Cultroribula altaica, 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 : 45-49

Cultroribula altaica sp. nov.

( Figs. 1–3 )

Diagnosis. Medium-sized species, covered with thin cerotegument; rostrum with 15–17 teeth, among them three central teeth much larger than lateral teeth; lamellae wide, fused medially; lamellar cusp long and wide, with large outer and inner teeth of subequal size; rostral and lamellar setae moderately long, with conspicuous barbs, interlamellar seta short, smooth; sensillus with short stalk and long fusiform head, its distal end setiform, long; tutorium wide at base, with long cusp sharply pointed distally; humeral process of notogaster sharply projected distally; ten pairs of notogastral setae short; six pairs of genital setae, legs tridactylous.

Measurements. Body length: 318–336 (328) μm; width of notogaster 201–214 (208) μm. In total 15 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 15–17 teeth, among them three central teeth much larger than lateral teeth; most central tooth slightly shorter than two lateral teeth; size of rostral teeth becoming smaller toward posterior direction ( Figs. 1 & 3 E). Rostral seta (ro) moderately long, with sparse barbs. Lamella wide, fused medially; lamellar cusp slightly longer, but narrower than basal part of lamella, with large outer and inner teeth of subequal size. Lamellar seta (le) long, about 1.5 times as long as ro, sparsely barbed; interlamellar seta (in) short, smooth. Bothridium (bo) large, with wide opening directed anterolaterad, partly concealed under anterior margin of notogaster. Exobothridial seta (ex) short, as long as in, smooth. Sensillus (ss) with short stalk and long fusiform head, its distal end setiform, long. Tutorium (tu) wide at base, with long cusp sharply pointed distally almost reaching alveolus of rostral seta ( Fig. 1 C).

Notogaster. Oval, longer than wide, anterior margin almost straight, slightly rounded; humeral process sharply projected distally in both dorsal and lateral views ( Fig. 1 A & C). Ten pairs of notogastral setae short, thin, smooth, all setae equal in length. Lyrifissures im, ih, ips, ip and opisthonotal gland opening (gla) small in size; lyrifissure ia not evident.

Gnathosoma . Subcapitular mentum nearly as long as wide, without noticeable microtubercles. Hypostomal setae a, m and h medium long, thin, smooth ( Fig. 1 B). Chelicera typical for genus as shown in figure 3B, slender with few slightly sclerotized blunt teeth; seta cha barbed, about 1.4 times as long as smooth chb; Trägårdh’s organ well developed, large. Palp typical for genus as shown in figure 3A, palpal setation: 0-2-1-3-9, including solenidion ω of tarsus.

Epimeral region. Apodemes apo.2, apo. sj and apo.3 well developed, 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. 1 B).

Ano-genital region. Anal and genital apertures medium in size, situated far from each other. Genital aperture nearly rounded, genital plates with six pairs of short, smooth setae; aggenital seta (ag) 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 (iad) well developed, situated adjacent to anterolateral corner of anal plate ( Fig. 1 B).

Legs. Tarsi heterotridactylous, median claw conspicuously thicker than lateral claws. Trochanter and femora of all legs with large porose areas. 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 (1-5-2-4-16), 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). Setation of legs as shown in figures 2 and 3D.

Material examined. Holotype (female): Mts. Mongol Altai, close to Lake Dayan, District Sagsai, Province Bayan-Ulgii, litter of cool temperate larch forest interior ( Larix sibiricus Ledebour, 1833 ), N48o14’, E88o57’, elevation 2375 m a.s.l., 10 July 2010, Coll. B. Bayartogtokh; fourteen paratypes (eight females and six males): same data as holotype. The holotype and ten paratypes are deposited in the collection of the Department of Zoology, National University of Mongolia, Ulaanbaatar, Mongolia, and four paratypes are in the collection of the Senckenberg Museum of Natural History, Görlitz, Germany. All type specimens are preserved in alcohol.

Remarks. Cultroribula altaica sp. nov. is easily distinguishable from other species of Cultroribula by the combination of following characters: sensillus with very long setiform tip, dentation of rostrum and sharply projected humeral process of notogaster. Among the known species of Cultroribula , only two Palaearctic species, namely C. neonominata Subías, 2004 and C. variolosa Fujikawa, 1991 resemble the present new species in the fusiform sensilli with pointed distal tip. However, both mentioned species are easily distinguishable from the new species in the short distal tip of sensilli as opposed to very long setiform distal tip of sensilli in Cultroribula altaica sp. nov. Moreover, they differ by the smoothly rounded tip of lamellar cusps in contrast to cusps with large outer and inner teeth in the new species, 11 pairs of very marginally placed notogastral setae as opposed to normally situated 10 pairs of setae in the new species, and different structure of rostrum. Both C. neonominata and C. variolosa are only known from Japan ( Aoki 1965; Fujikawa 1991).

Figures

FIGURE 1. Cultroribula altaica sp. nov. (A) Dorsal view of idiosoma; (B) Ventral view of idiosoma; (C) Lateral view of prodorsum and anterior part of notogaster. A and B to same scale.

FIGURE 2. Cultroribula altaica sp. nov. (A) Leg I, right, paraxial view; (B) Leg II, right, paraxial view; (F) Leg III, left, antiaxial view. All to same scale.

FIGURE 3. Cultroribula altaica sp. nov. (A) Palp, left, antiaxial view; (B) Chelicera, left, antiaxial view; (C) Subcapitulum; (D) Leg IV, left, antiaxial view; (E) Rostrum in lateral view. B – E to same scale.