Serpophaga tyrannulets are a tricky bunch, both in terms of taxonomy and identification, both of which are unresolved. This individual is the same as the 4 previous photos in the sequence, but different from the final (6th) pic in the sequence. The bird in photos 1-5 appears to be a classic 'subcristata'. The bird in the 6th is also 'subcristata' although its greyer mantle and lack of yellow underparts are reminiscent of the form that is called 'munda' (but may be conspecific with subcristata).