Merida Flowerpiercer is a medium sized species of the genus Diglossa, a genus distinguished by its upturned bill with a sharp hook at the end used to pierce flowers and obtain nectar (Ridgely and Tudor 2009). This species is primarily colored black, chestnut, and gray (Hilty 2003). It has a chestnut colored belly and black upper parts, and is easily distinguished from other species by its gray shoulder patch and narrow gray supercilium (Hilty 2003). It was previously considered a subspecies of Gray-bellied Flowerpiercer Diglossa carbonaria (as also were Black Flowerpiercer Diglossa humeralis and Black-throated Flowerpiercer Diglossa brunneiventris), but now is classified as its own species (Dickinson and Christidis 2014, Clements et al. 2015) and as a member of the carbonaria superspecies (Vuilleumier 1969). The name Diglossa gloriosa has both Greek and Latin origins (Jobling 2010). The genus name Diglossa comes from the Greek word diglōssos, meaning "double-tongued" or "speaking two languages"; and the species name gloriosa comes from the Latin word gloriosus, meaning "glorious" or "famous" (Jobling 2010).
Merida Flowerpiercer is similar in appearance to many members of the genus Diglossa that are generally black and unpatterned, but with a conspicuously rufous belly (Vuilleumier 1969). It formerly was considered a subspecies of Gray-bellied Flowerpiercer D. carbonaria, together with the other members of what is now considered a superspecies group – D. carbonaria, Black Flowerpiercer D. humeralis, and Black-throated Flowerpiercer D. brunneiventris (Ridgely and Tudor 2009); these are similarly sized, geographically taxa, all of which have a gray shoulder patch and are mostly black. Merida Flowerpiercer overlaps geographically with Rusty Flowerpiercer D. sittoides, which is gray (not black) above, and which has entirely tawny underparts (rather than a black throat and breast); and with Glossy Flowerpiercer D. lafresnayii, which is larger, and which entirely black underparts (Ridgely and Tudor 2009). It also overlaps with Blue-backed Conebill Conirostrum sitticolor, which is superficially similar, but which has a blue back, and a smaller, pointed (not hooked) bill (Ridgely and Tudor 2009). Merida Flowerpiercer is most similar in plumage pattern to two allopatric species, Black-throated Flowerpiercer (of Colombia, Peru, and northwestern Bolivia) and Chestnut-bellied Flowerpiercer Diglossa gloriosissima (of Colombia). Black-throated Flowerpiercer is further distinguished by its deeper chestnut breast and belly, and chestnut submoustachial stripe. The plumage pattern of Chestnut-bellied Flowerpiercer is strikingly similar to that of Merida Flowerpiercer, but Chestnut-bellied is larger, lacks the indistinct gray supercilium, has a bluer should patch, and has deeper chestnut belly and undertail coverts. The general behavior of Merida Flowerpiercer is similar to that of Glossy Flowerpiercer, although Merida is considered less stealthy (Hilty 2003).
Adult: Merida Flowerpiercer is deep, but not glossy, black with a chestnut colored breast, belly, and undertail coverts (Hilty 2003). Some individuals of this species may also show traces of a rufous submoustachial stripe (Hilty 2003). The bill is black and characteristic of Diglossa with a slender, slightly upturned bill and longer upper mandible with a sharp hook at the end (Ridgely and Tudor 2009). The sexes are similar in appearance to the human eye (Hilty 2011). However, the species is sexually dichromatic when quantified using a model of avian vision (Burns and Shultz 2012). Therefore, these tanagers can visually distinguish between males and females, even though humans are unable to see these differences.
Juvenile: Dingy, grayish brown above, with faint mottling and streaking on back (Restall et al. 2007, Hilty 2011). The color is paler below, with dark brown streaking on the breast and throat (Restall et al. 2007, Hilty 2011). The remiges are dark brown with buff edges (Hilty 2011).
Immature: Fjeldså and Krabbe (1990) describe the immature Merida Flowerpiercer as dusky brown and faintly streaked above with a dark brown throat and chest with pale streaking. There is sometimes white mottling on the face that would suggest a moustache and supercilium. The lower parts are a somewhat streaked rusty buff color (Hilty 2003).
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 (Isler and Isler 1987), and this prebasic molt likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). Many species have been found to breed in subadult plumage (Isler and Isler 1987). Although a juvenile and "immature" plumage is described for Diglossa gloriosa (Restall et al. 2007, Hilty 2011) more specific information on molt and its timing is not available for this species.
Bill: black, basal half of mandible pale gray
Iris: dark brown
Legs: dark gray
Bare parts color data from Hilty (2011).
Total length, both sexes: 12 cm (Isler and Isler 1987), 13.5 cm (Hilty 2011)
Mass: male, 11. 0 g (n = 1; Vuilleumier and Ewert 1978); female, 11.5 g (n = 1; Vuilleumier and Ewert 1978)