Cultroribula taigagica, Bayartogtokh, Badamdorj, 2007

Bayartogtokh, Badamdorj, 2007, Oribatid mites of the family Astegistidae (Acari: Oribatida) in Mongolia, Zootaxa 1472, pp. 55-68 : 59-62

Cultroribula taigagica sp. nov.

( Figs. 2 & 3 )

Diagnosis. Relatively small species; body yellowish to yellowish-brown in color, covered with thin cerotegument; rostrum with 17–19 teeth, among them three central teeth much larger than lateral teeth; lamellae wide, fused medially; lamellar cusps long and wide, with large lateral teeth, small median teeth present or absent; rostral, lamellar and interlamellar setae moderately long, with conspicuous barbs (length of ro: 31–36 Μm; le: 50–56 Μm; in: 64–72 Μm); sensilli medium in length, with fusiform head, distal end of which with a few minute barbs; tutoria relatively short and narrow, distally pointed; ten pairs of short notogastral setae; six pairs of genital setae.

Measurements. Body length: 318–336 (328) Μm; width of notogaster 201–214 (208) Μm. In total 16 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. Body yellowish to yellowish-brown in color.

Prodorsum. Rostrum with 17–19 teeth, among them three central teeth much larger than lateral teeth; size of rostral teeth becoming smaller toward posterior direction. Rostral setae (ro) moderately long, with sparse barbs. Lamellae wide, fused medially; lamellar cusps nearly as long and wide as basal part of lamellae, with large lateral teeth; small median teeth rarely present. Lamellar (le) and interlamellar (in) setae conspicuously longer than ro, with distinct barbs. Bothridia (bo) relatively large, directed anterolaterad, partly concealed under anterior margin of notogaster. Exobothridial setae (ex) short, thin, smooth. Sensilli (ss) medium in length, with fusiform head, distal end of which with a few minute barbs. Tutoria (tu) relatively short and narrow, not reaching the insertions of rostral setae, its distal tip pointed ( Fig. 2 A, C, D, E & F).

Notogaster. Oval, longer than wide, dorsosejugal suture almost straight; humeral projections well developed. Ten pairs of short, thin, smooth notogastral setae; p2 and p3 shorter than other notogastral setae. Lyrifissures im, ih, ips, ip and opisthosomal gland opening (gla) small in size; lyrifissure ia not evident ( Fig. 2 A).

Gnathosoma . Infracapitular mentum nearly as long as wide, without noticeable microtubercles. Hypostomal setae a, m and h medium long, thin, smooth ( Fig. 2 B). Chelicerae narrow, elongate, with a few small teeth.

Epimeral region. Apodemes apo.2, apo. sj, apo.3 and apo.4 well developed, nearly transversely oriented. Epimeral setae medium long, smooth; setal formula: 3-1-3-3. Discidium well developed, projected distally; circumpedal carina well developed ( Fig. 2 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 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 equal in size. Adanal lyrifissure (iad) well developed ( Fig. 2 B).

Legs. Tarsi heterotridactylous, median claw conspicuously thicker than lateral claws. Femora of all legs with large porose areas; porose area of trochanter IV indistinct. Setae a ’ and a” of legs I and IV strong, with thick barbs. 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 (1-2-1-3-12); 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 figure 3.

Material examined. Holotype (male): Khonin Nuga area, District Mandal, Province Selenge, litter and soil of cool temperate larch forest in taiga zone, 49o20’N, 107o40’E, elevation 1720m. a.s.l., 23 May 2002; 17 paratypes (ten females and seven males): same data as holotype; one paratype (male): Basin river Minj Gol, District Batshireet, Province Khentii, litter of cool temperate pine forest in taiga zone, 49o12’N, 108o30’E, elevation 1050m a.s.l., 27 July 2002, Col. B. Bayartogtokh. The holotype and 11 paratypes are deposited (alcohol preserved) in the collection of the Department of Zoology, National University of Mongolia, Ulaanbaatar; three paratypes in the collection of the Zoological Museum, Moscow State University, Moscow, and three paratypes in the collection of the Zoological Museum, Institute of Systematics and Ecology of Animals, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.

Ecology. The present new species is a typical inhabitant of the coniferous forests in the temperate taiga zone, and mostly prefer the humid habitat.

Distribution. Known only from the type localities.

Remarks. The species, Cultroribula taigagica sp. nov. is easily distinguished from other species of the genus Cultroribula by the number and shape of the teeth on the rostrum; the large lateral teeth of the lamellar cusps; the well-developed humeral projection of the notogaster; and the long, barbed interlamellar setae.

Among the known species of Cultroribula , the Holarctic species, C. dentata , described by Willmann (1950) is somewhat similar by having well-developed lateral teeth of lamellar cusps. However, C. dentata differs from C. taigagica sp. nov. in the relatively short and smooth interlamellar setae (setae in are reaching the tip of rostrum and conspisuously barbed in C. taigagica sp. nov.); presence of only five pairs of genital setae rather than six pairs in the new species; different form of rostral teeth, and the relatively short, but more strongly swollen head of sensilli.

Another species, C. vtorovi , described by Krivolutsly (1971) from Kirgisia is also similar with the new species by the shape of lamellar cusps and rostrum. The former species, however, can be differentiated from C. taigagica sp. nov. by the much shorter interlamellar setae; more strongly developed median teeth of lamellar cusps; fewer number of lateral teeth on the rostrum, and the presence of only five pairs of genital setae.

The most common species in the Holarctic region, C. bicultrata (Berlese, 1905) differs from the new species in the smoothly rounded tip of lamellar cusps; very short interlamellar setae; smooth rostral and lamellar setae; relatively long stalk, but shorter head of sensilli, and fewer number of teeth on the rostrum.

Etymology. The specific epithet “ taigagica ” refers to the name of habitat, where the type specimens are found.

Figures

FIGURE 2. Cultroribula taigagica sp. nov. A: Dorsal view; B: Ventral view; C: Lateral view of proterosoma; D: Sensillus and bothridium; E: Anterior part of prodorsum (flattened); F: Lamellae.

FIGURE 3. Cultroribula taigagica sp. nov. A: Leg I (right, antiaxial aspect); B: Femur, genu and tibia II (right, paraxial aspect); C: Femur, genu and tibia III (right, paraxial aspect); D: Leg IV (right, paraxial aspect).