Water mites of the genus Unionicola are common parasites of freshwater mussels, living on the gills or mantle of their hosts and using these tissues as sites of oviposition. Although surveys of this mite fauna among North American unionid mussels indicate that these mites represent highly diverse assemblages, we know very little regarding the determinants of Unionicola species diversity among their molluscan hosts. The present study addresses the relationship between host diversity and mite diversity for Unionicola assemblages associated with unionid mussels of North America. The results of this study found a significantly positive relationship between host species richness and mite species richness, adding to a growing body of evidence that host diversity is an important determinant of parasite diversity. In recent years, molecular sequence data have discovered cryptic biodiversity among unionid mussels, yielding revisions in the nomenclature and systematic taxonomy of the group. DNA sequence variation has also revealed cryptic species complexes among Unionicola mites. Collectively, these findings suggest that the results of the present study may be underestimating species richness among mites and their host mussels. Unfortunately, human perturbations are known to have caused high recent rates of extinction in the mussel and mite faunas of North America and could play a major role in influencing patterns of species richness for this host–parasite system moving forward.

Unionicola属的水螨是淡水贻贝的常见寄生虫，生活在其寄主的ill或地幔中，并将这些组织用作产卵的部位。尽管在北美无性系贻贝中对这种螨类动物进行的调查表明，这些螨类代表了高度多样的种群，但我们对软体动物寄主中Unionicola物种多样性的决定因素知之甚少。本研究解决了Unionicola寄主多样性与螨类多样性之间的关系与北美的软体动物贻贝相关的组合。这项研究的结果发现宿主物种丰富度与螨类物种丰富度之间存在显着的正相关关系，这增加了越来越多的证据表明宿主多样性是寄生虫多样性的重要决定因素。近年来，分子序列数据已经发现了贻贝贻贝之间的神秘生物多样性，从而对该群体的术语和系统分类法进行了修订。DNA序列变异也揭示了Unionicola之间的隐性物种复合体螨。总体而言，这些发现表明，本研究的结果可能是低估了螨及其寄主贻贝之间的物种丰富度。不幸的是，已知人类扰动导致北美贻贝和螨类动物近来高度灭绝，并且可能在影响这种寄主－寄生虫系统向前发展的物种丰富度方面发挥重要作用。