in other loricariines, except Rineloricaria aequalicuspis which has up to 15 narrow teeth with nearly symmetrical cusps, and some hartiini, which also have many asymmetrical premaxillary teeth) (Ref. 86762).