Hydrachnidia

Hydrodroma sp., copyright Martin Steinmeier.

Belongs within: Parasitengonina.
Contains: Protohydrachnidia, Rhynchohydracaridae, Hydryphantidae.

The Hydrachnidia are a large group of predatory water mites with parasitic larvae. Authorities differ as to whether the divergent Stygothrombiidae, a family of predatory mites found in interstitial aquatic habitats in the Northern Hemisphere, should be placed within this group or not. Members of this family have a vermiform, posteriorly elongated idiosoma, a fused palpfemur and genu, and strongly pectinate leg claws. Larvae of stygothrombiids are parasites of Plecoptera (stoneflies). Hydrachnidia excluding the Stygothrombiidae have palps with the femur and genu separate, and usually relatively simple claws (Walter et al. 2009). Members of the clade Euhydrachnidia produce spermatophores with lateral spines on the apical wings, that are deposited in rows.

Characters (from Walter et al. 2009, as Stygothrombiidae + Hydrachnidiae): Active in or on water, or (as larvae) parasitic on aquatic insects. Adults with idiosoma and appendages usually not hypertrichous; idiosoma with series of stomatoid fissures or glandularia comprising gland-like structures that each open on a small platelet, often adjacent to associated seta. Larvae with palpgenu bearing two setae.

<==Hydrachnidia [Hydrachnellae] RFF05
    |  i. s.: Thyopsis cancellata W01
    |         Tetramegapus quadruporus G49
    |         Thyasides sphagnorum S99
    |--Stygothrombidiidae [Stygothrombiae, Stygothrombidioidea, Stygothrombiinae] DPD16
    |    |--Charonothrombium Motas & Tanasachi 1946 S86a
    |    |    `--C. racovitzai Motas & Tanasachi 1946 S86a
    |    |--Hydrothrombium Robaux 1969 S86a
    |    |    `--H. cooki Robaux 1969 S86a
    |    |--Victathrombium Habeeb 1974 S86a
    |    |    `--V. ivarum (Habeeb 1974) S86a
    |    |--Cerberothrombium Viet 1934 S86a
    |    |    |--C. armatum Viets 1934 S86a
    |    |    |--C. bispinosum Schwoerbel 1962 S86a
    |    |    |--C. caudatum Habeeb 1955 S86a
    |    |    |--C. ida Habeeb 1973 S86a
    |    |    |--C. paulhenrii Hebeeb 1979 S86a
    |    |    |--C. stella Habeeb 1973 S86a
    |    |    |--C. vermiforme (Sokolow 1944) [=Baikalacarus vermiforme] S86a
    |    |    `--C. vikrami Habeeb 1979 S86a
    |    `--Stygothrombium Viets 1932 S86a
    |         |--S. angelieri André 1949 S86a
    |         |    |--S. a. angelieri S86a
    |         |    `--S. a. minor André 1949 S86a
    |         |--S. chappuisi Walter 1947 S86a
    |         |--S. cooki WL09
    |         |--S. gallicum André 1949 S86a
    |         |    |--S. g. gallicum S86a
    |         |    `--S. g. delphinensis André 1949 S86a
    |         |--S. hercyniensis Viets 1955 S86a
    |         |--S. japonicum Imamura 1956 S86a
    |         `--S. karamani Viets 1932 S86a
    `--Hydrachnidiae [Hydracarina, Hydrachnida, Limnocharini] WL09
         |  i. s.: Prymnopsella bucculata GS96
         |--Protohydrachnidia W91
         `--Euhydrachnidia [Hydryphantoidea] WWO01
              |--Rhynchohydracaridae RFF05
              |--Malgasacaridae ZF11
              |--Hydryphantidae W91
              |--Thermacarus Sokolow 1927 [Thermacaridae] RFF05
              |    |--T. andinus Martín & Schwoerbel 2002 RFF05
              |    `--T. nevadensis Marshall 1928 RFF05
              |--Teratothyadidae ZF11
              |    |--Teratothyas WL09
              |    `--Teratothyasides WL09
              |         |--T. sagariphorus WL09
              |         `--T. undulatus WL09
              |--Ctenothyadidae ZF11
              |    |--Ctenothyas verrucosa WL09
              |    `--Stellulathyas WL09
              |         |--S. lundbladi WL09
              |         `--S. magnifica WL09
              |--Zelandothyadidae ZF11
              |    |--Australiothyas Cook 1986 H98 [Australiothyadidae, Australiothyadinae WL09]
              |    |    `--A. swaini Cook 1986 H98
              |    `--Zelandothyas [Zelandothyadinae] WL09
              |         `--Z. diamphida WL09
              `--Hydrodroma Koch 1837 W91, RFF05 [Hydrodromidae]
                   |--H. americana PW01
                   |--H. danuviensis MK91
                   |--H. despiciens (Müller 1776) RFF05 [=Hydrachna despiciens H98]
                   |    |--H. d. despiciens RFF05
                   |    |--H. d. brevirostris Lundblad 1941 RFF05
                   |    |--H. d. clavipes Lundblad 1953 RFF05
                   |    |--H. d. crassiseta Viets 1954 RFF05
                   |    |--H. d. longiseta Viets 1954 RFF05
                   |    |--H. d. macronyx Viets 1954 RFF05
                   |    |--H. d. micronyx Viets 1954 RFF05
                   |    `--H. d. pilosa MK91
                   |--H. monticola (Piersig 1906) [=Diplodontis despiciens var. monticolus] H98
                   |--H. peregrina (Koenike 1905) RFF05
                   |    |--H. p. peregrina RFF05
                   |    `--H. p. robusta Viets 1954 RFF05
                   |--H. rheophila Cook 1967 S86b
                   |--H. stalagmophila Lundblad 1941 RFF05
                   |--H. torrenticola S86b
                   `--H. ungulata Lundblad 1941 RFF05

*Type species of generic name indicated

REFERENCES

[DPD16] Dabert, M., H. Proctor & J. Dabert. 2016. Higher-level molecular phylogeny of the water mites (Acariformes: Prostigmata: Parasitengonina: Hydrachnidiae). Molecular Phylogenetics and Evolution 101: 75–90.

[G49] Grandjean, F. 1949. Remarques sur l'évolution numérique des papilles génitales et de l'organe de Claparède chez les hydracariens. Bulletin du Muséum, 2e série 21 (1): 75–82.

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

[MK91] Meyer, E., & K. Kabbe. 1991. Pigmentation in water mites of the general Limnochares Latr. and Hydrodroma Koch (Hydrachnidia). In: Schuster, R., & P. W. Murphy (eds) The Acari: Reproduction, development and life-history strategies pp. 379–391. Chapman & Hall: London.

[PW01] Proctor, H., & K. Wilkinson. 2001. Coercion and deceit: water mites (Acari: Hydracarina) and the study of intersexual conflict. 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. 155–169. CSIRO Publishing: Melbourne.

[RFF05] Rosso de Ferradás, B., & H. R. Fernández. 2005. Elenco y biogeografía de los ácaros acuáticos (Acari, Parasitengona, Hydrachnidia) de Sudamérica. Graellsia 61 (2): 181–224.

[S86a] Schwoerbel, J. 1986a. Acari: Stygothrombiidae und Thrombidiidae. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 648–651. E. J. Brill/Dr W. Backhuys: Leiden.

[S86b] Schwoerbel, J. 1986b. Acari: “Hydrachnellae”. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 652–696. E. J. Brill/Dr W. Backhuys: Leiden.

[S99] Smith, B. P. 1999. Larval Hydrachnidia and their hosts: biological inference and population structure. In: Needham, G. R., R. Mitchell, D. J. Horn & W. C. Welbourn (eds) Acarology IX vol. 2. Symposia pp. 139–143. Ohio Biological Survey: Columbus (Ohio).

[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.

[W91] Wohltmann, A. 1991. Nutrition and respiratory rate of water mites (Actinedida: Hydrachnidia) from a phylogenetic point of view. In: Dusbábek, F., & V. Bukva (eds) Modern Acarology: Proceedings of the VIII International Congress of Acarology, held in České Budĕjovice, Czechoslovakia, 6–11 August 1990 vol. 2 pp. 543–548. SPB Academic Publishing: The Hague.

[W01] Wohltmann, A. 2001. Closely related species of Parasitengonae (Acari: Prostigmata) inhabiting the same areas: features facilitating coexistence. 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. 121–135. CSIRO Publishing: Melbourne.

[WWO01] Wohltmann, A., H. Witte & R. Olomski. 2001. Organismal patterns causing high potential for adaptive radiation in Parasitengonae (Acari: Prostigmata). 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. 83–99. CSIRO Publishing: Melbourne.

[ZF11] Zhang, Z.-Q., Q.-H. Fan, V. Pesic, H. Smit, A. V. Bochkov, A. A. Khaustov, A. Baker, A. Wohltmann, T. Wen, J. W. Amrine, P. Beron, J. Lin, G. Gabryś & R. Husband. 2011. Order Trombidiformes Reuter, 1909. In: Zhang, Z.-Q. (ed.) Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness. Zootaxa 3148: 129–138.

Last updated: 19 July 2022.