Mite (Acari) associates of seven species of Geomys (Rodentia : Geomyidae)

One-hundred and three pocket gophers were collected, of these, 76 individuals had mite associates. All host species (including 8 subspecies of Geomys and 2 subspecies of Cratogeomys) were infested, with Geomys texensis having the highest infestation percentage.

A total of 1222 mites was collected and identified to species, representing 8 different taxa and all 3 major groupings of mites (Astigmata, Mesostigmata, and Prostigmata): Geomylichus floridanus (Astigmata); Androlaelaps geomys (Mesostigmata); Echinonyssus femuralis (Mesostigmata); Echinonyssus geomydis (Mesostigmata); probable new species of Euschoengastoides (Prostigmata); Hyponeocula desertícola (Prostigmata); Parasecia gurneyi campestris (Prostigmata); and, Pseudoschoengastia farneri (Prostigmata). This is the first time that these four prostigmatid taxa have been collected from pocket gophers. Of the mite taxa collected, E. geomydis was collected the most frequently and had the highest number of mites collected, however, A. geomys was collected from the most host taxa.

The following criteria appeared to have no effect on the number of mites collected: the sex of the pocket gophers, the date of collection, and the amount of yeast injected for chromosomal determination or the number of days the pocket gophers were injected with yeast prior to mite collection. One criterion that did show significance was the number of days the hosts were held in captivity. Mite density per host decreased with time held in captivity. In particular, A. geomys (a facultative parasite), showed the most significant negative relationship.

Using both the species and subspecies host taxa, three contrasting methods (Jaccard, Morisita, and Renkonen) were used to analyze similarities and groupings of the hosts and mite associates. Consistencies across the phenograms included: (1) the similarity between host taxa G. arenarius arenarius and C. castanops clarkii, (2) G. a. arenarius as the least similar of the host taxa, (3) the similarity between mite taxa E. geomydis and A geomys, (4) the similarity between mite taxa E. sp. and P. farneri, and (5) E. femuralis as the least similar of the mite taxa.

Euschoengastoides sp. and P. farneri were the only mite taxa collected from a single host species. However, the Euschoengastoides sp. may represent a new species which may be found on other hosts, and P. farneri has been collected from other mammals, possibly tracking a resource. Therefore, it does not appear that host-specificity is occurring between Geomys and its mite associates at the species level.