Karyotypic and morphological study of five species of the genus <Emphasis Type="Italic">Wilhelmia</Emphasis> Enderlein (Diptera,Simuliidae)

Karyotypic features as well as larval and imaginal morphology have been studied in five species of the black fly genus Wilhelmia, viz. W. equina (Linnaeus, 1758), W. pseudequina (Seguy, 1921), W. lineata (Meigen, 1804), W. veltistshevi (Rubzov, 1940), and W. salopiensis (Edwards, 1927). Photomaps of polytene chromosomes are given for all species (those for W. pseudequina and W. veltistshevi, for the first time). Species-specific karyological and morphological characters have been revealed. According to principal karyological features, the species examined are divided into the equina and salopiensis groups. The validity of the species rank is confirmed for all species. Clear karyological and morphological distinctions between W. salopiensis and W. lineata give evidence that synonymization of W. salopiensis with W. lineata was erroneous.     

Comparative karyological study of 2 close species of blackflies of the genus Eusimulium]

The structure of polytene chromosomes in the salivary gland of two hard for distinguishing species Eusimulium montium Rubz. and E. gviletense alizadei Djaf. was studied. The comparative-karyologic analysis of the taxons showed many common features in their karyotypes: complete conjugation of the homologous chromosomes in the connection between the length and the arms of chromosomes. At the same time these species are well distinguished karyologically according to the two inversions of the homozigotic type in the chromosomes I and III, to the duplication in IIL, and to the deficiency of the telometric region in IIIL of E. montium. These readjustments are considered to be secondary which suggests E. gviletense alizadei to be phylogenetically older than E. montium.     

Cytogenetic analysis of the noxious bloodsucker Boophthora erythrocephala (Diptera: Simuliidae) from different geographic zones

Boophthora erythrocephala is a widely spread species inhabiting both small polluted water-bodies and large rivers. Three populations from Samara region in Russia and from Donetsk and Chernigov regions in the Ukraine have been studied. Five populations of this species in Russia were described earlier (Polyanskaya, Tsapygina, 1968; Petrukhina, 1972). For identification of this species the chromosome map of Adler and Werner (personal communication) was used. Comparison of 8 populations studied was performed. All of them belong to the species B. erythrocephala but everyone has its own individual characteristics. Inversion polymorphism was observed in each population comprising from 88 to 100 %. Mean number of heterozygous inversions per individual is low fluctuating around 3.6. There is one inversion in IIS observed in all populations that proves panmixy among them. Other inversions occur in a part of the individuals.     

Morphological diversity of centromere regions in polytene chromosomes of blackflies (Diptera, Simulidae)

Karyotypes of more than 120 species of 33 genera of the Palearctic blackflies (Simuliidae) were studied on squashed acetoorcein stained preparations of salivary gland polytene chromosomes in larvae. In the course of evolution of the family, a significant complication was noticed in the morphology of centromere regions of polytene chromosomes. In plesiomorphic species, centromeres are not pronounced morphologically and the general picture does not differ from that of other bands and interbands of the polytene chromosome. In species with apomorphic characters, a distinct precentromeric heterochromatin appears, whose manifestation is responsible for morphological diversity of centromere zones in polytene chromosomes. They are represented either by conspicuous slightly thickened heterochromatic bands or by large amplified blocks of heterochromatin or puff-like structure, being considerably extended as a result of despiralization of precentromeric heterochromatin. There are species, which more commonly lack chromocentre and their chromosomes are separated. Some other species have ectopic contacts between pricentromeric heterochromatin. In some species, this heterochromatin is organized as a compact chromocentre. This has been found only in representatives of southern latitudes, most frequently in evolutionarily young species with narrow specialization.     

Morphological and karyotypic analysis of five blackfly species of the genus Cnetha (Diptera: Simulidae): description of the novel species from the Dzhrvezhskiĭ canyon in Armenia

Morphological and karyotypical features of a new blackfly species Cnetha akopi sp. n. from Armenia are described. Comparative analysis of the new species and four closely related endemic species from Caucasus is performed. Photographic maps of polythene chromosomes are provided.     

Cytogenetic Features of Blackfly Wilhelmia paraequina Puri (Diptera: Simuliidae) from Armenia

Three blackfly Wilhelmia paraequina populations of Armenia (rivers Debet and Megriget, channel Megri) were studied. 2n = 6: IS + IIL, IIS + IL, IIIS + IIIL. Cytological maps of polytene chromosomes were constructed. High inversion polymorphism (95.63%) was observed, with 2.6 inversions per individual. Three inversions proved to be associated with male development: Y₁ was characterized by a combination of two heterozygous inversions, IIL-3 + IIL-1, while Y₂ had another combination of heterozygous inversions, IIL-5 + IIL-3. The X chromosome had a standard homozygous IIL band pattern. The populations were shown to be similar in autosomal polymorphism. A tendency for differentiation was observed with respect to frequencies and types of sex-linked inversions: the sex determination system was Y₁X–XX in the Debet and Megriget populations and Y₂X–XX in the channel (Megri) population. On the strength of these findings, one W. paraequina morphotype was assumed to involve two cytotypes, A (Debet and Megriget populations) and B (Megri population).     

Karyotypic characteristics of the genus Prosimulium Roub. (Simuliidae) and the problems of systematics

A comparative-karyologycal study of 12 species of black flies of the genus Prosimulium was carried out. Species referring to the groups hirtipes and macropyga have similar karyotypical characteristics differing in general in the degree of ploidy of chromosomal sets. Species which form the group alpestre possess peculiar karyologycal characters occupying due to this an intermediate position between the genera Prosimulium and Helodon. They should be separated into a distinct superspecies taxon, Ahaimophaga Chubareva et Rubzov gen. n. P. multicaulis differs karyotypically from other species of the genus Prosimulium but displays a great resemblance to species of Helodon; due to this it should be assigned to the latter.