Oribatella quadricornuta ( Michael, 1880 )

Behan-Pelletier, V. M., 2011, Oribatella (Acari, Oribatida, Oribatellidae) of eastern North America, Zootaxa 2973 (1), pp. 1-56 : 39-40

Oribatella quadricornuta ( Michael, 1880)

Comb./Syn.: Oribata quadricornuta Michael, 1880, p. 181

Notaspis quadricornuta ( Michael, 1880) , p. 1

Oribatella quadricornuta ( Michael, 1880) , p. 407

Oribates flammula sensu Oudemans, 1896, p. 56

Oribatella calcarata sensu Willmann, 1931, p. 180

Material examined: Canada, Newfoundland, St. John’s , 5.viii.1976 ( EEL) 3 from weeds, moss, sod, by harbour edge ; Prince Edward Island, Cavendish , 21.viii.1968 ( EEL) 1 from litter under bushes, primarily Ledum ; New Brunswick, Kouchibouguac National Park , 8.viii.1977 ( EEL) 1 from sedges in saltmarsh; same data except, 28.vii.1978 ( IMS) 2 from litter in basal hole in black locust .

Diagnosis. Total length of adult 490-525 µm. Integument of prodorsum, notogaster, anal and ventral plate micropunctate, mentum punctuate to striate; striae present on lamellae, pedotectum I, coxisternal region, and genital plates. Rostrum with distinct crest in dorsal and lateral aspect ( Bernini 1975 his figs 9o-q). Rostral margin rounded to undulating with or without minute dens laterally ( Bernini 1975 his figs 8e, f). Lamellar cusps about half length of lamella; medial dens without teeth subequal in length to lateral dens, lateral dens with about 2 teeth on lateral margin, number of lateral teeth varying among specimens and on either side of same specimen. Translamella with tooth, rounded to triangular in shape. Bothridial setae with barbed, fusiform head, rounded to tapered distally. Seta ex short and smooth. Genal tooth broad, subrectangular, rounded distally, without dens ventrodistally, with longitudinal ridge ventrally. Tutorium extending anterior of rostrum, cusp rectangular, distal margin with about 5-9 dens ( Bernini 1975, his figs 8a, b). Custodium tapered, about half to two-thirds length seta 4c ( Bernini 1975 his figs 8c, 10i-s). Anterior margin of notogaster undulating, convex lateral of bothridium, with about 10 transverse ridges. Notogastral setae barbed, acuminate, lm posterior or posteromedial to Aa, lp anterior to A1. Setal pair h 1 distinctly directed posteriorly, tapered distally; distance h 1 – h 1 equidistant to distance p 1 –p 1. Epimeral seta 4c thickest and longest epimeral seta, seta 3c slightly thicker than other epimeral setae, other than 4c. Genital setae 2+4, 2 setae on anterior margin of genital plate. Mentum with transverse carina anteriorly; with tectum ( Bernini 1975, his Fig. IV4). Tarsi heterotridactylous.

Remarks. Oribata quadricornuta was redescribed thoroughly by Bernini (1975) based on examination of type material, and his redescription forms the basis for the diagnosis given above. As he noted this species often has been confused in the literature with O. calcarata . Bernini (1975) noted variability in a number of characters (noted in diagnosis), but all specimens showed setal pair h 1 distinctly directed posteriorly, translamella with tooth and the long, thick, barbed seta 4c. In eastern North America O. quadricornuta is most similar to O. jacoti sp. nov. from which it differs in overall size, the presence of translamellar tooth, and shape of seta 4c.

This species has been recorded from Alaska and Virginia in the USA and from Yukon, Northwest Territories and Québec in Canada (references in Marshall et al. 1987). The specimens from Québec, identified as part of a study on arthropods associated with Polyporus betulinus and Fomes fomentarius are considered members of O. flagellata sp. nov. (see above). The record from Yukon represents a different, and undescribed, species of Oribatella . I have not been able to confirm records from Alaska, Virginia and Northwest Territories. The record from Alberta ( Walter et al. 2010), will be re-examined as part my study on Oribatella species of western North America.

Distribution and Ecology. Oribata quadricornuta has a Holarctic distribution, as indicated by records cited by Marshall et al. (1987), and later by Kahwash et al. (1990), Weigmann (2006), Arroyo and Bolger (2007), Borges (2008), Shtanchaeva and Subías (2009), Siepel et al. (2009) and Moraza (2009).

This is the most thoroughly studied species of Oribatella , with publications on the following aspects since those referenced by Marshall et al. (1987): the structure of the lenticulus ( Alberti & Fernandez 1990), the sequence of, the D3 domain of the 28S rRNA gene and its flanking regions ( Maraun et al. 2003), feeding preferences ( Schneider & Maraun 2005), soil recolonization ( Domes et al. 2006), as vectors for soil microfungi ( Renker et al. 2005), as intermediate hosts of tapeworms ( Denegri 1993), and presence in metal contaminated sites in Europe ( Khalil et al. 2009). In addition to typical substrates (litter, moss) it has been found associated with the feathers of the tree sparrow ( Krivolutsky & Lebedeva 2004).