Primitive-arachnids
Guides
Opilioacarida
Opilioacarida is a small order of mites containing a single family, Opilioacaridae, with approximately 13 genera and 53 valid taxa. These mites are among the largest of their kind (1.5–2.5 mm) and are considered primitive due to retained ancestral traits including six pairs of eyes and abdominal segmentation. Molecular phylogenetics places them within Parasitiformes, though historically they were treated as distinct from both Acariformes and Parasitiformes. The group has a worldwide distribution with notable diversity in the Americas.