Heterochromatin variation in chromosomes of Anopheles (Nyssorhynchus) darlingi Root and A.(N.) nuneztovari Gabaldon (Diptera : Culicidae)

C-banding was used to study the variations in heterochromatic block marking s in chromosomes of Anopheles darlingi and A. nuneztovari from Manaus, Stat e of Amazonas, and Macapa, State of Amapa, Brazil. Both species had two dif ferently shaped X chromosomes and a Y chromosome that was entirely heteroch romatic. The X, chromosome of A. darlingi had markings that extended 1/3 of the total length whereas in the X-2 chromosome the markings were located a round the centromeric region. The markings on autosomal chromosomes were co ncentrated in the centromeric region in both species, with a heterochromati c block in one arm of chromosome II of A. darlingi. A. nuneztovari had thre e heterochromatic blocks in chromosome X-1 (longer) and two blocks in X-2 ( shorter). X2X2 females were not detected in either species. The X-1 and X-2 chromosomes of males were found in A. darlingi, whereas in A. nuneztovari only the X-1 chromosome was detected. Only intraspecific variation was foun d in heterochromatic block markings in the sex chromosomes and autosomes in the two populations of both species at each location.