We examined the dynamic of periphytic diatom colonization and litter decompositional pattern in an intermittent stream of South India. Litter bags containing 5 g of fresh fallen leaves (belongs to five different species of angiosperms) were fixed in the five stream pools and they were collected after 7, 14, 21, and 28 days of incubation.This experiment showed the diversity, richness, and abundance of diatoms developed on leaf litter. In total, 131 μl −1 cells of diatoms under four species in three families were collected from decomposing leaves in benthic area of stream pools. During experiment, 142 μl −1 cells representing 11 taxa in 10 families were observed in litter bags. The colonization of epiphytic diatom was rapid in early stage of litter decomposition. The higher number of colonization made by Asterionella and Stenopterobia found in litter bags of all experimental weeks. These findings suggest that the rapid microbial colonization (ephiphytic algae) was occurred in the early stage of litter decomposition in an intermittent tropical stream and a comprehensive ecological investigation in perennial natural streams in India is needed. K E Y W O R D Scolonization, decomposition, diatom, India, leaf litter

A new black fly species, Simulium (Nevermannia) karavalliense sp. nov. is described from Southern Eastern Ghats of South India. This new species is placed in the Simulium ruficorne species-group of the subgenus Nevermannia. S. (N.) karavalliense sp. nov. is characterized by female with a long sensory vesicle, male upper eye with 14 vertical columns and 16 horizontal rows of large facets, pupal gill with 8 filaments and larval hypostoma with 6 hypostomal bristles lying parallel to lateral margin. Taxonomic keys are provided to distinguish this new species from related species in India.

Simulium (Gomphostilbia) kumbakkaraiense sp. n. is described based on adults, pupae and mature larvae from Kumbakkarai stream, in the Palani Hills of Western Ghats, South India. This new species is placed in the Simulium batoense species-group of the subgenus Gomphostilbia Enderlein. This new species is characterized by a scutum with three brownish-black longitudinal vittae and hind basitarsus in the female 5.3 times as long as wide, and in male the large facets of the upper eye in 13 vertical columns and 14 horizontal rows, the respiratory gill with short common basal in the pupa and postgenal cleft arrow-head-shaped in the larva. Taxonomic notes are provided to distinguish this new species from related species. [Zoobank register: http://zoobank.org/urn:lsid:zoobank.org:act:C575FB25-B6B2-414B-AE11-0468A1871DFA]

Two new black fly species, Simulium (Gomphostilbia) dinakarani sp. nov. and Simulium (Gomphostilbia) krishnani sp. nov. are described based on reared adult, pupal and larval specimens collected from the Western Ghats of India. These two new species are placed in the Simulium batoense species-group of the subgenus Gomphostilbia Enderlein. The morphological characters of two new species are compared with other related species of batoense species-group in India. The COI gene has successfully differentiated these two new species from its allies, S. (G.) panagudiense and S. (G.) takaokai of the batoense species group and the phylogenetic analysis by using COI gene sequences supporting its morphological classification.