Adrodamaeus magnisetosus (Ewing, 1909)

(Figs. 9–14)

Damaeus magnisetosus Ewing, 1909

Heterodamaeus magnisetosus (Ewing, 1909) (Ewing 1917)

Adrodamaeus magnisetosus (Ewing, 1909) (Paschoal 1984, Marshall et al. 1987, Subías 2004)

Material examined: CANADA, ONTARIO: 2 females, Burley Campground, Lake Huron Pinery Provincial Park, 15.viii.1974, E.E. Lindquist, ex moss pads on sand dunes; 7 adults, Eganville, Shaw Woods Nature Reserve; 20. v. and 30.ix.1993; B. Bissett; ex mixed forest litter; one adult, St Lawrence Islands National Park, Grenadier Island, 8–9 July 1975, D. Spaner; 2 adults, F-site Azilda, 46.31.51N, 81.6.10E, ex moss and birch litter, 15.vii.1997, M St John & G. Bagatto, all in the CNC; 3 adults, Shaw Woods Nature Reserve (46.63N, 77.07E), 30.ix.1993, VB138-93, V. Behan, in PMAE.IZ.

Comments: Most Gymnodamaeidae have a large, cup-like tectum on trochanters III and IV that protects the trochanteral-femoral joint; however, species of Adrodamaeus have similar retrotecta protecting their distal leg joints as well (Figs. 13–14). Since predators of adult oribatid mites often attack these mites at their leg joints, snipping off legs and penetrating to the hemolymph (Molleman & Walter 2001), it seems likely that retrotecta evolved in response to predation pressure. This genus is similar to Arthrodamaeus Grandjean, 1954 a (see Bayartogtokh & Weigmann 2005) and may be a junior synonym (G. Weigmann, Institute for Zoology, Freie Universitaet Berlin, pers. comm.).