Astegistes pilosus ( C.L. Koch, 1840 )

Bayartogtokh, Badamdorj, 2007, Oribatid mites of the family Astegistidae (Acari: Oribatida) in Mongolia, Zootaxa 1472, pp. 55-68 : 56-58

Astegistes pilosus ( C.L. Koch, 1840)

( Fig. 1 )

Zetes pilosus C.L. Koch, 1840 , Vol. 31(12).

Liacarus bicornis Warburton & Pearce, 1905 , p. 566, pl. 19, fig. 4.

Cultrozetes pilosus: Hull, 1916 , p. 383.

Astegistes pilosus: Sellnick, 1928 , p. 30, fig. 69; Willmann, 1931, p. 151, figs. 210 & 211; Balogh, 1943, p. 69; Bulanova-Zakhvatkina, 1967, p. 177, fig. 187; Krivolutsky, 1975, p. 182, fig. 373; Subias, 2004, p. 92; Weigmann, 2006, p. 233, fig. 123a–c.

Diagnosis. Medium in size; body yellowish to yellowish brown in color, covered with thin cerotegument; rostrum rounded with two incisions laterally; lamellae narrow, almost fused medially; lamellar cusps well developed, rounded at tip; rostral and lamellar setae moderately long, with minute barbs; interlamellar setae minute, hardly visible; sensilli medium in length, with finely barbed, elongate-fusiform head; tutoria narrow, distally pointed; ten pairs of notogastral setae; setae c1, p2 and p3 minute, but visible; other notogastral setae medium in length.

Measurements. Body length: 552–570 (564) Μm; width of notogaster 425–436 (432) Μm. In total 21 specimens were measured.

Integument. Integument nearly smooth and shiny in reflected light at low magnification, but at high magnification prodorsum, lateral part of podosoma and peripheral regions of ventral plate exhibit minute granulation.

Prodorsum. Rostrum rounded, with two incisions laterally. Rostral setae (ro) moderately long, with minute barbs. Lamellae narrow, almost fused medially; lamellar cusps nearly as long as basal part of lamellae, but narrower than latter, smoothly rounded distally. Lamellar setae (le) nearly as long as ro, with minute barbs. Interlamellar seta (in) minute, hardly visible only under high magnification. Bothridia (bo) relatively small, directed anterolaterad. Exobothridial setae (ex) about half as long as setae le, thin, smooth. Sensilli (ss) medium in length, with finely barbed, elongate-fusiform head. Tutoria (tu) narrow, with moderately long, pointed distal tip extending beyond insertions of rostral setae ( Fig. 1 A & C).

Notogaster. Nearly round in shape, dorsosejugal suture absent medially. Ten pairs of thin, smooth notogastral setae; c1, p2 and p3 minute, but visible, other notogastral setae moderately long. Lyrifissures im, ih, ips, ip and opisthosomal gland opening (gla) small in size; lyrifissure ia under humeral region ( Fig. 1 A).

Gnathosoma . Infracapitular mentum slightly wider than long, without noticeable microtubercles. Hypostomal setae a, m and h medium long, thin, smooth ( Fig. 1 B). Chelicerae narrow, elongate, with a few small teeth. Palpal setation: 0-2-1-3-8 including solenidion ω.

Epimeral region. Apodemes apo.2 and apo. sj well developed, nearly transversely oriented. Epimeral setae medium long, smooth; setal formula: 3-1-3-3. Discidium distinctly projected distally; circumpedal carina well developed ( Fig. 1 B).

Ano-genital region. Anal and genital apertures large, situated close to each other. Genital aperture nearly rounded; genital plates with six pairs of medium long, thin, smooth setae. Aggenital setae as long as genital setae, thin, smooth. Anal aperture widened posteriorly, slightly longer than wide; anal and adanal setae ad1, ad2 slightly longer than genital setae; ad3 slightly shorter than other adanal setae ( Fig. 1 B).

Legs. Tarsi heterotridactylous, median claw conspicuously thicker than lateral claws.

Material examined. Twenty-eight specimens (12 males and 16 females): Basin river Degee Gol, District Khalkhgol, Province Dornod, soils of the bank of river, and organic debris accumulated under willow, 47o01’N, 119o11’E, elevation 880m a.s.l., 28 May 2003, Col. B. Bayartogtokh.

Ecology. The species inhabits the moist soils of the river basin, and litter or organic debris accumulated under willows, broad leaved trees and between rocks.

Distribution. This is a Palaearctic species, and commonly distributed in majority of areas of Europe. However, the present species is relatively rarely represented in Asia, and up to date it is recorded only in Japan, China and Mongolia ( Fujikawa et al. 1993; Wang et al. 2002, and see also synonymic list).

Remarks. Though the European specimens have relatively large body size (560–630 Μm in length) than Mongolian ones, most characters of the latter accord well with those of the former. In his description, Weigmann (2006) indicated the presence of 3–4 lateral incisions on the rostrum. Also he noted only nine pairs of notogastral setae (seta lp is missing). However, in the Mongolian specimens, I found only two lateral incisions on the rostrum, and ten pairs of notogastral setae. These might be considered as variations in different populations.

Figures

FIGURE 1. Astegistes pilosus (C. L. Koch, 1840). A: Dorsal view; B: Ventral view; C: Prodorsum.