Oribatella nortoni, Behan-Pelletier, 2011
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Oribatella nortoni sp. nov.
Material examined. Holotype: adult female. USA: Alabama: Lee Co., nr. Auburn in coastal plain, 7.xi.1975 (unknown), RAN 75–150; deposited in the CNC, type number 23957 . Paratypes: 20 (15 females, 5 males) with same data as holotype; deposited in the CNC, RNC and the FM.
Other material examined. New York, Newcomb, Lake Harris Campground, i. vii.1971 ( EEL) 1 from moss on tree trunk; Arkansas, Polk Co., N. slope Rich Mountain, below 272–82 intersection, 25.iii.1992 ( HWR) 4 from oldgrowth; Canada, New Brunswick, Kent Co., Kouchibouguac National Park, 21.vii.1978 ( IMS) 3 from moss and litter at base of red oak (living); same data except 3 from bark and litter at base of red oak (dead) ; same data except, 15.vi.1978 (R. Cope) 1 from moose dung in mixed woods ; same data except, 9.viii.1977 ( EEL) 2 from mixed deciduous litter .
Diagnosis. Length of adult 295–320 µm. Rostrum flattened medially with minute lateral teeth. Translamella without tooth, about 9 µm at greatest width, 13 µm at greatest depth. Medial dens on lamellar cusp about 7–10 µm long, without marginal teeth, less than third length lateral dens; latter about 31 µm long, without marginal teeth. Bothridial setae about 100 µm long, with barbed, long bacilliform head, tapered distally, stalk short, smooth; head directed slightly anterodorsally. Ten pairs of short, smooth notogastral setae present, 24 to 41 µm long, with c seta longest, setae lm medial to Aa, lp anteromedial to A1; distance h 1 –h 1 about 27 µm, wider than distance p 1 –p 1 about 21 µm. Epimeral seta 3c barbed, about 32 µm, and 4c smallest, thinnest epimeral seta, about 8 µm long. Genital setae in single curved line, or 2+4. Mentum with thickened, reverted transverse ridge anteriorly, with tectum. Femur III with 2 setae, l’ absent. Tarsi monodactylous.
Description. Adult. Dimensions: Mean total length female (n = 10) 317 µm (range 310–320), mean total length male (n = 9) 301 µm (range 295–310). Mean notogastral width female (n = 3) 208 (range 205–210); mean notogastral width male (n = 4) 208 µm (range 200–225).
Integument: Prodorsum, notogaster, venter and mentum faintly micropunctate. Coxisternum, lamellae and pedotectum I with fine striae, lamella laterally with strong striae ( Fig. 15 View FIGURE 15 ).
Prodorsum: Rostrum flattened medially with minute lateral teeth ( Fig. 16 View FIGURE 16 ). Lamella (including cusp) about 118 µm long, cusp about 70 µm long, about 41 µm wide at level of insertion of seta le. Lamellar cusps contiguous, or not, anteromedially, separated posteromedially, leaving prodorsum visible through long oval opening, 9 µm wide x 16 µm long; translamella without tooth, about 9 µm at greatest width, 13 µm at greatest depth ( Fig. 15 View FIGURE 15 ). Medial dens on lamellar cusp about 7–10 µm long, without marginal teeth, less than third length lateral dens; latter about 31 µm long, without marginal teeth ( Figs. 15 View FIGURE 15 , 19A View FIGURE 19 ). Setae ro about 80 µm long, strongly barbed along length, acuminate, curved anteromedially. Setae le about 93 µm long, thick, heavily barbed, tapered. Setae in about 133 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of insertions of pair about 47 µm. Bothridial setae about 100 µm long, with barbed, long bacilliform head, tapered distally, stalk short, smooth; head directed slightly anterodorsally ( Fig. 15 View FIGURE 15 ). Exobothridial setae about 20 µm long, thin, acuminate.
Lateral aspect of podosoma: Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrally ( Fig. 19B View FIGURE 19 ). Tutorium about 120 µm long of, which cusp about 72 µm long, rectangular; distal margin variable, with distinct dorsal and ventral dens ( Fig. 19B View FIGURE 19 ), or with 6–10 dens along anterodorsal and distal margin. Custodium about 29–40 µm long, tapered ( Fig. 16 View FIGURE 16 ). Porose area Al about 11 µm in diameter.
Notogaster: Length subequal to width. Anterior margin undulating, convex lateral of bothridium, with 5–7 transverse ridges. Pteromorph with striae along margin; with small dens on anteroventral margin. Octotaxic system in form of small porose areas, about 7 µm in diameter. Ten pairs of short, smooth notogastral setae present; 24 to 41 µm long, with c seta longest, setae positioned medially and laterally, lm medial to Aa, lp anteromedial of A1; distance h 1 –h 1 about 27 µm, wider than distance p 1 –p 1, about 21 µm ( Fig. 15 View FIGURE 15 ). Subtriangular lenticulus present.
Ventral region: Seta 3c largest epimeral seta, barbed, about 32 µm, 4c smallest, thinnest, about 8 µm long; other epimeral setae mostly 14–18 µm long, smooth. Genital, aggenital, anal and adanal setae weakly barbed, about 11 µm long. Genital setae in single curved line or 2+4. Lyrifissure iad anterior of anterolateral corner of anal plates. Postanal porose area oval 18 x 6 µm.
Gnathosoma: Mentum with thickened, reverted transverse ridge anteriorly, with tectum. Axillary saccule about 5 x 2 µm.
Legs: Setation (I to IV): trochanters, 1-1-2-1; femora, 5-5-2-2; f, 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’ absent from femur III. Setae l” on genua I and II 22-24 µm. Tarsi monodactylous.
Description. Immatures. Dimensions: Length: larva (n = 1) (specimen distorted, not measured); protonymph (n = 1) 235 µm; tritonymph (n = 1) 290 µm.
Larva. Prodorsum: Setae ro le, in and ex strongly barbed, tapered, in thickest seta, about 32, 49, 73 and 37 µm long, respectively. Mutual distance of setae ro about 9 µm, of setae le about 13 µm and of setae in about 20 µm. Setae ex directed laterally, other prodorsal setae directed anteriorly or anterolaterally ( Fig. 17 View FIGURE 17 ). Bothridial seta setiform, heavily barbed, about 80 µm long, almost blunt distally ( Fig. 17 View FIGURE 17 ).
Gastronotic region: Rounded; outline slightly uneven, caused by swelling around setal tubercles ( Fig. 17 View FIGURE 17 ). Humeral organ as for tritonymph ( Fig. 17 View FIGURE 17 arrow). Gastronotal setae, other than h 2, long, broad, heavily barbed, tapered, seta h 2 thin, weakly barbed, acuminate; seta h 1 absent; all setae, other than h 2, directed posteriorly, h 2 directed laterally; setae c 1, da and dm overlapping in larva and on larval scalps carried by protonymph. Setal lengths (in µm) approximate (due to difficulty in measurement): c 1 (78), c 2 (81), c 3 (54), da (52), dm (49), dp (36), la (48), lm (44), lp (35), h 3 (32), h 2 (21); distance da–da and dm–dm subequal 14–15 m, distance dp–dp about 23 µm.
Ventral region: Epimeral setation 3-1-2; setae all smooth, about 5 µm, except 1c scaliform.
Tritonymph. Integument: weakly sclerotized; weakly microtuberculate.
Prodorsum: Setae ro le, in and ex broad, strongly barbed, tapered, about 36, 84, 90 and 60 µm long, respectively. Mutual distance of setal pair ro about 12 µm, of pair le about 17 µm and of pair in about 38 µm. Setae ex directed laterally, other prodorsal setae directed anteriorly or anterolaterally ( Fig. 18A View FIGURE 18 ). Bothridial seta setiform, heavily barbed, about 120 µm long ( Fig. 18A View FIGURE 18 ).
Gastronotic region: Margin carinate except anteriorly; outline slightly uneven, caused by weak swelling around setal tubercles ( Fig. 18A View FIGURE 18 ). Two oval porose regions closely medial to each seta lp; about 13 µm at widest dimension (not illustrated). Opisthonotal gland opening ventromedial to seta lp ( Fig. 18B View FIGURE 18 ). Humeral organ present as small saccule 3 x 3 µm, ventral to seta c 3 ( Fig. 18A View FIGURE 18 , arrow). Setae c 2 broken from specimen examined. Other gastronotal setae long, broadened, heavily barbed, tapered; c 1, da, directed posteriorly. Setal lengths (in µm) approximate (due to some terminal breakage and difficulty in measurement): c 1 (45), c 2 (broken), c 3 (108), da (75), dm (90), dp (50), la (105), lm (110), lp (108), h 1 (97), h 2 (81), h 3 (103), p 1 (52), p 2 (47), p 3 (24). Distance da–da about 22 µm, dm–dm about 42 µm and dp–dp about 82 µm; c 1 and dp broadest setae, subequal in shape and length; da narrowest seta, subequal in shape to bo; setae p 1 and p 2 subequal in size and shape, broader than p 3. Ventral surface of scalps with pair of sheathlike callosities, accommodating seta da of previous instar; sheaths browner, more sclerotized than rest of scalp.
Ventral region: Epimeral plates contiguous medially. Epimeral setation 3-1-3-3; all smooth, about 5 µm, except 3c barbed, about 8 µm. Five pairs of genital setae, about 6 µm, aligned in longitudinal row. Aggenital seta smooth, about 8 µm. Three pairs of adanal setae about 8 µm, ad 1 barbed, ad 2 and ad 3 smooth ( Fig. 18B View FIGURE 18 ); two pairs of anal setae smooth, about 5µm; cupule iad present. Axillary saccule present, about 4 x 2 µm.
Legs: Setae l” of femur, genu and tibia I, II and l’ of genu III very broad, barbed, spinous, almost blunt distally.
Protonymph. Similar to tritonymph in form and proportions. Epimeral setation 3-1-2-1. Paraprocts atrichous in protonymph. Scalps of protonymph with molded integument to accommodate setae da of larval scalp.
Legs: Ontogeny of leg setae and solenidia for known immatures and adult given in Table 3.
Etymology. This species is named in honour of my friend, colleague and preeminent expert on oribatid mites, Dr. Roy A. Norton.
Remarks. Adults of Oribatella nortoni sp. nov. are very similar to those of O. sexdentata , described from Italy on the basis of a single specimen ( Berlese 1916), see also Mahunka and Mahunka-Papp (1995). This species was redescribed by Bernini (1977) and Chistyakov (1984a), and is keyed to species in Bernini (1978) and in Weigmann (2006). The redescription of this species by Bernini (1977) and Chistyakov (1984a) is used for comparison herein, and character states for O. sexdentata are in parentheses below. In O. nortoni sp. nov. seta bo is tapered distally (blunt distally); notogastral seta lm is medial of Aa (posterior to posteromedial of Aa: Bernini 1977, his Fig. XII b; Chistyakov 1984a, his Fig. 13 View FIGURE 13 ; see also, Weigmann 2006, his Fig. 193 a and Shtanchaeva & Subías 2009, their Fig. 7 View FIGURE 7 ). Epimeral seta 4c is the smallest, thinnest epimeral seta in O. nortoni (a character state also found in O. eutricha Berlese, 1908 known from Italy); unfortunately, this character is broken on the type of O. sexdentata ( Bernini 1977) and is not illustrated in Chistyakov (1984a).
The immatures of O. sexdentata were described by Chistyakov (1984a). These differ markedly from immatures of O. nortoni in the shape of gastronotal setae. Furthermore, seta c 1 of all nymphs of O. sexdentata are smooth and shorter than other gastronotal setae, whereas in known nymphs of O. nortoni seta c 1 are equally well barbed and broad as other gastronotal setae.
Bernini (1977) questioned the record of O. sexdentata from Virginia, USA ( Sengbusch 1957). It is possible that this record related instead to O. nortoni . However, Sengbusch’s specimens are not available, so both species are included in the key to species (see below).
Development of leg setae is similar to that given for Oribatella canadensis ( Behan-Pelletier & Eamer 2010) except on leg II, v’ is tritonymphal on the genu and pair (v) are tritonymphal on the tibia (adult in O. canadensis ); on leg III, l’ is absent from the femur; and on legs III and IV, (l) is tritonymphal on the tibia (adult in O. canadensis ).
Distribution and Ecology. This species is known only from a few localities in eastern North America from New Brunswick, Canada to Alabama, USA ( Table 1).
Canadian National Collection of Insects, Arachnids, and Nematodes
Department of Nature, Fujian Province Museum
Institute of Marine Sciences
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