Family UROSTYLIDIDAE Dallas, 1851
This Eastern Hemisphere family includes two subfamilies, eleven genera, and just over 170 species. Urostylidids occur from the Indo-Pakistan region eastward throughout most of China and Japan, and then south into Southeast Asia; they are absent from the Austral-Pacific and African regions. The Saileriolinae is a small subfamily both in number of species and in stature, containing three genera and four species of very small (usually less than 5 mm) bugs. The nominotypical subfamily is further divided into two tribes, the Urolabidini and the Urostylidini, both of which contain a number of genera and species of larger (usually much greater than 5 mm), more elongate, coreoid-looking insects. Very little is known about the biology of most species. Several species of Urostylidinae have been recorded from various trees, and have occasionally been reported as pests on pears. Also, adults and immatures of Ruckesona vitrella Schaefer & Ashlock have been collected from an unidentified palm, suggesting that this is probably a host for this species. At least in some areas of China, urostylidids tend to occur only in mountainous regions, being quite rare in lowlands.
The systematic placement of this family has long been a matter of conjecture. They have variously been associated with the Acanthosomatidae, the Pentatomidae, or the Pyrrhocoridae (Kumar, 1971, near the base of the Pentatomomorpha). Others (China & Slater, 1956; Schaefer & Ashlock, 1970) have placed the urostylidids near the base of the Pentatomidae + Coreidae + Lygaeidae, or near the base of the Pentatomoidea, respectively. The trichobothrial placement and pattern suggests that they belong in the Pentatomoidea, but much further work is needed.
There is no modern comprehensive treatment of the family as a whole. Palaearctic catalogue: Rider (2006a). Ahmad et al. (1992) reviewed the taxa from the Indian subregion; the Chinese species have been treated several times (Yang, 1939; Maa, 1947; Hsiao & Ching, 1977), but Ren in a series of papers (1984-2004), and several other Chinese workers (J.J. Li, 1981b; Zhang & Xue, 1992; Z.Y. Chen, 1994; etc.), have added many new species. The species were not catalogued by Kirkaldy (1909a); the last world catalogue is that of Lethierry & Severin (1893). Kobayashi (1953, 1965a) has examined the immature forms of several species.