Oribatella minuta Banks, 1896

Behan-Pelletier, V. M., 2011, Oribatella (Acari, Oribatida, Oribatellidae) of eastern North America, Zootaxa 2973 (1), pp. 1-56 : 28-29

Oribatella minuta Banks, 1896

Oribatella minuta Banks, 1896, p. 76

( Fig. 14A–E )

Material examined. Holotype male ( MCZ 92834), USA: New York, Sea Cliff , under hemlock bark.

Other material examined. New York, Onondaga Co., CESF, Lafayette Experimental Station , Lafayette Road , 31.x.1973 (J. Philips) 1 from decomposing bald eagle pellet, specimen compared with type by R.A. Norton ( RNC); Wisconsin : Northern Highland State forest near Trout Lake LTER, Star Lake Nature Trail , 46°02’N 89°28’W, 25.x.1998 (VBP and M. Behan) 1 from polypore fungus on oak; Illinois: White Heath, 25.i.1907 (J. D. Hood) 1 from under bark on soft maple tree; Missouri: Lake of the Ozarks State Park , Woodland Trail, elv. 900ft., 14.v.1999 ( VBP) 2 from barren, rocky area in forest with moss, reindeer moss and lichen and oak litter; 2 from litter at base of large oak; Canada: Ontario: Leeds-Grenville Co. , nr. Otter Lake , 44°34.87’N 76°19.77W, 23.vii.2003 (J. Chen, J. Johnson, VBP) 1 from epiphytes on trunk; 2 mi E Dunrobin, 23.iii.1978 ( EEL) 1 from under bark of elm; Point Pelee National Park , 13.viii.1974 ( EEL) 1 from oak-juniper litter on sand; St. Laurence Islands National Park , Mcdonald Island, 30.viii.1976 ( IMS) 1 from litter and soil; Rondeau Provincial Park, 9.viii.1974 ( EEL) 1 from rotten stump; Québec, Gatineau Park, 27.ix.1967 (W.G. Matthewman) 1 from Fomes fomentarius ; New Brunswick: Kouchibouguac N.P. 28.vii.1978 ( IMS) 1 from litter in basal hole of black locust; same data except 1 from litter and soil in basal hole in red oak; same data except (S.J. Miller) 1 from rotten apple tree litter; same data, except 26.vii.1978 ( IMS), 1 from beneath bark of fallen beech; same data except 27–29.ix.1977 ( IMS) 1 from decaying wood and litter in fir stump .

Diagnosis. Total length of adult 300–340 µm. Integument of notogaster, ventral and anal plates reticulate with interspersed micropuncta and microtubercles ( Fig. 14A, B ). Integument of prodorsum, lamella, tutorium and pedotectum I with distinct foveae ( Fig. 14C ). Integument of rostrum and mentum with small reticulate pattern ( Fig. 14D ). Rostrum rounded in dorsal aspect, with small U-shaped indentation medially ( Fig. 14D ). Lamella (including cusp) about 127 µm long, cusp about 79 µm long, about 48 µm wide at level of insertion of seta le. Cusps contiguous or overlapping anteromedially, separated posteromedially, leaving prodorsum visible through oval opening, about 10 x 10 µm. Medial and lateral dens on lamellar cusp subequal, about 48 µm long. Medial dens without teeth, lateral dens with 1–3 teeth on lateral margin, varying among specimens and on either side of same specimen. Lamella without striae. Translamella without tooth, about 10 µm at greatest width, 10 µm deep. Setae ro about 75 µm long, strongly barbed along length, acuminate, strongly directly medially. Setae le about 120 µm long, thick, heavily barbed, tapered. Setae in about 134 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of pair about 51 µm. Bothridial setae about 99 µm long, with barbed, fusiform to clavate head, rounded distally, stalk short, smooth; head directed anteriorly ( Fig. 14C ). Exobothridial setae about 32 µm long, thin, barbed. Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrally. Tutorium about 131 µm long of which cusp about 51µm long, rectangular, distal margin with 4 to 5 dens. Custodium very small, about 6 µm, triangular ( Fig. 14E ). Porose area Al about 8 µm in diameter. Notogastral length subequal to width. Anterior margin undulating, convex lateral of bothridium, with about 10 transverse ridges. Pteromorph with small dens on anteroventral margin. Porose areas present, about 6 µm in diameter. Ten pairs of barbed, tapered notogastral setae present, 37–65 µm long, with c longest; lm medial to posteromedial of Aa, lp anterior and slightly anteromedial of A1. Distance setae h 1 –h 1 about 26 µm, slightly wider than distance p 1 –p 1, about 19 µm. Small U-shaped lenticulus present. Coxisternum with short striae. Epimeral setae mostly 25 µm long, weakly barbed, 3b, 3c about 40 µm long, subequal in length, 4c about 48 long, thicker and more heavily barbed than other epimeral setae ( Fig. 14E and insert). Genital, aggenital, anal and adanal setae weakly barbed, about 9–14 µm long. Genital setae 2+4, 2 pairs of genital setae on anterior margin of genital plates. Postanal porose area oval 30 x 12 µm. Mentum with transverse carina anteriorly, without tectum ( Fig. 14D arrow). Axillary saccule about 4 x 2 µm. Leg setation (I to IV): trochanters, 1-1-2-1; femora, 5-5-2-2; genua, 3(1)-3(1)-1(1)-2; tibiae 4(2)-4(1)-3(1)-3(1); tarsi, 20(2)-15(2)-15-12. Setae l” of genu I about 31 µm, l” of genu II about 40 µm. Tarsi heterotridactylous.

Remarks. This species may be confused in the literature with the widely distributed O. reticulata (Diagnosis below), which also has polygonal sculpture on the notogaster. The two species differ by the following character states (those of reticulata in parentheses): Integument of pedotectum I with dense small foveae, without distinct reticulation of notogaster (integument of pedotectum I reticulate, similar to that of notogaster). Notogastral seta c about 50–65 µm long, weakly barbed, directed laterally (c about 80–90 µm long, strongly barbed, closely following curvature of body); seta lm medial to Aa (seta lm posteromedial to Aa)

Distribution and Ecology. This species is distributed throughout central and eastern North America ( Table 1). It has also been recorded from Oregon (see Marshall et al. 1987).

Figures

FIGURE 14. A–E Oribatella minuta Banks, differential interference contrast microscope images of adult. A, detail of notogaster; B, detail of anogenital region (genital plates to right); C, pedotectum I; D, mentum, with arrow to reflected ridge on mentum; E, custodium and seta 4c, with arrow to custodium; insert of seta 4c. Scale bars = 25 µm.