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 homologo..., , # The gnathosoma is a bad character rather than evidence for mite monophyly

Dataset DOI: [10.5061/dryad.pc866t21f](10.5061/dryad.pc866t21f)

## Description of the data and file structure

The files are confocal z-stacks of mite mouthparts that were generated using a Zeiss LSM 710 (*Nanorchestes* sp. 1, and *Stigmalychus* sp.) and an Olympus Spectral FV1000 (*Micropsammus* sp. 1, *Nanorchestes* sp. 2, and *Tydeus* sp.). The files can be viewed as 3d models in ImageJ (see code/software).

Excitation was via lasers of 405 nm (*Micropsammus* sp. 1 and *Nanorchestes* sp. 1) and 488 nm (*Nanorchestes* sp. 2, *Stigmalychus* sp. and *Tydeus* sp.). Autofluorescence was captured via broad detection bands from the wavelength of the laser up to around 650 nm.

## Code/software

ImageJ is recommended because it is open source and freely available.

[https://imagej.net/ij/](https://imagej.net/ij/)

In order to view the models, the bio-formats plugin may need to be installed.

[https://docs.openmicro...,