Family ARADIDAE Brullé, 1836 - Flat Bugs
The family includes eight subfamilies, about 200 genera and at least 2000 species presently known. The three extralimital subfamilies (Chinamyersiinae, Isoderminae, and Prosympiestinae) are restricted to the Australia-New Zealand-South America belt. While most of the Aradinae inhabit the Holarctic arboreal, the by far largest number of taxa classified in the Aneurinae, Calisiinae, Carventinae and Mezirinae occurs in tropical and subtropical forests. Ranging from 2.2 to 20 mm in size, most of the Aradidae are flattened dorsoventrally and live on or under the bark of decaying trees and twigs or in debris on the floor of moist forests, always associated with fungal mycelia. Several species of Aneurinae, Aradinae and Calisiinae feed on sap of dying or living trees.
Nearly all Palaearctic species are macropterous, although wing polymorphism occurs in some species of Aradus and Quilnus, but in the tropics there is a large number of apterous genera and species with highly modified dorsal body structures.
Only one species, Aradus cinnamomeus is of some economic importance, causing severe damage in pine forests in N Europe, sucking on the phloem, cambium and xylem of living pine trees (Heliövaara, 1984).
The suprageneric classification follows the basic work of Usinger & Matsuda (1959). Phylogenetic relationship of Aradid subfamilies is still discussed, the most recent study is by Grozeva & Kerzhner (1992). The presently adopted placement of the superfamily Aradoidea within the infraorder Pentatomomorpha, however, is questioned by Sweet (1996), whose proposal for a separate infraorder Aradomorpha is strongly supported by several unique apomorphies, such as the lack of trichobothria, occurring in all other Pentatomomorphan superfamilies. Henry (1997b) hypothesizes that Aradoidea belong to and are the sister group to the remainder of Pentatomomorpha.
Catalogues: Oshanin, 1912 (Palaearctic, outdated); Stichel, 1957, 1959 (Palaearctic); Kormilev & Froeschner, 1987 (World). Monographs: Usinger and Matsuda, 1959 (World); Kiritshenko, 1913a (Palaearctic); S.L. Liu, 1981a (CH).
Note: The citations of names of varieties in subspecies format by Kormilev & Froeschner (1987) are not considered as upgradings to subspecific rank in itself.