Analogues: Larval Xyrichtys have no melanophores and often markedly-narrowed eyes. The absence of external melanophores is shared with larval Doratonotus megalepis, which are distinctly wider-bodied and have large round eyes. All other regional labrid and scarid larvae have melanophores. X. novacula recruits have a lateral stripe broken up into patches or spots and the first two dorsal fin spines are extended while X. martinicensis recruits have an intact stripe and no extended first dorsal fin spines. X. splendens recruits develop a complex pattern of bars and reticulations.
Description: Body thin and long with a markedly narrowed eye (pre-transitional) to large and round (recruits) with a pointed snout and a terminal small mouth. Pectoral fins medium, reach to vent. Pelvic fins stubs. Dorsal and anal-fin bases long, caudal peduncle short. There are no surface or internal melanophores. Transitional recruits show a lateral stripe broken up into patches or spots and the first two dorsal-fin spines are extended.
Diagnosis: The fin-ray count of D-IX,12 A-III,12 and Pect-12 indicates the razorfish genus Xyrichtys. One other regional labrid, Halichoeres cyanocephalus, shares the median-fin ray count, but has 13 pectoral-fin rays and a clearly different body shape. The three Caribbean razorfishes, X. martinicensis, X. novacula, and X. splendens, share fin-ray counts and the larvae overlap in appearance. The species become distinct as they develop juvenile markings: X. novacula recruits are recognized by lateral stripe broken up into patches or spots and the first two dorsal fin spines are extended. The extended dorsal fin spines persist until juveniles reach about 25 mm SL.
