Oribatella gigantea Berlese, 1916

Behan-Pelletier, V. M., 2011, Oribatella (Acari, Oribatida, Oribatellidae) of eastern North America, Zootaxa 2973 (1), pp. 1-56 : 15-16

Oribatella gigantea Berlese, 1916

Oribatella gigantea Berlese, 1916, p. 306

( Fig. 4C–E )

Topotypic material examined. Topotypes: 2 males, 1 female, compared with type by R.A. Norton 19.viii.1988, from USA, Missouri, Boone Co., Hinkson Creek , Columbia, S.U. Mo. Campus, 25.iv.1985 FMHD #85–130 (J. Kethley, R.A. Norton) from mixed mesophytic flood plain ( RNC) .

Other material examined. Missouri, Boone Co., Ashland Wildlife Management Res., 26.iv.1985, FMHD #85–137 (J. Kethley, R.A. Norton) 1 from mixed mesophytic litter with maidenhair fern ( RNC) .

Diagnosis. Total length of adult 606–653 µm, length topotype males 614, 624 µm, topotype female 653 µm. Integument of prodorsum, notogaster, venter and mentum micropunctate. Rostrum pointed in dorsal aspect, with medial crest; rostral margin round, smooth to undulating. Lamella (including cusp) about 225 µm long, cusp 160 µm long, about 75 µm wide at level of insertion of seta le. Lamellar cusps contiguous anteromedially; separated posteromedially, leaving prodorsum visible through oval opening, about 36 µm at greatest width, 56 µm long ( Fig. 4C, D ). Medial and lateral dens on lamellar cusp subequal, about 63 µm long. Medial dens with 0–2 teeth, lateral dens with 2 teeth. Longitudinal striae on lamella laterally ( Fig. 4D ). Translamella without tooth, about 38 µm at greatest width, 25 µm deep ( Fig. 4D ). Setae ro about 138µm long, strongly barbed along length, acuminate, strongly directly medially. Setae le about 113 µm long, thick, heavily barbed, tapered. Setae in about 252 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of pair about 100 µm. Bothridial setae 137 µm long, with barbed, narrowly fusiform head, tapered distally, subequal in width to lamellar setae ( Fig. 4C ); stalk short, smooth; head directed anteromedially. Genal tooth broad, subrectangular, rounded distally, without dens ventrodistally, with longitudinal ridge ventrally. Tutorium about 238 µm long, extending anterior of rostrum, of which cusp about 138 µm long, rectangular, convex ventrally, distal margin with 5 to 7 dens. Custodium about 50–63 µm long, tapered. Porose area Al about 10 µm in diameter. Notogaster length subequal to width. Anterior margin undulating, convex lateral of bothridium, with 12–14 transverse ridges. Pteromorph with short ridges at anterior margin; with small dens on anteroventral margin. Porose areas present, about 18 µm in diameter. Ten pairs of long, barbed, acuminate notogastral setae present, about 113 µm long, lm medial to posteromedial of Aa, lp medial and slightly anterior to A1. Distance h 1 –h 1 about 48 µm, distance p 1 –p 1 about 29 µm. Subtriangular lenticulus present. Coxisternum with distinct longitudinal striae ( Fig. 4E ). Epimeral setae mostly about 24 µm long, weakly barbed, 3c about 55 µm long, subequal in shape and width to other epimeral setae, 4c about 65 µm long subequal in shape and width to other epimeral setae. Genital, aggenital, anal and adanal setae weakly barbed, about 9–14 µm long. Genital setae 1+5, 1 pair of genital setae on anterior margin of plates. Postanal porose area oval 25 x 12 µm. Mentum with transverse carina anteriorly, with small tectum. Axillary saccule about 4 x 2 µm. Legs setation (I to IV): trochanters, 1- 1-2-1; femora, 5-5-3-2; genua, 3(1)-3(1)-1(1)-2; tibiae 4(2)-4(1)-3(1)-3(1); tarsi, 20(2)-15(2)-15-12. Setae l” on genu I about 50 µm, l” on genu II about 70 µm. Tarsi heterotridactylous.

Remarks. This is one of the species described by Berlese (1916) from “Columbia (N.A.)” which caused consistent problems in the literature until the provenance was clarified as Columbia, Missouri by Norton and Kethley (1989, p. 422). These authors subsequently collected topotypes from this locality, which were examined (see above).

Distribution and Ecology. This very large species is known only from its type locality and from 1 other location in Missouri.

Figures

FIGURE 4. A–E Oribatella dentaticuspis Ewing and Oribatella gigantea Berlese, differential interference contrast microscope images of adults. O. dentaticuspis: A. prodorsum (7 layers combined), with insert of leg I; B, lamellae, with arrow to translamella. O. gigantea, topotypic female, C, prodorsum (9 layers combined); D, lamellae; E, coxisternal region (6 layers combined). Scale bars: A, B = 50µm; C–E = 100µm.