| Mountaingem | |
|---|---|
 | |
| Purple-throated Mountaingem (Lampornis calolaemus)♀ inCosta Rica | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Clade: | Strisores |
| Order: | Apodiformes |
| Family: | Trochilidae |
| Tribe: | Lampornithini |
| Genus: | Lampornis Swainson, 1827 |
| Type species | |
| Lampornis amethystinus[1] Swainson, 1827 | |
| Species | |
6-8, see text | |
Mountaingems are agenus ofhummingbirds,Lampornis, which inhabit mountainous regions from the south-western United States to theIsthmus of Panama.
These are medium-sized to large (10–13 cm) hummingbirds with shortish slightly curved black bills. The males typically have green upperparts and a brightly coloured throat, which is a dull colour in the female. The females of some species also may differ significantly from the males in other plumage features.
The female mountaingem is entirely responsible for nest building and incubation. She lays two white eggs in a deep plant-fibre cup nest. Incubation takes 15–19 days, and fledging another 20–26.
The food of this genus is nectar, taken from a variety of small flowers. Like other hummingbirds, mountaingems also takes small insects as an essential source of protein.
6-8 species have been traditionally recognized, the main point of dispute being whether the southern forms which have fulvous-breasted females, found from Nicaragua to Panama, are one ("variable mountaingem"), two, or three species. Analysis ofbiogeography andmitochondrial andnuclear DNAsequences by García-Morenoet al. (2006) have largely confirmed the arrangement and the suspectedevolutionary relationships, but a few surprising results have emerged:
First, thewhite-throated mountaingem and thegray-tailed mountaingem are probably conspecific, but thepurple-throated mountaingem seems to be a distinct species. However, the southern group has apparently evolved in a very short time and their conspicuous differences in appearance are not yet reflected in molecular divergence; as mates are of course chosen according to their appearance and not their molecular differences, it seems prudent to split the group according to throat color as advocated by theAmerican Ornithological Society. However, thespeciation process is ongoing.
Second, the exact relationship between the suspectedsister taxaL. clemenciae andL. amethystinus, the northernmost species, is not as straightforward as assumed; it is not clear whether they are each other's close relatives or whether theblue-throated hummingbird is the oldest lineage of the genus, theamethyst-throated hummingbird diverging later. In addition,L. amethystinus may constitute two species, but not the violet-throated subspeciesmargaritae but the southernmost, red-throated forms are the most distinct ones.
Most puzzling, however, is the fact that thewhite-bellied mountaingem constantly failed to form amonophyletic group with the other taxa. These results suggest that it is better placed in themonotypic genusOreopyra, the relationships of which need more study. It might be closely related to thefiery-throated hummingbird, but these two species are very different at least morphologically. Thegarnet-throated hummingbird, which is sometimes considered to be the closest relative of the mountaingems, is indeed not distantly related to the group, but closer to theEugenes hummingbirds. It is intermediate in appearance betweenLampornis and those species.
García-Moreno's team refrains to date the emergence of the genus because of the absence of fossils or other robust evidence. It can be assumed though thatLampornis was present at the closing of the Isthmus of Panama, about 3.8MYA, and that by that time, the northernmost lineage(s) had already diverged.
These results are interesting, because they agree with a general trend for southern Mexican taxa (including to colonize the Isthmus and there form distinct species. Also, the Isthmus group ofLampornis provides a glimpse at an intermediate stage in evolution, with one form (L. calolaema) having recently evolved into a distinct species, while its white-throated relatives are in the process of splitting into two species but have not yet done so. mtDNA (which is inherited from the mother only) suggests that thepurple-throated mountaingem still can form fertilehybrids with the white-throated forms and indeed not infrequently does so.
According to the updated taxonomy, the species are:
| Common name | Scientific name and subspecies | Range | Size and ecology | IUCN status and estimated population |
|---|---|---|---|---|
| Blue-throated mountaingem
Male
| Lampornis clemenciae (Lesson, 1830) Three subspecies
| Mexico and the United States. | Size: Habitat: Diet: | LC |
| Amethyst-throated mountaingem
| Lampornis amethystinus Swainson, 1827 | El Salvador, Guatemala, Honduras, and Mexico | Size: Habitat: Diet: | LC |
| Green-throated mountaingem
Male
| Lampornis viridipallens (Bourcier & Mulsant, 1846) Four subspecies
| El Salvador, Guatemala, Honduras, and Mexico | Size: Habitat: Diet: | LC |
| Green-breasted mountaingem
| Lampornis sybillae (Salvin & Godman, 1892) | Honduras and Nicaragua | Size: Habitat: Diet: | LC |
| Purple-throated mountaingem
Male
| Lampornis calolaemus (Salvin, 1865) Three subspecies
| Costa Rica, Nicaragua, and Panama. | Size: Habitat: Diet: | LC |
| White-throated mountaingem
Male
| Lampornis castaneoventris (Gould, 1851) | Panama. | Size: Habitat: Diet: | LC |
| Gray-tailed mountaingem
Male
| Lampornis cinereicauda (Lawrence, 1867) | Costa Rica. | Size: Habitat: Diet: | LC |
| White-bellied mountaingem
| Lampornis hemileucus (Salvin, 1865) | Costa Rica and Panama. | Size: Habitat: Diet: | LC |
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