Drawing of Opilioacarus texanus, copyright Encyclopædia Britannica, Inc..

Belongs within: Parasitiformes.

The Opilioacarids are a small group of relatively large, soft-bodied mites that are noteworthy for retaining traces of the ancestral segmentation, lost in most other mite groups.

Characters (from Walter & Harvey 2009): Cuticle leathery, with purple or bluish markings and no distinct plates, body setae isotropic. Opisthosoma with relatively few to many setae; four pairs of dorsolateral spiracles present in adults and tritonymphs, peritremes absent. Prodorsum with two or three pairs of lateral ocelli and numerous setae. Pair of sternal verrucae present between coxae II; genital region with paired setose verrucae, eugenital setae sometimes present; anus with two setose valves. Females with well-developed extrusible ovipositor terminating in 2-3 lobes. Gnathosoma always with more than four pairs of ventral setae, paired rutella, with discoid or biramous With's organ lateroventrally, and a large denticulate labrum; chelicerae three-segmented, with 3-5 setae and two lyrifissures on middle article, palpi five-segmented, with well-developed, usually terminal, pair of claws. Tritosternum represented by unfused sternapophyses; leg coxae free, trochanters III-IV and tarsi I-IV divided in tritonymphs and adults.

<==Opilioacaridae [Notostigmata, Opilioacariformes, Opilioacaroidea] WH09
    |  i. s.: Phalangiacarus brosseti WP99
    |         Panchaetes WH09
    |         Salfacarus WH09
    |         Adenacarus arabicus WH09
    |         Vanderhammenacarus WH09
    |--+--Paracarus Chamberlin & Mulaik 1942 H02
    |  |    `--P. hexophthalmus WH09
    |  `--Siamacarus Leclerc 1989 H02
    |       `--S. withi S07
    `--+--Eucarus With 1904 H02
       |    |--E. arabicus With 1904 H02 [=Opilioacarus arabicus S04]
       |    `--E. italicus With 1904 H02 [=Opilioacarus italicus S04]
       `--Opilioacarus With 1902 H02
            |--O. platensis Silvestri 1904 S04
            |--O. segmentatus With 1902 [=Eucarus segmentatus] H02
            `--O. texanus (Chamberlin & Mulaik 1942) [=Neoacarus texanus] DA07

*Type species of generic name indicated


[DA07] Domes, K., M. Althammer, R. A. Norton, S. Scheu & M. Maraun. 2007. The phylogenetic relationship between Astigmata and Oribatida (Acari) as indicated by molecular markers. Experimental and Applied Acarology 42 (3): 159-171.

[H02] Harvey, M. S. 2002. The neglected cousins: What do we know about the smaller arachnid orders? Journal of Arachnology 30 (2): 357-372.

[S07] Shultz, J. W. 2007. A phylogenetic analysis of the arachnid orders based on morphological characters. Zoological Journal of the Linnean Society 150 (2): 221-265.

[S04] Silvestri, F. 1904. Note Aracnologiche I-III. Redia 2: 239-261.

[WH09] Walter, D. E., & M. S. Harvey. 2009. Order Opilioacarida. In: Krantz, G. W. & D. E. Walter (eds) A Manual of Acarology, 3rd ed., pp. 104-106. Texas Tech University Press.

[WP99] Walter, D. E. & H. C. Proctor. 1999. Mites: Ecology, Evolution and Behaviour. CABI Publishing: Wallingford (UK).

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