Adrodamaeus magnisetosus ( Ewing, 1909 )

Walter, David Evans, 2009, Genera of Gymnodamaeidae (Acari: Oribatida: Plateremaeoidea) of Canada, with notes on some nomenclatorial problems, Zootaxa 2206, pp. 23-44 : 30

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.).

Figures

FIGURES 9 – 14. Adrodamaeus magnisetosus (Ewing, 1909), Ontario, Canada; scale bars = 0.1 mm, except Fig. 11 = 1 μm. 9, Adult, dorsal view with cerotegument intact; 10 Adult, dorsal view with notogastral cerotegument scraped off to show lateral (arrow) and median ridges; 11, Notogastral pustules (and fungal hyphae); 12, Light micrograph of venter showing ano-genital bridge (arrow); 13, Genu III joints with femur (top) and tibia showing retrotecta (arrows); 14, Genu IV joints with femur (top) and tibia showing retrotecta (arrows).