The adult male is primarily turquoise and black with a yellow iris. A turquoise eye ring interrupts an otherwise black mask, with the throat, mantle, tail and wings also black, and with the crown and nape turquoise (Hilty and Brown 1986, Restall et al. 2006). The bill is stubbier and less pointed than in other species of Dacnis (Ridgely and Tudor 1989); this feature led earlier authors to classify it in a monotypic genus, Pseudodacnis, although it otherwise is very similar in appearance to Black-faced Dacnis (Dacnis lineata). The adult female is drab, dull brown above, and grayish buff below (Ridgely and Tudor 1989).
The contrasting deep black and brilliant blue hues of the male Turquoise Dacnis are not unique among Dacnis, and in particular are shared by two species that overlap geographically with Turquoise Dacnis, Black-faced Dacnis (Dacnis lineata) and Blue Dacnis (Dacnis cayana). The male Blue Dacnis is deeper blue than the male Turquoise, and has red irides and a small black mask, instead of yellow irides and with a broad black mask extending through the auriculars onto the nape (Meyer de Schauensee 1964, Restall et al. 2006). Furthermore, the bill of Turquoise Dacnis is shorter, less pointed, and thicker than the bill of Blue Dacnis (Meyer de Schauensee 1964). The male Turquoise Dacnis can be distinguished from the male Black-faced Dacnis by its completely turquoise belly and black throat, whereas male Black-faced has a blue throat, and its belly is white or yellow (Hilty and Brown 1986, Ridgely and Tudor 1989). The relatively drab female Turquoise Dacnis is also similar to the female of Black-faced Dacnis; female Turquoise Dacnis is darker brown above and buff below, whereas Black-faced Dacnis is more olive above and paler, buffy white below (Hilty and Brown 1986, Ridgely and Tudor 1989, Restall et al. 2006).
The following description is based primarily on Hilty (2011):
Adult male: The plumage is primarily turquoise and black. A black mask passes from just above the bill, encompassing the eyes, and meets on the nape where it connects with the black mantle. The crown is turquoise, extending to a point on the upper nape. There is a narrow black throat patch,. The wings and tail also are black; the tertials are edged and tipped with blue. The scapulars, sides of the back, rump, and uppertail coverts are turquoise. A broad, tapering malar, the sides of the neck, and the underparts, including the undertail coverts, are turquoise. The adult male highly reflects UV light, which is visible light to birds (Burns and Shultz 2012). UV is highly dichromatic in all other Dacninae species (Burns and Shultz 2012). Therefore, Turquoise Dacnis almost certainly is dicrhomatic in UV as well; however, no female specimens were available to be measured by Burns and Shultz (2012).
Adult female: Upperparts dull and plain brownish. The wings are plain (lacking wingbars), although with the wing coverts and flight feathers are narrowly edged with buff (Hilty 2011). The underparts are pale gray buff, becoming slightly more yellow towards the center of the belly.
Currently, the juvenile plumage of the Turquoise Dacnis is undescribed and there is no information available on their molt cycle. Tanagers that have been studied have either a Complex Basic Strategy or Complex Alternative Strategy (Ryder and Wolfe 2009). However, most tanagers only molt once a year, and this prebasic molt likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). Museum and field specimens provide evidence that the preformative molt is incomplete in many tropical tanagers (Ryder and Wolfe 2009). Many species have been found to breed in subadult plumage (Isler and Isler 1987). More specific information on molt and its timing is not available for Turquoise Dacnis.
The bill of Turquoise Dacnis is blackish, and is relatively thick and heavy.
The irides typically are described as bright yellow in the male, and orange yellow in the female, although inspection of color photographs suggests that color is orange yellow in both sexes.
Tarsi and toes are dark gray.
Bare parts color data from Hilty and Brown (1986) and Hilty (2011).
The length of both sexes is 11-11.4 cm (Hilty and Brown 1986, Restall et al. 2006). There is currently no information regarding the mass or other measurements of Turquoise Dacnis.