Phylloscartes kronei is a small Brazilian endemic flycatcher similar to Mottle-cheeked Tyrannulet (Phylloscartes ventralis). Similar to several other species of Phylloscartes, Restinga Tyrannulet has dull olive upperparts, with a faint yellowish supercilium, a blackish stripe through the eye, yellowish underparts, and pale yellowish wing bars, fringes, and tertial spots. Compared to Mottle-cheeked Tyrannulet, the face of Restinga Tyrannulet is more yellow, the post-auricular crescent appears darker, and the crown and mantle are brighter green (Clay et al. 1998). Restinga Tyrannulet also is rapidly identified by the characteristic disyllabic call and twittering song.
Restinga Tyrannulet is similar to Mottle-cheeked Tyrannulet (Phylloscartes ventralis), but differs in the color pattern of the supercilium (more yellow in Restinga), darker crescent-shaped mark on the rear of the auriculars, brighter green to the upperparts, and shorter tail and longer bill. Also the vocalizations of these two species are quite different (Willis and Oniki 1992, Sick 1997).
The following description is based in Willis and Oniki (1992) and Fitzpatrick (2004):
Adult: Sexes are similar. Greenish olive above, slightly browner on crown. Narrow supercilium and eyering yellow. Dusky stripe from the lores extending past the eye along the upper edge of the above auriculars, and then extending down at rear to form distinct dusky auricular crescent. Face mottled dusky and yellowish. Wings dusky; the greater and medium coverts with yellow tips forming two wing bars; tips of inner secondaries yellow on their outer webs; outer fringes of remiges yellowish. Rectrices dusky olive, narrowly edged with greenish. Lower face and throat pale yellow; underparts medium yellow, brighter on abdomen and paler on throat, clouded with very faint greenish mottling on flanks and breast to throat; thighs barred yellow and greenish.
Juvenile: Not described in detail, but paler than the adult and mandible with a large orange area (Fitzpatrick 2004, Gussoni 2010).
Tail molt in January and February (Gussoni 2010).
Iris: brown (Willis and Oniki 1992)
Bill: maxilla black; mandible paler (whitish) with black distal third (Willis and Oniki 1992)
Tarsi and toes: gray (Fitzpatrick 2004, Gussoni and Pizo, unpublished data).
Total length: 12 cm (Sick 1997)
Linear measurements: measurements (mm) of one female and one male (Willis and Oniki 1992):
Wing length: 50.0, 55.5 mm
Tail length: 45.0, 45.8 mm
Bill length (culmen from base): 13.5, 15.1 mm
Tarsus length: 17.0, 20.0 mm
Mass: 7.8 g (female, n = 1)-8.8 g (male, n = 1) (Willis and Oniki 1992); 7.5-10 g (Gussoni and Pizo, unpublished data). Males are slightly larger than females (Willis and Oniki 1992).