Abstract
Nine new species (Unionicola (Unionicolides) parkeri, gowani, alleni, bogani, gailae, gordoni, guilloryi, hendrixi and kavanaghi) are described for the first time. Each of these species was previously considered as a part of the Unionicola vamana Mitchell and Wilson-comples. Unionicola (Unionicolides) vikitrella new species is also described. It was formerly considered as a part of the Unionicola vikitra Mitchell and Wilson-complex. Each of these new species is apparently host specific in one or a few related species of fresh-water mussles. Adaptive speciation is suggested for this group of incipient species, since each mite species is apparently isolated within specific host mussels.