Guasuctenus gen. nov., a new Neotropical spider genus of Ctenidae (Araneae).

The new genus Guasuctenus gen. nov. is described based on the results of a recent phylogenetic analysis. This phylogeny, which included representatives of all Ctenidae subfamilies, showed that the genus Ctenus as currently defined, does not comprise a monophyletic group. The results indicated that several species are misplaced in Ctenus and should be transferred to new genera. Aiming to correct the placement of two species originally described in Ctenus, we propose the new genus Guasuctenus to accommodate those species and better represent their phylogenetic relationships. Guasuctenus is supported by the presence of a dorsal cymbial projection in the male palp. Previously regarded as a subspecies, Ctenus longipes vittatissimus Strand, 1916 is here ranked as species, and Guasuctenus longipes (Keyserling, 1891) new comb. and G. vittatissimus (Strand, 1916) new rank, new comb. are redescribed. Ctenus griseus Keyserling, 1891 is recognized as a junior synyonym of Ctenus longipes Keyserling, 1891. Lectotypes and paralectotypes of Guasuctenus vittatissimus (Strand, 1016) are designated for stability. The species of the genus are distributed in southern Brazil and Uruguay.