Olive-crowned Crescentchest

The olive-crowned crescentchest (Melanopareia maximiliani) is a species of bird in the family Melanopareiidae. It is found in Argentina, Bolivia, and Paraguay. == Taxonomy and systematics == The crescentchests (genus Melanopareia) were previously included in family Rhinocryptidae, the tapaculos. A 2010 publication confirmed earlier work and created their present genus. The olive-crowned crescentchest has three subspecies, the nominate Melanopareia maximiliani maximiliani, M. m. argentina, and M. m. pallida. The last has been suggested as a separate species due to vocal differences. In addition, a subpopulation of M. m. pallida might be an undescribed taxon. == Description == The olive-crowned crescentchest is 15 cm (5.9 in) long. Males weigh 17.1 to 18.0 g (0.60 to 0.63 oz), one female weighed 16.7 g (0.59 oz), and unsexed specimens weighed 16.9 to 18.2 g (0.60 to 0.64 oz). The nominate subspecies' crown and upperparts are olive-brown, the throat deep buff, and the chest and belly ochraceous. It has a narrow buff supercilium with a black mask below and a black crescent and chesnut band between the throat and chest. M. m. argentina is similar but has paler underparts. M. m. pallida is paler still, its throat is more cinnamon than buff, and the…