Metabelba (Pateribelba) romandiolae ( Sellnick, 1943 )

Miko, Jan Mourek Ladislav & Bernini, Fabio, 2011, Taxonomy of European Damaeidae (Acari: Oribatida) IV. Partial revision of Metabelba Grandjean, 1936 with proposal of one new subgenus, one new species and redescriptions of two known species, Zootaxa 3099, pp. 1-42 : 18-27

Metabelba (Pateribelba) romandiolae ( Sellnick, 1943)

Synonymy. Damaeus romandiolae Sellnick, 1943 . Metabelba gladiator Mihelčič, 1963 . Metabelba romandiolae: Bernini (1982) ; Bernini et al. (1987); Bernini et al. (1996)

Diagnosis. Propodolateral apophysis P absent. Single pair of anterior centrodorsal tubercles (Da) present on prodorsum posteromedial from insertions of interlamellar setae; posterior centrodorsal (Dp), postbothridial (Ba, Bp) and lateral (La) tubercles absent. Parastigmatic apophyses (Sa, Sp) slender, spiniform, with convergent tips. Sensillus (ss) very long, thin, flagellate, with minute barbs in middle part, basal part and flagellate tip smooth. Interlamellar seta (in) longer than ½ sensillus length, thin, attenuate, covered with minute barbs. Notogastral setae of the series c1-h3 always longer than the mutual distance between the insertions of the two respective setae in pair; strong, erect, directed in radial pattern; darkly pigmented with hyaline bases and faintly serrate tips. Leg setae, except on distal parts of tarsi, of unique shape: broadly flattened basally with long attenuate tip, sparsely covered with minute spines. Discidium spiniform, curved posterolaterad, well developed. Cerotegument with long filamentous excrescences.

Type material examined. Collection of Pietro Zangheri, Museo Civico di Storia Naturale, Verona: slide n. 17897 (box 42) containing two specimens, labelled as “ Oribata Romandiolae Selln. n. sp. ”. The localization is “Poggio Orticai terr.[iccio di] faggete, 5.V.1929, racc. Zangheri, det. Sellnick”. The two specimens are prepared by Zangheri and embedded “in Faure Andrè, Nov. 1946 ” as registered on a separate label on the slide. These specimens were apparently used in the original description of the species by Sellnick (1943) and therefore are to be considered as syntypes according to article 72.4.1 of ICZN (International Commission on Zoological Nomenclature, 1999). The dorsally placed specimen, even if crushed ( Fig. 11 A), is complete and Bernini (1982) has stated it as the neotype. The second specimen in the slide is ventrally placed, but completely embedded in cerotegument and in a dirty medium and was utilized only for measurements. According to article 74.1 of ICZN (op. cit.) we designate the first, dorsally placed, specimen as the lectotype, and the second, ventrally placed one as the paralectotype. Presumably, the other two specimens of the type series mentioned by Sellnick (1943) in original description were destroyed by the fire of the Sellnick’s house in Königsberg (now Kaliningrad, Russia) during the World War II ( Bernini, 1982; H. Dastych, 2009—pers. comm.). The Sellnick’s collection in the Zoologisches Institut und Zoologisches Museum Universität Hamburg contains only the material collected after 1950.

Collection of Franz Mihelčič, Tiroler Landesmuseum Ferdinandeum, Innsbruck: Slide MIH 1-42 labelled as " Metabalba gladiator n. sp. Mih. Type “. The locality is hardly legible; according to Totschnig (2001) it is “St. Veit, Jauntal, Kärnten, A, Boden, Moos, trocken Juli 1962.” The specimen is crushed (see Fig. 9 ), but complete. It is embedded probably in a medium based on gum arabic and mounted between two cover slides, which are attached to a piece of pasteboard with central hole. The remaining three specimens mentioned in the original description ( Mihelčič, 1963) were not found in the collection.

Further material examined. Collection of Fabio Bernini, Department of Evolutionary Biology, Siena: six specimens (two of which given to the Collection of J. Mourek, Dept. of Zoology, Faculty of Science, Charles University Prague, Czech Republic) labelled as Metabelba romandiolae and collected by Prof. R. Dallai in the forest of Picea abies near the village of S. Benedetto in Alpe, about 900 m a.s.l., 10 km from the type locality, Poggio Orticai, Tosco-Emiliano Apennine.

Collection of Carl Wilmann, Zoologische Staatssammlung München: slide labelled as " Belba setiger Kulcz. / Abs. Det C. Willmann", 1 specimen (sex unknown), locality and date of collection not given.

Redescription (adult). Figs. 9–16 . Dimensions. The crushed lectotype from Zangheri’s collection ( Fig 11 AB) could not be measured accurately, thus we have measured the second specimen present in the same slide placed ventrally: total length about 640 μm and notogastral width 420 μm. Similarily the type specimen of Metabelba gladiator from Mihelčič’s collection ( Figs. 10 B, 12–16) is crushed, ventral length approximately 585 μm. Specimen from Willmann’s collection labelled as " Belba setiger " ( Fig. 11 CDE): ventral length measured in dorsal view 584 μm, maximum notogastral width 408 μm. In the original description of M. gladiator by Mihelčič (1963) the body length ranged from 680 to 720 μm (mean calculated by us 708 μm) and the maximum notogastral width 410– 430 μm (mean calculated by us 421 μm); n = 4. Ventral length of specimens of M. romandiolae from S. Benedetto in Alpe was 568–576 (572) μm, maximum notogastral width 408–440 (424) μm; n = 2. Detailed measurements of legs in Table 1.

Integument. Body colour medium brown. Cerotegument with long "wool-like" filamentous excrescences ( Fig. 11 E, 16AB); excrescences shorter on legs, longer in sejugal area, on epimeres and around notogastral setae. Underlying cuticle mostly smooth, but faintly granular on apophyses. Gastronotic exuviae (scalps) not present in the studied specimens and not noted in original descriptions ( Sellnick, 1943; Mihelčič, 1963).

Prodorsum. Figs. 9 A, 12A. Prodorsum of roughly triangular shape. Anterior centrodorsal tubercle (Da) present, posterior centrodorsal tubercle (Dp) absent, but cuticle slightly thickened in normal position of Dp; postbothridial (Ba, Bp) and lateral (La) tubercles absent. Parastigmatic apophyses (Sa, Sp) slender, spiniform, with convergent tips. Rostral (ro) and lamellar (le) setae thin long, of approximately equal length, strongly curved inwards. Seta ro thin, almost hyaline, with few minute barbs on outer curvature. Seta le thicker and darker than ro, with dense short barbs on outer curvature. Interlamellar seta (in) arising on minute apophysis, comparatively long, slightly longer than half of sensillus length, dark, densely covered with short barbs, flagellate. Exobothridial seta (ex) comparatively long, thin, covered with short barbs on outer curvature ( Fig. 10 A, 12B). Sensillus (ss) long, thin, flagellate; covered with short barbs in middle 1/3, basal part and flagellate tip smooth. Bothridial funnel of regular shape, normal for family.

Notogaster. Figs. 9 A, 10AB. Notogaster of roughly circular outline in dorsal view. Notogastral setae of series c1-c2, la -lp and h1-h3 longer than mutual distances within respective setal pairs, strong, erect, directed in radial pattern. Setae darkly pigmented with hyaline bases and faintly serrate tips, the "teeth" directed backwards ( Fig. 10 B). Seta c1 shorter than c2-h3. Setae ps1-ps3 comparatively long, thin, with row of short barbs on outer curvature, ps1> ps2> ps3, seta ps1 very long with attenuate fragile tip ( Fig. 10 AB), projecting distinctly more posteriad than seta h1.

Gnathosoma . Fig 9 B, 13A. Subcapitulum normal for family: diarthric, with three pairs of thin and comparatively long setae (m> h> a) and two pairs of setiform processes (or1,2). Setae m, h, a covered with few minute barbs on outer curvature. Setation of chelicera not discernible, setal formula of pedipalp (from trochanter to tarsus, solenidion in parenthesis): 0-2-1-3-9(1).

Epimeral region. Fig. 9 B, 13A. Medial pit cp on coxisternum I not developed Propodoventral (E2a, E2p) and ventrosejugal (Va, Vp) enantiophyses absent. Apodeme I well developed in lateral parts and weakly defined in medial part, apodemes 2 confluent, ventrosejugal furrow complete. Epimeral setal formula (I to IV): 3-1-3-4, normal for Metabelba , rarely 3-1-4-4 ( Fig. 9 B). Epimeral setae comparatively long, smooth or with several minute indistinct barbs. All epimeral setae at least slightly flattened and broadened with long attenuate tips, similar to leg setae; broadening especially well developed in setae 3a,b,c and 4b,c,d ( Fig. 13 B).

Anogenital region. Fig. 9 B, 13A. Discidium (di) spiniform, well developed, curved posterolaterad. Setal formulas of anogenital region normal for the Damaeidae ( Grandjean 1960; Norton 1977b), identical as in M. denscanis n.sp., see above. All anogenital setae slightly flattened and broadened. Lyrifissure iad oblique, divergent posteriad.

Legs. Figs. 14 , 15 . Legs monodactyl, moderately long, segments distinctly swollen in distal part (moniliform). Leg IV distinctly longer than body, leg I and III approximately as long as body, leg II slightly shorter than body (detailed measurements of leg segments in Table 1). Leg setae, except those on distal parts of tarsi, of unique conspicuous shape: broadly flattened in basal part, with long attenuate tip, sparsely covered with minute spines on outer surface. Leg setal formula identical with those of Metabelba pulverosa Strenzke, 1953 (see Norton 1977a), and M. denscanis n. sp. (see above). Solenidia ω 1,2 on tarsus I, φ 1 on tibia I, ω 1,2 on tarsus II and φ on tibia IV long, tactile; φ 1 on tibia I about 3x longer than φ 2; φ on tibia IV more than 2x longer than tibia itself. Solenidia of tibiae II and III and genua I, II and III of approximately same length as their respective setae d.

The two specimens from Zangheri’ collection present variations in the leg setation: in lectotype femur I with 9 setae on the right and 10 on the left; genua II with 4 on the right and 5 on the left; tibia III with 5 setae in the lectotype and 4 in paralectotype.

Geographical distribution and ecology. M. romandiolae was collected originally by Pietro Zangheri ( Zangheri 1966, as Damaeus r.), a well-known naturalist from Romagna ( Ruffo 1987), on Poggio Orticai (about 1000 m, Tosco-Emiliano Apennine, at present in the territory of the Italian National Park of Foreste Casentinesi) in humus of Fagus sylvatica , and later determined and described by Max Sellnick (Sellnick 1943).

Twenty years later, Mihelčič (1963) collected and described this species as M. gladiator . We found no published record of Metabelba gladiator besides the type locality, Sankt Veit im Jauntal in Kärnten, South Austria ( Mihelčič 1963), a village located at approximately 540–560 m a.s.l. Mihelčič (1963) found the specimens in open landscape and forest margins, all dry stands.

The specimen from Willmann’s collection may relate to the record of one individual of " Belba setiger (Kulcz.) " from Moravian Karst (Moravia, Czech Republic), published by Willmann (1954). It was collected by Prof. Karel Absolon in 1900 from moss in the cave of Michalova jeskynĕ (about 440–450 m a. s. l.).

M. romandiolae was collected in further Italian localities: Farma valley (2–300 m a.s.l.), near Siena (southern Tuscany) and Altopiano del Cansiglio (Mt. Pizzoc, 1200 m a.s.l., Treviso, Venetian Pre-Alps) ( Bernini, 1982), Pollino Massif (Southern Italy, Calabria) ( Bernini et al., 1987) and Nebrodi Mountains (north-eastern Sicily) ( Bernini et al., 1996).

This species occurs mainly in the Italian peninsula reaching in the south to Sicily Island, but large populations are found very rarely. Despite these southern localizations, M. romandiolae is considered to be a mesophilous species generally inhabiting montane sites all characterized by humus of Fagus sylvatica , and by elevations over the thousand meters. The unique exception is the Farma Valley, a site located at 2–300 m a.s.l., but retained as a “mesic oasis”, almost an “island”, colonized during the past glaciations by montane elements ( Bernini et al. 1995). The putative record of this species from a cave in Moravian Karst presented above ( Willmann 1954), might represent another glacial relict.

Remarks. M. romandiolae can be easily recognized by the unique shape of its leg setae. Moreover, the tips of the notogastral setae are finely serrated with minute backward teeth.

The original description of M. romandiolae ( Sellnick, 1943) is insufficient and was not illustrated; Bernini (1982) designated the neotype (now designated as the lectotype by us) of this species on the specimens returned by Sellnick to Pietro Zangheri and belonging to the type series of Sellnick (1943), but did not make a redescription.

The original description of M. gladiator by Mihelčič (1963) is comparatively detailed and sufficiently illustrated, but some important characters were described incorrectly, as we revealed with detailed study of the type specimen. Namely, he described and illustrated the species with two pairs of centrodorsal tubercles (Da, Dp), but in fact only Da is present. He presented the following incorrect leg setal formulas (solenidia and famulus were not distinguished from normal setae): leg I (from femur to tarsus) 7-3-6-18; leg II (from femur to tarsus) 7-3-5-16; leg III (trochanter to tarsus) 3-6-4-5-11; leg IV (trochanter to tarsus) 3-6-3-5-11. The generally lower numbers on particular segments might raise doubts about the generic placement of M. gladiator , but in fact the leg setation of the type specimen is normal for Metabelba (see above and Figs. 14 , 15 ). Parastigmatic apophyses (Sa, Sp) are neither illustrated nor described in the text. Mihelčič also did not describe the filamentous cerotegument and only stated that the body surface is smooth or “covered by debris” ("Schmutz" in German original).

Subías (2004, 2008, 2009) was the first author who listed M. gladiator as a junior synonym of Metabelba romandiolae ( Sellnick 1943) . He provided no reasons or reference to previous works, but kindly informed us (L. Subías pers. comm., 2010) that his assumption was based on Bernini et al. (1987), who hypothesized that the species might be identical.

In the present paper we analyzed the type material of both names and provided a modern redescription. We consider the synonymy of M. gladiator ( Mihelčič, 1963) with respect to M. romandiolae ( Sellnick, 1943) conclusive.

Figures

FIGURE 9. Metabelba romandiolae — specimen from S. Benedetto in Alpe. A—dorsal view, arrows point to light spots; Bventral view. Legs only partly drawn, leg setae and cerotegument not drawn.

FIGURE 10. Metabelba romandiolae. A—specimen from S. Benedetto in Alpe, partial lateral view; B) specimen from collection of F. Mihelčič labelled as " type of Metabelba gladiator " (junior synonym) — details of some notogastral setae. Cerotegument not drawn.

FIGURE 11. Metabelba romandiolae. — lectotype, coll. of P. Zangheri, drawn by F. Bernini (A, B); specimen from coll. of C. Willmann, labelled as " Belba setiger ", drawn by L. Miko (C, D, E). A—dorsolateral view; B—tibia, genu and distal part of femur IV; C—trochanter and femur III; D—trochanter IV; E—dorsal view. Cerotegument not drawn in A, B and partly drawn in C, D, E.

FIGURE 13. Metabelba romandiolae — specimen from collection of F. Mihelčič labelled as " type of Metabelba gladiator " (junior synonym). A) ventral view in total. Legs only partly drawn, cerotegument and setae of legs and pedipalps not drawn; B) detail of epimeral seta 4 c.

FIGURE 14. Metabelba romandiolae — specimen from collection of F. Mihelčič labelled as " type of Metabelba gladiator " (junior synonym) — leg I and II. A) left trochanter and femur I, antiaxial view; B) left genu, tibia and tarsus I, antiaxial view; C) left femur II, paraxial and slightly ventral view; D) left genu and tibia II, paraxial view; E) left tarsus II, paraxial view.

FIGURE 15. Metabelba romandiolae — specimen from collection of F. Mihelčič labelled as " type of Metabelba gladiator " (junior synonym) — leg III and IV. A) right genu, tibia and tarsus I, antiaxial view; B) left trochanter and femur III, antiaxial and slightly ventral view; C) left genu, tibia and tarsus IV, antiaxial and slightly ventral view; D) left trochanter and femur IV, antiaxial and slightly ventral view.