Oribatella altaica Ermilov, 2022

Ermilov, Sergey G., Khaustov, Alexander A., Joharchi, Omid, Döker, Ismail & Khaustov, Vladimir A., 2022, A New Sexually Dimorphic Species Of The Genus Oribatella (Acari, Oribatida, Oribatellidae) From Russia, Acta Zoologica Academiae Scientiarum Hungaricae 68 (1), pp. 73-84 : 74-81

Oribatella altaica Ermilov sp. n.

( Figs 1–6 )

Diagnosis – Body size: 348–398 × 207–240. Body surface microgranulate.

Rostrum with small median concave. Inner margins of lamellae separated by elongate oval gap and fused basally by short translamella; outer and inner teeth of lamella similar in length. Rostral seta setiform, heavily ciliated unilaterally; lamellar seta bacilliform, barbed; interlamellar seta longest on

(gnathosoma and legs not shown). Scale bar: 50 μm

prodorsum, setiform, barbed. Bothridial seta long, slightly fusiform, with narrowed head, barbed. Posterior part of notogaster with unpaired concavity in males (versus concavity absent in females). Pteromorph pointed laterally, with several serrations and stria on anterolateral margin. All notogastral setae of medium length, setiform, barbed; c and la longest, p 1 – p 3 shortest. Males with two pairs of porose areas (A3 medially positioned at lateral edges of unpaired concavity in posterior midline); females with three or four pairs of porose areas (A3 located openly on notogastral surface) or with asymmetrical number of pairs. Epimeral seta 4c longest on epimeres, thickened, barbed; 3c slightly thickened, barbed; others setiform, slightly barbed. Anogenital setae short, setiform, slightly barbed. Postanal porose area elongate oval. Legs het- erotridactylous.

Description of adults. Measurements – Body length: 365 (holotype: male), 348–365 (11 male paratypes), 381–398 (12 female paratypes); notogaster width: 215 (holotype), 207– 215 (11 male paratypes), 232–240 (12 female paratypes).

Integument – Body colour brown. Surface densely microgranulate. Lateral side of lamella, anterior and anterolateral parts of pteromorph and dorsal side of pedotectum I with some stria. Pedotectum I, posterior part of tutorium and ventrolateral part of epimere I tuberculate. Subcapitular mentum sparsely microfoveolate.

antiaxial view. Scale bars: 50 μm (A, B), 10 μm (C, D, E) left, antiaxial view. Scale bar: 20 μm

Prodorsum – Rostrum protruding, narrowed, with small median concave. Anterior part of prodorsum slightly hump-like. Distal part of lamella with well-developed teeth (outer and inner teeth similar in length, straight, outer tooth laterally with one or two small teeth) and deep U-shaped indentation between them. Inner margins of lamellae separated by elongate oval gap, fused basally by short translamella (median tubercle absent). Rostral seta (77–82) setiform, heavily ciliated unilaterally. Lamellar seta (77–82) bacilliform, barbed. Interlamellar seta (131–135) setiform, nearly straight, barbed. Bothridial seta (86– 94) fusiform, with slightly developed narrowly elongate head having narrowed distal part, barbed. Exobothridial seta (20–24) setiform, slightly barbed. Tutorial cusp with four to six teeth distally. Genal tooth large, rectangular. Dorsosejugal porose area oval, poorly visible.

Notogaster – Anterior margin slightly convex medially. Subtriangular lenticulus well visible. Posterior part of notogaster with large and deep unpaired concavity in males (versus concavity absent in females). Pteromorph pointed laterally, with some serrations on anterolateral margin. Notogastral setae (c: 41–49; la: 41–45; lm, lp, h 3: 28–32; h 1, h 2: 20–24; p 1 – p 3: 16–20) setiform, barbed. Porose areas rounded (8–12, sometimes some areas reduced up to 4); males with two pairs of porose areas, posterior pair (A3) medially positioned at lateral edges of unpaired concavity in posterior midline; some females with three or four pairs of porose areas, but majority of specimens with asymmetrical number of pairs (two versus three, two versus four, three versus four), posterior pair (A3) located openly on notogastral surface. Opisthonotal gland opening and all lyrifissures (except ia not observed) distinct.

Gnathosoma – Subcapitulum size: 82–86 × 65–69. Subcapitular (a: 10–12; m: 20–28; h, 20–24) and adoral (6–8) setae setiform, barbed. Palp (length: 61–65) with typical setation 0–2–1–3–9(+ω). Postpalpal seta (4) spiniform, smooth. Axillary saccule distinct, slightly elongated. Chelicera length: 86–94. Cheliceral setae (cha: 24–28; chb: 16) setiform, barbed.

Epimeral and lateral podosomal regions – Epimeral setal formula: 3–1–3–3. Seta 4c (32–41) thickened, barbed; 3c (28–32) slightly thickened, barbed; 3b, 4b (20–24), 1b, 4a (16– 20), 1a, 2a, 3a, 1c (12) setiform, slightly barbed. Custodium, discidium and circumpedal carina well developed. Humeral porose area Ah oval; Am not observed.

Anogenital region – Genital (g 1: 12–14; g 2: 10–12; g 3 – g 6: 8), aggenital (8), anal (8), and adanal (8) setae setiform, slightly barbed. Adanal setae ad 1 and ad 2 located posteriorly, ad 3 laterally to anal aperture. Adanal lyrifissure inverse diagonal, located close and anterolat- erally to anal plate. Postanal porose area elongate oval (20–28 × 6–8).

Legs – Tridactylous; median claw distinctly thicker than laterals, all slightly barbed on dorsal side. Porose area on femora I–IV and on trochanters III, IV well visible. Formulas of leg setation and solenidia: I (1–5–3–4–20) [1–2–2], II (1–5–3–4–15) [1–1–2], III (2–3–1–3– 15) [1–1–0], IV (1–2–2–3–12) [0–1–0]; homology of setae and solenidia indicated in Table 1. Famulus of tarsus I mini-stickform, slightly swollen and blunt-ended apically, inserted posteriorly to solenidion ω 1. Seta s of tarsus I eupathidial, located before setae a. Setae l” on genua I, II, tibiae I, II and l’ on genu IV, tibia IV thick, heavily barbed. Solenidia ω 1, ω 2 on tarsus II and σ on genu III bacilliform, other solenidia setiform.

Material examined – Holotype (male) and 11 paratypes (five males and six females): Russia, Altai, Ongudaysky region, 50°49’52.0”N, 85°37’12.0”E, 1475 m a.s.l., soil-litter in steppe, 18.07.2021 (collected by A. A. Khaustov, O. Joharchi, I. Döker, and V. A. Khaustov); 12 paratypes (six males and six females): Russia, Altai, Ust-Kansky region , 50°56’11.0”N, 84°51’35.0”E, 1525 m a.s.l., soil-litter in steppe, 18.07.2021 (collected by A. A. Khaustov, I. Döker, V. A. Khaustov, and R. V. Latyntsev).

Type deposition – The holotype and two paratypes are deposited in the collection of the SMNH; twenty-one paratypes are deposited in the collection of the TSUMZ. All specimens are preserved in 70% solution of ethanol with a drop of glycerol .

Etymology – The specific name altaica refers to the geographical place of origin, Altai.

Remarks – Oribatella altaica Ermilov sp. n. is morphologically most similar to Oribatella canadensis Behan-Pelletier et Eamer, 2010 from Canada in having sexual dimorphism (males with unpaired posterior notogastral concavity versus females without concavity). However, the new species differs from the latter by the presence of microgranulate body surface (versus microfoveolate), slight median indentation of the rostrum (versus indentation deep, with some teeth), slightly fusiform bothridial seta with narrowed head (versus clavate, with rounded head), similar outer and inner teeth on lamella (versus outer tooth longer than inner tooth), two pairs of notogastral porose areas in males (versus three pairs), elongate oval postanal porose area (versus oval), epimeral seta 4c distinctly thicker than 3b, 3c (versus 3b, 3c, 4c similar in thickness), and by the absence of a tubercle in the notogastral concavity in males (versus present).

Figures

Fig. 1. Oribatella altaica Ermilov sp. n., adult: A = dorsal view of male (legs not shown); B = ventral view of male (gnathosoma and legs not shown); C = right lateral view of male

Fig. 2. Oribatella altaica Ermilov sp. n., adult: A, B, C = notogaster of female; D = anterior part of prodorsum, dorsoanterior view. Scale bars: 50 μm (A, B, C), 20 μm (D)

Fig. 3. Oribatella altaica Ermilov sp. n., adult: A = posterior view of male; B = posterior view of female; C = subcapitulum, ventral view; D = chelicera, left, paraxial view; E = palp, right,

Fig. 4. Oribatella altaica Ermilov sp. n., adult: A = leg I, right, antiaxial view; B = leg II, with- out tarsus, right, antiaxial view; C = leg III, without tarsus, left, antiaxial view; D = leg IV,

Fig. 5. Oribatella altaica Ermilov sp. n., adult, SEM micrographs: A, C = dorsal view of fe- male; B = dorsal view of male; D = dorsoposterior view of male

Fig. 6. Oribatella altaica Ermilov sp. n., adult, female, SEM micrographs: A = dorsoanterior view; B = lateral view; C = ventral view; D = right ventrolateral view