Cichlasoma zarskei sp.n. is herein described from the rio Maranhão basin, northern Brazil. The new species differs from all its congeners, except C. orientale, by having a conspicuous posterior band of the longitudinal stripe and dorsal, anal and caudal fins faintly dotted. It is also distinguished from its congeners by the precense of the following character states: trisserial predorsal squamation, four anal-fin spines, reduction of the squamation between dorsal and anal-fins rays, forâmen between infraorbital plate 3+4 and plate 5 smaller, deeper entopterygoid, premaxilla with teeth on its entire dentigerous surface, caudal-fin base spot not ocellated, fewer pleural ribs, more scales on E1 series, shorter last dorsal-fin spine, shorter last anal-fin spine, longer snout, wider head and shorter lower jaw. A new diagnosis for C. orientale, without overlapping character states, is herein presented.

Cichlasomatini, Cichlinae, new species, systematics, South American cichlids, taxonomy.