Acariformes

Actinotrichida

Suborder Guides

Astigmata
Endeostigmata(Endeostigmatan Mites)
Oribatida(beetle mites)
Sarcoptiformes
Trombidiformes(Trombidiform Mites)

Acariformes is one of two of mites, representing the more diverse lineage with over 32,000 described in 351 and an estimated total of 440,000–929,000 species. Recent phylogenomic analyses indicate Acariformes is the most deeply rooted chelicerate lineage, rendering the traditional grouping of all mites into a single scientifically problematic. The superorder comprises two main clades: Sarcoptiformes (including Oribatida and Astigmatina) and Trombidiformes, with the enigmatic Endeostigmata representing primitive forms of uncertain placement.

Damaeus by (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY), uploaded by Alexis Tinker-Tsavalas. Used under a CC-BY license.

Epidermoptidae by (c) Cricket Raspet, some rights reserved (CC BY), uploaded by Cricket Raspet. Used under a CC-BY license.

Psoroptidae by (c) Oleksii Vasyliuk, some rights reserved (CC BY), uploaded by Oleksii Vasyliuk. Used under a CC-BY license.

Pronunciation

How to pronounce Acariformes: /ˌækəˈrɪfɔːrmiːz/

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Images

Distribution

Global; fossil record extends to early Devonian (approximately 410 million years ago, Rhynie Chert, Scotland)

Human Relevance

Includes economically significant agricultural pests (spider mites, Tetranychidae; gall mites, Eriophyoidea), medically important (, ; mites, Sarcoptidae), and beneficial used in

Similar Taxa

ParasitiformesOther of mites; distinguished by phylogenetic position (Parasitiformes is more closely related to other chelicerates including spiders and horseshoe crabs, whereas Acariformes is the most deeply rooted chelicerate lineage), and by morphological differences in mouthpart structure including the traditional gnathosoma configuration
Arachnida (non-mite)Spiders, scorpions, and other arachnids share the class Arachnida but lack the highly reduced body plan and minute size characteristic of Acariformes; recent phylogenetic analyses place some traditional mite groups closer to these other arachnids than to Acariformes

Misconceptions

The traditional concept of 'mites' (Acari) as a natural, has been challenged by recent phylogenetic analyses. The gnathosoma—a modified mouthpart region long cited as the defining synapomorphy of mites—is now understood to be absent or differently configured in many , with separate palpal present in numerous Acariformes and possibly Parasitiformes. The classification of mites as a single based on this character reflects circular reasoning that has persisted for over a century.

More Details

Phylogenetic Position

Acariformes represents the earliest diverging lineage of chelicerates in most phylogenomic analyses, with a divergence time potentially exceeding 400 million years based on fossil and molecular evidence. This placement challenges the monophyly of traditional 'Acari' and suggests that 'mite-like' evolved convergently or was retained from chelicerate ancestors.

Major Clades

Sarcoptiformes primarily contains microherbivores, fungivores, and (Oribatida), plus vertebrate-associated (Astigmatina: , mites, stored product mites). Trombidiformes includes the most significant plant-parasitic mites (spider mites, gall mites), (velvet mites), and animal parasites. The Endeostigmata comprises 10 of minute, soft-bodied mites with poorly resolved relationships.

Evolutionary Significance

has evolved repeatedly in Acariformes, with some ancient parthenogenetic lineages in Oribatida estimated at 400–300 million years old. The Eriophyoidea (gall mites) represent one of the largest and earliest adaptive radiations of plant-parasitic arthropods, with Triassic fossils indicating diversification by 230 million years ago. Some analyses suggest Eriophyoidea may be nested within Nematalycidae, a of deep soil mites, rather than within Trombidiformes as traditionally classified.