Oribatella ewingi, Behan-Pelletier & Walter, 2012

Behan-Pelletier, Valerie M. & Walter, David E., 2012, 3432, Zootaxa 3432, pp. 1-62 : 16-18

Oribatella ewingi sp. nov.

( Figs. 6E–H, 7, 14D, 28B)

Material examined. Holotype: adult female. USA: California, Matea Co., 6 mi SE Halfmoon Bay, 13.vi.1981 ( DSC) from redwood litter; deposited in the CNC, type number 24038 . Paratypes: 4 (2 females, 2 males) with same data as holotype; California, Butte Co., 2 mi SW Stirling City, 8.v.1984 ( DSC) 6 females 4 males from maple leaf litter; 2 mi SW Stirling city, 2900’, 29.v.1981 ( DSC) 8 from maple and oak litter; Oregon, Benton Co., McGlynn Creek ravine, 23.1.1977 (L. Russell) 1 male from moss on bank; 5 mi SW Alsea Ground, 23.i.1977 (L. Russell) 3 males from grasses in mixed woods; Curry Co. , Loeb State Park , 8mi NE Brookings, 12.viii.1985 ( EEL) 2 females from rotting deciduous log; Nevada, Little Valley , 6,600 ft., xii.1970 (N. Stark) 1 male ( RNC); Canada: Alberta, ABMI-996 (54.39379883, -119.614182), from upper soil organic layers in mesic upland pine forest with labrador tea and feathermoss understory, 30.v.2011, 1 male; ABMI-1231 (52.99143219, -117.452957), from upper soil organic layers in mesic upland forest, labrador tea and feathermoss understory, 10.vi.2011, 1 male; British Columbia, Smuggler’s Cove Provincial Park , 49°30.67N 123°56.77W, 6.x.2007 ( VBP) 3 females, 1 male from Douglas fir and sassafras litter; Manning Provincial Park , Rhododendron Flats , 7.ix.1988 ( VBP) 1 female, 2 males from Rhododendron macrophylum litter; Osoyoos , Haynes Lease Reserve , Throne area , 10.vii.1986 ( VBP) 3 females, 1 male from Heuchera ovalifolia litter; Penticton , Madeline Lake , 10.vii.1986 ( VBP) 1 female, 3 males from Douglas fir litter . Paratypes deposited in the CNC, PMAE . IZ, RNC and the USNM.

Diagnosis. Length of adult 490–564 µm. Rostral margin convex with distinct medial tooth. Lamella with textured pattern of ridges. Lamellar cusps diverging anteromedially, separated posteromedially, leaving prodorsum visible through narrow oval opening (5–7 µm wide x 5–7 µm long); translamella without tooth. Medial dens of lamellar cusp distinctly narrow (50–62 µm long); lateral dens of similar length (57–64 µm long) but 2–3 times as wide. Bothridial seta about 115 µm long, with barbed, long bacilliform head, tapered distally. Ten pairs of weakly barbed acuminate notogastral setae present (29–58 µm long) c seta longest, setae lm posterior of Aa, lp anterior of A1; distance h 1 –h 1 about 32 µm, wider than distance p 1 –p 1, about 22 µm. Custodium about 56 µm long, tapered. Seta 4c largest epimeral seta, barbed, thickened, about 60 µm, 3c barbed, subequal in shape to other epimeral setae, about 37 µm long. Tarsi heterotridactylous.

Description. Adult. Dimensions: Mean total length female (n = 8) 534 µm (range 515–564), mean total length male (n = 8) 504 µm (range 490–535). Mean notogastral width female (n = 7) 375 µm (range 356–396); mean notogastral width male (n = 7) 354 µm (range 340–366).

Integument: Prodorsum, notogaster, venter, anal and genital plates, and mentum micropunctate. Coxisternum, pedotectum I and pteromorph with fine striae forming weakly reticulate pattern ( Figs 6F, G), lamella laterally with strong striae, with textured pattern of ridges medially ( Figs 6F, 14D). Rostrum with textured pattern of ridges ( Fig. 6E).

Prodorsum: Rostral margin convex with distinct medial tooth ( Figs 6F, 7A). Lamella 150–165 µm long, of which cusp 113–117 µm long, 54–57 µm wide at level of insertion of seta le. Lamellar cusps diverging anteromedially, separated posteromedially, leaving prodorsum visible through small oval opening (5–7 µm wide x 5–7 µm long); translamella without tooth, 5–7 µm at greatest width, about 10 µm at greatest depth. Medial dens of lamellar cusp distinctly narrow (50–62 µm long) ( Figs 6F, 14D); lateral dens of similar length (57–64 µm long) but 2–3 times as wide, and with usually 2 marginal teeth. Seta ro 111–120 µm long, strongly barbed along length, acuminate, curved anteromedially. Seta le 96–115 µm long, thick, heavily barbed, tapered. Seta in about 155 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of insertions of pair 50–53 µm. Bothridial seta about 115 µm long, with barbed, long bacilliform head, tapered distally, stalk short, smooth; head directed slightly anterodorsally ( Figs 6F, 7A). Exobothridial seta very short, smooth, about 8 µm long.

Lateral region of podosoma: Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrolaterally ( Figs 6E, 7B). Tutorium about 175 µm long, of which cusp about 86 µm long, rectangular; distal margin with 6–10 dentes along anterodorsal and distal margin ( Fig. 7B). Custodium about 56 µm long, tapered ( Fig. 28B). Porose area Al about 11 µm in diameter.

Notogaster: Length subequal to width. Anterior margin undulating, convex region lateral of bothridium with 7–10 transverse ridges ( Fig. 7A). Pteromorph with striae forming weak reticulate pattern; anteroventral margin minutely serrate ( Fig. 6G). Octotaxic system in form of small porose areas, about 8 µm in diameter. Ten pairs of weakly barbed, acuminate notogastral setae present (29 to 58 µm long) c seta longest, setae lm posterior of Aa, lp anterior of A1; distance h 1 –h 1 about 32 µm, distance p 1 –p 1 about 22 µm ( Fig. 7A). Subtriangular lenticulus present.

Ventral Region: Seta 4c largest epimeral seta, barbed, thickened, about 60 µm ( Figs 6H, 28B), 3c barbed, subequal in shape to other epimeral setae, about 37 µm long; other epimeral setae mostly 19–27 µm long, weakly barbed. Genital, aggenital, anal and adanal setae weakly barbed, about 10 µm long. Genital setae 2+4. Lyrifissure iad on level with anterolateral corner of anal plates. Postanal porose area oval about 29 x 9 µm.

Gnathosoma : Anterior margin of mentum with tectum, without reflected ridge. Axillary saccule about 5 x 2 µ m.

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” on genua I and II about 39 and 44 µm, respectively; l” on tibiae I and II about 38 and 43 µm, respectively; l” on genua I and II about 43 and 48 µm, respectively. Tarsi heterotridactylous.

Etymology. This species is named in honour of the late H. E. Ewing, who worked extensively on Acari, including Oribatida, from western North America during 1907 to 1947.

Distribution and Ecology. Oribatella ewingi is known from British Columbia to California, in similar habitats as O. banksi , i.e., deciduous and coniferous forest litter, but those of O. ewingi are drier. These species have not been recorded from the same sites to date.