Untitled Document

What are these mites?

Following are pictures of 4 species of deutonymphal mesostigmatid mites, specimens of which were found in a number of samples of mites collected from African army ants. I assume the mites were phoretic since the ants were collected by hand picking or aspirating them from foraging columns.

The mites have a divided dorsal sclerite with a complete setation. Posterior marginal setae appear to be on small platelets, and many of these are modified spines. Ventrally, there is a large ventrianal sclerite. Anterior to the ventrianal sclerite are a series of small, seta-bearing platelets. Peritremes are well developed and extend to bases of leg II. Cheliceral digits are edentate, hyaline in species 1-3 and slightly more sclerotized in species 4; there is a conspicuous arthrodial brush at the base of the movable digit; corniculi are reduced and hyaline; hypostomal setae are the typical gamasine 1/2/1 pattern; the tectum (where visibie) is triramous with the median branch much longer than the lateral ones. The palpal apotele is 3-tined. Leg setation is not reduced; genu & tibia III have 8 setae each and genu and tibia IV have 10 setae each; genu and tibia II of species 1-3 have some lateral setae enlarged and hooked as are 2 terminal dorsal setae of tarsus II; species 4 doesn't have these modified setae but has two ridged swellings on tarsus III at the ventral base and dorsal apex. The pretarsi have well developed membranous ambulacra, but the claws are highly reduced or absent.

Species 4 is somewhat different from the others. In addition to the lack of modified setae on leg II and the modifications on tarsus III, it has large metapodal sclerites and rounded, peg-like setae in the sternigenital region and on the small platelets anterior to the ventrianal sclerite. Some of the anterior dorsolateral setae are also peg-like.

I'm looking for a family ID or better if anyone recognizes these mites. The only families I could think of whose phoretic deutonymphs have 3-tined apoteles are Parasitidae, Halolaelapidae, and the rhodacaroids. This mite doesn't seem to fit in any of these, but I don't claim to know the diversity in those groups, especially in the deutonymphs.

If anyone has thoughts on the identity of these mites, please contact me by e-mail at bmoc@umich.edu.

Thanks! - Barry OConnor

Species 1.