Gymnodamaeidae

Walter, David Evans, 2009, Genera of Gymnodamaeidae (Acari: Oribatida: Plateremaeoidea) of Canada, with notes on some nomenclatorial problems, Zootaxa 2206, pp. 23-44 : 41

Key to genera of Gymnodamaeidae in North America

1 Genital and anal plates share a common opening, and are separated by soft cuticle, rather than a sclerotized ano-genital bridge; preanal organ hinged to spurs from ventral plate ( Figs. 4, 7 ) .................................................................... 5

- Genital and anal plates separated by a distinct band of sclerotized cuticle (the ano-genital bridge) under which the preanal organ is inserted ( Figs. 12 , 23 ) ........................................................................................................................ 2

2 Distal segments of the legs with cup-like basal retrotectum forming a ball-and-socket joint with previous segment ( Figs. 13–14 arrows); lamellar seta (le) inserted laterally near rostral seta ( Fig. 10 ); notogaster gently convex dorsally ................................................................................................................................ Adrodamaeus Paschoal, 1982

- Distal segments of the legs without cup-like basal retrotectum ( Fig. 8 ); lamellar seta inserted dorso-medially, distant from rostral seta ( Figs. 6 , 31 , 36); notogaster flattened to concave (Figs. 17, 22) ....................................................... 3

3 Interlamellar setae inserted between bothridia, on relatively small apophyses, bothridial ridge absent; 4 pairs notogastral setae (h 1, p 1-3), seta h 2 absent ( Fig. 24 ); medial margin of genital shields smooth, without interlocking teeth; small mites with ventral lengths <0.4 mm .................................................................................................................. 4

- Interlamellar setae inserted anterior to bothridia, on strong apophyses at median corner of bothridial ridges (Fig. 18 arrow); 5 pairs notogastral setae (h 1-2, p 1-3); medial margin of genital shields each with a series of teeth that interlock in a zipper-like fashion (Fig. 19); large mites with ventral length 0.73–0.9 mm ........ Odontodamaeus Paschoal, 1982

4 Apophyses of posterior notogastral setae h 1, p 1 strongly developed and clustered medially (Figs. 20-21); 7 pairs of genital setae, g2 posterior and lateral to g1; notogastral cerotegument with raised cell in mature adults...................... ................................................................................................................................................... Jacotella Banks, 1947

- Apophyses of posterior notogastral setae variously developed, but not clustered medially ( Fig. 24 ); 6 pairs of genital setae, g2 inserted posterior to g1 and in line with other genital setae; notogastral cerotegument forming series of longitudinal folds in cerotegument ( Fig. 22 ) ............................................................................ Joshuella Wallwork, 1972

5 Notogaster with a maximum of 5 pairs of setae, seta h3 absent; bothridial rim without posterior tooth .................... 6

- Notogaster with 6 pairs of setae including h3 inserted about midway between lyrifissures im and ip; bothridial rim with posterior tooth (Fig. 15) ................................................ Donjohnstonella nom. nov. (pro Johnstonella Paschoal )

6 Notogastral cerotegumental pustules spherical ( Figs. 3 , 28 ); prodorsum with interlamellar setae opposed to distinct median tubercle and forming enantiophysis ( Figs. 1–2 , 31 )......................................................................................... 7

- Notogastral cerotegumental pustules longer than their diameter, bullet-shaped to digitiform, resembling morel mushrooms (Figs. 35, 39); interlamellar setae not opposed to median tubercle (which is poorly developed or absent) ......................................................................................................Roynortonella nom. nov. (pro Nortonella Paschoal )

7 Cerotegument on notogaster without raised pattern of ridges or cells ( Fig. 27 ), but with anterior median patch of strong tubercles ( Figs. 29–30 ); posterior seta h 1 inserted on posterior wall of notogaster; pedotectum II acuminate distally ( Fig. 31 ) ............................................................................................................... Pleodamaeus Paschoal 1982

- Cerotegument on notogaster with lateral folds and with median pattern of raised ridges (sometimes forming closed cells) in mature adults ( Fig. 5 ); posterior notogastral seta h 1 on dorsal surface of notogaster; pedotectum II with rounded margin ( Fig. 2 ) ........................................................................................... Gymnodamaeus Kulczynski 1902

Figures

FIGURES 1 – 8. Gymnodamaeus cf. ornatus Hammer, Alberta, Canada; scale bars = 0.1 mm, except Fig. 3 = 1 μm. 1, Prodorsum showing interlamellar seta (in) on apophysis at median edge of bothridial ridge and opposed to median prodorsal tubercle (larger arrow); 2, Prodorsum and anterior notogaster; 3, Spherical crystalline notogastral pustules; 4, Ano-genital region, arrow points to soft cuticle between genital and anal openings; 5, Dorsal habitus view showing Ushaped raised notogastral ridge pattern; 6, Rostrum from anterior view; 7, Light micrograph of ano-genital region, arrow points to preanal organ; 8, Genu IV (DIC micrograph) showing normal joint, i. e. lacking retrotecta, between femur (top) and tibia.

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).

FIGURES 22 – 31. J oshuella agrosticula Paschoal, 1983, Alberta, Canada. 22, Dorsal view (arrow points to longitudinal notogastral ridge), scale bar = 0.05 mm; 23, Ventral view (arrow points to anogenital bridge), scale bar = 0.05 mm; 24, Posterior notogaster showing 4 pairs of setae, scale bar = 10 μm; 25, Notogastral pustules, scale bar = 1 μm; 26, Tritonymph with stacked scalps, scale bar = 0.05 mm. Pleodamaeus plokosus (Woolley & Higgins, 1973), South Dakota, USA. 27, Dorsal habitus, scale bar = 0.1 mm; 28, Notogastral pustule, scale bar = 1 μm; 29, Tubercular patch (arrow) on median anterior rim of notogaster, scale bar = 10 μm; 30, Light micrograph showing tubercular patch and median prodorsal tubercle. Pleodamaeus sp., Alberta, Canada. 31, Anterior notogaster and prodorsum showing acuminate pedotectum II (arrow), scale bar = 0.05 mm.