Oribatid mites are a dominant component of the microfauna of forest soils throughout the world, but they also climb trees. The last post’s Neotrichozetes is one such arboreal beastie as is this week’s Tuparezetes. One clue to its arboreal life style is the globular head of the sensillus (what oribatid workers call the bothridial seta in a trichobothrium). Another is the long stiff-haired look.
These shots are of an immature Tuparezetes, probably a tritonymph. All stages can be found on shrubs and trees with densely hairy leaves in cool temperate to tropical rainforests in eastern Australia and in New Zealand where they graze on fungi growing among the hairs. The genus was described by AV Spain in 1969 and the type species, Tuparezetes christineae, was collected from Leatherwood or Tupare (hence the generic name): Olearia colensoi, a kind of shrubby daisy in the subalpine zone of New Zealand. He also described a second species, Tuparezetes philodendrus, from Nothofagus solandri and Olearia lacunosa. In Australia, I collected the genus (probably undescribed species) from Blanketleaf (Bedfordia arborescens) in cool temperate rainforest in Victoria, from canopy fogging in subtropical rainforest in Lamington National Park and from an unidentified tropical rainforest tree near Paluma in Queensland.
I’ve always considered Alister Spain’s descriptions a model of how a taxonomic paper should be. As well as a detailed morphological analysis the genus and species are based on numerous collections and there is a section on the ecology of each species including the identification of fungal species found in gut contents. In not sure that I agree with Alister’s explanation for the most bizarre feature of this mite, though – the deep waxy crest present between the dorsal setae. He suggests this is an arboreal adaptation related to water balance, but the hairy leaves that this mite inhabits should have a well developed boundary layer and good humidity retention even in high winds. Still, I have no better hypothesis to offer.
Hunt, G., Colloff, M.J., Dallwitz, M., Kelly. J. & Walter, D.E. 1998. An interactive key to the oribatid mites of Australia. CSIRO Publishing, Collingwood, Victoria. (Compact Disk and User Guide).
Spain AV. 1969. A new genus and two new species of arboreal Oppiidae (Acari: Cryptostigmata) from New Zealand. Pacific Insects 11: 155-163.