ULTRASTRUCTURAL AND PHYLOGENETIC ASSESSMENT OF WAX GLANDS IN PIT SCALES (HOMOPTERA, COCCOIDEA)

TEM/SEM and computerized images of 5 wax glands for 3 type species of Coccoidea (Homoptera): Asterodiaspis variolosa (Asterolecaniidae), Cer ococcus quercus (Cerococcidae) and Lecanodiaspis sardoa (Lecanodiaspid idae) were studied. Their cuticular structures were compared with 142, 56, and 61 species in their respective families to determine relation ships among pit scale taxa. Significant differences include: the morph ology of the outer and inner ductule of the tubular duct gland, struct ure of the pores (8-shaped, multilocular and quinquelocular), and the absence or presence of cribriform plates and their structural variatio ns. Three distinctive tubular duct shapes (asterform, ceroform and lec anoform) are common in pit scale species. Apomorphic characteristics o f the asterform tubular ducts include an absence of the inner ductule and the progressive reduction of the outer ductule's diameter from the pore to its inner end. These characters easily separate asterolecanii ds from the cerococcid-lecanodiaspidid lineage. The constricted lecano form tubular ducts and the curved teeth on the rim at the inner end of the outer ductile in the ceroform tubular ducts are regarded as autap omorphic. The presence of 8-shaped pores is considered a plesiomorphic condition. Specific cuticular variations of the 8-shaped pores, chara cterizing familial taxa, include pores even with the surface in astero lecaniids, pores with raised walls in cerococcids, and bent pores in l ecanodiaspidids. The dominant 8-shaped pore patterns in pit scales are those arranged in a marginal band in lecanodiaspidids, in a swirl-lik e pore pattern in the cerococcids, and in a marginal row in asteroleca niids. A divergent evolutionary trend is noted for the structure of th e cribriform plate; they are with micro-orifices in cerococcids, but w ithout micro-orifices in lecanodiaspidids. The former state is conside red apomorphic. Cribriform plates arranged in clusters characterize th e cerococcids, while plates in longitudinal rows characterize the leca nodiaspidids. These data confirm the concept that the pit scales const itute a paraphyletic group and the Asterolecaniidae, Cerococcidae and Lecanodiaspididae are monophyletic.