Differs from other members of the A. erythrinus complex by having the following characteristics: from all others by having a much longer second dorsal fin spine, reaching to at least the base of third ray of second dorsal fin when depressed (spine in other species do not reach third ray); from A. indicus by having 14 pectoral fin rays (versus 13, rarely 12 or 14), and by lacking pigment on the dorsal surface of the caudal peduncle (present in A. indicus); from A. marquesensis by lacking scattered chromatophores on sides of caudal peduncle that extend anteriorly as a band from caudal fin base to vertical from ends of dorsal and anal fin rays (pigment extends forward as a band in A. marquesensis); from A. susanae by having pigment present on scale edges at front of second dorsal fin and sometimes along its base and scattered chromatophores on caudal fin base (absent in A. susanae) (Ref. 40822).