Simulium (Gomphostilbia) williei sp. nov. and S. (G.) sachini sp. nov. are described on the basis of pupal and/or larval specimens collected from Darjeeling in the northeastern sub-Himalayan region of India. Simulium (G.) williei sp. nov. is characterized by the pupal gill composed of an inflated horn-like structure bearing eight slender thread-like filaments, and S. (G.) sachini sp. nov. is characterized by the pupal gill of inflated Y-form with six short finger-like projections and eight slender thread-like filaments.

A new black fly species, Simulium (Nevermannia) subratai sp. nov., is described on the basis of female, pupal and larval specimens collected from Darjeeling, India. This new species is assigned to the feuerborni species-group of the subgenus Simulium (Nevermannia), and is characterized by the entirely yellow female thorax and the larval abdomen without any colored markings. This is the first record of a black fly species with the adult having an entirely yellow thorax in the Oriental Region.

The polytene chromosomes are mapped for a scarce Himalayan simuliid, Simulium (Montisimulium) ghoomense Datta, from the Darjeeling area of India. This species has three tightly paired polytene chromosomes with a haploid number of 3. Chromosomes I, II, and III account for 39.6%, 30.3%, and 30.1% of the total complement length, respectively. The centromeres of chromosomes II and III consistently form a putative partial chromocenter. Sex chromosomes are undifferentiated and polymorphisms and sibling species are lacking in a sample of 35 larvae. This is the first chromosomal map for a species in the subgenus Montisimulium in India.

High quality polytene chromosome maps (n=3) of a Himalayan Simuliid Simulium praelargum Datta, 1973 are presented and represent the first cytological description of a taxon found in the feuerborni group, subgenus Nevermannia. Polytene chromosomes one (I) and two (II) are metacentric, chromosome three (III) is submetacentric with the length of each chromosome occupying 37.25 %, 31.36 % and 31.34 % of the total complement length, respectively. Typical simuliid diagnostic intergeneric chromosomal markers are found within the polytene complement of this species. The nucleolar organizer (N.O.) is found at the base of the short arm of chromosome one (IS), the Ring of Balbiani (R.B.), double bubble (D.B.) and triad occur in the short arm of chromosome two (IIS), the Parabalbiani Ring (P.B.) and grey band (gb) occur in the long arm of chromosome two (IIL) and the Blister (BL) and Capsule (Ca) occur in the short arm of chromosome three (IIIS).Terminal bands at the end of IIIS are heterochromatinized and present atypically with respect to other simuliid fauna. Populations studied so far are unique among the Simuliidae in that they exhibit chromosome structural monomorphism. These high resolution polytene chromosome maps will form the basis for future cytological characterization and phylogenetic comparisons amongst members of the feuerborni group.

Cytological descriptions are given for two sympatric sibling species, Simulium praelargum IIIL-st and Simulium praelargum IIIL-1.2, from Darjeeling, West Bengal, India. Sibling IIIL-1.2 differs from IIIL-st by a two step fixed included inversion (IIIL-1.2) found on the long arm of chromosome III. Both siblings possess heterochromatinized IIIS polytene chromosome ends, while IIIL-1.2 is unique within the Simuliidae in that it exhibits a very large enhanced chromocentre that persists in normal somatic tissue, contrary to other chromocentre-containing taxa. In IIIL-1.2, the chromocentre occurs as a positively allocyclic heteropycnotic body in normal mitotic interphase cells of neuroblast ganglia, oogonia, and spermatogonia. In mitotic metaphase chromosomes, the chromocentre forms large pronounced primary (centromere) constrictions and appears to be associated with nonhomologous pairing. Initial cytological studies on taxa within the feuerborni group have revealed heterochromatic chromosomal polymorphisms. Progressive fixation of these polymorphisms in different taxa within the group opens up the possibility of using comparative molecular or genomic approaches to begin to define the functional and structural aspects of the epigenome and to further characterize mitosis and meiosis in S. praelargum IIIL-1.2.