Mesostigmata, Baker, 1999

Cocker, Scott L., Proctor, Heather C., Galloway, Terry D., Miskelly, James, Jensen, Britta J. L. & Froese, Duane G., 2025, Pleistocene grasshoppers, fleas, thrips, and mites: rare and new records from Arctic ground squirrel middens in east Beringia in Yukon Territory, Canada, The Canadian Entomologist (e 21) 157, pp. 1-25 : 9

Mites: Mesostigmata and Astigmata

In all, 44 mites were collected from two middens, SC22-EC-1 (MNI = 2) and DF18-37 (MNI = 42) and represent members of Astigmata and Mesostigmata in various life stages. Identification to finer taxonomic levels using keys was problematic because of many missing or obscured features. Midden SC22-EC-1 from Eureka Creek contained two individuals of Mesostigmata , of which one lacks characters to identify it further than indeterminate Mesostigmata (male). The other was identified as cf. Haemogamasus sp. ( Laelapidae : Haemogamasinae) (male or a nymph), based in part on the dense setae covering the idiosoma (= hypertrichy; Fig. 5A ). Midden DF18-37 from Mint Gulch contained individuals of both Mesostigmata (MNI = 11) and Astigmata (MNI = 31). Individuals of Mesostigmata are represented by cf. Haemogamasus sp. (MNI = 1; possible female), cf. Macronyssidae (MNI = 1; female), and indeterminate Mesostigmata (MNI = 9; two nymphs, one possible male, one possible female, and five unclear as to sex or life stage). Astigmata are represented among the specimens solely by the genus Fusacarus sp. ( Glycyphagidae ), of which three specimens are males, seven are females, and 21 are indeterminate as to sex or life stage ( Fig. 5B–D ). This genus is unusual among Glycyphagidae in being strongly sclerotised rather than having a soft cuticle ( OConnor 2009). Female Fusacarus spp. have a very distinctive oviporus (egg opening) region with strongly sclerotised shields ( Fig. 5C ; Halliday and Walter 2006). Like Fusacarus laminipes Michael, 1903 , F. volantis Volgin, 1971 , and an undescribed species of Fusacarus from Algeria ( Grandjean 1953), both sexes of our specimens have well-developed flanges on the ventral sides of the femora and genua of first and second pairs of legs ( Fig. 6 ).

Figures

Figure 5. Mites collected from middens of Urocitellus parryii in the Klondike goldfields, Yukon Territory, Canada: A, cf. Haemogamasus sp. (male or a nymph), SC22-EC-1; B, Fusacarus sp. (female), DF18-37; C, Fusacarus sp. (female; inset showing distinctive genital region), DF18-37; and D, Fusacarus sp. (male; inset shows genital region), DF18-37. Scale bars are 200 μm.

Figure 6. Anterior two legs of a male Fusacarus sp. specimen (stacked image). Scale bar is 100 μm. Abbreviations: tr, trochanter; fe, femur; ge, genu; ti, tibia; ta tarsus.