Simpsonichthys

[[Genus Simpsonichthys]] Simpsonichthys Carvalho is the most diverse genus of Neotropical annual killifishes, comprising 40 valid species, all inhabiting seasonal pools in central and northeastern South America. Monophyly of Simpsonichthys and intrageneric species assemblages have been defined in recent phylogenetic studies (e. g., Costa, 2003). Among these assemblages, the clade herein termed Simpsonichthys notatus species group comprises S. notatus (Costa & Brasil), from the upper Rio Tocantins basin, and S. stellatus (Costa & Brasil), S. rufus Costa & Nielsen, S. similis Costa & Hellner, S. trilineatus Costa & Brasil, S. auratus Costa & Nielsen, from the middle Rio São Francisco basin, and S. ocellatus Costa, Nielsen & De Luca, from the Rio Jequitinhonha basin. It is diagnosed by a unique frontal squamation pattern, in which the A-scale has all margins free (Costa, 2003). A new species of this clade, collected in a temporary pool associated to the headwaters of the Rio Crixás, upper Rio Tocantins basin, central Brazil, is described.Published as part of Wilson J. E. M. Costa & Gilberto C. Brasil, 2004, Simpsonichthys radiosus sp. n. (Teleostei: Cyprinodontiformes: Rivulidae): a new annual killifish from the upper Rio Tocantins basin, central Brazil., pp. 1-7 in Zootaxa 737 on page