The wing vestiture of the non-ditrysian Lepidoptera. (Insecta). Comparative morphology and phylogenetic implications

The ultrastructure of the dorsal forewing vestiture in exemplars of all fam ily group taxa of non-ditrysian Lepidoptera is examined, and the evolutiona ry implications at family level and above are discussed. Wing-scale termino logy is reviewed. Three different types of bilayer wing-scale covering are recognized; only a few groups have a single-layer wing-scale covering. The general scale arrangement is random, but a few taxa have clustered scale ar rangements and scattered heteroneurans have scales arranged in transverse r ows. Cross ribs are present in all taxa, but only as vestiges in eriocranii d cover scales. Ridge dimorphism is widespread in Neolepidoptera. Surprisin gly, ridges and cross ribs on the adwing scale surface are of general occur rence in Neopseustidae and Hepialidae, and are even found on parts of the g round scales of many other Neolepidoptera. Morphological evidence strongly indicates that the fused wing-scale types found in non-Coelolepidan Lepidop tera and Neolepidoptera are independently evolved, as evidenced from the pr esence of vestigial perforations. Absence of perforations is not infallible evidence that a scale is solid. Microtrichia are independently reduced in a number of taxa and probably re-evolved in at least higher nepticulids. Wi ng vestiture and scale characters indicate that Tischerioidea may be the si ster group of Ditrysia.