THE SPERMATOZOON OF ARTHROPODA: ZOOTERMOPSIS NEVADENSIS AND ISOPTERAN SPERM PHYLOGENY

In this paper, the ultrastructure of the spermatozoon of Zootermopsis nevadensis (Isoptera, Hodotermitidae) and of some Rhinotermitidae and Termitidae is described. Zootermopsis sperm is rod like, aflagellate, immotile, and without an acrosome; it is composed of a filiform nucleus encircled by a monolayered microtubular manchette, and a few mitochondria. This spermatozoon was previously thought to be flagellate, and therefore the most primitive in Isoptera: our present study suggests a new phylogenetical position for Hodotermitidae. All the species of Rhinotermitidae and Termitidae studied by us show a similar spheroidal sperm model, devoid of acrosome, flagellum and manchette at spermatid stage, and are made up of only a round nucleus, two mitochondria and a centriole. This widely distributed model seems to be the more evolved in the order. The nature of sperm evolution in the Isoptera is considered.