Comments: See Hershkovitz (1977:601-603). For a summary of interrelationships between species, using external, cranial, vocalization and DNA evidence, see Groves (2001c:137-8), who divided the genus into the following species groups: (1) S. midas group (midas, niger), (2) S. nigricollis group (nigricollis, graellsi, fuscicollis, melanoleucus, tropartitus), (3) S. mystax group (mystax, pileatus, labiatus, imperator), (4) S. bicolor group (bicolor, martinsi), (5) S. oedipus group (oedipus, geoffroyi, l...