Maideria falipoui n. sp., n. g., a new primitive long snouted brachythoracid from the Lower or Middle Givetian of South Morocco (Presaharian Anti-Atlas) is described. The monophyletic group Migmatocephala, a taxon erected by White 1952, is redefined, together with the monophyly Eubrachythoraci. A phylogenetic analysis has been performed using PAUP program based on 53 characters coded for 12 taxa. Three equally parsimonious topologies have been found, in which Maideria is considered as the most primitive brachythoracid, and Holonema included in Eubrachythoraci.