The first sexually dimorphic species of Oribatella (Acari, Oribatida, Oribatellidae) and a review of sexual dimorphism in the Brachypylina Author Behan-Pelletier, Valerie M. Author Eamer, Barbara text Zootaxa 2010 2332 1 20 journal article 10.5281/zenodo.193123 86b47982-b5b5-44c0-af52-00a6920649ad 1175-5326 193123 Oribatella Banks 1895 Type species : Oribatella quadridentata Banks Diagnosis. Adult. Species comprising this genus are unique among Oribatellidae ( Grandjean 1954a , Bernini 1978 ) in having the following combination of character states. Adults with pteromorphs immovable; 4 pairs of porose areas or saccules; sexual dimorphism in octotaxic system usually absent, when present octotaxic system of male modified; 10 to 14 pairs of short to very long notogastral setae; lamellae long, broad, with large cusps, medially converging or contiguous, cusps generally with large medial and lateral dens; with or without medial tooth in translamellar region; tutorium broad, lamelliform, cusp rectangular, with dens distally, lying parallel to dorsal contour of prodorsum in lateral aspect, extending anterior of insertion of rostral seta; bothridial wall distally expanded; custodium with short to long, free distal point; axillary saccule present at base of palp; chelicera chelate-dentate; humerosejugal porose organ Ah expressed as porose area; porose area Al present or absent. Legs monodactylous, bidactylous or tridactylous; femur III with seta l’ present or absent; seta v' of genua I and II present or absent; one or two anterodorsal spines present on tibia I close to, or between, solenidia φ1 and φ2. Immatures. Apopheredermous, with scalps of preceding instar maintained away from dorsal integument by setae da and dorsally directed h1. Body colorless, cuticle without plicae. All or most gastronotic setae long; setation unideficient; larva with 12, nymphs with 15 pairs (adult loses at least c1 ). Setae dm and dp subequal in length to da in all immatures, or much shorter than da in deutonymph and tritonymph. Without hysterosomal sclerites other than small setal tubercles. Pair of humeral organs present laterally in sejugal region. Without apodemato-acetabular tracheal system or porose homologues. Paraprocts atrichous in larva, protonymph and deutonymph. Genital and aggenital setal formula (larva to adult): 0-1-3-5-6 and 0-0-1-1-1, respectively. Opisthonotal gland present in all instars. Cupule development normal. Bothridium and sensillus fully formed in all instars. Setation of protonymphal leg IV normal (0-0-0-0-7). All immature instars with circular line of dehiscence, such that dorsal scalp separates from ventral piece at ecdysis.