Abstract
Myrmornis torquata has often been considered an intermediate form between the ground antbirds and the typical antbirds. Although molecular phylogenies have consistently placed M. torquata in the Thamnophilidae (typical antbirds), this species has notbeen the subject of a thorough anatomical study, and no phylogeny based on morphological characters has been published. We undertook a cladistic morphological analysis of M. torquata and representatives of all families in the infraorder Furnariides, to clarify the systematic affinities of this species. In a parsimony analysis of 66 osteological and syringeal characters, Myrmornis clustered with other thamnophilids with high support values, sharing with them five sy-napomorphies of unambiguous optimization in all most-parsimonious trees. Two synapomorphies are syringeal features exclusive to the family: (1) the presence of processes on the ventral surface of supporting A-elements of the syrinx cranial to the membrana tracheosyringealis, and (2) the division of the musculus sternotrachealis into two fasciculi near its insertion on the syrinx. A third syringeal synapomorphy (presence of the musculus vocalis ventralis) also occurs in the Den-drocolaptidae and Furnariidae as a homoplasy. Two unambiguous osteological synapomorphies were found: (1) the narrowing of the foramen orbitonasale, and (2) the confluence of the foramen obturatum and the fenestra ischiopubica, a reversal also found in the Furnariidae. Our results provide strong morphological supportfor the placement of Myrmornis in the Thamnophilidae.
NSTL