Oribatella quadridentata Banks, 1895

Behan-Pelletier, V. M., 2011, Oribatella (Acari, Oribatida, Oribatellidae) of eastern North America, Zootaxa 2973 (1), pp. 1-56 : 40-44

Oribatella quadridentata Banks, 1895

Oribata quadridentata ( Banks, 1895) ( Michael 1898, p. 19)

Syn. Oribatella magniseta Ewing 1909, p. 123 ( Marshall, Reeves and Norton 1987, p. 317)

( Figs. 20–22 )

Material examined: As Oribatella 4-dentata, Holotype female ( MCZ 92784), USA: New York, Sea Cliff ( MCZ).

Other material examined: USA: D.C. Washington, 4.ix.1964 (W.S. Suter) 5 from forest floor litter, FM ( HD) 64–58 ( RNC); North Carolina, Wake Co. , Umstead State Park, 10.iii.1963 (Metz and Farrier) from hardwood litter ( RNC) ; Buncombe Co., Bent Creek Experimental Forest , v.1974, 2 from oak/pine forest litter ( RNC) ; Virginia , Chandler’s Mill Pond, 14.vii.1973 (M. Delfinado and E.W. Baker) 1 ( RNC) ; Mississippi : Grenada Co., T 21, 29.v.1991 (G. T. Baker) 1; Louisiana: Cameron Co., Hackberry Prairie, 29º58’26”N 93º25’43”W, 21.ii.1993 ( VBP) 2 from wild rose and shrubby tree on small rise; Cameron Prairie , 29º56’45”N 93º05’20”W, 23.ii.1993 ( VBP) 1 from litter of wax myrtle and herbaceous plants; Georgia, Clarke Co., Athens , Simonton Bridge Rd. , Botanical Gardens, 1982 (D. Mallow) 2 from mixed litter ( RNC) .

Diagnosis. Total length 600–711 µm; length holotype female 663 µm (given as 600 µm in Banks (1895); length holotype of O. magniseta given as 711 µm by Woolley (1958)). Integument of notogaster, ventral and anal plates and coxisternal region microtuberculate. Integument of prodorsum, tutorium and gnathosomal mentum micropunctate. Integument of pteromorph micropunctate and strongly reticulate ( Fig. 20B ). Coxisternum with reticulate striae laterally. Rostrum strongly triangular, rostral margin flattened medially, with pair of distinct lateral dens. Rostral seta strongly directed medially, about 172–206 µm long, with long barbs. Lamella with short striae laterally. Lamella (including cusp) about 253 µm long, lamellar cusps about 199 µm long, 89 µm at width of seta le; medial dens 108–120 µm long, longer than lateral dens 88–106 µm; medial and lateral dens usually without teeth, latter occasionally with 1 tooth on lateral margin. Lamellar cusps contiguous anteromedially, occasionally diverging; separated posteromedially, leaving prodorsum visible through narrow oval opening, about 2 µm wide, 4–20 µm long. Lamellar setae about 200 µm long, thick, heavily barbed, tapered, arising anteroventrally, positioned medially on cusp. Interlamellar setae about 240–288 µm long; less thick than seta le, equally barbed, tapered. Mutual distance of setae in about 104–108 µm. Bothridial setae about 144 µm long, barbed, narrow, blunt distally, subequal in shape to le. Exobothridial seta absent, reduced to alveolar vestige. Genal tooth narrow, elongated, subrectangular, with long dens ventrodistally, with longitudinal ridge ventrally. Tutorium reticulate, flat, blade-like, about 240 µm long, of which cusp about 122 µm long, with 6-8 dens distally. Porose area Al with distinct border, developed as broad inverted sac, about 12 µm in diameter. Ah developed as large sac, Am as porose area. Epimeral setae long, finely barbed, acuminate, 1a, 2a about 36 µm long, 1b about 60 µm, 3b, 3c subequal in shape to other setae, about 100 µm long, 4c thickest seta, acuminate about 100 µm long. Custodium absent. Genital setae in longitudinal line medially on plate, 1+5, only g 1 on anterior margin of plate; setae thin, barbed, about 24– 29 µm long. Lyrifissure iad parallel to and anterior of anterolateral margin of anal plate. Anal setae about 14 µm. Adanal setae thick barbed, 40–60 µm. Postanal porose area about 19 x 6 µm. Notogastral length subequal to width (flattened in Fig. 20A ). Anterior margin undulating, with small projection lateral of bothridium, with about 11 transverse ridges ( Fig. 20A ). Pteromorph with small dens at anteroventral margin ( Fig. 20B ). Four pairs of porose areas, Aa about 12 µm in diameter. Eleven pairs of roughened notogastral setae present, about 192–240 µm

long; c 2 and c 3 longest; c 3 positioned laterally on pteromorph ( Fig. 20B ); lm medial of Aa, lp medial of A1; mutual distance of pair h 1 –h 1 about 101 µm, wider than distance p 1 –p 1, about 82 µm. Gnathosoma elongate, chelicera elongate, narrowly chelate-dentate ( Fig. 20D , 21C ). Subcapitulum strongly tapered, triangular ( Fig. 21A ). Rutella with reduced sclerotization. Mentum without transverse carina or tectum; setae a, m and h, acuminate, about 40, 44, and 24 µm long respectively ( Fig. 21A ). Axillary saccule 9 x 2 µm, at base of palp ( Fig. 21A arrow). Palptarsal setation 0-2-1-3-8(1) with solenidion ω recumbent and 2.5 x length acm; acm associated with distal cluster of eupathidia and touching solenidion ω along distal half its length ( Figs. 20E , 21B, D ). Leg setation (I to IV): trochanters, 1-1-1- 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 ( Fig. 22 ). Setae l” of genu I about 65 µm; seta l’ absent from trochanter III and femur III. Spines absent anterodorsally on tibia I. Tarsi heterotridactylous.

Remarks. Oribatella quadridentata is the type species of the genus, and is the most unusual among species known from eastern North America (see above under Remarks on the genus). Adults have a number of character states unusual for species in the genus. (1) Notogastral seta c 3 is present, giving a notogastral setation of 11 pairs. (2) Humerosejugal porose area Ah is developed as a thin-walled sac or pouch; it is similar in structure to Ah of the achipteriid Achipteria nitens (Nicolet) , as Grandjean (1962) discussed and illustrated, except that the latter is everted as a vesicle. Alberti et al. (1997) illustrated the porose structure of the thin wall of the similar Ah of A. coleoptrata (L.) with scanning microscopy and it has the same appearance as that of O. quadridentata . (3) The custodium is absent. (4) Only seta v’ is developed on trochanter III; seta l’ is absent. (5) The components of the gnathosoma are elongated, including subcapitulum, chelicerae and rutella. (6) The palptarsal setation is 0-2-1-3-8(1) with solenidion ω recumbent and acm is associated with a distal cluster of eupathidia and touching solenidion ω only along a small part of its length. This expression of solenidion ω and eupathidium acm is almost identical to that illustrated for the oripodoid Stelechobates megalotrichus Grandjean ( Grandjean 1965, his Fig. 4A ). As these character states have either not been described, or are poorly described in most descriptions of known Oribatella , it is presently impossible to evaluate their uniqueness in O. quadridentata .

This species was partially redescribed by Woolley (1958), under its synonym O. magniseta .

Distribution and Ecology. Oribatella quadricornuta is widely distributed throughout eastern USA, from New York to Louisiana (see Marshall et al. 1987) ( 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.

FIGURE 20. A–E Oribatella quadridentata Banks, differential interference contrast microscope images of adult: A, notogaster (5 layers combined); B, detail of pteromorph (3 layers combined); C, postanal organ, genital region to right (4 layers combined); D, chelicera; E, palp, larger arrow to solenidion ω, smaller arrow to eupathidium acm. Scale bars: A = 100 µm; B, D, E = 50 µm, C = 25 µm.

FIGURE 21. A–D Oribatella quadridentata Banks, adult; A, subcapitulum, with arrow to axillary saccule; B, palp, adaxial view, arrow to solenidion; C, chelicera, adaxial view; D, palptarsus, dorsal-adaxial view, arrow to solenidion. Scale bars: A, B, C = 50 µm, D = 20 µm.

FIGURE 22. A–D Oribatella quadridentata Banks, adult female, legs I to IV. All legs in abaxial view; legs I and II trochanter not illustrated. Scale bar = 50 µm.