Diaphanopterodea

The Diaphanopterodea, also known as the Paramegasec-optera, were relatively rare insects of moderate to large size and are known from some of the earliest deposits containing winged insects (e.g., Kukalova-Peck and Braukmann, 1990; Kukalova-Peck, 1992; Brauckmann et al., 1996). Defining features of the order include a reduction of the tarsus to three tarsomeres (trimerous), complete loss of the archedictyon (perhaps a character uniting Dicliptera, Protohymenoptera, Eumegasecoptera, and some Eubleptoptera?), the simple MA vein, and flexion of the wings. Indeed, perhaps the single most fascinating aspect of the Diaphanopterodea is the convergence on neoptery, or the ability to flex the wings over the abdomen during rest (Tillyard, 1936; Carpenter, 1947; Carpenter and Richardson, 1971; Sharov, 1973; Kukalova-Peck,

1974). The venational similarity with Megasecoptera (in which many species of diaphanopterodeans were at one time placed) and their possession of a sucking beak clearly indicate their place in the Palaeodictyopterida, and not at all with Neoptera. Furthermore, Neoptera possess a third axillary sclerite responsible for the flexion of the wings, and Diaphanopterodea apparently lacked this sclerite (based on the limited preservation), having developed neoptery via a novel means. In the Palaeodictyopterida the wing base was apparently composed of a series of large, articular plates, so flexion of the wings over the abdomen in Diaphanopterodea was enabled by the reduction of the various articular plates along with the formation of a basal fold line (Kukalova-Peck, 1974).

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