Several species have been assumed to exist, but due to a lack of physical evidence they can only be regarded as hypothetical or potential species. Hypothetical species are usually believed to be extinct. They have caused confusion, as they may have been a separate species, a subspecies, an introduced species or a misidentification. It can also refer to species that are hypothesised to have existed evolutionarily.

List of hypothetical species

Birds

Albin's macaw
Arkansaw siskin, Fringilla spaltria
Barraband's mystery black-breasted twelve-wired bird-of-paradise
Bird of Washington, Haliaetus washingtoni
Blue-browed fig parrot
Blue Mountain warbler, Sylvia montana
Blue-thighed lory, Lorius tibialis
Dominican green-and-yellow macaw, Ara atwoodi
Carbonated warbler, Sylvia carbonata
Cuvier's kinglet, Regulus cuvieri
Geoffroyus aureus
Guadeloupe amazon, Amazona violacea
Guadeloupe parakeet, Psittacara labati
Hypothetical relatives of the Rodrigues parrot
Jago fowl, Gallus giganteus
Jamaican red macaw, Ara gossei
Leguat's giant, Leguatia gigantea
Lesser Antillean macaw, Ara guadeloupensis
Madeira finch, Goniaphea leucocephala
Martinique amazon, Amazona martinicana
Martinique macaw, Ara martinicus
Meidum geese
Painted vulture, Sarcoramphus sacra/Sarcoramphus papa ssp.
Raiatea starling, Aplonis? ulietensis
Red-headed macaw, Ara erythrocephala
Roper River scrub robin, Drymodes superciliaris colcloughi
Réunion swamphen, Porphyrio caerulescens
Small-headed flycatcher, Muscicapa minuta
Sushkin's goose, Anser neglectus
Tahiti crake, Zapornia nigra
Tanna ground dove, Pampusana ferruginea
Townsends' dickcissel or Townsend's finch, Spiza townsendi (originally Emberiza townsendi)
Unicolored lory, Eos unicolor
Unidentified Jamaican parrot
Zhenniao

Non-avian dinosaurs
Proavis (partim)

Mammals
Andean wolf, Dasycyon hagenbecki
Chilihueque, Lama araucana
Chinese elephant, Elephas maximus rubridens
Giraffa sahara
Javan elephant, Elephas maximus sondaicus
Kallana
Long-necked seal, Phoca mutica
Shrewdinger
Sonnerat's shrew, Diplomesodon sonnerati
Steller's sea ape, Simia marina
Sumxu
Unidentified extinct canid populations
Waitoreke
Zebro

Fish
Abyssal rainbow gar
Five-lined constellation fish, Bathysidus pentagrammus
Giant dragonfish, Bathysphaera intacta
Pallid sailfin, Bathyembryx istiophasma
Three-starred anglerfish, Bathyceratias trilynchnus

Arthropods
Acarus crossi
Battus polydamas antiquus

Other invertebrates
Thermozodium esakii
Porpita prunella
Salinella salve

Plants
Laysan fan palm, Pritchardia? sp.
Silphium

Other organisms
Last universal common ancestor

See also
Chimera
Cryptozoology
Species inquirenda

References