Notholebias , a genus of seasonal miniature killifishes from south-eastern Brazil, contains two species threatened with extinction, N. minimus and N. fractifasciatus, and one possibly extinct species N. cruzi. These species are mainly distinguishable by male colour patterns. Species limits were tested using a combination of morphological characters and phylogenetic trees derived from the analyses of 650 bp sequences comprising a fragment of the mitochondrial gene cytochrome c oxidase I, taken from 16 specimens representing four populations along the whole geographic distribution of the genus, excluding the area inhabited by N. cruzi. The analysis supports a fourth species, N. vermiculatus, new species, as an exclusive lineage endemic to the Saquarema lagoon system, sister to N. fractifasciatus, from which it differs by details of the caudal fin colour pattern in males. The new species differs from other congeners analysed by 14 unique nucleotide substitutions, exhibiting genetic distances of 9.8 - 11.5 %.

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LL scale count (average)0.0