Oribatella yukonensis, Behan-Pelletier & Walter, 2012

Behan-Pelletier, Valerie M. & Walter, David E., 2012, 3432, Zootaxa 3432, pp. 1-62 : 48-56

Oribatella yukonensis sp. nov.

( Figs. 10D, E, 14E–G, 25–27, 29D, 30I, J)

Material examined. Holotype: female, Canada: Yukon, Carcross Dunes, 1.vii.1985 ( VBP) from semi-stabilized dunes with grass, sedge, Polemonium , Stellaria , deposited in the CNC, type number 24046. Paratypes: 7 (5 females, 2 males) with same data as holotype; Yukon, Herschel Island, 25.vii.1983 (R.A. Cannings) 1 male from Salix, Hedysarum at base of dry S-facing slope on mud slump; 3 from moss litter and Dryas mats on top of tussock; Running River, 68°57.5’N 137°17’W, 7.vii.1987 ( VBP) 3 males, 2 females from litter of Pyrola , Saxifraga, Castilleja, Epilobium , moss lichens; Klondike Highway, ca. 108 km N intersection with Alaska highway, 23.vi.1987 ( VBP) 1 female from rose and willow litter with moss and lichens; Dempster Highway km 210N, Ogilvie River, 26.vi.1987 ( VBP) 3 from Papaver , Dryas , moss; Richardson Mountains, Summit Lake, 67°43’N 136°30’W, 3.vii.1987 ( VBP) 1 female from Cypripedium, Eriophorum, Tofieldia litter and moss; Blow River, 68°56’N 137°06’W, 7.vii.1987 ( VBP) 2 from Arctostaphylos , Vaccinium, Pedicularis litter on bluffs above river; 6 males, 6 females from willow litter and moss in small gorge. Paratypes deposited in the CNC, PMAE. IZ, RNC and USNM.

Other Material Examined: Alberta, ABMI-2 (60.00878143, -112.146973), 10 km SW of Fort Smith, NT, 10.vi.2009, from organic soil layer in mesic upland black spruce forest, labrador tea and feathermoss understory, 1 male; ABMI-344 (57.95811844, -115.978279) 10 km SE of Buffalo Head Prairie, 12.vi.2008, from organic soil layer in mesic upland aspen forest with understory of low-bush cranberry, buffalo-berry, blueberry, rose, 1 female; ABMI-359 (57.45488358, -111.054222), 13 km E of McClelland Lake, 15.vi.2007, from organic soil layer in mesic upland mixed aspen forest with understory of low-bush cranberry, buffalo-berry, blueberry, rose, 1 male; ABMI-690 (55.78954315, -114.290833), 30 km SW of Wabasca-Demarais, 12.vi.2008, from organic soil layer in open, disturbed site, 1 female, 1 male; ABMI-825 (54.8119545, -111.665276), 11 km SE of Tweedle, 30.v.2007, from organic soil layer in mesic upland aspen forest with understory of low-bush cranberry, buffalo-berry, blueberry, rose, 1 female, 1 male; ABMI-867 (55.09334183, -118.651749), 12 km SE of Grande Prairie, 11.vi.2008, from organic soil layer in mesic upland aspen mixed forest with understory of low-bush cranberry, buffalo-berry, blueberry, rose, 2 females, 1 male; ABMI-1069 (53.91085815, -117.963562), 20 km N of Pinto Creek Canyon Natural Area, 18.vi.2007, from organic soil layer in moist upland spruce forest with understory of horsetail, dogwood, rose, willow, 1 female; ABMI-1133 (53.56852341, -118.216782), 30 km SW of Pinto Creek Canyon Natural Area, from organic soil layer in dry upland spruce forest with understory of hairy wild rye, bearberry and buffalo-berry, 16.vi.2007, 1 male; ABMI-1232 (52.96974945, -117.215393), NE of Mountain Park, 12.vi.2011, from organic soil layer in open, rocky area, 1 female; ABMI-1402 (51.70927429, -115.120628) 20 km SE of Bearberry, 2.vi.2008, from organic soil layer in rich upland spruce forest with understory of dogwood, fern, feathermoss, 1 female; Cypress Hills Provincial Park, Lodgepole pine Campground area, 1 mi S Elkwater, 20–27.vii.1978 ( EEL) 4 females, 1 male from rotten stump with some moss; 1 female from liverwort mat; 1 female from moss and rotten wood; 1 male from vertical moss mat; 1 male from rotten log with moss; same data, except 3 mi S Elkwater, 1 female from old cow manure; Johnson Canyon, 9.x.1981 (A. Tomlin), 1 male from soil scrapings from limestone outcrop; Kinsella, University of Alberta Ranch, 15.vii.1983 ( VBP) 1 female from Agropyron, Stipa, Boutelea litter and sod; Waterton Lakes National Park, Tamarack Trail, 2438m, 19.vii.1986 ( VBP) 3 females, 1 male from Erigeron , Potentilla, Eritrichium, Senecio , Saxifraga, Artemesia litter.

Diagnosis. Total length of adult 432–505 µm. Rostrum with medial crest; margin flattened to concave, with or without 2 small lateral dens. Integument punctate. Translamella without tooth. Medial dens on lamellar cusp 50–75 µm long, without teeth, subequal or longer than lateral dens 45–75 µm long with 2–8 teeth on lateral margin. Area defined by medial and lateral dens broadly triangular. Bothridial seta about 131 µm long, with barbed, narrow, fusiform head, tapered distally. Notogastral porose areas large, about 13 µm in diameter, with deep pore canals. Ten pairs of notogastral setae present, with short barbs, 39–55 µm long, with seta c longest, lm posterior of Aa, and lp anterior of A1. Mutual distance p 1 –p 1 about 22–25 µm, less than distance h 1 –h 1 about 28–40 µm. Custodium 35–48 µm long. Tarsi heterotridactylous.

Description. Adult. Dimensions: Mean total length: female (n = 10) 490 µm (range 455–505); male (n = 7) 464 µm (range 455–470) (based on specimens from Yukon). Mean notogastral width: female (n =6) 323 µm (range 310–340); male (n =7) 309 µm (range 300–320). (Specimens from ABMI Site 867 NE 11.vi.2008 are slightly smaller than the range for specimens from Yukon.)

Integument: Prodorsum, notogaster, anal plates, genital plates and venter micropunctate, mentum punctate to foveate; striae on tutorium, coxisternum, genital plates, pedotectum I and anteriorly on pteromorph, those on pedotectum I irregular distally ( Figs 10D, E). Lamellae with irregular strong, longitudinal striae laterally, fine striae medially ( Fig. 25).

Prodorsum: Rostrum pointed, distally triangular in dorsal aspect; margin flattened in ventral aspect, with or without 2 small lateral dens ( Fig. 14G). Lamella 143–160 µm long, of which cusp 113–120 µm long, 55–60 µm wide at level of insertion of seta le, not touching medially (may be distorted on slide mounted specimens). Lamellar cusps separated along length by about 7 µm, leaving prodorsum visible; translamella without tooth, about 10 µm at greatest width, 10 µm depth ( Fig. 25). Medial dens on cusp 50–75 µm long, without teeth; subequal or longer than lateral dens 45–75 µm long with at 2–8 teeth on lateral margin. Area defined by medial and lateral dens broadly triangular. Seta ro 105–119 µm long strongly barbed along length, acuminate, curved anteromedially. Seta le 100–125 µm long, thick, heavily barbed tapered. Seta in 162–189 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of pair 60–75 µm. Bothridial seta about 131 µm long, with barbed, narrowly fusiform head, tapered distally, stalk short, smooth; head directed slightly anterodorsally ( Fig. 25). Exobothridial seta 29–38 µm long, thin, smooth.

Lateral region of podosoma: Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrolaterally ( Fig 14G). Tutorium broad, rectangular, convex ventrally, about 168 µm long of which cusp about 100 µm long, distal margin with 6–8 teeth ( Figs 14E–G). Custodium 35–48 µm long, extending to middle of pedotectum II ( Fig. 29D). Porose area Al about 10 µm in diameter.

Notogaster: Length subequal to width. Anterior margin undulating, convex lateral of bothridium with 7–9 transverse ridges. Pteromorph with striae; with or without small dens on anteroventral margin. Octotaxic system in form of relatively large porose areas with deep pore canals, about 13 µm in diameter ( Figs 30I, J). Ten pairs of roughened, or weakly barbed notogastral setae present, 39–55 µm long, with c seta longest, lm posterior of Aa, and lp anterior of A1 ( Fig. 25); distance p 1 –p 1 22–25 µm, less than distance h 1 –h 1 about 28–40 µm. Subtriangular lenticulus present.

Ventral Region: Epimeral setae mostly about 12–35 µm long, weakly barbed, 4c shortest seta, 12–16 µm long, 3c longest seta, about 50 µm, equal in shape to other epimeral setae. Genital, aggenital, anal and adanal setae weakly barbed, genital setae 1+5 or 2+4, 13–15 µm long; anal and adanal setae 6–8 µm long. Lyrifissure iad anterolateral and almost parallel to anal plate. Postanal porose area oval 13 x 5 µm.

Gnathosoma : Anterior margin of mentum with transverse, reflected carina, with narrow tectum ( Fig. 14G). Axillary saccule about 5 x 3 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” on genua I and II about 45 µm; l” on tibiae I and II about 37 µm. Tarsi heterotridactylous.

Immatures. Dimensions: Mean length: larva (n = 2) 230 µm (220, 240); protonymph (n = 2) 287 µm (275, 300); deutonymph (n = 2) 350 µm (350, 350); tritonymph (n = 1) 430 µm.

Larva. Sclerotization encompassing gastronotal setae of d series and h 1 ( Fig. 26); weakly encompassing c setae additionally in one specimen.

Prodorsum: Setae in and ex long, barbed, tapered, about 76 and 56 µm long, respectively (setae ro and le broken off). Mutual distance of pair ro about 7 µm, of pair le about 16 mm and of pair in about 29 µm. Seta ex directed laterally, other prodorsal setae directed anteriorly or anterolaterally ( Fig. 26). Bothridial seta narrowly clavate, heavily barbed, about 71 µm long ( Fig. 26). Bothridial seta narrowly clavate, heavily barded, about 71µm.

Gastronotic region: Margin carinate except anteriorly; outline uneven, caused by weak swelling around setal tubercles. Twelve pairs of setae, long, barbed, tapered, other than setae c 1, da, dm, dp broad, barbed tapered; setae c 1, da and dm overlapping in larva and on larval scalps carried by protonymph ( Fig. 26). Setal lengths (in µm) approximate (due to some terminal breakage and difficulty in measurement): c 1 (133), c 2 (125), c 3 (89), da (128), dm (120), dp (116), la (112), lm (96), lp (81), h 1 (11), h 2 (21), h 3 (60). Distance (in µm) da–da, dm–dm and dp–dp about 29, 32 and 51, respectively.

Ventral region: Epimeral setation 3-1-2; setae smooth, about 5 µm, except 1c scaliform.

Tritonymph: Integument weakly sclerotized and faintly micropunctate; sclerotization encompassing all of gastronotal region, ventral region anterior to level of cupule iad, adanal and anal plates and lateral part of coxisternal region. Sclerotization weakest medially in area outlined by dotted line on Fig. 27.

Prodorsum: Setae ro, le, in and ex barbed, tapered, about 73, 130, 142 and 109 µm long, respectively. Mutual distance of setae ro about 14 µm, of setae le about 25 µm and of setae in about 49 µm. Seta ex directed laterally, other prodorsal setae directed anteriorly or anterolaterally ( Fig. 27). Bothridial seta barbed, tapered, subequal to in except blunt distally, about 143 µm long. Bothridium with ridges transecting posterior margin ( Fig. 27).

Gastronotic region: Margin carinate except anteriorly; outline slightly uneven, caused by weak swelling around setal tubercles ( Fig. 27). Setae barbed, tapered, with da thinnest seta, with fewest barbs, followed by dm and dp ( Fig. 27). Setae c 1, c 2, da, dm, dp directed posteriorly; c 1 lying beneath scalps of previous instars. Setae c 3 la, lm, lp, h 3, h 2 directed posterolaterally. Setal lengths (in µm) approximate (due to some terminal breakage and difficulty in measurement): c 1 (86), c 2 (191), c 3 (broken), da (115), dm (108), dp (132), la (142), lm (129), lp (200), h 1 (131), h 2 (160), h 3 (151), p 1 (76), p 2 (28), p 3 (21). Distance (in µm) da–da, dm–dm and dp–dp about 16, 53 and 136, respectively. Ventral surface of scalps with pair of setiform, sheathlike callosities, accommodating seta da of preceding instar; sheaths browner, more sclerotized than rest of scalp.

Ventral region: Epimeres sclerotized laterally. Epimeral setation 3-1-3-3; all smooth, about 6 µm. Five pairs of genital setae, about 6 µm, aligned in longitudinal row. Aggenital seta about 6 µm. Three pairs of adanal setae barbed, about 9–13 µm; two pairs of anal setae weakly barbed, about 7µm; cupule iad present. Axillary saccule present, about 4 x 2 µm.

Other nymphal instars: Similar to tritonymph in form and proportions, except as follows. In protonymph distance (in µm) da–da, and dm–dm about 24 and 37, respectively (distance dp–dp distorted in single specimen); in deutonymph, distance (in µm) da–da, dm–dm and dp–dp about 30, 56 and 120, respectively.

Legs: Seta l” of femur, genu and tibia I, II and l’ of genu III very broad, barbed, spinous, almost blunt distally. Ontogeny of leg setae and solenidia for known nymphs and adult given in Table 3.

Etymology. This species is named in the genitive singular for Yukon, where type material was collected.

Remarks. In Alberta this species can easily be mistaken for O. heatherae sp. nov., described above. Both species are large, and have a similar habitus. They differ mainly in: the shape of the lamellar cusps, with a broadly triangular indentation in O. yukonensis and a broadly subrectangular indentation in O. heatherae ; the integument of pedotectum I, with short ridges in O. yukonensis , without ridges in O. heatherae ; and in dimensions of various characters, with O. heatherae the slightly larger species. We initially questioned the existence of two species, but the hysterosomal setae of the larva, difference in sclerotization of the tritonymph and length of hysterosomal setae in the tritonymph clearly argue against conspecificity. Furthermore, hysterosomal setae c 1, da, dm, dp of larval O. yukonensis are broadly expanded, whereas in O. heatherae they are similar in shape to those of the tritonymph. Adults of this species and O. transtriata Behan-Pelletier 2011 from northeastern Canada ( Behan-Pelletier 2011) have a similar habitus, but porose areas of the octotaxic system are larger in O. yukonensis (about 13 mm vs. about 8 mm in O. transtriata ). Immatures of O. transtriata are not known. These species may prove to be conspecific, but we consider this unlikely. As already noted, the diversity of species in other brachypyline taxa from this biologically rich region of western North America argues for caution.

Distribution and Ecology. This species is known from dry habitats in Yukon Territory and at from upland aspen and spruce forests in western Alberta. In Alberta, gravid females carry up to 3 eggs; gut contents are composed primarily of dark and hyaline fungal hyphae.