Liebstadia similis (Michael)

Bayartogtokh, B., 2001, Oribatid mites of Liebstadia (Acari: Oribatida: Scheloribatidae) from Mongolia, with notes on taxonomy of the genus, Journal of Natural History 35 (8), pp. 1239-1260 : 1252-1255

Liebstadia similis (Michael)

(®gures 24±31) Notaspis similis Michael, 1888: 363 , pl. 31, ®gures 9±12. Liebstadia similis: Oudemans, 1906: 101 ; Willmann, 1931: 153, ®gure 219; Hammer, 1952: 43,

®gure 64; 1967: 50, ®gure 63; Schweizer, 1956: 308, ®gure 248; Haarlov, 1957: 39, ®gure 11; IGS 24, 25. Liebstadia similis (Michael, 1888) . (24) Dorsal aspect of typical form. (25) Ventral aspect of typical form.

IGS 26±28. Liebstadia similis (Michael, 1888) . (26) Dorsal aspect of non-typical form with narrow and long notogaster (female). (27) Ventral aspect of non-typical form with narrow and long notogaster (female). (28) Dorsal aspect of non-typical form with narrow and long notogaster (male).

Weigmann, 1969: 429, ®gures 16-17; Ayyildiz, 1988: 141, ®gure 9; Wunderle et al., 1990: 34, ®gures 17±20; PeÂrez-InÄigo, 1993: 214, ®gure 77a; Aoki, 1995: 191, ®gures 4, 5, 8; Miko and Weigmann, 1996: 90, ®gures 14±17.

Protoribates silesius Sellnick, 1925: 163 , ®gure J.

Protoribates serratomarginatus Mahunka, 1983: 391 , ®gures 28±33. syn. nov.

Liebstadia similis was ®rst described as Notaspis similis by Michael (1888) based material collected in Great Britain. The species has been recently redescribed by several authors and it is one of the well-known species of the genus Liebstadia . However, this species exhibits a wide range of morphological variability, mainly in the shape and size of the body, in the sensillus and in the length of the prodorsal and notogastral setae. The features of Mongolian material are mostly well in accord with those of European specimens, and some supplementary characters are given in the following redescription.

Diagnosis. Rather long and robust species. Lamellae rather wide, sublamella and prolamella well developed; interlamellar setae situated on the median margin of the lamellae; all prodorsal setae rather long, barbed, but variable in size; sensillus long, with a lanceolate head and a smooth, narrow stalk. Shape of notogaster variable; four pairs of areae porosae, oval; pteromorphae small, its outer margin undulated serrated.

Measurements. Body length 472±560 (503.1) m m; width of hysterosom a 268±336 303.9) m m; width of proterosoma 168±184 (178.9) m m; length of lamellae 74±78 75.9) m m; length of sensilli 53±64 (58.1) m m.

Integument. Yellowish brown to deep reddish brown in colour. Cerotegument thin, being present in very small granules. Lateral region of podosoma with small, but densely scattered granules. Integument ®nely punctate.

Prodorsum. Rostrum slightly protruding, Lamellae relatively wide, sublamellae 1254 IGS 29±31. Liebstadia similis (Michael, 1888) . (29) Lateral aspect. (30) Leg I, trochanter removed (left, antiaxial aspect). (31) Leg II, trochanter removed (right, antiaxial aspect).

and prolamellae well developed. Rostral, lamellar and interlamellar setae long, thin, weakly barbed bilaterally. Insertions of interlamellar setae situated on the median margin of the lamellae. Sensillus with a lanceolate or fusiform head ®nely barbed and a smooth stalk. Bothridium mostly concealed under anterior margin of the notogaster; posterolateral scale of bothridium well developed (®gures 24, 26, 28).

Notogaster. Shape of notogaster somewhat variable, rounded oval or elongate oval, about 1.1±1.5 times as long as wide. Surface of lateral and posterior margins notogaster with numerous muscle sigillae. Dorsosejugal suture extending well beyond the level of the bothridium, the median part poorly developed and hardly visible. Pteromorphae small, but conspicuously developed. Lateral margin of pteromorphae slightly undulated or serrated (®gures 24±28). Ten pairs of notogastral setae, medium in length, smooth. Four pairs of areae porosae with sclerotized borders. Area porosa Aa the largest and A smallest. Lyri®ssures ia, im, ip, ips well 3

developed; im situated anteromedial to area porosa A; ip laterad to seta h; ia and 2 1

ips visible only in lateral view; ih inconspicuous. Lateroabdominal gland opening gla situated posterolateral to im (®gures 24, 26, 28).

Lateral aspect. Relatively robust species in lateral view, dorso-ventral thickness postgenital transect 226±258 (237.8) m m. Exobothridial region and lateral part of podosoma ®nely granulated. Region between lamella and pedotecta I and II with a few muscle sigillae. In lateral aspect, lamella relatively wide, sublamella well developed, and prolamella reaching to the insertions of the rostral setae. Carina circumpedalis rather long, but not reaching to the lateral margin of the ventral plate. Lyri®ssures ih well developed, while ips inconspicuous (®gure 29).

Ventral aspect. Subcapitulum, palps and chelicerae normally developed for the genus, without notable diOEerences from other species. Apodemata apo.2, apo. sj and apo.3 well developed, rather long. Epimeral region with round muscle sigillae. Setal formula of epimerata: 3-1-3-3. Discidium well developed as a rounded blade, bearing seta 4c. Carina circumpedalis well developed, but sometimes not reaching to the lateral margin of the ventral plate (®gures 25, 27, 29). Four pairs of genital and one pair of aggenital setae, medium in length. One female specimen bears two pairs of aggenital setae (®gure 27), but this is considered an abnormal character. Distance between bases of aggenital setae almost equal or slightly shorter than that between setae ad -ad. Two pairs of anal and three pairs of adanal setae fairly long; seta ad 3 3 3 preanal position. Adanal lyri®ssures iad situated adjacent and parallel to each lateral margin of anal aperture (®gures 25, 27, 29).

Legs. All tarsi monodactylous, dorsal surface of claws with slight serration. The character of leg setation is typical of the genus, only legs I and II are shown in gures 30, 31. The formula of leg setation including famulus: I (1-5-3-4-1 8); II (1- -2-4-1 5); III (2-3-1-3-15); IV (1-2-2-3-1 2), and the formula of solenidia: I (1-2-2); (1-1-2); III (1-1-0); IV (0-1-0).

Material examined. Sixty-six specimens: Mt. Bogd Khan, Central Province, 6 km south of Ulaanbaatar, litter of larch forest ( Larix sibiricus ), 47ss55¾N, 106ss30¾E, March 1996; 14 specimens: Mt. Zaan Terelj, District Erdene, Central Province, litter of larch forest ( Larix sibiricus ), 47ss20¾N, 107ss40¾E, 18 September 1990; ®ve specimens: Mt. Bulgan, District Erdenebulgan, Arkhangai Province, litter of birch forest ( Betula plataphyll a), 48ss20¾N, 101ss25¾E, 18 May 1996, Leg. B. Bayartogtokh. Remarks. Among the Mongolian material of L. similis I have found a slightly diOEerent (non-typica l) form which is distinguished in some characters from its typical form. The diOEerences are the much narrower and more slender shape of the notogaster, the long interlamellar setae, the slightly narrow and long sensilli and the small body size. Both the male and female show the same range of morphological variabilin the shape of the notogaster and sensilli (®gures 26±28). Sensilli of most specimens were typically lanceolate (®gure 24), but relatively narrow and fusiform heads were observed in the sensilli of some specimens (®gures 26, 28). However, the diOEerences found are not considered to be signi®cant at the species level. Other characters of Mongolian specimens of L. similis were more constant.

Distribution. Nearctic region (Marshall et al., 1987; Behan-Pelletier, 1993, 1997); Indomalaysian region (Bhaduri and Raychaudhuri, 1981); Oceanian region ( Spain 1256 and Luxton, 1971; Luxton, 1985); Palaearctic region (Karppinen et al., 1986, 1987, 1992; SalonÄa Bordas and Iturrondobeitia Bilbao, 1990; Fujikawa et al., 1993; Krivolutsky, 1995; Niedbala and Olszanowski, 1997; Niemi et al., 1997), and see the synonymic list and`Material examined’ section.