ALYCIDAE Canestrini & Fanzago 1877 (= Pachygnathidae Kramer 1877, Bimichaeliidae Womersley 1944)

Alycus Koch, 1841 (Alychus Canestrini & Fanzago, 1877: 168; also Alichus)

Type species: Alycus roseus CL Koch 1842 (= Pachygnathus dugesi Grandjean 1937)

Alycus occidentalis Womersley 1944 - Australia; Alycus trichosus (Grandjean) Europe; Alycus marinus (Schuster) Europe; Alycus denasutus (Grandjean) Europe.

Pachygnathus Dugês, 1836

Type species: Pachygnathus villosus Dugês [in Oken], 1836 (=P. ornithorhynchus Grandjean 1937)

Pachygnathus silvaticus de Alzuet & Delgado (selvaticus?)

Petralycus Grandjean, 1943: 1-59.

Type species: Petralycus unicornis Grandjean, 1943 – Europe

Petralycus longicornis Theron, 1977 – acacia soil in South Africa; Petralycus brevicornis Theron, 1977 – pasture soil in South Africa; Petralycus caryapecaus McDaniel & Bolen; Petralycus celtisacinus McDaniel & Bolen

Bimichaelia Sig Thor, 1902 – >17 spp.

Type species: Michaelia augustana Berlese 1884

Bimichaelia arbusculosa Grandjean; Bimichaelia augustana (Berlese 1884); Bimichaelia australica Womersley 1944; Bimichaelia campylognatha Grandjean; Bimichaelia crassipalpis Halbert; Bimichaelia diadema Grandjean, 1939; Bimichaelia dimixsetosa McDaniel (Bimichaelia dimixsetosa texana); Bimichaelia disetosa McDaniel; Bimichaelia novazealandica Womersley; Bimichaelia pusilla Womersley 1944; Bimichaelia ramosa Mihelčič; Bimichaelia rectangula Willman; Bimichaelia reticulata Shiba; Bimichaelia sarekensis (Trägårdh) Europe; Bimichaelia setigera (Berlese); Bimichaelia stellaris Womersley 1944; Bimichaelia subnuda (Berlese)

Amphialycus penophthalmus Zachvatkin, 1949 Ukraine; A. leucogaster (Grandjean) Europe.

Orthacarus tremli Zachvatkin, 1949; O. oblongus (Halbert, 1920) Ireland.

Coccalicus clavatus Willmann 1952

Protacarus crani Hirst – Rhynie Chert fossil beds, Devonian

 

DIAGNOSIS.  Prodorsum with 2 pairs of trichobothria (sci, ve) and 2-4 pairs of setae (in and/or exp may be absent); sci and ve either filiform or capitate; naso nude, reduced; lateral and median eyes present or absent.  Rutella present or absent; chelicerae chelate-dentate to attenuate-edentate, each with 0-2 setae.  Opisthosoma usually hypertrichous; 3 pairs of genital papillae.  Leg IV not modified for jumping.

 

REMARKS.  This is the most difficult family of Endeostigmata to diagnose because of the remarkable variation in characters and it may not be a natural group.  A fossil species is known from the Devonian Rhynie Chert and many extant species appear to be among the most plesiotypic Endeostigmata known.  Some species of Alycus feed on nematodes (Walter 1988), which usually do not form visible gut contents, but others have gut boluses with fungal material.  An unidentified species of ‘Pachygnathus’ from the intertidal is reported to have gut boluses with the cuticle of copepods and tardigrades (Schuster 1979).  Although probably the most commonly encountered genus of Endeostigmata in forest litter, and certainly the largest in body size, the feeding biology of Bimichaelia is unknown.  These mites have elongate, needle-like chelicerae and, although an occasional specimen with a fungal spore impaled on the tips of the chelicerae has been found, no one has reported any feeding observations.  Theron (1979) speculated that species of Bimichaelia might suck juices from plant roots, and Lindquist (1998) expanded on the possible evolution of phytophagy in the Bimichaeliidae and the similarity of their mouthparts to those in Eriophyoidea.  Although an intriguing idea, perhaps feeding on ectomycorrhizae is more likely.

 

References

Delgado-A-G-C; de-Alzuet-A-B.  1987.  Estudio comparativo de la region genito-anal en Pachygnathus silvaticus (Acarina Prostigmata: Pachygnathidae).  Revista Sociedad Entomologica Argentina 44(3-4) 1985[1987]: 337-340

Grandjean F.  1936.  Le genre Pachygnathus Dugês (Alycus Koch) (Acariens).  Ire partie.  Bull. Mus. nat. hist. 8 (ser. 2):398-405.

Grandjean F.  1937a.  Le genre Pachygnathus Dugês (Alycus Koch) (Acariens).  Deuxième partie.  Bull. Mus. nat. hist. 9 (ser. 2): 56-61, figs 1-3.

Grandjean F.  1937b.  Le genre Pachygnathus Dugês (Alycus Koch) (Acariens).  Troisième partie.  Bull. Mus. nat. hist. 9 (ser. 2):134-138, figs 4-5.

Grandjean F.  1937c.  Le genre Pachygnathus Dugês (Alycus Koch) (Acariens).  Quatrième partie.  Bull. Mus. nat. hist. 9 (ser. 2):199-205, figs 6-8.

Grandjean F.  1937d.  Le genre Pachygnathus Dugês (Alycus Koch) (Acariens).  Cinquième et dernière partie.  Bull. Mus. nat. hist. 9 (ser. 2):262-269, fig 9.

Grandjean F.  1942.  Queques genres d’Acariens appartenant au groupe des Endeostigmata, 2e Série. Première partie.  Ann. Sci. nat. Zool. 11e sér 4:85-135.

Grandjean F.  1943.  Queques genres d’Acariens appartenant au groupe des Endeostigmata, 2e Série . Deuxiérme partie.  Ann. Sci. nat. Zool. 11e sér 5:1-59.

Halbert JN. 1920. The Acarina of the seashore.  Proc. R. Irish Acad. Sec. B 35(7): 106-152.

Halliday, B.  1998.  Mites of Australia, A Checklist and Bibliography.  Monographs on Invertebrate Taxonomy Vol. 5.   CSIRO Publishing, Collingwood.

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Kethley, J.  1991b.  Probable tritonymphal sexual dimorphism in Alycus roseus (Bimichaeliidae: Acariformes: Acari).  Journal of Entomological Science 26(1) 1991: 130-135

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Lindquist EE.  1998.  Evolution of phytophagy in trombidiform mites.  Exp Appl Acarol 22:88-100.

McDaniel B.  1980.  New species of the genus Bimichaelia Thor (Acari, Endeostigmata) from South Dakota.  Acarologia 21(2) 1980: 177-186

McDaniel B, Bolen EG.  1983.  Mites of the family Pachygnathidae (Acari: Endeostigmata) from Texas.  Proceedings of the Entomological Society of Washington 85(4) 1983: 811-817

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Theron PD.  1979.  The functional morphology of the gnathosoma of some liquid and solid feeders in the Trombidiformes, Cryptostigmata and Astigmata (Acarina).  pp. 575-579 in E. Piffl (ed.), Proceedings of the 4^th International Congress of Acarology.  Akadémiai Kiadó: Budapest.

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