Cultroribula rarisetosa, Bayartogtokh, Badamdorj, 2012

Bayartogtokh, Badamdorj, 2012, The genus Cultroribula (Acari: Oribatida: Astegistidae) in Mongolia, with new findings from Altai Mountains and remarks on known species of the world, Zootaxa 3302, pp. 44-60 : 49-51

Cultroribula rarisetosa sp. nov.

( Fig. 4 )

Diagnosis. Medium-sized species, covered with thin cerotegument; rostrum with 13–15 teeth, among them four central teeth much larger than lateral teeth; lamellae wide, fused medially; lamellar cusp long and wide, with large outer tooth, but without inner tooth; rostral and lamellar setae moderately long, with conspicuous barbs, interlamellar seta short, smooth; sensillus with short stalk and club-shaped head with minute barbs; tutorium wide at base, with long cusp sharply pointed distally; humeral process of notogaster not sharply projected, but rounded distally; ten pairs of notogastral setae short; four pairs of genital setae, legs tridactylous.

Measurements. Body length: 338–346 (342) μm; width of notogaster 187–194 (191) μm. In total two specimens were measured.

Integument. Body yellowish to yellowish-brown in color. Surface of body and leg segments with very thin, nearly smooth cerotegument. Integument microtuberculate on lateral part of prodorsum and around leg acetabula.

Prodorsum. Rostrum with 13–15 teeth, among them four central teeth much larger than lateral teeth; two most central teeth slightly shorter than next lateral teeth; size of rostral teeth becoming smaller toward posterior direction ( Fig. 4 B & C). Rostral seta moderately long, with long barbs. Lamella wide, fused medially; lamellar cusp slightly longer, but narrower than basal part of lamella, with large outer tooth, but without inner tooth ( Fig. 4 D). Lamellar seta long, about 1.6 times as long as ro, sparsely barbed; interlamellar seta short, thin, smooth. Bothridium large, with wide opening directed anterolaterad, partly concealed under anterior margin of notogaster. Exobothridial seta short, as long as in, smooth. Sensillus with short stalk and long fusiform head, distal end of which setiform, long. Tutorium wide at base, with long cusp sharply pointed distally, almost reaching alveolus of rostral seta ( Fig. 4 A & G).

Notogaster. Oval, longer than wide, anterior margin almost straight, slightly rounded; humeral process not sharply projected, but rounded distally in both dorsal and lateral views ( Fig. 4 A & G). Ten pairs of notogastral setae short, thin, smooth, all setae equal in length. Lyrifissures im, ih, ips, ip and opisthonotal gland opening well developed; lyrifissure ia not evident.

Gnathosoma . Subcapitular mentum nearly as long as wide, with minute microtubercles. Hypostomal setae a, m and h medium long, thin, smooth ( Fig. 4 F). Chelicera typical for genus as shown in the previous species, with few slightly sclerotized blunt teeth; seta cha barbed, about 1.5 times as long as smooth chb; Trägårdh’s organ well developed, large. Palp typical for genus as in the previous species, palpal setation: 0-2-1-3-8, including solenidion ω of tarsus.

Epimeral region. Apodemes apo.2, apo. sj and apo.3 well developed, slightly obliquely or nearly transversely oriented. Epimeral setae short, smooth; setal formula: 3-1-3-3. Discidium well developed, projecting distally; circumpedal carina well developed, its anterior tectum reaching level of pedotectum II ( Fig. 4 F).

Ano-genital region. Anal and genital apertures medium in size, situated far from each other. Genital aperture nearly rounded, genital plates with four pairs of short, smooth setae ( Fig. 4 E). Aggenital seta as long as genital setae, thin, smooth. Anal aperture widened posteriorly, slightly longer than wide; anal and adanal setae short, equal in size. Adanal lyrifissure well developed, situated adjacent to anterolateral corner of anal plate ( Fig. 4 F).

Legs. Tarsi heterotridactylous, median claw conspicuously thicker than lateral claws. Trochanter and femora of all legs with large porose areas. Setation of legs as in the former species. Most of tarsal and tibial setae barbed, but those of genua, femora and trochanters mostly smooth. Formula of leg setation (including famulus): I (1-5-3-4-18), II (1-5-2-4-15), III (1-3-1-3-15); IV (1-3-2-3-12); formula of solenidia: I (1-2-2); II (1-1-2); III (1-1-0); IV (0-1-0).

Material examined. Holotype (female): Mts. Mongol Altai, close to Lake Dayan, District Sagsai, Province Bayan-Ulgii, foliose or subfruticose lichens growing on bare rocks ( Xantoria candelaria , Melanelixia exasperatula , Parmelia sulcata ), N48o15’, E88o54’, elevation 2337 m a.s.l., 16 July 2010, Coll. B. Bayartogtokh; one paratype (female): same data as holotype. The holotype and a paratype are deposited in the collection of the Department of Zoology, National University of Mongolia, Ulaanbaatar, Mongolia. All type specimens are preserved in alcohol.

Remarks. Cultroribula rarisetosa sp. nov. is clearly distinguishable from other species of Cultroribula by the combination of following characters: absence of inner tooth of lamellar cusp, presence of only four pairs of genital setae and dentation of rostrum. Among the known species of Cultroribula , only four Palaearctic species, C. lata Aoki, 1961 , C. angulata Aoki, 1984 , C. elongata Fujikawa, 1972 and C. neonominata Subías, 2004 are being with four pairs of genital setae. However, none of these species show outer teeth of lamellar cusps, and moreover they differ in the structure of rostral dentation and sensilli.

In the description of a Siberian species, C. ligulata, Grishina (1980) illustrated four pairs of genital setae, but she did not mention about this structure in the description. Judging the figure 4 of her work, it is obvious that she overlooked the genital seta g1, which is always at the anterior edge of genital plate. Moreover, C. ligulata have different structures of rostrum (with only three large teeth deeply incised in-between), lamella with smoothly rounded narrow cusp, sensillus with rough barbs throughout its head, and very short interlamellar and notogastral setae, in which its clearly differs from C. rarisetosa sp. nov.

Figures

FIGURE 4. Cultroribula rarisetosa sp. nov. (A) Dorsal view of idiosoma; (B) Variation of rostrum, dorso-frontal view; (C) Rostrum, ventral view; (D) Cusp of lamella; (E) Lateral view of prodorsum and anterior part of notogaster; (F) Ventral view of idiosoma. B – E to same scale.