LARGER ECTOPARASITES OF THE IDAHO GROUND-SQUIRREL (SPERMOPHILUS-BRUNNEUS)

We sampled both subspecies of the Idaho ground squirrel (Spermophilus brunneus) to document die larger ectoparasites of this rare endemic. S . b. brunneus was host (+ = new host record, = new Idaho record) to 4 flea species (Neopsylla inopina+, Oropsylla idahoensis+, O. tubercul ata, and Thrassis pandorae+), 1 tick (Ixodes sculptus+), and an eyewor m (Nematoda: Rhabditis orbitalis+, also 1st records from Sciuridae); S. b. endemicus was host to a louse species (Neohaematopinus laeviuscu lus+), 5 flea taxa (Rhadinopsylla sp.+, O. t. tuberculata, Thrassis f. francisi+, T. f. barnesi+, and T. f. rockwoodi), and a mite (Androlae laps fahrenholzi+). Spermophilus brunneus had fewer known ectoparasite species than other congeners. Although all of their parasites had man y other hosts, S. b. endemicus and S. b. brunneus shared only a single parasite species in common, whereas all but one of their ectoparasite s also occurred on die closely related Townsend's ground squirrel (S. townsendii). The proportion of parasitized individuals and the parasit e loads per individual were significantly lower in S. b. brunneus, whi ch Lives in small, isolated populations, than in S. b. endemicus, whic h has larger less fragmented populations, suggesting a relationship be tween host population structure,parasite loads, and parasite species d iversity hll but one of the flea species have been linked to plague tr ansmission.