The genus Ecpleopus is diagnosed within Group II of the Teiidae by the elongate, keeled dorsal scales arranged in diagonal and transverse rows, smooth ventral scales in diagonal and transverse rows, first superciliary elongate, first supraocular in contact with the frontonasal and loreal, and superciliary series incomplete so that only first and fourth supraoculars are separated from the palpebrals. The usual presence of plicae on the anterior part of the tongue suggests relationships with Ptychoglossus and Alopoglossus, which are distinctive within Group II because they have completely plicate tongues. Leposoma and Arthrosaura also appear to be related to Ecpleopus. The diagnostic characters of Ecpleopus, however, suggest that its relationships to these four genera are not especially close. I consider Arthroseps a synonym of Ecpleopus. The genus is apparently monotypic. Arthroseps werneri, A. fluminensis, and Alopoglossus gracilis are junior synonyms of Ecpleopus gaudichaudi. Aspidolaemus, with Ecpleopus (Aspidolaemus) affinis as the only species, is recognized as a separate genus related to Prionodactylus and Pholidobolus. Ecpleopus gaudichaudi is known from altitudes of less than 1000 m above sea level in eastern Brazil from Goyas south to Santa Catarina. E. gaudichaudi, in contrast to most members of Group II, may mature only a single egg at a time.