Search

Unionicola (Wolcottatax) arcuata (Wolcott, 1898) (Acari: Hydrachnidia: Unionicolidae) commonly occurs in parasitic association with Cristaria plicata (Leach), Anodonta woodiana elliptica (Heude) or Anodonta woodiana pacifica (Heude) during one or more stages of its life cycle. The mitochondrial 12S rRNA gene was sequenced and analysed from U. arcuata obtained from nine populations of these freshwater mussels from six large lakes in the middle and lower reaches of the Yangtze River, China. The 382 base sequence alignments for these nine populations of U. arcuata had two gaps and contained 51 (13.4%) variable nucleotides. The pairwise divergences among U. arcuata sequence data ranged from 0 to 10.9%, with the lowest intraspecific divergences (0–0.5%) observed among U. arcuata obtained from the same host species and the highest intraspecific divergences (6.7–10.9%) found among U. arcuata from different species of hosts. The results of sequence alignment and divergence were consistent with the heterogeneity in sequence data of the 12S rRNA gene observed in other studies of acarines. Maximum parsimony and maximum likelihood analyses each yielded a single tree with the same topology and high bootstrap support. The gene trees indicate three major clades, with U. arcuata from C. plicata, A. woodiana elliptica and A. woodiana pacifica each forming a distinct clade. Overall, the results of this study indicated that host association, rather than patterns of geographic distribution, plays an important role in the degree of genetic divergence among populations of U. arcuata. [ABSTRACT FROM AUTHOR]