Lord Howe Island is a small, remote island about east of Australia. Ships first arrived on the island in 1788, including two which supplied the British
penal colony on
Norfolk Island and three transport ships of the British
First Fleet. When passed the island, the ship's commander named it after
First Lord of the Admiralty Richard Howe. Crews of the visiting ships captured native birds (including white swamphens), and all contemporary descriptions and depictions of the species were made between 1788 and 1790. The bird was first mentioned by the
master of HMS
Supply,
David Blackburn, in a 1788 letter to a friend. Other accounts and illustrations were produced by
Arthur Bowes Smyth, the fleet's naval officer and surgeon, who drew the first known illustration of the species;
Arthur Phillip, governor of
New South Wales; and
George Raper,
midshipman of . Secondhand accounts also exist, and at least ten contemporary illustrations are known. The accounts indicate that the population varied, and individual bird plumage was white, blue, or mixed blue-and-white. The
binomial name in White's book,
Fulica alba, was provided by the English naturalist
George Shaw. The
specific name is derived from the Latin word for white (
albus). White found the bird most similar to the
western swamphen (
Porphyrio porphyrio, then in the
genus Fulica). Although he apparently never visited Lord Howe Island, White may have questioned sailors and based some of his description on earlier accounts. He said he had described a skin at the
Leverian Museum, and his book included an illustration of the specimen by the artist
Sarah Stone. It is uncertain when (and how) the specimen arrived at the museum. This skin, the
holotype specimen of the species, was purchased by the
Natural History Museum of Vienna in 1806 and is catalogued as specimen NMW 50.761. The naturalist
John Latham listed the bird as
Gallinula alba in a later 1790 work, and wrote that it may have been a variety of purple
swamphen (or "
gallinule"). The zoologist
Coenraad Jacob Temminck assigned the white swamphen to the swamphen genus
Porphyrio as
P. albus in 1820, and the zoologist
George Robert Gray considered it an
albino variety of the
Australasian swamphen (
P. melanotus) as
P. m. varius alba in 1844. The belief that the bird was simply an albino was held by several later writers, and many failed to notice that White cited Lord Howe Island as the origin of the Vienna specimen. In 1873, the naturalist
Osbert Salvin agreed that the Lord Howe Island bird was similar to the takahē, although he had apparently never seen the Vienna specimen, basing his conclusion on a drawing provided by von Pelzeln. Salvin included a takahē-like illustration of the Vienna specimen by the artist
John Gerrard Keulemans, based on von Pelzeln's drawing, in his article. In 1875, the ornithologist
George Dawson Rowley noted differences between the Vienna and Liverpool specimens and named a new species based on the latter:
P. stanleyi, named after Lord Stanley. He believed that the Liverpool specimen was a juvenile from Lord Howe Island or New Zealand, and continued to believe that the Vienna specimen was from Norfolk Island. Despite naming the new species, Rowley considered the possibility that
P. stanleyi was an albino Australasian swamphen and considered the Vienna bird more similar to the takahē. In 1901, the ornithologist
Henry Ogg Forbes had the Liverpool specimen dismounted so he could examine it for damage. Forbes found it similar enough to the Vienna specimen to belong to the same species,
N. alba. The zoologist
Walter Rothschild considered the two species distinct from each other in 1907, but placed them both in the genus
Notornis. Rothschild thought that the image published by Phillip in 1789 depicted
N. stanleyi from Lord Howe Island, and the image published by White in 1790 showed
N. alba from Norfolk Island. He disagreed that the specimens were albinos, thinking instead that they were evolving into a white species. Rothschild published an illustration of
N. alba by Keulemans where it is similar to a takahē, inaccurately showing it with dark
primary feathers, although the Vienna specimen on which it was based is all white. In 1913, after examining the Vienna specimen, Iredale concluded that the bird belonged in the genus
Porphyrio and did not resemble the takahē. of
P. albus), by Keulemans, 1875 In 1928, the ornithologist
Gregory Mathews discussed a 1790 painting by Raper which he thought differed enough from
P. albus in proportions and colouration that he named a new species based on it:
P. raperi. Mathews also considered
P. albus distinct enough to warrant a new genus,
Kentrophorina, due to having a claw (or
spur) on one wing. In 1936, he conceded that
P. raperi was a
synonym of
P. albus. In 1941, the biologist
Ernst Mayr proposed that the white swamphen was a partially-albinistic population of Australasian swamphens. Mayr suggested that the blue swamphens remaining on Lord Howe Island were not stragglers, but had survived because they were less conspicuous than the white ones. In 1967, the ornithologist
James Greenway also considered the white swamphen a subspecies (with
P. stanleyi a synonym) and considered the white individuals albinos. He suggested that the similarities between the wing feathers of the white swamphen and the takahē were due to
parallel evolution in two isolated populations of reluctant fliers. The ornithologist
Sidney Dillon Ripley found the white swamphen to be intermediate between the takahē and the purple swamphen in 1977, based on patterns of the leg-scutes, and reported that X-rays of bones also showed similarities with the takahē. He considered only the Vienna specimen to be a white swamphen, whereas he considered the Liverpool specimen to be an albino Australasian swamphen (listing
P. stanleyi as a junior synonym of that bird) from New Zealand. In 1991, the ornithologist Ian Hutton reported
subfossil bones of the white swamphen. Hutton agreed that the birds described as having white-and-blue feathers were hybrids between the white swamphen and the Australasian swamphen, an idea also considered by the ornithologists Barry Taylor and Ber van Perlo in 2000. }} The ornithologists Hein van Grouw and
Julian P. Hume concluded in 2016 that many of the old accounts had errors in the bird's provenance, that it was
endemic to Lord Howe Island, and suggested when the specimens were collected (between March and May 1788) and under which circumstances they arrived in England. They concluded that the white swamphen was a valid species which changed colouration with age, after reconstructing the colouration of juvenile birds before turning white (which was distinct from other swamphens). Van Grouw and Hume found the white swamphen anatomically more similar to the Australasian swamphen than the Philippine swamphen, and suggested that studies with more-complete
data sets than the earlier DNA might yield different results. Due to their anatomical similarities, geographic proximity and the recolonisation of Lord Howe and Norfolk Island by Australasian swamphens, they found it likely that the white swamphen was descended from Australasian swamphens. ==Description==