A guide to Oribatid Identification for the ABMI: - Royal Alberta Museum

Almanac of Alberta Oribatida 2.3 13 January 20132. Notogaster broad, subrectangular, more or less dorso-ventrally flattened, divided by a singletransverse band of soft cuticle (scissure); sensillus pectinate (Fig. 2.1B) ............................................................................................................................... Hypochthoniidae, Hypochthonius- Notogaster more or less diamond-shaped, somewhat laterally compressed, appearing to haveone complete and one incomplete transverse scissures (anterior band interrupted betweensetae d1) (Fig. 2.1C); sensillus pectinate or with barbed club ................................................................................................................................................... Eniochthoniidae, EniochthoniusBrachychthonioideaBrachychthoniidae Thor, 1934Comments: Species of Brachychthoniidae are very common and often abundant in Alberta soils,but most species are much less than 0.3 mm in length. There is one exception.Eobrachychthonius Jacot, 1936Diagnostic characters: Enarthronotides with 2 simple scissures dividing the notogaster intothree plates (Anterior, Median, Pygidial), a more or less fusiform sensillus (bo), 2 pairs ofpleural plates (PL1, PL2), and 4 pairs of suprapleural plates (SpC, SpD, SpE, SpF), SpCbears seta c3; aggenital sclerite entire and bearing ag or divided with ag on small sclerite.Also Known As: Brachychythonius Berlese, 1910Type species: Brachychthonius latior Berlese, 1910 (=Eobrachychthonius sexnotatus Jacot,1936)World species: 6 speciesEtymology – Eo (dawn) + brachy (short) + chthonius (of the soil)Comments: Among the high diversity of Brachychthoniidae found in Alberta soils, this is theonly genus with species that exceed 0.3 mm in length. Information on the smallerspecies may be found in Part II of the Almanac.Canadian species listed on DOC (bold = AB): Eobrachychthonius borealis Forsslund, 1942 YTNU NT; Eobrachychthonius latior (Berlese, 1910) YT NU NT MB ON QC NF;Eobrachychthonius oudemansi van der Hammen, 1952 NU NT; Eobrachychthonius sp.ON*Eobrachychthonius latior (Berlese, 1910) (ITIS 735041)Also Known As: Eobrachychthonius sexnotatus Jacot, 1936, Brachychthonius grandis Sellnick,1944ABMI code/Common name: EOBRLAT; Common Name: Orange Scissured OribatidDiagnostic characters: aggenital sclerite entire and bearing a seta; large brachychthoniids, 270-370; sclerites orange in adults, lilac in immatures.Overview: This is the only brachychthoniid mite to meet the ABMI 0.3 mm length criterion.26