Archocentrus

Key to Archocentrus and allied genera

1a Maxilla very protractile; ascending process of premaxilla extending beyond orbit, contained ininterorbital groove; caudal fin profile strongly rounded .............................................................. Caquetaia

1b Maxilla and premaxilla not as above; caudal fin profile, if rounded, not as strongly as above ......... 2

2a(1b) Caudal fin emarginate ................................................................................................... Hypsophrys (8)

2b Caudal fin rounded or (sub)truncate ................................................................................................. ..3

3a(2b) Genital papilla long, contours mostly parallel, as seen from rostral face, terminal notch rounded; upper symphysial teeth abruptly larger than adjacent teeth; lower symphysial teeth smaller than adjacent teeth, which are enlarged; frenum on lower lip absent ....................................... Parachromis

3b Genital papilla not as above; outer teeth on upper jaw gradually increasing in size anteriorly (symphysial teeth abruptly larger in Rocio, Amatitlania, and some Cryptoheros); frenum on lower lip present or absent ............................................................................................................................. 4

4a(3b) Frenum on lower lip absent; total gill-rakers on first arch 14-20; pharyngeal plate longer than wide. ......................................................................................................................................... Amphilophus

4b Frenum present in lower lip or absent; total gill-rakers on first arch 7-15; pharyngeal plate about as wide as long, or wider.........................................................................................................................5

5a(4b) Lateral stripe extending from snout to a blotch on mid-body; eight bars on sides; ocellated spot on caudal fin, dorsal to lateral line; lower jaw usually extending beyond upper jaw.................. Rocio (9)

5b Lateral stripe absent; usually 6-7 bars on side of body; caudal blotch, if present, not ocellated, not entirely dorsal to lateral line, or not entirely on fin; mouth usually terminal......................................6

6a(5b) First bar on side of body Y-shaped, caudal arm discontinuous; caudal blotch on fin (sometimes obsolete) .......................................................................................................................... Amatitlania (11)

6b First bar on side of body I- or V-shaped (may be Y-shaped in some Cryptoheros, but caudal arm continuous); caudal blotch usually on peduncle (may lie on fin in some Cryptoheros)......................7

7a(6b) A. IX-XII; genital papilla oval, in females opening strongly crenulated; two interorbital bands......... .................................................................................................................................. Archocentrus (14)

7b A. VI-IX; genital papilla not as above; no interorbital bands................................... Cryptoheros (16)