The long-billed starthroat (Heliomaster longirostris) is a species of hummingbird in the "mountain gems", tribe Lampornithini in subfamily Trochilinae. It is found in Mexico, Central America, Trinidad, and all but the four southernmost countries of South America. Taxonomy and systematics At one time the long-billed starthroat was placed in genus Anthoscenus but since the mid-1900s has had its current placement in Heliomaster. It has three subspecies, the nominate H. l. longirostris, H. l. pallidicepts, and H. l. albicrissa. Description The long-billed starthroat is long. Males weigh and females about . Both sexes of all subspecies have a long, almost straight, black bill and a small white spot behind the eye. Males of the nominate subspecies have a glittering blue to greenish blue crown; the rest of its upperparts are dark bronzy green with the exception of a white stripe down the center of the rump. The face is black below the crown and has a white malar stripe below the black. Its tail is rather short and square-tipped. The feathers are bronzy green near the body and black away from it, and the outer two or three pairs have white tips. The chin is black, the gorget dark metallic purple, the breast gray with bronzy green sides, and the lower breast and belly dull white. The undertail coverts are gray with white edges. Nominate females are very similar but the blue of the crown is much reduced or absent and the gorget is narrower and dusky gray. Subspecies H. l. pallidicepts has a more greenish blue crown than the nominate and the sides of the breast are golden bronze. H. l. albicrissa is identical to the nominate except that its undertail coverts are mostly to entirely white. Distribution and habitat Subspecies H. l. pallidicepts of long-billed starthroat is the northernmost; it is found from southern Mexico through Belize, Guatemala, Honduras, and El Salvador into Nicaragua. The nominate H. l. longirostris is the most widespread. It is found from Costa Rica through Panama, into South America as far south as eastern Peru and eastern Bolivia and east through the Guianas well into Brazil, and on Trinidad. H. l. albicrissa has a restricted range in western Ecuador and northwestern Peru. The species inhabits a variety of humid semi-open landscapes including the edges of woodland, isolated woodlands, pastures with trees, gallery forest, and secondary forest. It shuns the interior of closed forest. It