A PRIMITIVE EARWIG IN CRETACEOUS AMBER FROM MYANMAR (DERMAPTERA: PYGIDICRANIDAE)

The earwigs comprise an order (Dermaptera) of polyneopterous insects allied to the Dictyoptera and Grylloblattodea (Giles, 1963; Hennig, 1969; Boudreaux, 1979). Dermaptera have at times in the past been allied with the Phasmida, Embiodea, and Plecoptera (e.g., Blacklith and Blacklith, 1968; Jamieson, 1987) but these relationships do not seem to be congruent with the overall body of data for Polyneoptera phylogeny and the monophyly of a Grylloblattodea + Dermaptera + Dictyoptera clade currently has perhaps more evidence than competing hypotheses (e.g., Carpenter and Wheeler, 1999; Wheeler et al., 2001). However, revised morphological and paleontological evidence may suggest that Dermaptera are basal within Anartioptera—a clade consisting of Plecopterida, Orthopterida, Grylloblattodea, and Mantophasmatodea, as well as the earwigs (e.g., Engel and Grimaldi, 2004). The earwigs are certainly autapomorphic, like many polyneopterous insects, and their definitive placement remains elusive. The order comprises approximately 1,900 species of distinctive insects with relatively flattened bodies, tegminous forewings without venation, an enlarged subgenital plate (sternum 7) in females, trimerous tarsi, and elongate forcipate cerci. Species are fairly mobile and generally prefer damp, concealed habitats such as under bark or stones. The order has a cosmopolitan distribution but is principally found in tropical or warm temperate regions. Two unusual groups, the traditional suborders “Arixeniina” and “Hemimerina,” are apomorphic lineages that are highly specialized for their epizoic lifestyles and at least the latter group has at times been excluded from the order (e.g., Popham, 1973) owing to its peculiar, paedomorphic differences from other earwigs. The five species of arixeniids live in the roosts of molossid bats on Southeast Asia islands (Nakata and Maa, 1974), while the 10 species of hemimerids live under the fur of rodents in Africa (Rehn and Rehn, 1935). The arixeniids have been demonstrated to be derived from the forficuloids, perhaps even …