Oribatella parallelus, Behan-Pelletier & Walter, 2012

Behan-Pelletier, Valerie M. & Walter, David E., 2012, 3432, Zootaxa 3432, pp. 1-62 : 34-37

Oribatella parallelus sp. nov.

( Figs. 17, 18A, 29A, B, 30E)

Material examined. Holotype: adult female; Canada, British Columbia, Hwy 6, 14.7mi N Burton, 1500ft, 4.ix.1975 (B. D. Ainscough) from cedar, hemlock and birch litter under fallen log; deposited in the CNC, type number 24043 . Paratypes: 20 (15 females, 5 males) with same data as holotype; British Columbia, Trinity Valley Field Station , 6 mi N Lumby, 18.vii.1966 ( EEL) 1 male from pure cedar Douglas fir duff, no herbs; Valley of Ste. Wiskin Creek , 5 mi S Nakusp, 25.v.1972 (P. Kevan) 3 males . Paratypes deposited in the CNC, RNC and the USNM.

Diagnosis. Total length of adult 525–584 µm. Integument of pedotectum I reticulate basally, lamella laterally with strong striae. Rostral margin undulating to concave, with small, rounded lateral teeth. Lamellar cusps contiguous along most of length; separated posteromedially, leaving prodorsum visible through long oval opening, 9 µm wide x 16 µm long; translamella without tooth. Medial dens of lamellar cusp 50–64 µm long, lateral dens, 40–50 µm. Bothridial seta 142–161 µm long, with barbed, long bacilliform head, tapered distally. Custodium about 41 µm long, tapered. Ten pairs of weakly barbed notogastral setae present (37 to 67 µm long) with c seta longest, and h 1 shortest; lm posteriad Aa, lp anteriad A1; seta h 1 distinctly directed posteriorly. Distance h 1 –h 1 22–25 µm, subequal or shorter than distance p 1 –p 1, 25–33 µm. Epimeral seta 4c smallest, thinnest epimeral seta, about 27 µm long; 3c longest seta, about 63 µm, slightly thicker and more barbed than other epimeral setae. Tarsi heterotridactylous.

Description. Adults. Dimensions: Mean total length female (n = 4) 567 µm (range 545–584), mean total length male (n = 2) 535 µm (525, 545). Mean notogastral width female (n = 4) 391 µm (range 386–396); mean notogastral width male (n = 2) 371 µm (range 366, 376).

Integument: Prodorsum, notogaster, venter and mentum micropunctate; coxisternum, lamellae medially and pedotectum I with fine striae, pedotectum I reticulate basally, lamella laterally with strong striae ( Fig. 18A).

Prodorsum: Rostral margin undulating to concave, with small, rounded lateral teeth. Lamella about 182 µm long, of which cusp 133–135 µm long, about 61 µm wide at level of insertion of seta le. Lamellar cusps contiguous along most of length, separated posteromedially, leaving prodorsum visible through long oval opening, 9 µm wide x 16 µm long; translamella without tooth, about 9 µm at greatest width, about 5 µm at greatest depth ( Figs 17, 18A). Medial dens on lamellar cusp 50–64 µm long, without teeth, lateral dens 40–50 µm long, without teeth ( Figs 17, 18A). Seta ro about 124 µm long strongly barbed along length, acuminate, curved anteromedially. Seta le about 100 µm long, thick, heavily barbed, tapered. Seta in about 210 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of insertions of pair about 64 µm. Bothridial seta 142–161 µm long, with barbed, long bacilliform head, tapered distally, stalk short, smooth; head directed slightly anterodorsally ( Fig. 18A). Exobothridial seta about 29 µm long, thin, acuminate.

Lateral region of podosoma: Genal tooth broad, subrectangular, rounded distally, without ventrodistal dens, with longitudinal ridge ventrolaterally. Tutorium extending anterior of rostrum, about 207 µm long, of which cusp about 111 µm long, rectangular, with 6–10 teeth distally. Custodium about 41 µm long, tapered (shape modified on one side of one specimen ( Figs 29A, B)). Porose area Al about 14 µm in diameter.

Notogaster: Length subequal to width. Anterior margin undulating, convex region lateral of bothridium with about 12 transverse ridges. Pteromorph with striae along margin; with ridges on anteroventral margin. Porose areas about 13 µm in diameter ( Fig. 30E). Ten pairs of weakly barbed notogastral setae present (37–67 µm long) with seta c longest, and h 1 shortest, lm posteriad Aa, and lp anteriad A1; seta h 1 distinctly directed posteriorly; distance h 1 –h 1 22–25 µm, distance p 1 –p 1, 25–33 µm ( Fig. 17). Subtriangular lenticulus present.

Ventral Region: Epimeral setae mostly 27–63 µm long, weakly barbed; 4c smallest, thinnest epimeral seta, about 27 µm long; 3c longest seta, about 63 µm, slightly thicker and more barbed than other epimeral setae ( Fig. 29A). Genital, aggenital, anal and adanal setae weakly barbed, 8–12 µm long. Genital setae 2+4. Lyrifissure iad anterior of anterolateral corner of anal plate. Postanal porose area oval 23 x 6 µm.

Gnathosoma : Anterior border of mentum with reflexed transverse ridge, with narrow 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 44 µm; l” of tibiae I and II about 45 and 35 µm, respectively. Tarsi heterotridactylous.

Etymology. The specific epithet is a substantive noun in apposition and refers to the nearly parallel medial margins of the lamellar cusps.

Remarks. This species is similar to Oribatella similis Fujikawa, 1990 , known from spruce forest in Hokkaido ( Fujikawa 1990), the holotype and paratypes of which the senior author has examined. They differ by the following characters (those of O. similis in parentheses): body length 524–584 µm (560–609 µm); medial and lateral dens of lamellar cusp about 50 µm (about 75 µm); lamellar cusps laterally without teeth (lamellar cusps laterally with small teeth). This species is also similar to O. jacoti from eastern North America ( Behan-Pelletier 2011). They differ by the following characters (those of O. jacoti in parentheses): body length 524–584 µm (576–624 µm); medial and lateral dens of lamellar cusp about 50 µm (about 72 µm); tutorium about 207 µm long, of which cusp about 111 µm long (tutorium about 228 µm long of which cusp about 144 µm long). Eventually, all three species may prove conspecific, but we retain them as separate species herein because of size differences in multiple character states, and their discrete distributions.

Distribution and Ecology. This species is known only from forest habitats in an area on the western slopes of the Rocky Mountains in interior British Columbia, in Ecoregion 44 of the Montane Cordillera Ecozone ( Atlas of Canada 2007).