The Ryukyu kingfisher (''Todiramphus cinnamominus miyakoensis'') is an

enigmatic taxon ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertaint ...

of tree kingfisher. It is

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

and is only known from a single specimen. Its taxonomic status is doubtful; it is most likely a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of the Guam kingfisher, which would make its scientific name ''Todiramphus cinnamominus miyakoensis''. As the specimen is at the Yamashina Institute for Ornithology, the question could be resolved using DNA sequence analysis; at any rate, the Guam kingfisher is almost certainly the closest relative of the Ryukyu bird. The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

considers this bird a subspecies and has hence struck it from its redlist. The one known bird, probably a male, was according to its label collected on Miyako-jima, the main island of the Miyako group,

Ryūkyū Shotō The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ōsumi, Tokara, Amami, Okinawa, and Sakishima Islands (further divided into the Miyako and Yaeyama Islands), with Yonaguni ...

, on February 5, 1887. While it is often and correctly stated that specimen labels may be incorrect or misleading, the locality, to the northwest of the extant populations of ''Todiramphus cinnamominus'', seems sound in a

biogeographical Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, i ...

sense. At least the specimen labels of Ryukyu collections by later Japanese collectors are usually very reliable; whether this is true for earlier collection too is not known. The only differences between the Miyako-jima bird and males of the Guam kingfisher (the nominate subspecies of the Micronesian kingfisher; presently only surviving in captivity) are the former's lack of a black nape band and the red feet (black in Guam birds). The bill color is unknown due to damage to the specimen, and supposed differences in the proportion of the remiges are almost certainly an artifact of specimen preparation. Indeed, the specimen was not recognized as distinct until some 30 years after its collection. If the bird was indeed a resident of the Miyako group (and as there was better habitat on neighboring Irabu-jima, it is probable that it would have been found there too), it became extinct in the late 19th century. While this seems early, the population must have always been small as there never was much habitat available in historic times. Certainly, thorough research in the early 20th century failed to find the bird again. The reasons for the disappearance of the population would have been land clearance and draining of wetlands for agriculture.

References

Todiramphus Controversial bird taxa Extinct birds of Oceania Extinct animals of Asia Extinct animals of Japan Birds of the Ryukyu Islands Birds described in 1919 Taxa named by Nagamichi Kuroda {{Coraciiformes-stub