Archive for June, 2013

Tuparezetes: A hairy mite with a penchant for hairy leaves

June 16, 2013
Tuparezetes nymph - Scale bar = 0.1 mm

Tuparezetes nymph – Scale bar = 0.1 mm

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.

Tuparezetes nymph dorsal view - Scale bar = 0.1. mm

Tuparezetes nymph dorsal view – Scale bar = 0.1. mm

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.

Adult Tuparezetes showing wax cap (modified from Hunt et al. 1998).

Adult Tuparezetes showing wax cap (modified from Hunt et al. 1998).

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.

References

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.

Advertisements

A Trichy Mite in Need of a Trim

June 7, 2013
Neotrichozetes from rainforest canopy in Queensland

Neotrichozetes from rainforest canopy in Queensland

I received a request for information on neotrichy in oribatid mites from a colleague this morning. I wasn’t able to answer it with any authority, but it did remind me of this interesting oribatid mite in the genus Neotrichozetes. ‘Neo’, of course, means ‘new’ and ‘tricho’ is Greek for ‘hair’, so if I were forced to generate a common name for this mite, I suppose I might try the ‘New Hair Mite’. Perhaps not, though, as this would imply a hypothesis that the hairs are new editions to the proper number of hairs a mite should have (the state of having the correct number of hairs is called holotrichy). Neotrichozetes is probably neotrichous, most of its apparent close relatives have no more than 14 pairs of notogastral setae, but there is as yet no robust phylogenetic hypothesis to support this tricky interpretation.

Zetes, for those who may be wondering, was a winged being and a son of the North Wind (Boreas) and Oreithyia, a young lady who made the mistake of wandering too far from home. Many mite genera end in ‘-zetes‘, which seems to come from the Greek ‘zetetes’ or ‘searcher’ and I assume is related to Zetes, the Argonauts and their quest for the Golden Fleece. Perhaps ‘Hairy Canopy Wanderer’ would be a better common name.