Ferreting up a Bird's Nose

Mites, as I may have commented before, seem to have an almost fractal level of diversity: the closer you look, the more there is of it. This is nowhere more apparent than when it comes to parasitic mites which infest almost any host in any way that you can imagine. For the subject of this post, I drew one such mite: the honeyeater nasal mite Ptilonyssus myzanthae.

Venter (left) and dorsum of female Ptilonyssus myzanthae, from Domrow (1964). The scale bar equals 500 µm.

Bird nasal mites of the family Rhinonyssidae are, as their name indicates, inhabitants of the nasal passages of birds. General adaptations of the family for their parasitic lifestyle include tendencies towards reduction of the body sclerotisation and reduction in the length and number of setae. They use the claws on their front legs to tear openings in the host's mucous membranes and then feed on its blood. Transmission of nasal mites seems to happen during bill-to-bill contact such as when parents are feeding their young or during mating activities, or indirectly through water or on the surface of perches or the like. Rhinonyssid nasal mites are not known to transmit any actual diseases between hosts but they can cause the formation of lesions or inflammation or the like. All in all, probably not very pleasant for the bird (see here for some more details).

Whole-body illustration of a different rhinonyssid species, from Greg Spicer.

Nevertheless, infection rates in bird populations can be very high and most (if not all) bird species will be host to some nasal mite species. Most species of nasal mite are very host specific, known on only one or a few bird species (it must be noted, though, that the question of just how many researchers choose to look up a bird's schnozz in search of mites may not be irrelevant here). Ptilonyssus myzanthae was described by Domrow (1964) from two species of honeyeater in Queensland, Australia: the noisy miner Manorina melanocephala and the little wattlebird Anthochaera chrysoptera. Distinctive features of this species compared to others in the genus include a subhexagonal anterior dorsal shield on the body, a narrow genital shield, and a divided pygidial shield (the small pair of shields near the rear of the dorsum). Both of the known hosts are widespread and common in eastern Australia and it is likely that this mite is similarly ubiquitous. Studies of honeyeater phylogeny tend to place the genera Manorina and Anthochaera as close relatives, so it is possible that P. myzanthae has been infesting them since before their lineages diverged. It would be worth looking for the species in other related honeyeaters to see if we find any further clues.

REFERENCE

Domrow, R. 1964. Fourteen species of Ptilonyssus from Australian birds (Acarina, Laelapidae). Acarologia 6 (4): 595–623.