Sperm structure of Limoniidae and their phylogenetic relationship with Tipulidae (Diptera, Nematocera)

The sperm ultrastructure of a few species of Limoniidae (Limonia nigropunctata; L. nubeculosa; Chionea n. sp.; C. alpina; C. lutescens) was studied. The two species of Limonia have a monolayered acrosome with crystallized material, a three-lobed nucleus in cross section, a ring of centriole adjunct material and a flagellum which consists of a 9 + 9 + 1 axoneme and a single mitochondrial derivative. The central axonemal tubule is provided with 15 protofilaments in its tubular wall, while the accessory tubules have 13 protofilaments and are flanked by the electron-dense intertubular material. The three species of Chionea share a monolayered acrosome, a nucleus with two longitudinal grooves, a centriole adjunct material which surrounds the centriole and the initial part of the axoneme. The axoneme is of conventional type, with 9 + 9 + 2 microtubular pattern, with accessory tubules provided with 13 protofilaments and intertubular material. However, in C. lutescens the accessory tubules start with 15 protofilaments and transform into a tubule with 13 protofilaments. These data are discussed in the light of the phylogenetic relationship between Limoniidae and Tipulidae. For this purpose, the sperm ultrastructure of Nephrotoma appendiculata was also considered comparatively.