Xenillus amboroensis Ermilov et Starý, 2021

Ermilov, Sergey G. & Starý, Josef, 2021, Two New Species Of Oribatid Mites Of The Genus Xenillus (Acari, Oribatida, Liacaridae) From Bolivia, Acta Zoologica Academiae Scientiarum Hungaricae 67 (4), pp. 301-311 : 306-310

Xenillus amboroensis Ermilov et Starý sp. n.

( Figs 3 , 4C, F, G )

Diagnosis. Body size: 630–747 × 415–514. Body surface macrofoveolate and microgranulate. Lamellar cusp distally with small inner and outer pro- cesses (teeth) and indistinct concavity between them. Rostral, lamellar and interlamellar setae long, stiff, ro pointed apically, barbed, le and in blunted apically, heavily barbed; ro thinner than others, le bent medially, inserted on ventral side of lamellar cusp. Bothridial seta of medium length, fusiform, heavily barbed, with well-developed stalk, fusiform head and stiff apex. No- togastral setae of medium length (p 1 shorter than others), stiff, blunted or indistinctly dilated apically, heavily barbed. Epimeral and anogenital setae short, slightly stiff, pointed apically, barbed; ad 1 and ad 2 longer than others.

Description of adult. Measurements. Body length: 664 (holotype: female), 630–747 (three paratypes: three females); notogaster width: 431 (holotype), 415–514 (three paratypes).

Integument ( Figs 4S, F, G ). Body brown. Surface foveolate (diameter of foveola up to 12) and densely microgranulate (diameter of granule less than 1), covered by a thin layer of colorless, gel-like cerotegument.

Prodorsum ( Figs 3A, C ; 4C, F ). Rostrum with rectangular ledge, two incisions and two lateral triangular teeth. Lamella (without cusp) as long as half of prodorsum. Lamellar cusp of medium size, distally with small inner and outer processes (teeth) and indistinct concav- ity between them. Lamellar cusps parallel, slightly divergent apically, connected basally by one small, triangular interlamellar tubercle. Rostral seta (65–73) stiff, pointed apically, barbed; lamellar (82–94) and interlamellar (102–110) setae stiff, blunted apically, heavily barbed; ro thinner than others, le bent medially, inserted on ventral side of lamellar cusp. Bothridial seta (90–102) fusiform, heavily barbed, with well-developed stalk, fusiform head and stiff, blunted apically apex. Exobothridial seta not observed. Tutorium long, ridge-like.

Notogaster ( Figs 3A, C ; 4C, F, G ). Anterior notogastral margin straight. Eleven pairs of notogastral setae (p 1: 36–45; others: 53–65) stiff, blunted or indistinctly dilated apically, heavily barbed. Opisthonotal gland opening and all lyrifissures well visible.

Gnathosoma. Generally, similar to Xenillus pseudobolivianus sp. n. Subcapitulum longer than wide (151–155 × 110–114). All subcapitular (a: 20; m: 36; h: 16–20) and adoral (16–18) setae setiform, barbed. Palp (102–106) with setation: 0–2–1–3–9(+ω). Postpalpal seta (6) spini- form, smooth. Chelicera (164–168) with two setiform, barbed setae (cha: 49–53; chb: 32–36).

Epimeral and lateral podosomal regions ( Figs 3B, C ). Epimeral setal formula: 3–1–3–3. All epimeral setae (1b, 3b: 20–24, 1c: 10–12; 4a, 4b: 16–20; others: 12–16) slightly stiff, pointed apically, barbed. Circumpedal carina not observed.

Anogenital region ( Figs 3B, C ). Four pairs (two specimens with four seta on one plate and five setae on other plate) of genital (16–20), one pair of aggenital (16–20), two pairs of anal (16–20), and three pairs of adanal (ad 1, ad 2: 28–36; ad 3: 16–20) setae slightly stiff, pointed apically, barbed.

Legs ( Fig. 4C ). Generally, similar to Xenillus pseudobolivianus sp. n. Median claw thicker than lateral claws, all slightly barbed on dorsal side. Femur I with small tubercle distoventrally, femur II with narrowly triangular process distoventrally, femora III and IV broadly triangular ventrodistally. Dorsoparaxial porose area on all femora and on tro- chanters III, IV distinct. Formulas of leg setation and solenidia: I (1–5–3–4–20) [1–2–2], II (1–4–3–4–16) [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.

Material examined. Holotype (female) and three paratypes (three females): Bolivia, Espejillos environs near Amboró National Park, 17º53’22”S, 63º26’48”W, 562 m a.s.l., sifting leaf litter in rain forest, 29.XI.2009 (collected by B. GREENWAY).

Type deposition. The holotype is deposited in the collection of the SMNH; three paratypes are deposited in the collection of the TSUMZ. All specimens are preserved in 70% solution of ethanol with a drop of glycerol.

(A–C), 50 μm (D, F), 20 μm (E, G)

Etymology. The specific name amboroensis refers to the Amboró National Park, near which the type material was collected.

Remarks. In having fusiform bothridial seta with long, stiff apex, Xenillus amboroensis sp. n. is similar to Xenillus amazonensis Pérez-Íñigo et Baggio, 1997 from Brazil (see PÉREZ-ÍÑIGO & BAGGIO 1997), X. disjunctus Balogh et Mahunka, 1977 from Chile (see BALOGH & MAHUNKA 1977), X. diversisetosus P. Balogh, 1986 , X. fecundus P. Balogh, 1986 and X. longipes Mahunka, 1984 from the Neo- tropical region (see P. BALOGH 1986, MAHUNKA 1984), and X. ornatus ( Covarrubias, 1967) from Chile ( COVARRUBIAS 1967). However, the new species differs from the species listed above by the following characters: lamellar cusp distally with small inner and outer teeth and indistinct concavity between them (versus cusp with large inner and outer teeth and deep indentation between them in X. amazonensis , X. diversisetosus , X. fecundus , and X. longipes ; cusp tri- angular in X. disjunctus and X. ornatus ); lamellar seta located on ventral side of lamellar cusp (versus lamellar seta located distally on lamellar cusp in X. amazonensis , X. longipes and X. ornatus ; lamellar seta located on dorsal side of lamellar cusp in X. disjunctus , X. diversisetosus and X. fecundus ); and all noto- gastral setae of medium length, stiff, heavily barbed (versus notogastral setae h 1 and p 1 – p 3 short, simple in X. amazonensis ; some notogastral setae long in X. disjunctus , X. diversisetosus , X. longipes , and X. ornatus ; setae c 1 and c 2 shorter than others in X. fecundus ).

Figures

Fig. 3. Xenillus amboroensis sp. n., adult: A = dorsal view; B = ventral view (gnathosoma and legs not shown); C = lateral view (gnathosoma and legs not shown). Scale bar: 100 μm

Fig. 4. Xenillus pseudobolivianus sp. n. (A, B, D, E) and X. amboroensis sp. n. (C, F, G), adults, SEM micrographs (SEM HV: 5kV): A (view field: 816 μm; WD: 14.30 mm), B (view field: 689 μm; WD: 14.47 mm) = ventral view; C (view field: 1.09 mm; WD: 14.21 mm) = dorsal view; D (view field: 174 μm; WD: 14.30 mm), E (view field: 159 μm; WD: 14.43 mm); F (view field: 239 μm; WD: 14.18 mm) = bothridial seta and humeral notogastral setae; G (view field: 1.09 mm; WD: 14.21 mm) = some posterior notogastral setae. Scale bars: 200 μm