Laos, a new frontier for investigating black flies (Diptera: Simuliidae)

One of the world's least-known simuliid faunas was surveyed over a two-year period and evaluated morphologically, chromosomally, and molecularly. The number of species known from Laos increased from 8 to 31 and includes anthropophilic species and vectors of disease agents. The fauna is remarkably similar to that of Thailand; about 94% of the Laotian fauna is shared with Thailand. At the chromosomal level, species in Laos and Thailand are entirely congruent; no cryptic species were discovered. We also established the chromosomal characteristics of Simulium ubonae Thaijarern et al. to distinguish the larvae from those of its isomorphic sister species, S. fenestratum Edwards. Molecular evaluations using the mitochondrial cytochrome c oxidase I gene for 24 of 31 species indicated genetic similarity among Laotian populations and conspecificity with populations in neighboring countries. Despite streams that have suffered intense environmental assaults, the species richness per stream is high, averaging five species per stream, with as many as 11 species at one site at one point in time.