Oribatella dentaticuspis Ewing, 1910

Behan-Pelletier, V. M., 2011, Oribatella (Acari, Oribatida, Oribatellidae) of eastern North America, Zootaxa 2973 (1), pp. 1-56 : 11

Oribatella dentaticuspis Ewing, 1910

Oribatella dentaticuspis Ewing , l910, p. 99.

( Fig. 4A, B )

Type material examined. Cotype female, Illinois: Urbana , 21.iii.1908 (H. E. Ewing) from under dead bark (label reads: “ Urbana, Ill. Mar. 21 by myself. Under dead bark. Or. C. ho. 18. Cl. Oil berg. M. in bal. Mar. 24, ’08. H.E. Ewing ”) ( USNM) .

Other material examined. USA, New York: Onondaga Co., 1988 (J.R. Philips) from nest of red-tailed hawk ( RNC); Cortland Co., Truxton, Taylor Valley State Forest, iii.1974 (W. Jones) from elm log ( RNC); Missouri: Boone Co., Hinkson Cr., Columbia, S.U. Mo. Campus, 25.iv.1985 (J. Kethley, R.A. Norton) FMHD #85–130, from mixed mesophytic forest litter, flood plain ( RNC); Canada, Ontario: 2 mi E Dunrobin, 23.iii.1978 ( EEL) 1 from under bark of elm; S. shore Black Sturgeon Lake, 49° 17.5N 88°48’W, 23.viii.1972 ( EEL) 1 from small polypore bracket on fir log; same data except, 2 from burrow debris under rotten cedar stump; same data except, 1 from under rotten log; Québec, Gatineau Park, 1.ix.1967 (D.P. Pielou); 30.vii.1968 (D.P. Pielou) from Polyporus betulinus (Bull.) Fr. ; same data except 27.ix.1967 (W.G. Matthewman) from Fomes fomentarius (L.:Fr.) Kickx.; New Brunswick, Kouchibouguac National Park, 27–29.ix.1977 ( IMS) 1 from ant workings and soil under fir log; same data except, 1 from decaying wood and litter in fir stump.

Diagnosis. Total length of adult 366 –372 µm. Notogastral width 246–253 µm. Integument of prodorsum, notogaster, venter and mentum microtuberculate. Rostrum with deep, wide parallel-sided indentation, forming 2 lateral teeth; margin between teeth with single medial tooth, two-thirds to equal length of lateral teeth. Lamella (including cusp) 106–110 µm long, cusp about 72 µm long, 38–43 µm wide at level of insertion of seta le. Lamellar cusps contiguous anteromedially; separated posteromedially, leaving prodorsum visible through oval opening, about 10 µm wide, 18 µm long. Medial dens on lamellar cusp 24–32 µm long, without teeth, lateral dens 43–51 µm long, with 1–4 teeth on lateral margin (varying among specimens and on either side of same specimen); medial dens narrower than lateral dens ( Fig. 4A, B ). Short, longitudinal striae on lamella laterally and medially. Translamella without tooth, about 11 µm at greatest width, 10 µm deep ( Fig. 4B ). Setae ro about 75 µm long, strongly barbed along length, acuminate, strongly directed medially. Setae le about 79 µm long, thick, heavily barbed, tapered. Setae in about 130 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of insertions 41–47 µm. Bothridial setae 70–80 µm long, with barbed, clavate head, rounded distally, stalk short, smooth; head directed anteromedially. Exobothridial setae about 19 µm long, thin, barbed tapered. Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrally. Tutorium about 104 µm long, of which cusp about 53 µm long, rectangular, distal margin with 2 to 3 dens. Custodium about 22–30 µm long, apex directed anteroventrally. Porose areas Al about 10 µm in diameter. Notogastral length subequal to width. Anterior margin undulating, convex lateral of bothridium, with 5–7 transverse ridges. Pteromorph with short ridges at anterior margin; without small dens on anteroventral margin. Porose areas about 8 µm in diameter. Ten pairs of long, smooth, acuminate notogastral setae present; c, and l and h series 48–58 µm long, with c longest, p series about 35 µm; setae positioned laterally, other than lm; lm posteromedial of Aa, lp anterior of A1. Distance p 1 –p 1 about 20 µm, subequal to distance h 1 –h 1. Subtriangular lenticulus present. Epimeral setae mainly 22 µm long, weakly barbed, 3b, 3c and 4c 38 µm long, subequal in shape and width to other epimeral setae. Genital, aggenital, anal and adanal setae weakly barbed, about 9–14 µm long. Genital setae either 2 + 4 or 3 + 3; 2 or 3 pairs of genital setae on anterior margin of plates. Postanal porose area oval 16 x 8 µm. Mentum without transverse carina anteriorly, without tectum. Axillary saccule about 6 x 2 µm. Leg s etation (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. Setae l” on genu I about 29 µm, l” on genu II about 43 µm. Tarsi heterobidactylous ( Fig. 4A insert).

Remarks. In all specimens of Oribatella dentaticuspis I examined, including a cotype female collected by Ewing, the legs are heterobidactylous. Ewing himself (1910) incorrectly described the legs as tridactylous, and this was repeated in the redescription of Woolley (1958) as a direct quote. Woolley relied heavily on illustrations of type specimens drawn by E. W. Baker (one of which was redrawn by Grabowski 1967), and apparently did not study the legs directly.

Woolley noted that the total length of 0.55 mm reported by Ewing (1910) was inflated; the illustrated cotype was instead 366 µm. The latter figure is consistent with the range indicated above.

Distribution and Ecology. This species is distributed throughout northcentral and northeastern North America, associated with forest litter and polypore fungi ( Table 1).

Figures

FIGURE 4. A–E Oribatella dentaticuspis Ewing and Oribatella gigantea Berlese, differential interference contrast microscope images of adults. O. dentaticuspis: A. prodorsum (7 layers combined), with insert of leg I; B, lamellae, with arrow to translamella. O. gigantea, topotypic female, C, prodorsum (9 layers combined); D, lamellae; E, coxisternal region (6 layers combined). Scale bars: A, B = 50µm; C–E = 100µm.