Oribatella abmi, Behan-Pelletier & Walter, 2012

Behan-Pelletier, Valerie M. & Walter, David E., 2012, 3432, Zootaxa 3432, pp. 1-62 : 5-10

Oribatella abmi sp. nov.

( Figs. 1–3)

Material examined. Holotype: adult female, Canada, Alberta, ABMI Site 1438 (51.10178757, -111.487175), 8 km east of Pollockville along Township Road 250, from upper organic soil layer in open field with grasses and sedges, 9.vi.2011; deposited in the CNC, type number 24036 . Paratypes: 9 females, 5 males with same data as holotype . Paratypes deposited in the CNC, PMAE . IZ, RNC , and the USNM.

Other material examined. ABMI 1126 (53.05752182, -110.746841), 7 km east of Auburndale along Township Road 473, upper organic soil layer in open field, 28.v.2011, 1 female ; ABMI-OG-1160-1 (52.78925323, -110.302109), 11 km north-northeast of Edgerton along Township Road 442; untreed site with lichen and bryophyte vegetation, 31.v.2011, 1 female, 2 males ; ABMI-OG-1190-1 (52.71193, -111.23734), 2 km east of Route 881 along Township Road 433 northeast of Hardisty, upper organic soil layer in untreed site with grasses and sedges, 1.vi.2011, 2 females ; ABMI-OG-1283-1 (52.13767624, -110.796417), 2 km NW Gooseberry Lake Provincial Park , upper organic soil layer in untreed site with grasses and sedges, 27.v.2011, 2 males ; ABMI-72L-3 (50.75932, -110.76165), 12.vi.2009, untreed site with grasses and sedges, one male; ABMI-72L-4 (50.77691, - 110.90216), 12.vi.2009, 7 km southeast of Buffalo , upper organic soil layer in untreed site with grasses and sedges, 4 females, 2 males ; Edmonton , Parkallen, liverworts and mosses in urban garden, 24.viii.2011, ( DEW) 2 females .

Diagnosis. Total length of adult 375–405 µm. Distinct longitudinal striae in coxisternal region; pedotectum I proximally with irregular transverse striae. Rostral margin medially undulating and with 2 strong, long, lateral teeth; medial crest weakly developed. Lamellar cusps contiguous anteromedially, separated posteromedially, leaving prodorsum visible through drop-shaped opening about 12 µm wide x 30 µm long; translamella without tooth. Medial dens on lamellar cusp about 34 µm long, without teeth; lateral dens slightly longer (about 36–40 µm) with 1–2 teeth. Bothridial seta about 86 µm long, with barbed, club-shaped head, tapered distally. Notogastral porose areas with deep pore canals, about 8 µm in diameter. Ten pairs of very weakly barbed notogastral setae present, about 24–60 µm long, with seta c longest, lm posteriad Aa, and lp anteriad A1; mutual distance p 1 –p 1 about 24 µm, slightly narrower than distance h 1 –h 1 about 29 µm. Tarsi heterotridactylous.

Description. Adults. Dimensions: Total length: females (n = 8) 399 µm (range 375–405); males (n = 3) 385 µm (range 375–390). Notogastral width: females (n = 7) 280 µm (range 265–300); males (n = 3) 265 µm (range 255–270).

Integument: Prodorsum, notogaster, anal plates, genital plates, venter and mentum micropunctate. Lamellae with distinct irregular striae laterally; pedotectum I proximally with irregular transverse striae ( Fig. 3C).

Prodorsum: Rostral margin medially undulating, sometimes forming pair of small cusps; with 2 strong long, lateral teeth ( Fig. 2A), overlapping in some flattened slide-mounted specimens ( Figs 2B, 3B). Lamella about 115 µm long, of which cusp about 66 µm long, about 40 µm wide at level of insertion of seta le. Lamellar cusps contiguous anteromedially, separated posteromedially, leaving prodorsum visible through oval opening (about 12 µm wide x 30 µm long); translamella without tooth, about 11 µm at greatest width, concave, about 9 µm deep ( Fig. 1). Medial dens on lamellar cusp about 34 µm long, without teeth; lateral dens slightly longer (about 36–40 µm) with 1–2 teeth ( Figs 1, 3A). Seta ro 74–88 µm long, strongly barbed along length, acuminate, curved anteromedially. Seta le about 87 µm long, thick, heavily barbed, tapered. Seta in about 149 µm long, thick (less so than le), barbed, tapered; pair parallel, mutual distance about 39 µm. Bothridial seta about 86 µm long, with barbed, club-shaped head, tapered distally, stalk short, smooth; head directed slightly anteromedially ( Figs 1, 3A). Exobothridial seta about 27 µm long, thin, weakly barbed.

Lateral region of podosoma: Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrolaterally ( Fig. 2A, B). Tutorium broadly rectangular about 121 µm long, of which cusp about 63 µm long, distal margin with 4–6 dens. Custodium about 26 µm long ( Fig. 2B). Porose area Al about 7 µm in diameter.

Notogaster: slightly longer than wide, 1.06:1. Anterior margin undulating, convex region lateral of bothridium with about 8 transverse ridges ( Fig. 1). Pteromorph punctate, anteroventral margin minutely serrate. Octotaxic system in form of porose areas with deep pore canals, Aa about 8 µm in diameter. Ten pairs of very weakly barbed notogastral setae present, 24–60 µm long, with c seta longest, lm posteriad Aa, and lp anteriad A1; mutual distance p 1 –p 1 about 24 µm, slightely narrower than distance h 1 –h 1 24–29 µm ( Fig. 1). Subtriangular lenticulus present.

Ventral Region: Epimeral setae mostly about 14–26 µm long, barbed acuminate, 3c about 29 µm long, distinctly barbed, 4c about 38 µm long, similar in shape to 3c, longest epimeral setae ( Fig. 2B). Genital, anal and adanal setae weakly barbed, about 8–10 µm long; genital setae 2 + 4 or 3+3. Aggenital setae about 10 µm. Lyrifissure iad anterolateral of anal plate, almost parallel. Postanal porose area about 26 x 4 µm.

Gnathosoma : Anterior margin of mentum without thickened transverse ridge, with narrow tectum. Axillary saccule about 6 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 36 and 42 µm, respectively; l” of tibia I and II about 35 µm. Tarsi heterotridactylous.

Etymology. This species is named as a noun in apposition derived from the initials for the Alberta Biodiversity Monitoring Institute (ABMI) that conducts biodiversity surveys in Alberta, includes Oribatida as a focal taxon, and whose field crews collected most of the known specimens.

Remarks. This species is very similar to Oribatella arctica , with which it shares similar lamellae, notogastral porose areas with deep pore canals when viewed in transmitted light, custodium, and setae 3c and 4c. They differ in the following character states (those for O. arctica in parentheses): body length 375–405 µm (420–490 µm), rostral margin medially undulating between 2 strong lateral teeth (rostral margin with medial tooth between 2 strong lateral teeth); distance h 1 –h 1 about 29 µm (26), distance p 1 –p 1, about 24 µm (19). This species is also similar to O. canadensis in size and general habitus, but the rostrum is prolonged into a pair of strong lateral teeth (rather than being indented) and the median crest in obsolete distally (rather than strongly developed). Also, the males do not exhibit the sexual dimorphism (A2–A3 fused and bracketing a dorsal tubercle) of O. canadensis .

Distribution and Ecology. This species is widely distributed throughout the Canadian province of Alberta and has been collected primarily in the upper soil organic layers on dry, untreed sites with grasses, sedges, and bryophyte cover. Gravid females carry two eggs; gut contents include dark fungi and spores.