CHARACTERISTICS OF THE FLAGELLAR AXONEME IN NEUROPTERA, COLEOPTERA, AND STREPSIPTERA

Spermatozoa from representatives of the five insect orders in superord er Neuropteroidea were examined by electron microscopy following a new fixation method that includes tannic acid in the primary fixative but has uranyl acetate rather than osmium tetroxide as the secondary fixa tive. The sperm axoneme was found to be similar in the four orders Meg aloptera, Raphidioptera, Neuroptera, and Coleoptera, and is characteri zed above all by its so-called intertubular material being divided int o two portions, one located outside, but in contact with the doublet, and the other projecting from the accessory tubule and having a beak-l ike shape. These features have not been seen in insects from other ord ers and may be a synapomorphy for these neuropteroid orders. The acces sory tubules in these four orders have 16 protofilaments. The shape of the accessory bodies adjacent to the mitochondrial derivatives is nea rly the same in insects from the more primitive neuropteroid orders an d in Coleoptera. The sperm tail of the examined strepsipteran deviates in several respects from that of other neuropteroids: the particle ro w in the wall of accessory tubules is incomplete, an intertubular mate rial is missing, and the mitochondria contain no crystal. (C) 1994 Wil ey-Liss, Inc.