SPERM STRUCTURE OF TRICHOPTERA .4. RHYACOPHILIDAE AND GLOSSOSOMATIDAE

The families Rhyacophilidae and Glossosomatidae (Trichoptera) are cons idered to be the most primitive ones within the order. We examined the spermatozoa of members of these families to see whether their ultrast ructure is consistent with an ancestral position. Axonemal structures, after fixation with a tannic acid-containing fixative, have been show n to be particularly useful as taxonomical indicators. It was found th at 4 members of Rhyacophilidae, representing 3 subgenera (Rhyacophila, Pararhyacophila, and Hyporhyacophila) all have motile spermatozoa, wi th a 9+9+2 axoneme in which inner (but no outer) dynein arms are prese nt. The accessory tubules have a wall consisting of 17 protofilaments, decreasing to 16 near the distal end, whereas the examined member of Glossosomatidae, Catagapetus nigrans, has accessory tubules with 18 pr otofilaments and a 9+9+2 axoneme with inner dynein arms and with motil ity similar to the Rhyacophilidae. Sperm motility is consistent with t he inclusion of these 2 families within the suborder Integripalpia, an d the axonemal pattern 9+9+2 indicates that the families indeed occupy a primitive position within Trichoptera.