Malaconothridae

Specimen of Malaconothrus monodactylus, from the Biodiversity Institute of Ontario (M. mollisetosus was listed as a synonym of M. monodactylus by Subías 2004).

Belongs within: Holonota.
Contains: Malaconothrus (Cristonothrus), Trimalaconothrus (Trimalaconothrus).

Malaconothrus is a cosmopolitan genus of oribatid mites found in wet habitats such as peatlands, streams and lakes (Norton & Behan-Pelletier 2009).

Trimalaconothrus is a cosmopolitan genus of oribatid mites characterised by a covering of birefringent cerotegument together with tridactyl legs.

An introduction to Malaconothrus
Published 20 December 2011

Malaconothrus is a genus of about sixty species of oribatid mites found almost worldwide. The only continent from which Malaconothrus species have not yet been recorded is Antarctica, though M. translamellatus is known from Île Amsterdam in the subantarctic Indian Ocean (Subías 2004). Malaconothrus species specialise in damp habitats, often found among moss or in marshes. They are small yellowish mites, often covered with an ornamented cerotegument (a thick waxy cuticle) (Luxton 1987a). They are also parthenogenetic, with females laying unfertilised eggs that hatch into more females.

Schematic drawing of Malaconothrus monodactylus (minus legs) from Luxton (1987a).

Malaconothrus belongs to a group of oribatids called the Crotonioidea (often also referred to as nothroids). Because crotonioids are long-lived, slow-breeding and poor dispersers, they have received a certain amount of attention as potential indicators of environment health. In the context of the post linked to above, crotonioids are part of the Desmonomata, so outside the large oribatid clade of the Circumdehiscentiae or Brachypylina*. They have broad genital and anal plates that take up the greater part of the underside behind the legs (Balogh & Balogh 1992). Malaconothrus and its most closely related genus, Trimalaconothrus, differ from other crotonioids in having a band of soft cuticle across the underside between the levels of the second and third legs, i. e. they are dichoid rather than holoid (Norton 2001). They also lack bothridia, specialised enlarged sensory setae that are present at the rear of the prodorsum in the majority of oribatids. Malaconothrus and Trimalaconothrus are distinguished from each other by Malaconothrus having one claw at the end of each leg, while Trimalaconothrus has three. Subías (2004) divided Malaconothrus between two subgenera: in Cristonothrus, the dorsum is divided by a pair of longitudinal ridges, but in Malaconothrus sensu stricto there are no dorsal ridges.

*For some reason, oribatids seem to suffer something of an embarrassment of higher taxon names.

Dorsal and ventral view of Malaconothrus rohri from Balogh (1997). Note the pattern of ridges on the dorsum characteristic of Cristonothrus.

Malaconothrus has suffered a certain degree of confusion about its type status (Luxton 1987a). When he first established Malaconothrus in 1904 (as a subgenus of Lohmannia), Berlese only listed one name in explicit combination, Lohmannia (Malaconothrus) egregia. However, in his discussion of this species, Berlese compared it to the pre-existing Nothrus monodactylus in a manner that implied the latter should also be included in his new subgenus. Subsequent authors have disagreed over whether L. egregia or N. monodactylus should be regarded as the type species of Malaconothrus, though more recent authors have settled on the latter.

Systematics of Malaconothridae
<==Malaconothridae
    |--Malaconothrus Berlese 1904S04
    |    |--M. (Malaconothrus)S04
    |    |    |--*M. (M.) monodactylus (Michael 1888)S04 (see below for synonymy)
    |    |    |--M. (M.) angulatus Hammer 1958S04
    |    |    |--M. (M.) atuelanus Hammer 1958S04
    |    |    |--M. (M.) calcehtokensis Palacios-Vargas & Iglesias 1997S04
    |    |    |--M. (M.) chajulensis Palacios-Vargas & Iglesias 1997S04
    |    |    |--M. (M.) conicus Hammer 1958S04
    |    |    |--M. (M.) crassisetosus Subías & Sarkar 1982S04
    |    |    |--M. (M.) dipankari Saha & Sanyal 1996S04
    |    |    |--M. (M.) dorsofoveolatus Hammer 1979S04
    |    |    |--M. (M.) egregius (Berlese 1904)S04 [=Lohmannia (M.) egregiusL87a; incl. M. pulcher Mihelčič 1957S04]
    |    |    |--M. (M.) globiger Trägardh 1910S04 [=Trimalaconothrus globigerL87b]
    |    |    |--M. (M.) hexasetosus Hammer 1971S04
    |    |    |--M. (M.) japonicus Aoki 1966S04
    |    |    |--M. (M.) laetus Sergienko & Melamud 1993S04
    |    |    |--M. (M.) marginatus Yamamoto 1998S04
    |    |    |--M. (M.) neonominatus Subías 2004 [=M. pulcher Hammer 1961 non Mihelčič 1957]S04
    |    |    |--M. (M.) pilosellus Balogh & Mahunka 1969S04
    |    |    |--M. (M.) praeoccupatus Subías 2004 [=M. punctulatus Balogh 1958 non Hammen 1952]S04
    |    |    |--M. (M.) processus van der Hammen 1952S04
    |    |    |--M. (M.) pseudolamellatus Willmann 1931S04
    |    |    |--M. (M.) punctulatus Hammen 1952S04
    |    |    |--M. (M.) purvisi Luxton 1987S04
    |    |    |--M. (M.) pygmaeus Aoki 1969S04
    |    |    |--M. (M.) scutatus Luxton 1987S04
    |    |    |--M. (M.) silvaticus Pérez-Íñigo & Baggio 1985S04
    |    |    `--M. (M.) yinae Yamamoto, Aoki et al. 1993S04
    |    `--M. (Cristonothrus)S04
    `--Trimalaconothrus Berlese 1916S04
         |--T. (Trimalaconothrus)S04
         `--T. (Tyrphonothrus Knülle 1957) [incl. Fossonothrus Hammer 1962]S04
              |--T. (T.) maior (Berlese 1910) (see below for synonymy)S04
              |--T. (T.) albulus Hammer 1972S04
              |--T. (T.) angustirostrum Hammer 1966S04
              |--T. (T.) australis Hammer 1958S04
              |--T. (T.) barrancensis Hammer 1961S04
              |--T. (T.) blancus Hammer 1961S04
              |--T. (T.) buresi Kunst 1959S04
              |--T. (T.) cajamarcensis Hammer 1961S04
              |--T. (T.) canopeus Iglesias, Palacios-Vargas & Mahunka 2001S04
              |--T. (T.) crassisetosus Willmann 1931S04
              |    |--T. c. crassisetosusS04
              |    `--T. c. fijiensis Hammer 1971S04
              |--T. (T.) glaber (Michael 1888)S04 [=Nothrus glaberS04, Angelia glabraM98, Malaconothrus glaberL87b]
              |    |--T. g. glaberS04
              |    `--T. g. javensis Willmann 1931S04
              |--T. (T.) humeratus Balogh 1997S04
              |--T. (T.) itatiaiae Balogh 1997S04
              |--T. (T.) latus (Hammer 1962)S04 [=*Fossonothrus latusBB92]
              |--T. (T.) lisosetosus Iglesias, Palacios-Vargas & Mahunka 2001S04
              |--T. (T.) magnilamellatus Yamamoto 1996S04
              |--T. (T.) magnisetosus Iglesias, Palacios-Vargas & Mahunka 2001S04
              |--T. (T.) novaezealandiae (Hammer 1966) [=Fossonothrus novaezealandiae]S04
              |--T. (T.) pitentzin Iglesias, Palacios-Vargas & Mahunka 2001S04
              |--T. (T.) saxosus Knülle 1957S04 (see below for synonymy)
              |--T. (T.) sculptus Knülle 1957S04
              |--T. (T.) undulatus Yamamoto, Kuriki & Aoki 1993S04
              |--T. (T.) wuyanensis Yamamoto, Aoki et al. 1993S04
              `--T. (T.) yunnanensis Yamamoto & Aoki 1998S04

*Malaconothrus (Malaconothrus) monodactylus (Michael 1888)S04 [=Nothrus monodactylusS04, Angelia monodactylaM98; incl. M. gracilis van der Hammen 1952L87b, M. mollisetosus Hammer 1952S04]

Trimalaconothrus (Tyrphonothrus) maior (Berlese 1910) [=Malaconothrus maior; incl. T. intermedius Cooreman 1941, M. novus Sellnick 1921, T. (*Tyrphonothrus) novus, M. sphagnicola Trägardh 1910]S04

Trimalaconothrus (Tyrphonothrus) saxosus Knülle 1957S04 [incl. Malaconothrus optatus Berlese 1908 (n. d.)S04, M. (Trimalaconothrus) optatusB16]

*Type species of generic name indicated

References

[BB92] Balogh, J., & P. Balogh. 1992. The Oribatid Mites Genera of the World vol. 1. Hungarian Natural History Museum: Budapest.

Balogh, P. 1997. New species of oribatids (Acari) from the neotropical region. Opusc. Zool. Budapest 29–30: 21–30.

[B16] Berlese, A. 1916. Centuria terza di Acari nuovi. Redia 12: 289–338.

[L87a] Luxton, M. 1987a. Mites of the genus Malaconothrus (Acari: Cryptostigmata) from the British Isles. Journal of Natural History 21 (1): 199–206.

[L87b] Luxton, M. 1987b. The oribatid mites (Acari: Cryptostigmata) of J. E. Hull. Journal of Natural History 21: 1273–1291.

[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.

[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.

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