Specimen of Stygothrombium, from Biodiversity Institute of Ontario.

Belongs within: Hydrachnidia.

The Stygothrombiidae are a family of predatory mites found in interstitial aquatic habitats in the Northern Hemisphere. Larvae of stygothrombiids are parasites of Plecoptera (stoneflies) (Walter et al. 2009).

Characters (from Walter et al. 2009): Adult gnathosoma retractable into idiosoma, chelicerae with movable digit bladelike and curved; palpal femur and genu fused, tibia bearing one or more enlarged spinelike setae adjacent to tibial claw and tarsus bearing long terminal solenidion; prodorsal area with slender prodorsal plate bearing unpaired anteromedial seta (vi), one pair of bothridia (si) and two pairs of posterior setae (ve and se); eyes absent; cuticle smooth, bearing relatively sparse complement of short, simple setae and several pairs of modified stomatoid lyrifissures without setiferous papillae; genital field bearing three pairs of stalked acetabula, pregenital tubercle absent; legs each with postaxial stomatoid lyrifissures on femur, genu and tibia, tarsus bearing pectinate claws and simple empodium. Larva moderately heteromorphic; gnathosoma with genu bearing two setae and tibial claw four-pronged; prodorsal plate bearing unpaired anteromedial seta (vi), one pair trichobothria (si), two pairs posterior setae (ve and se); venter bearing stalked urstigmata and well-defined anus, lacking setiferous anal plate; coxal plates I-III bearing 2, 1 and 1 pairs of setae, respectively, plates I-II contiguous; legs each with postaxial lyrifissures present on femur, genu and tibia, genu with more than four setae, tarsi each with pectinate claws and simple empodium.

<==Stygothrombiidae [Stygothrombiinae]
    |--Charonothrombium Motas & Tanasachi 1946 S86
    |    `--C. racovitzai Motas & Tanasachi 1946 S86
    |--Hydrothrombium Robaux 1969 S86
    |    `--H. cooki Robaux 1969 S86
    |--Victathrombium Habeeb 1974 S86
    |    `--V. ivarum (Habeeb 1974) S86
    |--Cerberothrombium Viet 1934 S86
    |    |--C. armatum Viets 1934 S86
    |    |--C. bispinosum Schwoerbel 1962 S86
    |    |--C. caudatum Habeeb 1955 S86
    |    |--C. ida Habeeb 1973 S86
    |    |--C. paulhenrii Hebeeb 1979 S86
    |    |--C. stella Habeeb 1973 S86
    |    |--C. vermiforme (Sokolow 1944) [=Baikalacarus vermiforme] S86
    |    `--C. vikrami Habeeb 1979 S86
    `--Stygothrombium Viets 1932 S86
         |--S. angelieri André 1949 S86
         |    |--S. a. angelieri S86
         |    `--S. a. minor André 1949 S86
         |--S. chappuisi Walter 1947 S86
         |--S. gallicum André 1949 S86
         |    |--S. g. gallicum S86
         |    `--S. g. delphinensis André 1949 S86
         |--S. hercyniensis Viets 1955 S86
         |--S. japonicum Imamura 1956 S86
         `--S. karamani Viets 1932 S86

*Type species of generic name indicated


[S86] Schwoerbel, J. 1986. Acari: Stygothrombiidae und Thrombidiidae. In Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) (L. Botosaneanu, ed.) pp. 648-651. E. J. Brill / Dr. W. Backhuys: Leiden.

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, 3rd ed., pp. 233-420. Texas Tech University Press.

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