The primitive family of Peloridiidae has been described as “the rarest and most remarkable of the Hemiptera” (Helmsing and China, 1937). Erected by Breddin (1897) for a single specimen, the family now comprises three genera and six species: the original genus Peloridium contains one species, Xenophyes one, and Hemiodoecus four species.
The original specimen, Peloridium hammoniorum Breddin, a macropterous male, was collected in forest at Puerto Toro, Navarin Island, Tierra del Fuego, Magellan Straits, in 1892. The second specimen, a sub-brachypterous female erroneously described as a new species Nordenskjoldiella insignis by Haglund (1899), was taken in 1896 under a decaying tree-trunk in forest near Punta Arenas, on the northern shore of the Magellan Strait. Until 1920 these two specimens were the sole representatives of the family.
The next specimens, a male and a nymph, came from New Zealand and were collected in November, 1920, by Mr H. Hamilton when sifting leafmould gathered in the forest at Ohakune, 2,100 ft. The adult was sent to Dr Bergroth, who considered it to be a new Peloridiid and described it in a new genus under the name Xenophyes cascus (Bergroth, 1924). The nymph, which was thought to be the same species, was described and figured by Myers in 1926. Attempts were made to obtain more material from the original locality at Ohakune, but without result.
In his paper dealing with the New Zealand species, Bergroth records also a nymph of an unknown species collected at Lord Howe Island. No further specimens have been recorded from this island, but it forms an interesting link in the distribution of the family.
When it was found that the Peloridiidae was represented in Australasia, unworked material in the British Museum was examined and two specimens (one male and one female) were found, these having been collected at Hobart, Tasmania. A new genus was erected for these specimens which were described by China (1924) as Hemiodoecus leai. The male of these two specimens was dissected in 1929 and the morphology described for the first time (Myers and China. 1929). From
their work it was concluded that the family could not remain in the Heteroptera, where it had previously been placed, and a new series in the Homoptera, the Coleorrhyncha, was erected to include it. In 1927 a further specimen of P. hammoniorum was found in material collected in Argentine Patagonia in 1910. This was a sub-brachypterous male and was described by China (1927).
To the six adult specimens representing the family in the entire entomological collections of the world, three were added in 1932. These had been taken in dense rain forest on the McPherson Range in southern Queensland by Hacker, and were believed to have been beaten from Antarctic beech, Nothofagus moorei. They were described by Hacker (1932) as belonging to a new species, Hemiodoecus veitchi. The following year the locality was visited by I. W. Helmsing and a number of specimens were collected from the moss Papillaria kermadecensis, which grows on dead twigs of Antarctic beech. This was the first time that any member of the family had been associated directly with a host plant (Helmsing and China, 1937). Evans (1936) described a new species, Hemiodoecus wilsoni, from “Beech Forest, Victoria,” and in the following year (Evans, 1937) he described a further new species. H. lidelis, from Tasmania.