Complete

Acariformes

The "mite-like" mites

Heather Proctor
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window
taxon links [up-->]Trombidiformes [down<--]Acari Interpreting the tree
close box

This tree diagram shows the relationships between several groups of organisms.

The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.

example of a tree diagram

You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.

For more information on ToL tree formatting, please see Interpreting the Tree or Classification. To learn more about phylogenetic trees, please visit our Phylogenetic Biology pages.

close box
modified from Norton et al. 1993
Containing group: Acari

Introduction

The Acariformes is one of the three major divisions of the Acari, the other two being the Parasitiformes (including ticks) and the Opilioacariformes. There are more than 30 000 described species of acariform mites, and they inhabit all imaginable biotic and abiotic habitats from hot springs to hydrothermal vents, from leaves to lizards, and from the ears of your pet cat to the eyebrows of your grandfather. They include such familiar scourges as dust mites, spider mites, scabies and chiggers, as well as a huge range of lesser-known parasites, predators, and fungivores. They are an ancient group of arachnids with representatives among the earliest assemblages of terrestrial invertebrates (Rhynie chert, Gilboa formation) (e.g. Kethley et al. 1979).

Characteristics

A number of developmental characteristics unite the Acariformes. Development is anamorphic, meaning that body segments are added between moults. Also, prior to moulting, the legs of the subsequent instar are formed within the body rather than within the hulls of the previous instar's legs. There are also several characteristics of acariform setae that differentiate them from other Acari. Another name for the Acariformes is the 'Actinotrichida', which refers to the fact that their setae have a layer of optically active chitin, 'actinochitin', that is birefringent under polarized light. Other mites - the Parasitiformes and Opilioacariformes - lack actinochitin and are sometimes grouped as the 'Anactinotrichida'. Trichobothria, specialized setae that are sensitive to vibrations and air currents, are found in the Acariformes but not in other mites. Other modified sensory setae unique to the Acariformes include solenidia and eupathidia. Lindquist (1984) provides a list of the apomorphic characters of this group.

Discussion of Phylogenetic Relationships

As can be gathered from the illustrated tree, monophyly is not the rule in the Acariformes. Acarologists have traditionally split this taxon into three major groups, the Endeostigmata, Trombidiformes (also called Prostigmata) and Sarcoptiformes (= Astigmata + Oribatida). However, the Endeostigmata is likely to be an artifical group composed of primitive members of both the trombidiform and sarcoptiform lineages. OConnor (1984) performed a cladistic analysis that showed the Prostigmata to share some derived setal and developmental characters with the endeostigmatan taxa Sphaerolichidae and Lordalychidae. He therefore suggested that the Prostigmata and Sphaerolichida (= Sphaerolichidae + Lordalychidae) make up a monophyletic group, and gave this group the name Trombidiformes. Within the Sarcoptiformes, the Astigmata and Oribatida have traditionally been represented as taxa of equal rank; however, it is quite apparent that the Astigmata are derived from within the Oribatida, making the latter taxon paraphyletic (e.g. OConnor 1984, Norton et al. 1993). Recent chemotaxonomic studies provide further evidence of paraphyly. A novel defensive compound is known only from Astigmata and middle-derivative Oribatida, but is absent in several early derivative oribatid taxa (Parhypochthonius, Gehypochthonius and Nehypochthonius) (Sakata & Norton 2001).

Other Names for Acariformes

References

Kethley, J.B., R.A. Norton, P.M. Bonamo and W.A. Shear. 1989. A terrestrial alicorhagiid mite (Acari: Acariformes)from the Devonian of New York. Micropaleontology 35:367-373.

Lindquist, E.E. 1984. Current theories on the evolution of major groups of Acari and on their relationships with other groups of Arachnida, with consequent implications for their classification. pp. 28-62 in D.A. Griffiths and C.E. Bowman (eds.) Acarology VI, Vol. I. Ellis Horwood Ltd., Chichester.

Norton, R.A., J.B. Kethley, D.E. Johnston, and B.M. OConnor.1993. Phylogenetic perspectives on genetic systems and reproductive modes of mites. pp. 8-99 in: D.L. Wrensch and M.A. Ebbert (eds.) Evolution and diversity of sex ratio in insects and mites. Chapman & Hall, New York.

OConnor, B.M. 1984. Phylogenetic relationships among higher taxa in the Acariformes, with particular reference to the Astigmata. pp. 19-27 in D.A. Griffiths and C.E. Bowman. 1984. Acarology VI, Vol. I. Ellis-Horwood Ltd., Chichester.

Sakata, T. and Norton, R. A. 2001. Opisthonotal gland chemistry of early-derivative oribatid mites (Acari) and its relevance to systematic relationships of Astigmata. International Journal of Acarology. in press.

Title Illustrations
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

Venter of acariform mite (Sarcoptiformes: Oribatida, Lohmanniidae: Meristolohmannia). SEM copyright © 1998, D. Walter.

Copyright © 1998
About This Page

Heather Proctor
University of Alberta, Edmonton, Alberta, Canada

Correspondence regarding this page should be directed to Heather Proctor at

Page: Tree of Life Acariformes. The "mite-like" mites. Authored by Heather Proctor. The TEXT of this page is licensed under the Creative Commons Attribution License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Proctor, Heather. 1998. Acariformes. The "mite-like" mites. Version 09 August 1998. http://tolweb.org/Acariformes/2563/1998.08.09 in The Tree of Life Web Project, http://tolweb.org/

edit this page
close box

This page is a Tree of Life Branch Page.

Each ToL branch page provides a synopsis of the characteristics of a group of organisms representing a branch of the Tree of Life. The major distinction between a branch and a leaf of the Tree of Life is that each branch can be further subdivided into descendent branches, that is, subgroups representing distinct genetic lineages.

For a more detailed explanation of the different ToL page types, have a look at the Structure of the Tree of Life page.

close box

Acariformes

Page Content

articles & notes

collections

people

Explore Other Groups

random page

  go to the Tree of Life home page
top