Oribatella rossicus ( Krivolutsky, 1974 )

Ermilov, Sergey G. & Behan-Pelletier, Valerie M., 2014, Revision of Fenestrobates (Acari, Oribatellidae) with description of F. marauni sp. nov., from South America, and new diagnosis for Oribatellidae, Zootaxa 3827 (2), pp. 258-272 : 267

Oribatella rossicus ( Krivolutsky, 1974)

Fenestrobates rossicus Krivolutsky, 1974 p. 1883

Material examined. Cotypes (male, female, on single slide) kindly loaned from the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia.

Diagnosis. Total length of adult 630 (measurement from Krivolutsky 1974). Integument of prodorsum, notogaster, venter and mentum micropunctate. Integument of coxisternum with distinct striae. Rostrum medially rounded with pair of small lateral teeth on margin, as in Oribatella brevicornuta Jacot, 1934 (see Fig. 2D, E, F in Behan-Pelletier 2011). Lamella (with cusp) about 191 long, cusp about 128 long, 63 wide at level of insertion of seta le. Lamellar cusps diverging anteromedially; separated posteromedially, leaving prodorsum visible through oval opening × about 12 at widest. Medial dens of lamellar cusps about 61, subequal or slightly shorter than lateral dens (68 long); medial dens smooth; lateral dens with about 3–4 small teeth on lateral edge (varying on either side of type female specimen). Long striae extending longitudinally along outer margin of lamella. Translamella without tooth, about 12 at greatest width, about 22 deep. Seta ro about 132 long, strongly barbed along length, acuminate, directed anteromedially. Seta le about 110 long, thick, heavily barbed, tapered. Setae in 213 long, thick (less so than le), heavily barbed, tapered; mutual distance of pair about 104 µm. Sensillus 127 long, subequal in width to seta le, except head slightly fusiform, stalk with small barbs distally; head directed slightly anteromedially. Exobothridial setae not visible. Genal tooth broad, subtriangular, rounded distally, without dens ventrodistally, with longitudinal ridge ventrally. Tutorium including cusp about 235 long, rectangular, distal margin with about eight dens. Ventral depression between pedotectum I and the lateral body wall similar to that in O. brevicornuta . Custodium about 56 long, Anterior margin of notogaster undulating, convex lateral of bothridium, with about 10 transverse ridges. Pteromorph with dens anteroventrally. Four pairs of porose areas present, Aa oval about 34 at widest. Eleven pairs of long, barbed notogastral setae present (data from Krivolutsky 1974); setae barbed, tapered, 14–30 long. Distance h 1 –h 1 and p 1 –p 1 could not be established. Lenticulus subtriangular. Epimeral setation 3(?)–1–3–3; about 12 to 48, barbed, tapered, except 4a, 4b, 4c, 3b, 3c long, spinous; 3b about 96, reaching anteriorly 3c about 80, 4a, 4b about 77, 4c about 48. Setae 3b, 4a, 4b, 4c strongly directed anteriorly to level of indentation of pedotectum I, seta 3b in longitudinal alignment with long spinous seta l’ of tibia IV when legs folded. Genital setae six pairs, two seta on anterior of genital plate; genital and aggenital setae about 11 long. Mentum with anterior tectum covering base of gena, reflexed anteriorly, similar in size and shape to that for Oribatella yukonensis Behan-Pelletier and Walter, 2012 (their Fig. 14G ). Seta l” of tibia I about 54, seta l’ of tibia IV about 54. Tarsi heterotridactylous.

Remarks. The description of this species by Krivolutsky (1974) is brief and lacks measurements other than for body length. The expanded description above is based on the slide mounted type specimens. These are mounted dorsal and ventral and thus some characters could not be re-evaluated. For example, Krivolutsky (1974) noted “Trochanters III, IV with long, thin, finger-like structure, directed anteriorly”; we were unable to evaluate this further.

Krivolutsky (1974) assigned this species to Fenestrobates on the basis of “Pore-like structure on coxes of legs II rounded, clearly visible in ventral view”. This is referring to the ventral depression between pedotectum I and the lateral body wall as seen through the coxisternal integument. However, we do not consider this depression to be as extensive as in the species of Fenestrobates , or to be flask-shaped. This species shares the long spinous setae 3b with species of Fenestrobates , but seta 4c is present in O. rossicus , whereas this seta is absent in species of Fenestrobates . Furthermore O. rossicus has about 10 ridges on the anterior margin of the notogaster, ridges that are present in all described species of Oribatella , but absent in Fenestrobates .

Figures

FIGURES 1–3. Fenestrobates marauni sp. nov., adult: 1—dorsal view; 2—ventral view (legs not illustrated); 3—lateral view. Scale bar 100 µm.

FIGURES 12–15. Fenestrobates marauni sp. nov., adult: 12—leg I, left, antiaxial view; 13—leg II, left, antiaxial view; 14—leg III, right, antiaxial view; 15—leg IV, right, paraxial view. Scale bar 20 µm.