About Lampornis amethystinus Swainson, 1827
Lampornis amethystinus Swainson, 1827, commonly called the amethyst-throated mountaingem, is 11.5 to 12.5 cm (4.5 to 4.9 in) long. Males weigh 5 to 7.8 g (0.18 to 0.28 oz), while females weigh 5 to 5.8 g (0.18 to 0.20 oz). All subspecies of both sexes share a medium-length straight black bill, dark ear patches, a whitish stripe behind the eye, and a broad, slightly forked tail.
Adult males of the nominate subspecies have a dark green crown and back, a bronze rump, and blackish uppertail coverts. The tail is black with gray tips on the outer feathers, and the male has a brilliant rosy pink gorget. Its breast and belly are dusky gray, and its undertail coverts are pale buff. Females are almost identical to nominate males except they have a cinnamon throat. Juveniles are similar to females, though juvenile males may have a small number of pink feathers on the throat.
Subspecies L. a. circumventris and L. a. salvini are nearly indistinguishable from the nominate subspecies. Males of L. a. nobilis have more bronzy green upperparts than the nominate, along with a purple rump and purplish-black uppertail coverts. This subspecies has a reddish purple gorget and dark smoke-gray underparts. Females of L. a. nobilis are also more bronzy on their upperparts and darker on their underparts than the nominate, and have a duller, darker cinnamon throat.
Subspecies L. a. margaritae shows the greatest difference from the nominate. Both sexes are much darker overall, and the male's gorget is violet to royal blue, unlike the red to reddish purple gorget of the other four subspecies. L. a. margaritae may potentially be a separate species. Researchers note that the color differences between this species and its close sister species appear to be a relatively recent evolutionary change.
The different subspecies of amethyst-throated mountaingem have the following distributions: L. a. amethystinus is found in central and eastern Mexico, from Nuevo León and Tamaulipas south to Veracruz and northern Oaxaca. L. a. margaritae occurs in southwestern Mexico, from Nayarit and Jalisco south to Michoacán and western Oaxaca. L. a. circumventres is limited to Sierra de Miahuatlán in southwestern Oaxaca. L. a. salvini ranges from Chiapas in southern Mexico south through Guatemala into El Salvador. L. a. nobilis is found in Honduras. There are two recorded sightings of the species north of Mexico: a male in Saguenay–Lac-Saint-Jean, Quebec, in July 2016, and a male in the Davis Mountains of Texas in October 2016.
The amethyst-throated mountaingem lives in the interior and edges of montane evergreen forest and pine-oak forest. In Mexico, it occurs at elevations ranging from 900 to 3,000 m (3,000 to 9,800 ft).
