Oribatella brevicornuta Jacot 1934
Creators: name: Behan-Pelletier, V. M.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Sarcoptiformes
Oribatellidae
Oribatella
Oribatella brevicornuta

description: Oribatella brevicornuta Jacot, 1934   
 Oribatella brevicornuta Jacot, 1934, p. 707.   
(Figs. 2A–F, 3A–D)  
 Type material examined. Specimens (3 females, 1 male) on 4 slides labelled paratype: USA, New York: Ithaca, Buttermilk Creek, 21.v., 26B81d, Remtd v. 1947, A.P. Jacot Coll. (MCZ). Specimens on 3 slides labelled Cotypes: New York: Danby to West Danby, 19.v.1917 (A.P. Jacot), slides labelled 171 Oo 1a (dissected female), 171 Oo 1b (1 female), 171 Oo 1c (1male, 1 female) (MCZ).   
 Other material examined. USA, Missouri: Roaring Rocks State Park, Trail to lookout tower, 13.v.1999 (VBP) 1 from soil under rotting oak; Arkansas: Montgomery Co., Crystal/Collier area, 3.iv.1992 (HWR); Newton Co., Richland Creek Wilderness, 35°46’308N 092°56’016”W, 21.ix.2001 (HWR) 2; Scott Co., Dry Creek Wilderness Area, NE boundary at 2100’, 6.iii.1999 (HWR) 2 from old growth; Georgia: Okefenokee, (RNC) 1; Glynn Co., Jekyll Island, 31°07.22’N 081°24.58W, 28.ii.2005 (VBP) 3 from Serenoa litter on seashore; Camden Co., Crooked River State Park, coastal shell midden forest, 30°50.79’N 081°32.80W, 26.ii.2005 (VBP) 2 from Quercus myrthifolia Willd. litter; same data, except 2 from litter of old Quercus laurifolia Michx.; Mississippi, Oktibbeha Co., HWY 25, 11 mi S from Starkville, 21.ix.1988 (G.T. Baker) 1; Texas, Aransas Co., Aransas National Wildlife Refuge, 28°16’24”N 096°47’56”W, 3.iii.1995 (VBP) 1 from moist yaupon, live oak, persimmon litter on sand by bay; Bandera Co., Lost Maples State Natural Area, East Trail, 29°48.984’N 099°34.999W, 27.ii.2007 (VBP) 1 from bigtooth maple and oak litter; Canada: Québec: Mont Orford Park, 2.viii.1985 (VBP) 1 from beech litter, some Lycopodium; Mont Joli, 25.x.1954 (J.E.H. Martin) 1; Cedarville, 45°01’30.35”N 72°13’58.97”W, Descente 20, 23.viii.1985 (VBP) 2 from litter under Hericium on fallen dead beech; Nova Scotia, Cape Breton Highlands National Park, Mackenzie Mountain, 25.viii.1983 (M. Sharkey) 1 from litter and moss.   
 Diagnosis. Total length of adult 470–572 µm. Notogastral width 300–382 µm. Integument of prodorsum, notogaster, venter and mentum micropunctate. Integument of coxisternum with distinct striae (Fig. 2D). Rostrum flattened, undulating, with (Fig. 2F, arrow) or without minute lateral teeth. Lamella (with cusp) 177–188 µm long, cusp 121–133 µm long, 61–65 µm wide at level of insertion of seta le. Lamellar cusps diverging or parallel anteromedially; separated posteromedially, leaving prodorsum visible through oval opening 35–54 µm long x 17–23 µm wide. Medial dens of lamellar cusps 38–50 µm, subequal or slightly shorter than lateral dens (48–65 µm long); medial dens smooth; lateral dens with 0–4 small teeth on lateral edge (varying among specimens and on either side of same specimen). Long striae extending longitudinally along outer margin of lamella. Translamella without tooth, about 17–19 µm at greatest width, about 13–16 µm deep (Fig. 2C). Setae ro 108–128 µm long, strongly barbed along length, acuminate, strongly directly medially. Setae le about 105–115 µm long, thick, heavily barbed, tapered. Setae in 197–228 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of pair about 57–74 µm. Bothridial setae 133–149 µm long, subequal in shape to seta le; with barbed, bacilliform head, rounded distally, stalk short, smooth; head directed slightly anteromedially (Fig. 2A). Exobothridial setae about 43–65 µm long, thin, smooth, acuminate. Genal tooth broad, subrectangular, rounded distally, without dens ventrodistally, with longitudinal ridge ventrally (Fig. 2D black arrow, 2E arrow). Tutorium 168–201 µm long, of which cusp about 106–127 µm long, rectangular, convex ventrally, distal margin with 5 to 7 dens (Fig. 2E). Custodium about 48–62 µm long, with 2 adjacent knobs along length (Fig. 3C) (1 cotype specimen with knob distally). Porose area Al about 10 µm in diameter. Anterior margin of notogaster undulating, convex lateral of bothridium, with about 10 transverse ridges (Fig. 2A–C). Pteromorph with short ridges at anterior margin; with dens anteroventrally. Porose areas present, Aa about 22 µm in diameter. Ten pairs of long, barbed notogastral setae present; c series 99–127 µm, l and h series 90–100 µm, p series about 77 µm long; c, l and h directed laterally, positioned so that lm medial of Aa, and lp anteromedial of A1. Distance  h 1 –h 1  about 58–67 µm, almost twice distance  p 1 –p 1  (38–41 µm). Lenticulus subtriangular. Epimeral setae about 22–65 µm long, barbed, 3b, 3c about 48 µm long, 4c about 65 µm long and more barbed than other epimeral setae, reaching tip of custodium (Fig. 3C). Genital setae in longitudinal row, 1+5, one seta on anterior of genital plate; genital and aggenital setae about 29 µm long; anal and adanal setae barbed, about 23–38 µm long. Postanal porose area oval, about 50 µm wide. Mentum with small reticulate pattern, with anterior tectum covering base of gena, with transverse carina anteriorly (Fig. 2D). Axillary saccule about 8 x 3 µm. Leg 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 and tibiae I and II about 43–55 µm. Tarsi heterotridactylous.   
 Remarks. Jacot (1934 a, p. 710) described the subspecies O. brevicornuta extensa, from Florida, Illinois, Indiana, Iowa, Ohio and Virginia. He distinguished the subspecies on the basis of lamellar cusps being longer and more slender than those of O. brevicornuta sensu stricto. Subsequently this subspecies was elevated to species status (Johnston 1965), without any rationale given. I examined one type specimen of O. brevicornuta extensa, specifically: cotype female (with 5 eggs) labelled Cotype: “26Ew147, Arcola Ill, July 4, 06. B147. K. & P. in 80% alc. M. July 7, ’06. H. e. Ewing” (MCZ). All character states fall within the range of variation in O. brevicornuta sensu stricto noted in the diagnosis given above. More specifically the length and width of lamellar cusps and the length and width at midlength of cusp dens fall within the range of variation for the type material of brevicornuta sensu stricto. Thus, the elevation of the subspecies to species by Johnston (1965) should be rejected, but I consider it premature to reject subspecific status, i.e., retention of O. brevicornuta extensa, until the species is studied with molecular methods.   
Jacot usually denoted his type material as “cotypes”. The word “ paratype ” on labels for the 4 specimens from USA, New York: Ithaca, Buttermilk Creek, 21.v.,.26B81d, Remtd v. 1947, A.P. Jacot Coll., noted in the Material Examined Section is not in Jacot’s handwriting.  
 Distribution and Ecology. Oribatella brevicornuta is widely distributed in deciduous forests throughout eastern North America, from Nova Scotia, Canada to Texas, USA (Table 1). In addition to the Material examined above, it has been recorded from Connecticut and North Carolina (refs. in Marshall et al. 1987).
description: Published as part of Behan-Pelletier, V. M., 2011, Oribatella (Acari, Oribatida, Oribatellidae) of eastern North America, pp. 1-56 in Zootaxa 2973 (1) on pages 7-10, DOI: 10.11646/zootaxa.2973.1.1, http://zenodo.org/record/5295835