Species diversity of black flies (Diptera: Simuliidae) in Oriental region and molecular phylogeny of the subgenus Gomphostilbia members

Abstract

Background & objectives: Black flies (Diptera: Simuliidae) are ecologically and medically important insects. Female adults of black flies are the solitary vectors of river blindness (onchocerciasis) and their larvae play a vital role in stream ecosystem. This study examined the distribution of black flies in the Oriental region and analyzed the phylogenetic relationship of the subgenus Gomphostilbia members based on two molecular loci.

Methods: The distribution data of black fly species in different countries of Oriental region were obtained from world black flies geographic inventory. The two gene sequences, COI and ITS1 were used to study the phylogenetic relationships of the members of subgenus Gomphostilbia members.

Results: The distribution analysis revealed that out of the 16 subgenera in the genus Simulium Latreille s., the species-level diversity of three subgenera (Gomphostilbia, Nevermannia and Simulium) contributes about thrice of total black fly species diversity. The highest diversity of species was found in the subgenus Simulium. The strict consensus of Tree analysis using New Technology (TNT) and Maximum Likelihood (ML) recovered similar topolo- gies for Gomphostilbia members and they formed as monophyly. The overall sequence identities of the 19 species of subgenus Gomphostilbia were high and shared 55-60% similarity.

Interpretation & conclusion: Results of this study highlighted that eight subgenera of Simulium Latreille s. str are commonly distributed in different parts of Oriental region. Among these the subgenera of Simulium, Gomphostilbia and Nevermannia are most common with high diversity in China, Pakistan, Thailand and Vietnam. The phylogenetic analysis of Gomphostilbia members demonstrates the inter-specific divergence, indicating the centre of origin (India) or the recipient of ancestral migrant lineages in Oriental region.