Mountaingem

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Mountaingem
Purple-throated mountaingem female.JPG
Purple-throated Mountaingem (Lampornis calolaemus) in Costa Rica
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
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 a genus of hummingbirds, Lampornis, which inhabit mountainous regions from the south-western United States to the Isthmus 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.

Systematics

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 of biogeography and mitochondrial and nuclear DNA sequences by García-Moreno et al. (2006) have largely confirmed the arrangement and the suspected evolutionary relationships, but a few surprising results have emerged:

First, the white-throated mountaingem and the gray-tailed mountaingem are probably conspecific, but the purple-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 the American Ornithological Society. However, the speciation process is ongoing.

Second, the exact relationship between the suspected sister taxa L. clemenciae and L. amethystinus, the northernmost species, is not as straightforward as assumed; it is not clear whether they are each other's close relatives or whether the blue-throated hummingbird is the oldest lineage of the genus, the amethyst-throated hummingbird diverging later. In addition, L. amethystinus may constitute two species, but not the violet-throated subspecies margaritae but the southernmost, red-throated forms are the most distinct ones.

Most puzzling, however, is the fact that the white-bellied mountaingem constantly failed to form a monophyletic group with the other taxa. These results suggest that it is better placed in the monotypic genus Oreopyra, the relationships of which need more study. It might be closely related to the fiery-throated hummingbird, but these two species are very different at least morphologically. The garnet-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 the Eugenes hummingbirds. It is intermediate in appearance between Lampornis 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 that Lampornis was present at the closing of the Isthmus of Panama, about 3.8 MYA, 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 of Lampornis 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 the purple-throated mountaingem still can form fertile hybrids with the white-throated forms and indeed not infrequently does so.

According to the updated taxonomy, the species are:

Genus Lampornis Swainson, 1827 – eight species
Common nameScientific name and subspeciesRangeSize and ecologyIUCN status and estimated population
Blue-throated mountaingem

Blue-throated Hummingbird South Fork Cave Creek AZ 2015-07-01at11-18-138 (33930794408).jpg
Male
Blue-throated Mountaingem, Cave Creek Canyon, Chiricahua Mts.jpg
Female

Lampornis clemenciae
(Lesson, 1830)

Three subspecies
  • L. c. clemenciae
  • L. c. phasmorus
  • L. c. bessophilus
Mexico and the United States.
Lampornis clemenciae map.svg
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Amethyst-throated mountaingem

Lampornis amethystinus 21183923.jpg

Lampornis amethystinus
Swainson, 1827

Five subspecies
El Salvador, Guatemala, Honduras, and Mexico
Lampornis amethystinus map.svg
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Green-throated mountaingem

Lampornis viridipallens 78744441.jpg
Male
Lampornis viridipallens 10004781.jpg
Female

Lampornis viridipallens
(Bourcier & Mulsant, 1846)

Four subspecies
El Salvador, Guatemala, Honduras, and Mexico
Lampornis viridipallens map.svg
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Green-breasted mountaingem

Lampornis sybillae (female).jpg

Lampornis sybillae
(Salvin & Godman, 1892)
Honduras and Nicaragua
Lampornis sybillae map.svg
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Purple-throated mountaingem

Purple-throated Moutain-Gem (6901527484).jpg
Male
Lampornis calolaemus Santa Elena.JPG
Female

Lampornis calolaemus
(Salvin, 1865)

Three subspecies
  • L. c. calolaemus
  • L. c. pectoralis
  • L. c. homogenes.
Costa Rica, Nicaragua, and Panama.
Lampornis calolaemus map.svg
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White-throated mountaingem

White-throated Mountain-gem.jpg
Male
Lampornis-castaneoventris-001.jpg
Female

Lampornis castaneoventris
(, )
Panama.
Lampornis castaneoventris map.svg
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Gray-tailed mountaingem

Grey-tailed Mountain-gem (49548569663).jpg
Male
Grey-tailed Mountain-gem (49548569448).jpg
Female

Lampornis cinereicauda
(Lawrence, 1867)
Costa Rica.
Lampornis cinereicauda map.svg
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White-bellied mountaingem

White-bellied Mountain-gem (Oreopyra hemileucus).jpg

Lampornis hemileucus
(Salvin, 1865)
Costa Rica and Panama.
Lampornis hemileucus map.svg
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References

  1. "Trochilidae". aviansystematics.org. The Trust for Avian Systematics. Retrieved 2023-08-05.