Oribatella transtriata Behan-Pelletier 2011, sp. nov.

Oribatella transtriata sp. nov.

(Figs. 23F, 26)

Material examined. Holotype: adult male. Canada, Cape Breton Highlands National Park, Aspy Trail, 28.viii.1984 (VBP) from lichens and moss on trunks of maple about 2m above ground; deposited in the CNC, type number 23959. Paratypes: 1 male, 1 female; Ontario, Leeds-Grenville Co., near Otter Lake, 44°34.87N 76°19.77W, 22.vii.2003 (VBP, J. Chen, J. Johnson) from moss with lichen on W-facing limestone slope; Newfoundland, Pasadena, 28.vii.1976 (EEL) 1 male, 1 female from moss on rotting log; New Brunswick, Kouchibouguac National Park, 21.ix.1977 1 male from mushrooms and leaf litter; Ontario, Leeds-Grenville Co., Chaffey’s Locks 30.v.1974 (IMS) 1 female from moss on rocks near spring. Paratypes deposited in the CNC and RNC.

Diagnosis. Total length of adult 450–452 µm. Prodorsum, notogaster, anal plate, pedotectum I with widely spaced micropuncta. Ventral plate with shallow foveae. Genital plate micropunctate with strong striae. Lamella with distinct transverse striae. Lamella (including cusp) about 175 µm long, cusp about 148 µm long, about 60 µm wide at level of insertion of seta le. Translamella without tooth. Medial dens on lamellar cusp, thickened, narrow, slightly concave laterally, about 80 µm long, without teeth; lateral dens shorter, about 65 µm long, 2-3 times width of medial dens, with 8–10 teeth. Bothridial setae with barbed, fusiform head, tapered distally. Epimeral seta 3c longest and thickest, about 49 µm long; 4c weakly barbed, about 17 µm long. Genital setae 2+4, 2 pairs of genital setae on anterior margin of genital plates. Ten pairs of long, curved, weakly barbed notogastral setae about 63 µm long, lm posterior of Aa, and lp anterior of A1. Tarsi heterotridactylous.

Description. Adult. Dimensions: Mean total length: female (n = 1) 450 µm; male (n = 2) 451 µm (450, 452). Mean notogastral width: female (n =1) 295 µm; male (n =2) 295 µm (290, 300).

Integument: Prodorsum, lateral of lamellae, notogaster, anal plate, pedotectum I with widely spaced micropuncta. Ventral plate with shallow foveae. Coxisternum, lamella, pedotectum I, anterior of pteromorph with striae and micropuncta. Lamella with distinct transverse striae (Figs. 23F, 26). Genital plate micropunctate with strong striae.

Prodorsum: Rostrum with distinct medial crest dorsally; rostral margin slightly undulating, with pair of minute dens laterally. Lamella (including cusp) about 175 µm long, cusp about 148 µm long, about 60 µm wide at level of insertion of seta le. Lamellar cusps parallel or diverging anteromedially; prodorsum visible through oval opening, about 15 µm wide, 37 µm long; translamella without tooth, about 15 µm at greatest width (Fig. 23F). Medial dens on lamellar cusp, narrow, thickened, slightly convex laterally, about 80 µm long, without teeth; lateral dens shorter, 2–3 times width medial dens, about 65 µm long with 8–10 teeth on lateral margin (Fig. 26), varying among specimens and on either side of same specimen. Setae ro 108–125 µm long, strongly barbed along length, acuminate, curved anteromedially. Setae le 130–133 µm long, thick, heavily barbed, tapered. Setae in 168–175 µm long, thick (less so than le), heavily barbed, parallel; mutual distance of pair about 80 µm. Bothridial setae 120–130 µm long, with barbed, narrowly fusiform head, tapered distally, stalk long, smooth; head directed slightly anterodorsally (Figs. 23F, 26). Exobothridial setae about 19 µm long, thin, barbed tapered.

Lateral aspect of podosoma: Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrally. Tutorium extending anterior of rostrum, about 200 µm long, of which cusp about 130 µm long, rectangular, slightly convex ventrally, distal margin with about 7 dens. Custodium 32–35 µm long, tapered. Porose area Al about 10 µm in diameter.

Notogaster: Length subequal to width. Anterior margin undulating, convex lateral of bothridium, with 5–7 transverse ridges. Pteromorph with short ridges at anterior margin; with small dens on anteroventral margin. Octotaxic system in form of 4 pairs of relatively small porose areas. Ten pairs of long, curved, smooth to weakly barbed notogastral setae present; about 63 µm long, lm posterial of Aa, and lp anterior of A1 (Fig. 26). Distance setae h 1 – h 1 about 35 µm, greater than distance p 1 –p 1 , about 25 µm. Lenticulus U-shaped.

Ventral region: Epimeral setae 10–50 µm long, barbed; 3c longest and thickest, about 49 µm long; 4c weakly barbed, about 17 µm long. Genital, aggenital, anal and adanal setae weakly barbed, about 8–10 µm long. Genital setae arranged in curve, 2+4, 2 pairs of setae on anterior margin of plates. Postanal porose area oval, 12 x 10 µm.

Gnathosoma: Mentum with transverse carina anteriorly, reflexed, without tectum. Axillary saccule about 5 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. Seta l” of genua I and II about 24 µm. Tarsi heterotridactylous.

Etymology. The specific epithet, transtriata, refers to the transverse striae on the lamellae.

Remarks. This species is easily distinguished from other eastern North American species of Oribatella by the transverse striae on the lamellae and by the very narrow medial dens of the lamellar cusp, which is distinctly longer than the lateral dens.

Distribution and Ecology. Oribatella transtriata is known from boreal habitats in eastern Canada, but it probably has a wider boreal distribution in North America.