Neocarus texanus, copyright Robert Deans.

Belongs within: Euchelicerata.
Contains: Mesostigmata, Ixodida.

The Parasitiformes are a group of usually well-sclerotised mites, many of which are predatory or otherwise feeders on animal matter (scavengers or parasites). They are characterised by having the respiratory openings at the side of the body, close to the hind pairs of legs. Four pairs of dorsolateral stigmata are present in Opilioacaridae but a single ventrolateral pair is present in other Parasitiformes. Earlier authors often treated the Opilioacaridae as the sister taxon to Parasitiformes rather than within the Parasitiformes proper but they are commonly included by recent authors.

Opilioacarids are relatively large, long-legged mites with a leathery integument known from tropical and warm temperate parts of the world. The prodorsum bears two or three pairs of lateral ocelli whereas at most one pair is present in other Parasitiformes, and the opisthosoma bears indications of the ancestral segmentation. Opilioacarids also differ from other Parasitiformes in the presence of a large pair of claws on the palptarsi and the division of trochanters III and IV in tritonymphs and adults (Walter & Harvey 2009).

The remaining Parasitiformes are divided between three lineages whose relationships are uncertain. Recent studies, both morphological and molecular, have suggested that the Holothyrida are more closely related to the Ixodida than to the Mesostigmata but the support for this position is weak (Walter 2009). The Holothyrida are large, heavily sclerotised mites with a relictual distribution in South and Central America and Australasia. Members of the family Neothyridae are found in the Americas whereas Allothyridae and Holothyridae are found in Australasia. Holothyridae are also found on islands in the Indian Ocean. Species are found in mesic litter habitats; where dietary habits are known, they have been observed to be scavengers (Walter 2009).

<==Parasitiformes [Anactinochaeta, Anactinochitinosi, Anactinotrichida, Gamasiformes, Parastigmata]WH09
    |--Opilioacaridae [Notostigmata, Opilioacarida, Opilioacariformes, Opilioacarina, Opilioacaroidea]WH09
    |    |  i. s.: Phalangiacarus brossetiWH09, WP99
    |    |         PanchaetesWH09
    |    |         SalfacarusWH09
    |    |         Adenacarus arabicusWH09
    |    |         VanderhammenacarusWH09
    |    |         Gibocellum Stecker 1876 [Gibocellinae]K18
    |    |           `--*G. sudeticum Stecker 1876K18
    |    |         Neocarus texanus (Chamberlin & Mulaik 1942)WH09, PL17 [=Opilioacarus texanusPL17]
    |    |--+--Paracarus Chamberlin & Mulaik 1942H02
    |    |  |    `--P. hexophthalmusWH09
    |    |  `--Siamacarus Leclerc 1989H02
    |    |       `--S. withiS07
    |    `--+--Eucarus With 1904H02
    |       |    |--E. arabicus With 1904H02 [=Opilioacarus arabicusS04]
    |       |    `--E. italicus With 1904H02 [=Opilioacarus italicusS04]
    |       `--Opilioacarus With 1902H02
    |            |--O. platensis Silvestri 1904S04
    |            `--O. segmentatus With 1902 [=Eucarus segmentatus]H02
            `--Holothyrida [Holothyriformes, Holothyrina, Holothyroidea, Tetrastigmata]W07
                 |  i. s.: HaplothyrusW09
                 |    |--Australothyrus van der Hammen 1983H98
                 |    |    `--*A. ocellatus van der Hammen 1983H83
                 |    `--Allothyrus Womersley 1961H98
                 |         |--A. australasiae (Womersley 1935) [=Holothyrus australasiae]H98
                 |         `--A. constrictus (Domrow 1955) [=Holothyrus constrictus]H98
                 `--+--Neothyrus [Neothyridae]W09
                    |    `--N. ana Lehtinen 1981H83
                         |    |--H. armatus Canestrini 1897H83
                         |    |--H. coccinella Gervais 1842H83
                         |    |--H. gardineri Warburton 1913H83
                         |    |--H. legendrei Van der Hammen 1983H83
                         |    |--H. seychellensis Thon 1906H83
                         |    `--H. testudineus Butler 1876H83
                         |--Sternothyrus braueriDW10
                              |  i. s.: H. braueri (Thon 1905) [=Holothyrus braueri, Thonius braueri]H83
                              |--H. (Hammenius)H83
                              |    |--H. (H.) fujuge Lehtinen 1981H83
                              |    |--H. (H.) ingii Lehtinen 1981H83
                              |    `--H. (H.) niger (Thon 1905)H83
                              |--H. (Leiothyrus van der Hammen 1983)H83
                              |    |--H. (*L.) holthuisi Van der Hammen 1983H83
                              |    |--‘Holothyrus’ expolitissimus Berlese 1923H83
                              |    `--H. (L.) nitidissimus (Thorell 1882) (see below for synonymy)H83
                              `--H. (Thonius)H83
                                   |--H. (T.) grandjeani (Van der Hammen 1961)H83
                                   |--H. (T.) longipes (Thorell 1882) (see below for synonymy)H83
                                   `--H. (T.) montanus Van der Hammen 1983H83
Nomen nudum: Holothyrus gervaisi Thon in Hughes 1959H83

Hammenius (Leiothyrus) nitidissimus (Thorell 1882) [=Holothyrus nitidissimus; incl. Ho. scutifer Thorell 1882]H83

Hammenius (Thonius) longipes (Thorell 1882) [incl. Holothyrus longipes var. ferrugineus Thorell 1882]H83

*Type species of generic name indicated


[AL37] André, M., & É. Lamy. 1937. Les Idées actuelles sur la Phylogénie des Acariens. Published by the author: Paris.

[DW10] Dabert, M., W. Witalinski, A. Kazmierski, Z. Olszanowski & J. Dabert. 2010. Molecular phylogeny of acariform mites (Acari, Arachnida): strong conflict between phylogenetic signal and long-branch attraction artifacts. Molecular Phylogenetics and Evolution 56 (1): 222–241.

[H98] Halliday, R. B. 1998. Mites of Australia: A checklist and bibliography. CSIRO Publishing: Collingwood.

[H83] Hammen, L. van der. 1983. New notes on Holothyrida (anactinotrichid mites). Zoologische Verhandelingen 207: 1–48.

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

[K18] Kury, A. B. 2018. Familial nomina in harvestmen (Arachnida, Opiliones). Bionomina 13: 1–27.

[PL17] Pachl, P., A. C. Lindl, A. Krause, S. Scheu, I. Schaefer & M. Maraun. 2017. The tropics as an ancient cradle of oribatid mite diversity. Acarologia 57 (2): 309–322.

[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.

[W07] Walter, D. E. 2007. A plethora of questions, but only a modicum of answers: Australian Parasitiformes of tropical forests. In: Morales-Malacara, J. B., V. M. Behan-Pelletier, E. Ueckermann, T. M. Pérez, E. G. Estrada-Venegas & M. Badii (eds) Acarology XI: Proceedings of the International Congress pp. 51–57. Instituto de Biología and Faculdad de Ciencias, Universidad Nacional Autónoma de México, Sociedad Latinoamericana de Acarología: México.

[W09] Walter, D. E. 2009. Order Holothyrida (Holothyrina, Tetrastigmata). In: Krantz, G. W., & D. E. Walter (eds) A Manual of Acarology 3rd ed. pp. 107–110. Texas Tech University Press.

[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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