# Diversity and Origin of Quill Mites of the Subfamily Syringophilinae (Acariformes: Syringophilidae) Parasitising the True Finches (Passeriformes: Fringillidae)

## TL;DR

This study explores quill mites living in finch feathers, revealing new species and how these mites evolve alongside their bird hosts.

## Contribution

The study identifies 20 mite species on finches, including four new species, and reveals patterns of host specificity and co-evolution.

## Key findings

- Most syringophilid mites parasitise finches that are closely related phylogenetically.
- Four new mite species were described from finch hosts.
- Mite diversification does not always align with host evolution.

## Abstract

Finches are a large and diverse group of birds found worldwide, yet little is known about the parasites of the family Syringophilidae that live inside their quill feathers. These parasites form close and often long-lasting relationships with their bird hosts. In this study, we investigated which species of syringophilid mites inhabit finches and how specific these mites are to particular bird species. We identified 20 different mite species on 51 finch species, including 4 species newly described for science. Our research indicates that most syringophilids are not strictly limited to a single bird species, but rather occupy birds that are closely related. Interestingly, we did not find any mites that switched between phylogenetically not closely related finch groups. These findings suggest that syringophilid mites and finches have evolved together over long periods of time. This kind of research helps us understand how parasites adapt to their hosts and how these hidden relationships shape biodiversity. It also shows the importance of studying old museum specimens, which can still reveal new scientific discoveries even after many decades.

Quill mites belonging to the family Syringophilidae are highly specialised external parasites that live inside feather quills. However, parasitologists have limited knowledge about their diversity and patterns of host specificity, particularly regarding how restricted syringophilids are in their choice of avian hosts across different bird lineages. This research presents the first complete overview of mites of the subfamily Syringophiline found on True Finches (Fringillidae). Based on a combination of all published records and extensive examinations of museum specimens of fringillids housed at the Bavarian State Collection of Zoology in Munich, Germany, we report 20 mite species from 5 genera parasitising 51 finch species across all 3 subfamilies: Fringillinae, Euphoninae, and Carduelinae. Four species are described here as new to science: Aulobia ruppelae sp. n., Aulonastus ritzerfeldi sp. n., Torotrogla enucleator sp. n., and T. janhafti sp. n. Herein, we also recognised that most syringophilid mites associated with the True Finches, parasitise hosts belonging to the same or phylogenetically closely related genera, suggesting strong phylogenetic conservatism. The variation in host range and speciation rate across mite genera suggests that quill mite diversification does not always proceed synchronously with host evolution. These discoveries offer an important understanding of how host–parasite relationships evolve over time.