The banding pattern of polytene chromosomes of Anopheles atroparvus has previously been studied and described by FRIZZI (1947a-b). Further studies carried out to date on characteristics of the maculipennis group, as far as the numeration of the chromosomes and of the zones, and their extension are concerned, have been based on the original codification of FRIZZI, which has been found entirely satisfactory for the study of the various chromosomal aberrations. Some zones however, especially those found in larvae approaching nymphosis, permit the observation of more detailed structures. These structures have been examined and described, always adhering to the original codification of FRIZZI as far as the numeration and the limits of the chromosomal sections are concerned. A detailed description of the banding pattern is necessary today in order to further studies on the topographic relationships, within the chromosomes themselves, between their different replicative entities, and between the structures of the chromosomes of the sibling species of the group. In this work autoradiographic labelling with TD-HS has been used to evidence DNA synthesis in the zones or regions which present more developed puff -like structure and to ascertain the presence of DNA in the nucleolar region. The species has been classified as A . atroparvus instead of A . maculipennis atroparvus, on the basis of the new status of the maculipennis group (STONE 1970) which agrees with the distinct separation, in nature, of the species A.atroparvus, from the other species of the group, and in particular from A . labranchiae. This separation has been evidenced on a zoogeographical, an ethological and recently on a genetic basis (BIANCHI 1968). STONE,A., 1970: A synoptic catalog of the mosquitoes of the World. Supplement IV (Diptera: Authors' address: species of European Anophinae mosquitoes. Nature 217, 382-383. 299-300. (fasc. l), 67-69. atroparvus. Am. Zool. 10 (4), 529 (abstract). Culicidae). Proc. Ent. SOC. Washington 72 (2), 37-188.

Males of Urosimulium stefanii Cont., (1963) from various populations in Sardinia, differ from females by a long asynaptic region in one pair of salivary gland chromosomes. This asynaptic tract does not seem to be due to inversions but rather to large structural changes. In meioses of the male, a pair of chromosomes does not show interstitial chiasmata. It is suggested that this pair of chromosomes represents the sex chromosome pair. The evolutionary process has been discussed.

Data are reported suggesting that automictic reproduction in Isidora truncata prevails; phases of female gametogenesis are described. Male gametes were observed in the hermaphroditic reproductive apparatus and inside the egg follicle.

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