CHARACTERISTICS OF SPERMATOZOA FROM 5 GALL-MIDGE SPECIES (DIPTERA, CECIDOMYIIDAE)

The gall-midge family Cecidomyiidae is one of the largest within the a nimal kingdom. Its characteristics include, among others, a chromosome elimination during spermiogenesis and a bewildering diversity in sper m ultrastructure. The sperm tail, in particular, is unusual in that it deviates from the conventional 9+2 pattern of microtubules. We descri be here the spermatozoa of five gall-midge species, all belonging to t he same supertribe Cecidomyiidi. In Bremia more than 100 microtubular doubters form a tight spiral around a central mitochondrion. In an und etermined binomen many doublers form a spiral around the mitochondria in the distal end of the sperm tail, but a single row along a peripher al cistern in the main part of the tail. In Coquillettomyia caricis a peripheral row of doublets resides in the proximal part and tightly pa cked doublets distally. In Arthrocnodax sp. the many doublets also for m a peripheral single or double row around a central mitochondrion. In Massalongia brachmaieri there are more than 500 doublets which form s everal rows around the nucleus and tightly packed doublers distally. T he nuclear membrane forms bundles of extensive outpocketings. There is no acrosome. The nucleus consists of both condensed and dispersed mat erial. Only outer dynein arms are present in all this species and the spermatozoa are motile. Cecidomyiidi species that have been examined f or sperm structure fall into two groups: those where the mitochondria are confined to the centre of the tail and those in which the mitochon dria lie in the head region and have a peripheral location. Most speci es belong to the first group, while Massalongia belongs to the second one. (C) 1997 Published by Elsevier Science Ltd on behalf of the Royal Swedish Academy of Sciences.