Acariformes

Parhypochthonius aphidinus, from Norton & Behan-Pelletier (2009, A Manual of Acarology).

Belongs within: Euchelicerata.
Contains: Sphaerolichida, Prostigmata, Endeostigmata, Palaeosomata, Brachychthoniidae, Hypochthonioidea, Holonota, Cosmochthonioidea, Mesoplophoridae, Heterochthonioidea.

The Acariformes are one of the two groups of arachnids known as mites (the other being the Parasitiformes); whether the mites as a whole are a monophyletic group remains open to much debate. Acariformes are characterised by the integration of the leg coxae into the venter of the podosoma, often forming coxisternal plates. Setae have an optically active core of actinopilin that is birefringent under polarised light. The Acariformes are divided between two major subgroups, the Trombidiformes and the Sarcoptiformes. The Trombidiformes lack a rutella on the subcapitulum and ancestrally have two pairs of setae in row c (the anteriormost row on the opisthosoma) whereas Sarcoptiformes usually possess a rutella or pseudorutella and most commonly have three or four pairs of setae in row c. Trombidiformes are divided between two subgroups, the small, weakly ornamented Sphaerolichida and the hyperdiverse Prostigmata (Lindquist et al. 2009).

The Sarcoptiformes include the armoured oribatids, the dust mites and related taxa in the Astigmatina, and a small number of plesiomorphic taxa generally grouped as the Endeostigmata (a potentially paraphyletic grouping). The Oribatida, beetle mites, are characterised by a more or less sclerotised body, though it is now widely accepted that the oribatids are paraphyletic to the less heavily sclerotised Astigmatina. Sclerotisation has also been reduced in some basal groups more typically regarded as oribatids such as the Atopochthonioidea. Many basal oribatids are parthenogenetic. In all oribatids except the basal Palaeosomata, the basifemur and telofemur of the legs have become fused, leaving the legs with five free segments (not counting the pretarsus). Oribatids have a fossil record going back to the Devonian, with Devonacarus sellnicki and Protochthonius gilboa known from the Gilboa shales. Both these species are poorly sclerotised oribatids with the femoral segments fused and have at least sixteen pairs of opisthosomal setae, four or five pairs of which are hypertrophied and erectile. Protochthonius gilboa has the setal pairs e1, e2, f1 and f2 erectile and differs from most living oribatids in the possession of a peranal segment. Devonacarus sellnicki has five pairs of erectile setae of more uncertain homology though they may belong to the e and f rows together with seta h1; Devonacarus also differs from oribatids other than some Palaeosomata in possession of a lobe-like naso bearing rostral setae (Norton et al. 1988).

A number of basal oribatids retain a divided notogaster, but in various subgroups the notogaster has become fused into a single sclerite. In the genera Elliptochthonius, Parhypochthonius and Gehypochthonius the notogaster is divided by a single transverse scissure between setal rows c and d and the mite as a whole is weakly sclerotised and pale in coloration. Elliptochthonius profundus has a rostral tectum covering most of the chelicerae in dorsal view, one pair of adanal setae, and a four-segmented palp with the trochanter and femur fused; Gehypochthonius have the rostral tectum poorly developed or absent, the palp five-segmented, and three pairs of adoral setae. Parhypochthonius species have the opisthonotal glands opening on a pair of flared, funnel-shaped protruberances that bear seta f2; this seta is represented only by an inconspicuous alveolus in Gehypochthonius species and the openings of the opisthonotal glands are not raised (Norton & Behan-Pelletier 2009).

The Brachychthoniidae are a family of small mites (usually less than 250 µm long) in which the notogaster bears two type E scissures (i.e. a simple band of non-telescoping cuticle). Members of this family include the cosmopolitan genus Eobrachychthonius, species of which have seta d2 in a marginal position and four pairs of suprapleural plates over the pleural region (Balogh & Balogh 1992 vol. 1).

The Atopochthonioidea have two or three transverse scissures and have most notogastral setae broad, phylliform or platelike. In Pterochthonius angelus and Phyllochthonius aoutii the notogastral setae are shield-like; those of Pterochthonius are not erectile and uniformly cover the notogaster whereas Phyllochthonius has the pair of setae e1 held in a permanently erect position. Atopochthonius has two pairs of erectile setae inserted on large, independent tubercles, with the erectile setae being phylliform, distally tapering, and distinctly larger than the remaining notogastral setae. The leg pretarsi are monodactylous in Pterochthonius and bidactylous in Atopochthonius and Phyllochthonius (Norton & Behan-Pelletier 2009). Atopochthonius and Pterochthonius are mostly Holarctic in distribution; Phyllochthonius is known from Ethiopia (Subías 2004).

The notogaster is undivided in the Epilohmanniidae, Perlohmanniidae, Ptyctima, Desmonomata and Eulohmannia ribagai. The Holarctic Eulohmannia is a small, light yellow oribatid with the proterosoma constricted behind the level of the bothridia and the hind epimera imperceptibly fused to the aggenital region; the legs are bidactylous and the palp has four free segments (Norton & Behan-Pelletier 2009).

<==Acariformes [Actinochaeta, Actinochitinosi, Actinotrichida, Cursoria, Endeostigmatina, Neocotylea, Pachygnathoidea]
    |--Trombidiformes [Actinedida, Thrombidoidea] LKW09
    |    |--Sphaerolichida WL09
    |    `--Prostigmata WL09
    `--Sarcoptiformes LSE13
         |--Endeostigmata DW10
         `--Oribatida (see below for synonymy) DW10
              |  i. s.: Devonacarus Norton, Bonamo et al. 1988 [Devonacaridae] NB88
              |           `--*D. sellnicki Norton, Bonamo et al. 1988 NB88
              |         Protochthonius Norton, Bonamo et al. 1988 [Protochthoniidae] NB88
              |           `--*P. gilboa Norton, Bonamo et al. 1988 NB88
              |         Elliptochthonius Norton 1975 [Elliptochthoniidae] S04
              |           `--*E. profundus Norton 1975 S04
              |         Pelonia Grube 1859 (n. d.) M98
              |           |--P. crinita Grube 1859 (n. d.) M98
              |           |--P. foliosa Grube 1859 (n. d.) M98
              |           `--P. tricuspidata Grube 1859 (n. d.) M98
              |         Pantalozetes pectinatus (Michael 1885) M63
              |--+--Palaeosomata PL17
              |  `--Brachychthoniidae SC19
              `--Monofemorata [Enarthronota, Parhypochthonioidea, Parhyposomata] W96
                   |--Hypochthonioidea PL17
                   `--+--+--Holonota PL17
                      |  `--+--Eulohmannia Berlese 1910 PL17, S04 (see below for synonymy)
                      |     |    `--*E. ribagai (Berlese 1910) (see below for synonymy) S04
                      |     `--+--Cosmochthonioidea PL17
                      |        `--+--Mesoplophoridae SC19
                      |           `--Gehypochthoniidae SC19
                      |                |--Gehypochthonimimus hibernicus SC19
                      |                `--Gehypochthonius Jacot 1936 PL17, S04
                      |                     |--*G. rhadamanthus Jacot 1936 S04 [=G. rhadamantus (l. c.) H98]
                      |                     |--G. antonii Lombardini 1962 (n. d.) S04
                      |                     |--G. frondifer Aoki 1975 S04
                      |                     |--G. gracilis Pankov 2002 S04
                      |                     |--G. marianoi Martínez & Laborde 2000 S04
                      |                     |--G. strenzkei Lee 1982 S04
                      |                     |--G. urticinus (Berlese 1910) [=Parhypochthonius urticinus] S04
                      |                     `--G. xarifae Strenzke 1963 S04
                      `--+--Parhypochthonius Berlese 1904 PL17, S04 [Parhypochthoniidae]
                         |    |--*P. aphidinus Berlese 1904 (see below for synonymy) S04
                         |    |--P. africanus Balogh 1958 (n. d.) S04
                         |    |--P. asiaticus Mahunka 1997 S04
                         |    |--P. botschi Schweizer 1956 (n. d.) S04
                         |    |--P. dubiosus Schweizer 1956 (n. d.) S04
                         |    |--P. macrorostrum Schweizer 1956 (n. d.) S04
                         |    |--P. nivalis Schweizer 1956 (n. d.) S04
                         |    |--P. pilosus Mahunka 1991 S04
                         |    `--P. stabelchodi Schweizer 1956 (n. d.) S04
                         `--+--Heterochthonioidea PL17
                            `--Atopochthonioidea MH04
                                 |--Phyllochthonius Travé 1967 S04 [Phyllochthoniidae NB-P09]
                                 |    `--*P. aoutii Travé 1967 S04
                                 |--Pterochthonius Berlese 1913 S04 [Pterochthoniidae PL17, Pterochthonioidea]
                                 |    `--*P. angelus (Berlese 1910) [=Cosmochthonius angelus] S04
                                 `--Atopochthonius Grandjean 1949 S04 [Atopochthoniidae NB-P09]
                                      |--*A. artiodactylus Grandjean 1949 S04
                                      `--A. maimaensis Grishina 1971 S04

Eulohmannia Berlese 1910 PL17, S04 [incl. Arthronothrus Trägardh 1910 S04; Eulohmanniidae, Eulohmannioidea]

*Eulohmannia ribagai (Berlese 1910) [=Lohmannia (*Eulohmannia) ribagai; incl. Arthronothrus biunguiculatus Trägardh 1910] S04

Oribatida [Apterogasterea, Archoribatida, Arthronota, Arthronotina, Arthroptyctima, Cryptostigmata, Dichostomata, Enarthronotides, Macropylina, Mixonomatides, Monofissurae, Novoribatida, Oribatei, Oribatidae, Oribatini, Oribatoidea, Parhypochthonata, Parhypochthonina, Parhyposomatides] DW10

*Parhypochthonius aphidinus Berlese 1904 [incl. P. aphidinus germanicus Willmann 1931, P. aphidinus octofilamentis Jacot 1938] S04

*Type species of generic name indicated

REFERENCES

[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.

[LSE13] Legg, D. A., M. D. Sutton & G. D. Edgecombe. 2013. Arthropod fossil data increase congruence of morphological and molecular phylogenies. Nature Communications 4: 2485.

[LKW09] Lindquist, E. E., G. W. Krantz & D. E. Walter. 2009. Classification. In: Krantz, G. W., & D. E. Walter (eds) A Manual of Acarology 3^rd ed. pp. 97–103. Texas Tech University Press.

[M63] Mahunka, S. 1963. Beiträge zur Kenntnis der Milbenfauna (Acari) von Säugetiernestern. Acta Zoologica Academiae Scientiarum Hungaricae 9 (3–4): 355–372.

[MH04] Maraun, M., M. Heethoff, K. Schneider, S. Scheu, G. Weigmann, J. Cianciolo, R. H. Thomas & R. A. Norton. 2004. Molecular phylogeny of oribatid mites (Oribatida, Acari): evidence for multiple radiations of parthenogenetic lineages. Experimental and Applied Acarology 33 (3): 183–201.

[M98] Michael, A. D. 1898. Oribatidae. In: H. Lohmann (ed.) Das Tierreich. Eine Zusammenstellung und Kennzeichnung der rezenten Tierformen vol. 3. Acarina pp. 1–93. R. Friedländer und Sohn: Berlin.

[NB88] Norton, R. A., P. M. Bonamo, J. D. Grierson & W. A. Shear. 1988. Oribatid mite fossils from a terrestrial Devonian deposit near Gilboa, New York. Journal of Paleontology 62 (2): 259–269.

[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.

[SC19] Schaefer, I., & T. Caruso. 2019. Oribatid mites show that soil food web complexity and close aboveground-belowground linkages emerged in the early Paleozoic. Communications Biology 2: 387.

[S04] Subías, L. S. 2004. Listado sistemático, sinonímico y biogeográfico de los ácaros oribátidos (Acariformes, Oribatida) del mundo (1758–2002). Graellsia 60 (número extraordinario): 3–305.

[WL09] Walter, D. E., E. E. Lindquist, I. M. Smith, D. R. Cook & G. W. Krantz. 2009. Order Trombidiformes. In: Krantz, G. W., & D. E. Walter (eds) A Manual of Acarology 3^rd ed. pp. 233–420. Texas Tech University Press.

[W96] Weigmann, G. 1996. Hypostome morrphology of Malaconothroidea and phylogenetic conclusions on primitive Oribatida. In: Mitchell, R., D. J. Horn, G. R. Needham & W. C. Welbourn (eds) Acarology IX vol. 1. Proceedings pp. 273–276. Ohio Biological Survey: Columbus (Ohio).

Last updated: 21 July 2021.