Unionicolidae

Likely Unionicola, copyright Stephen Luk.

Belongs within: Hygrobatoidea.
Contains: Koenikea, Neumania, Recifella, Unionicola.

The Unionicolidae are a diverse family of freshwater mites. Larvae, where known, are parasites of aquatic insects (Chironomidae or Trichoptera); adults are more diverse in habits, including predators of crustaceans, commensals or parasites of sponges, and associates of molluscs. They are divided between five subfamilies of which the Pionatacinae and Unionicola are cosmopolitan in distribution whereas Omanohydracarus, Pollicipalpus and Encentridophorus have more restricted distributions in the Palaeotropics (Walter et al. 2009). Unionicola species have five or six pairs of acetabula in the genital field whereas Pionatacinae have more than ten pairs of acetabula.

Characters (from Walter et al. 2009): Adults with dorsal and ventral shields or more soft-bodied; if with ventral shields, then openings for insertions of legs IV with large associated projections extending laterally or posteriorly; chelicerae fused or separate medially; claws simple or with clawlets; legs I often with numerous long thickened setae; glandularia absent on coxal plates IV. Larvae with cheliceral bases fused; dorsal and coxal plates reticulate; coxal plates I separate from posterior coxal group on each side; one pair of urstigmata borne distally between coxal plates I and II; coxal plates III bearing pointed projections posteriorly; legs with five movable segments; tibia I bearing nine setae (and two solenidia), including Ti10 and Ti11; tarsi I-III bearing ten setae and one solenidia; leg tarsi bearing paired claws.

Unionicolidae
    |  i. s.: VietsataxWP99
    |--Omanohydracarus [Omanohydracarinae]WL09
    |    `--O. arabicusWL09
    |--Pollicipalpus Viets 1924H98 [PollicipalpinaeWL09]
    |    |--P. australicus Cook 1986H98
    |    `--P. scutatusWL09
    |--Encentridophorus Piersig 1897H98 [EncentridophorinaeWL09]
    |    |--E. sarasini Walter in Sarasin & Roux 1915 [incl. E. indicus Cook 1967, E. lundbladi Cook 1967]H98
    |    `--E. similisWP99
    `--PionatacinaeWL09
         |  i. s.: KoenikeaWL09
         |         Schadeella Lundblad 1938RFF05
         |           `--S. crassipalpis Lundblad 1938RFF05
         |         Neumanikea Orghidan & Gruia 1980S86
         |           |--N. coenotica Orghidan & Gruia 1980S86
         |           `--N. guantanamense Orghidan & Gruia 1980S86
         |         Amazonella Lundblad 1930RFF05
         |           |--A. crassipalpis Lundblad 1941RFF05
         |           |--A. polypora Lundblad 1936RFF05
         |           |    |--A. p. polyporaRFF05
         |           |    `--A. p. curvimarginata Viets 1959RFF05
         |           `--A. ribagai Lundblad 1930RFF05
         |--NeumaniaS-TK22
         `--+--RecifellaS-TK22
            `--UnionicolaS-TK22

*Type species of generic name indicated

References

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

[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.

[S86] Schwoerbel, J. 1986. 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.

[S-TK22] Szudarek-Trepto, N., A. Kaźmierski, A. Skoracka, M. Lewandowski & J. Dabert. 2022. Molecular phylogeny supports the monophyly of the mite supercohort Eupodides (Acariformes: Trombidiformes) and greatly coincides with traditional morphological definition of the taxon. Annales Zoologici 72 (4): 757–786.

[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 3rd ed. pp. 233–420. Texas Tech University Press.

[WP99] Walter, D. E., & H. C. Proctor. 1999. Mites: Ecology, Evolution and Behaviour. CABI Publishing: Wallingford (UK).

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