''Apteribis'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

flightless bird Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the ...

s in the

ibis The ibises () (collective plural ibis; classical plurals ibides and ibes) are a group of long-legged wading birds in the family Threskiornithidae, that inhabit wetlands, forests and plains. "Ibis" derives from the Latin and Ancient Greek word f ...

subfamily that was

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

to the

Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost ...

in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

Distribution

The remains of the small ibises in the genus have only been found on the islands of Maui,

Lanai Lanai ( haw, Lānai, , , also ,) is the sixth-largest of the Hawaiian Islands and the smallest publicly accessible inhabited island in the chain. It is colloquially known as the Pineapple Island because of its past as an island-wide pineapple pl ...

, and

Molokai Molokai , or Molokai (), is the fifth most populated of the eight major islands that make up the Hawaiian Islands archipelago in the middle of the Pacific Ocean. It is 38 by 10 miles (61 by 16 km) at its greatest length and width with a us ...

, which formed part of the prehistoric island of

Maui Nui Maui Nui or Greater Maui, is a modern geologists' name given to a prehistoric Hawaiian Island built from seven shield volcanoes. ''Nui'' means "great/large" in the Hawaiian language. 1.2 million years ago, Maui Nui was , 40% larger than the pr ...

until about 200,000 years ago when

rising sea levels Rising may refer to: * Rising, a stage in baking - see Proofing (baking technique) *Elevation * Short for Uprising, a rebellion Film and TV * "Rising" (''Stargate Atlantis''), the series premiere of the science fiction television program ''Starga ...

fragmented it. Olson and

James James is a common English language surname and given name: *James (name), the typically masculine first name James * James (surname), various people with the last name James James or James City may also refer to: People * King James (disambiguat ...

speculate that the genus was endemic to Maui Nui, that the ibises were birds of the

forest floor The forest floor, also called detritus, duff and the O horizon, is one of the most distinctive features of a forest ecosystem. It mainly consists of shed vegetative parts, such as leaves, branches, bark, and stems, existing in various stag ...

, that because of their flightlessness they were susceptible to becoming trapped in

lava tube A lava tube, or pyroduct, is a natural conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow. If lava in the tube empties, it will leave a cave. Formation A lava tube is a type of lava ...

s, and that they may have exerted heavy

predation Predation is a biological interaction In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or o ...

pressure on Maui Nui's land snails.

Taxonomy

Analysis of the feathers from the Lanai specimen show an affinity to New World ibises of the genus ''

Eudocimus ''Eudocimus'' is a genus of ibises, wading birds of the family Threskiornithidae. They occur in the warmer parts of the New World with representatives from the southern United States south through Central America, the West Indies, and South Amer ...

''. The analyses also concluded that ''Apteribis'' may have had a brown-and-beige coloration similar to that of a juvenile ''Eudocimus'' ibis. This indicates that ''Apteribis'' may have evolved both their flightlessness and their coloration through a form of paedomorphosis.

Species

Two species have been described: * †''A. glenos'' Olson & Wetmore, 1976, the Moloka'i flightless ibis * †''A. brevis'' Olson & James, 1991, the Maui flightless ibis The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

of ''A. glenos'' is from the Moʻomomi dunes, and other specimens are from Ilio Point and

Kalaupapa peninsula Kalawao County ( haw, Kalana o Kalawao) is a county in the U.S. state of Hawaii. It is the smallest county in the 50 states by land area and the second-smallest county by population, after Loving County, Texas. The county encompasses the Ka ...

. Fossil material collected on Maui indicates that a third species apparently occurred there; it was generally larger in size and occurred at lower elevations than ''A. brevis'', and has been referred to as the “Maui lowland apteribis”. Another, extremely well-preserved specimen has also been recovered from Lanai, though it has not yet been described to the species level.

References

Notes

{{Taxonbar, from=Q1557120 Bird genera

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species). It is one of the modern descendan ...

Holocene extinctions Late Quaternary prehistoric birds Extinct birds of Hawaii Maui County, Hawaii

Fossil taxa described in 1976 Taxa named by Alexander Wetmore