Protoribates robustior Jacot, 1937

Walter, David Evans & Latonas, Sarah, 2013, A review of the ecology and distribution of Protoribates (Oribatida, Oripodoidea, Haplozetidae) in Alberta, Canada, with the description of a new species, Zootaxa 3620 (3), pp. 483-499 : 492-497

Protoribates robustior Jacot, 1937

Figs 18–26 , Map 1

Xylobates capucinus robustior Jacot, 1937: 244 ; Marshall et al. (1987): 267.

Xylobates robustior Jacot, 1937 —Norton and Kethley (1990): 490 (new status).

Diagnosis. Female ventral length 470–530, males unknown, body yellow-brown to brown in colour, cuticle smooth. Prodorsum ( Figs 18, 21, 22 ) with narrow lamellae, poorly developed sublamella, short (~40) tutorial ridge, rostrum ( Figs 18, 20 ) slightly raised medially, margin smooth, rounded; bo (~80) reflexed over notogaster, head narrowly expanded, acuminate distally, ciliate on anterior margin ( Fig 21 ); ex minute (~2); other prodorsal setae, barbed, tapering, acuminate: in (~90–95), le (~40); ro (40). Notogaster with alveoli for 10 pairs of setae and 4 pairs of well developed porose areas each surrounded by a ring-like region ( Fig 23 ), Aa (12–13) largest, A1 (5) with lp inserted on medial margin of ring; A2 (5), A3 (5); pteromorphs movable with hinge and well developed muscles ( Fig 23 ); dorsophragmata relatively short (25), widely separated (55). Discidium (~55 long) with long, needle-like custodial tip ( Fig 24 ); ad1 (30–40) somewhat longer than ad2 (25–27), both with short barbs, ad3 (~12–13) about half as long as ad2. Tarsus I (62–65 long, excluding apotele) with 17 setae ( Figs 25–26 ): 7 setal pairs (ft, tc, it, p, u, a, pv) setae s, v’ (l’’ and setal pair pl absent), famulus (5–7) peg-like; solenidion ω1 (30–32) narrow and tapering, but with rounded tip, ω2 (30–35) baculiform; seta a’ (22–25), thick, with 3–5 pectines. Tarsus II (52–55 long) with s (20–23) very thick, with 4–7 pectines; a’ (23–26) similar, but with more pectines; pv’’ (~38 long) somewhat thickened (shaft ~2 wide) with numerous ventral pectines; solenidia ω1–2 (20–22) both baculiform. Tibia I–II each with strong to weak basal-ventral tooth; femora II–IV each with ventral blade-like keel, prolonged into strong distal lobe on femur II; ventral porose areas apparently absent from tarsi and tibiae; monodactyl, each claw with dorsal series of short barbs. Palpal tarsal double-horn hook-like, on well developed apophysis.

Material examined. USA: Cotypes: 37 females on slide 34F21-1 (with one Scheloribates lanceoliger (Berlese)) , USNM; “from surface of soil (beneath the litter) of a 70 year old, mixed woodland, laboratory grounds, Bent Creek Experimental Forest, Buncombe Co., N. Car.; taken January 7th 1935, slide 34F21-1 (Jacot 1937); 5 females ex litter in second growth maple, beech, birch forest, Heiberg Memorial Forest (42.739, -76.077833), NY, 21.ix.2011, R.A. Norton. Alberta: 3 adults, Moose Pasture (53.656667, 112.759444), 2009; 4 Ƥ MacTaggart Park, Edmonton, 1 June 2012; Ƥ, ABMI 892 NE (54.36624146, -110.994919), 31.v.2010; Ƥ, ABMI 452 NW (56.85694885, -110.307251), 10.vi.2011; 3 Ƥ, ABMI 330 NE, SW (57.66861725, -110.962219), 14.vi.2007; Ƥ (545 SE (56.26429367, -110.207954), 1.vi.2007; 8Ƥ, ABMI 151 SW (58.76856232, -111.240944), 27.v.2010; Ƥ, ABMI 359 NE (57.45488358, -111.054222), 15.vi.2007; 2 adults (SEM) Onoway (53.77N, 114.06W), 13.iii.2008; 2 Ƥ, ABMI 64 NW (59.31958008, -111.284081), 27.v.2011; Ƥ, ABMI 1477 SW (50.88052368, -112.734695), MAP 1 Collections of Protoribates robustior Jacot, 1937 (filled circles) and Protoribates haughlandae sp. n. (open circles), in Alberta, Canada. Stars mark major cities.

24.vi.2008; Ƥ, ABMI 1601 NE (49.73745728, -113.825783), 12.vi.2007; 3 Ƥ, ABMI 1602 NW (49.6853714, -113.608124), 13.vi.2007; Ƥ, ABMI 1602 SE (49.6853714, -113.608124), 13.vi.2007; 1adult (SEM), ABMI 1618 SW (49.56171417, -113.921532), 11.vi.2008; F, 2 Ƥ, ABMI 1567 SE (50.08177185, -113.789474), 29.v.2009; 10 adults (3 SEM), ABMI OG-1218-1 NW (52.67760086, -112.46682), 28.v.2011; 1 adult, ABMI 1092 NE (53.23706055, -111.039818), 27.v.2011; 1 adult, ABMI 1461 NE (50.90753174, -111.286209), 15.vi.2011; Ƥ, ABMI 1434 NW (51.23065567, -112.634445), 12.vi.2008. All in PMAE.IZ. For habitat data see below and Table 1 .

Ecology and distribution. Of the 30 specimens sexed, all were females. Other species of Xylobates are suspected thelytokous parthenogens (Norton and Kethley 1990) and that may be true of this species as well. Gravid females carry 2–3 large eggs. Of the Alberta collections on hand, 11 are from dry, treeless sites with grasses and sedges, 5 from dry upland forest mostly dominated by pine, and 3 from aspen woodlands ( Table 1 ). The gut contents are difficult to interpret. Most gut boluses contain some fungal material, both dark and hyaline hyphae and the occasional spore. However, most boluses are composed mostly of coarse or sheet-like particulate matter, possible plant cell fragments, and a rare pollen grain. Hartenstein (1962) reported that P. lophotrichus fed primarily on the parenchyma of leaves and xylem fragments undergoing microbial decomposition and probably derived most of their nutrition from the microbes.

Remarks. Protoribates robustior appears to be widely distributed in eastern North America and can be distinguished from other species in this and similar genera by the characters in the key below. As far as we have been able to determine, this is the only species of Protoribates in North America where the setation of tarsus I is reduced by the loss of three fundamental setae and the absence of l’’ is usually easy to discern ( Figs 25 vs 29).

Figures

FIGURES 18 – 24. Protoribates robustior Jacot, 1937, New York, USA (18 – 20), Alberta, Canada (21 – 24). Adult (scale bars = 50 µm, except 20 = 10 µm) 18 frontal view 19 ventral habitus 20 lateral view palps, rutellum 21 dorsal view prodorsum 22 lateral habitus 23 light micrograph of porose area Aa (12 µm diameter) 24 discidium (60 µm long).

FIGURES 25 – 26. Protoribates robustior Jacot, 1937, New York, USA. Adult (scale bars = 10 µm) 25 tarsus and tibia I – II lateral view 26 tarsus I – II paraxial view.