Data from: The gnathosoma is a bad character rather than evidence for mite monophyly

In recent years, the case for the monophyly of mites or Acari
(Parasitiformes + Acariformes) has looked increasingly weak. Much of the
remaining doubt about the artificiality of this taxon stems from the
importance long attributed to the gnathosoma, widely considered the most
convincing morphological character supporting monophyly. The gnathosoma
has long been interpreted as originating via the fusion together of the
palpal coxae, which is thought to have contributed to the consolidation of
the mouthparts into a compact feeding apparatus that articulates as a
single unit. However, an investigation of the mouthparts of Acariformes,
reported herein, revealed that fusion together of the palpal coxae is an
uncommon state that convergently evolved in multiple acariform taxa rather
than evolving only once, as a synapomorphy uniting Acariformes and
Parasitiformes. Moreover, other defining features of the gnathosoma
involve either very different modifications or structures that are not
homologous between both main lineages of mites. Therefore, the gnathosoma
is a bad character—poorly defined and based on a series of
misinterpretations—that should not be treated as evidence for mite
monophyly.