Hypochthonioidea

Hypochthonius rufulus, photographed by Scott Justis.

Belongs within: Acariformes.
Contains: Mesoplophoridae, Lohmanniidae.

The Hypochthonioidea is a morphologically diverse group of oribatid mites: while most retain a notogaster dorsally divided by a transverse scissure (the ancestral form), the Lohmanniidae and the New Guinean species Nothrolohmannia calcarata have the notogaster fused into a single plate. Nothrolohmannia calcarata, known from rainforest soil in New Guinea, nevertheless appears more closely related to Hypochthoniidae than Lohmanniidae, sharing a number of features with the genus Malacoangelia such as hypertrophied, biramous rostral setae and a distinctive porose structure anteromedially on the notogaster (forming a single large porose area in Malacoangelia, and a ring of smaller porose areas in N. calcarata). Hypochthoniidae other than Nothrolohmannia have an S-type scissure with an intercalary sclerite running across the scissure, while Mesoplophoridae and Hypochthoniella have an L-type scissure with the cuticle behind the scissure telescoping underneath the anterior cuticle (Norton 2001). In Hypochthoniella, there is also a medially interrupted groove (pseudosuture) on the notogaster in front of the L scissure. Within the Hypochthoniinae, Eohypochthonius is distinguished from Hypochthonius by the division of the genital plates by a transverse suture (Balogh & Balogh 1992).

Synapomorphies (from Norton 2001): Lyrifissure im inserted on the pronotaspis; lateral fusion of sclerites bearing setae of row e, so that only a single intercalary sclerite is present in the transverse notogastral fissure (if present); posterior coxisternal plate bearing a sternal apodeme; aggenital plates fused broadly and imperceptibly with coxisterna IV; adoral seta or2 present, expanded distally and unilaterally pectinate with teeth directed medially, with lateral notch basal to seta setting off a relatively large tooth.

<==Hypochthonioidea
    |--+--Mesoplophoridae N01
    |  `--Hypochthoniella Berlese 1910 S04 (see below for synonymy)
    |       |--*H. minutissima (Berlese 1903) S04, DA07 (see below for synonymy)
    |       |--H. crosbyi (Ewing 1909) [=Hypochthonius crosbyi] S04
    |       |--H. fukushiraensis Shiraishi & Aoki 1994 S04
    |       |--H. paludicola Fujikawa 1994 S04
    |       `--H. sumatrana Mahunka 1989 S04
    `--+--Lohmanniidae DA07
       `--Hypochthoniidae N01
            |--Nothrolohmanniinae N01
            |    |--Nothrolohmannia Balogh 1968 [Nothrolohmanniidae] S04
            |    |    `--*N. calcarata Balogh 1968 S04
            |    `--Malacoangelia Berlese 1913 N01, S04 [Malacoangeliidae]
            |         |--*M. remigera Berlese 1913 S04
            |         |    |--M. r. remigera [incl. M. remigera symmetrica Wallwork 1960] S04
            |         |    `--M. r. indica Chakrabarti, Bhaduri & Raychaudhuri 1972 S04
            |         |--M. assamica Talukdar & Chakrabarti 1984 S04
            |         `--M. similis Sarkar & Subías 1982 S04
            `--Hypochthoniinae N01
                 |--Hypochthonius Koch 1835 S04
                 |    |--*H. rufulus Koch 1835 S04 [=H. (Hypocthoniella) rufulus H98]
                 |    |    |--H. r. rufulus (see below for synonymy) S04
                 |    |    |--H. r. carolinicus Jacot 1936 S04
                 |    |    |--H. r. europaeus Krivolutsky 1965 S04
                 |    |    `--H. r. paucipectinatus Jacot 1934 S04
                 |    |--H. elegans Hammer 1979 S04
                 |    |--H. latirostris Schweizer 1956 (n. d.) S04
                 |    |--H. luteus Oudemans 1917 [incl. H. luteus rectosetosus Krivolutsky 1965] S04
                 |    `--H. ventricosus (Canestrini 1898) [=Hermannia ventricosa] S04
                 `--Eohypochthonius Jacot 1938 N01, S04
                      |--E. (Eohypochthonius) [incl. Afrhypochthonius Balogh 1958] S04
                      |    |--*E. (E.) gracilis (Jacot 1936) [=Hypochthonius gracilis] S04
                      |    |--E. (E.) africanus Mahunka 1978 S04
                      |    |--E. (E.) asiaticus (Berlese 1910) [=Hypochthonius asiaticus] S04
                      |    |--E. (E.) becki Balogh & Mahunka 1979 S04
                      |    |--E. (E.) crassisetiger Aoki 1959 [=E. gracilis crassisetiger] S04
                      |    |--E. (E.) magnus Aoki 1977 S04
                      |    |--E. (E.) parvus Aoki 1977 S04
                      |    |--E. (E.) salicifolius Hammer 1979 S04
                      |    |--E. (E.) vermicularis Hammer 1979 S04
                      |    `--E. (E.) vilhenarum (Balogh 1958) [=Afrhypochthonius vilhenarum] S04
                      `--E. (Neoatrichosus Fernández 1984) S04
                           `--E. (*N.) travei Fernandez 1984 S04

Hypochthoniella Berlese 1910 S04 [=Hypocthoniella H98; incl. Arthrochthonius Ewing 1917 S04, Eniochthonius Grandjean 1933 S04; Eniochthoniidae N01, Eniochthoniinae]

*Hypochthoniella minutissima (Berlese 1903) S04, DA07 [=Hypochthonius minutissimus S04, Eniochthonius minutissimus DA07; incl. E. grandjeani Hammen 1952 S04, Hypochthonius pallidulus Michael 1888 non Koch 1835 CH98, *Arthrochthonius pallidulus CH98, *Eniochthonius pallidulus CH98, Hypochthoniella pallidulus CH98]

*Hypochthonius rufulus rufulus Koch 1835 [incl. H. rufulus brevisetosus Krivolutsky 1965, H. pallidulus Koch 1835] S04

*Type species of generic name indicated

REFERENCES

[CH98] Colloff, M. J., & R. B. Halliday. 1998. Oribatid Mites: A catalogue of Australian genera and species. CSIRO Publishing: Collingwood.

[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.

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

[N01] Norton, R. A. 2001. Systematic relationships of Nothrolohmanniidae, and the evolutionary plasticity of body form in Enarthronota (Acari: Oribatida). In: Halliday, R. B., D. E. Walter, H. C. Proctor, R. A. Norton & M. J. Colloff (eds) Acarology: Proceedings of the 10^th International Congress pp. 58–75. CSIRO Publishing: Melbourne.

[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.

Last updated: 12 January 2019.