Gymnodamaeus barbarossa

Weigmann, G. & Mourek, J., 2008, Contribution to the Central European Gymnodamaeus species G. barbarossa and G. bicostatus (Acari, Oribatida, Gymnodamaeidae, Zoosystematics and Evolution 84, pp. 255-264 : 255-260

Redescription of Gymnodamaeus barbarossa Weigmann, 2006

Figures 1-4, 6a-c,e, 7a

Diagnosis. With typical characters of Gymnodamaeus s. str.: Articulation of all leg segments without collars ("crispins ”); lamellar setae anterolaterally from large globular elevations and inserting on minute apophyses; interlamellar setae minute, on interlamellar costulae anterior to interbothridial region; notogaster flat; five pairs of notogastral setae at the posterior edge of notogaster; seven pairs of genital setae in one row each; two pairs of anal setae, two pairs of adanal setae. Specific characters: body length 460-540 µm; posterior submarginal notogastral setae h1 and h2 thin, covered with cerotegument, about 25 – 40 µm in length; posterior notogastral setae p1 – p3 on the ventral border of notogaster, about 10 – 12 µm in length; notogaster at the posterior edge with characteristic double-indentation; sensilli moderately stalked, head flattened-claviform with spines; interlamellar setae very small and stout, not on projecting apophyses.

General characters. Body length 460 – 540 µm, width of notogaster 250 – 300 µm; colour yellow-brown to brown. Body, legs and most setae covered with a coarsely granulated cerotegument layer, as can be observed in light-microscope. Additionally, at the midline of the notogaster a more or less opaque cerotegument mass in fresh specimens, forming specific ornamentation (see section Notogaster and figures 1a, 2a, b). The opaque cerotegument ornamentation may be partly (fig. 6a) or totally abraded, especially in old preserved material. The normal cerotegument layer consisting of a thin base layer with a mesh net of about 1 µm mesh width; mesh net formed by rows of micro-granula, hardly visible in light microscope, but well visible in SEM micrographs (fig. 6b); cuticula with corresponding mesh net pattern below the micro-granula pattern visible at areas with abraded cerotegument. The large cerotegument granula of about 1 – 2 µm in diameter with roundish-pointed form like a Morchella mushroom and covered with a dense mesh-net pattern formed by micro-granula (granula on prodorsum: see figure 6b; on leg 1: see figure 7a).

Prodorsum. Rostrum roundish, with moderately long rostral setae (about 40 µm in length), covered with cerotegument granula; lamellar setae of the same shape inserted anterolaterally at base of two large lateral globular elevations; a smaller median elevation present anterior of the interbothridial region of the prodorsum (fig. 2a, b). Exobothridial setae of moderate length inserted anteriolaterally from the bothridia; interlamellar setae minute, inserted anterior of the interbothridial region at the end of indistinct interlamellar costulae (visible in light microscope view; figure 1a). Large auricular pedotecta I and II. Sensilli with short stalks, head flat, longish-claviform with spines, about 80 – 100 µm in length (figs 1a, 2c).

Notogaster. Flat with more or less sharp edges, centrodorsal part slightly elevated. With a specific cerotegument-mass ornamentation in shape of a slender Y; anterior near the notogaster border with another semicircular cerotegument-mass ornamentation. Cuticle in central part of the notogaster rugged transversally (visible only after the removal of cerotegument). Posterior border of notogaster with a characteristic double-indentation (figs 1 a–b; 2d). Three pairs of lyrifissures, ia, im, ip. Five pairs of notogastral setae; h1 and h2 mostly covered with cerotegument granula, length about 25 – 40 µm, h1 directed posteriad, h2 laterad; p1 – p3 at the posterior notogaster margin, visible only from ventral aspect (fig. 1b), length about 10 – 12 µm.

Ventral side. Without obvious specific characters (fig. 1b). Anal and genital plate near to each other; two pairs of small anal setae; two pairs of adanal setae; one pair of short aggenital setae, seven genital setae on each plate in one longitudinal row. Epimeral setation formula 3-1-3-3.

Legs. Typical for the family, tridactylous, anterior apophyses of tibia I very large, bearing two solenidia. Legs moderately long, shorter than body (see Table 1 for details; figs 3, 4). Leg IV> leg I> leg III> leg II. In all legs femur> tarsus> tibia> genu. Femora with distinct widening ( “bulb”) in proximal part (maximal width in approximately 1/3 of their length). Setal formula of legs as follows (from trochanter to tarsus, famulus included, solenidia in parentheses, claws not included): I: 1-5-4(1)-5(2)-20(2); II: 1-4-4(1)-5(1)-16(2); III: 2-3-3(1)-4(1)-15; IV: 1-2-3-4(1)-12. Famulus epsilon on tarsus I minute, fully sunken in sclerotised cup (setal part invisible externally), hardly visible in light microscope. Leg setae comparatively long, thin, needle-like. Ventral seta on tibiae III and IV and most tarsal setae of all legs (except for prorals, iterals, tectals and fastigials) with short barbs on ventral side, the remaining leg setae smooth. Solenidion phi1 on tibia1 long, flagellate, tactile, with a thin short companion seta d inserted in common alveolus (often tightly clamped to the dorsal side of the solenidion, therefore hardly visible in light microscope); phi2 much thinner than phi1, piliform, free, length about 0.4 of phi1. All remaining solenidia on tarsi, tibiae and genua short, baculiform to ceratiform (terminology of shapes of solenidia after Grandjean, 1935, 1940, as adopted by Norton 1977). Solenidia on tibiae II-IV and genua I-IV inserted in separate alveoli, not in a common alveolus with the respective seta d.

Material examined

Germany

(1) Type material deposited in the collection of M. Moritz in the Museum für Naturkunde in Berlin, labelled as “ Allodamaeus pusillus ” from the Kyffhaeuser Mountain in Eastern Germany, near Bad Frankenhausen (51°21'N, 11°06'E); Collection Nr. 171/ B38 (the type specimen and 20 paratype specimens in alcohol), collected 29.9.1963; further specimens in 171/B41, B127, B159.

Czech Republic (listed chronologically)

(2) North Bohemia, Ceske stredohori Mts., northwest from Lovosice, Lovos Mt. (50°32' N, 14° 1' E), altitude 400 m, rocky steppe on basalt, tussocks of Festuca sp. and Sempervivum sp., 30.04.1959, M. Kunst leg. (5 specimens in alcohol); collection of Miroslav Kunst (Dept. of Zoology, Faculty of Science, Charles University Prague), labelled as “ Gymnodamaeus sensillatus ”.

(3) Vrsícek (without any specification of region), 22.04.1971 (2 specimens in alcohol); coll. M. Kunst, labelled as “ Gymnodamaeus pusillus ”.

(4) North Bohemia, Ceske stredohori Mts., northwest from Lovosice, Lovos Mt. (50°32'N, 14°1'E), altitude about 560 m, rocky steppe on basalt, south west slope, near the top of the mountain, tussocks of Sempervivum on rocks with a thin layer of soil, 18.03.2001, J. Mourek leg. (1 specimen); coll. J. Mourek (Dept. of Zoology, Faculty of Science, Charles University Prague).

(5) Southeast Moravia, northeast from the Pouzdrany village, Pouzdranska step National Reserve (48°57' N, 16°39' E), altitude about 390 m, warm grassland with groups of Staphylea pinnata , Prunus domestica , Acer campestre and Quercus pubescens on loess soil, top of the hill and eastern slope, 17.11.2000 F. St'áhlavský leg., (1 specimen in alcohol) ; 16.09.2006 J. Mourek leg., (14 specimens in alcohol) ; 14.05.2007 J. Mourek leg., (15 specimens in alcohol) ; all in coll. J. Mourek. Further voucher specimens from the same locality , 16.09.2006 J. Mourek leg., were deposited in coll. G. Weigmann, Berlin (10 specimens in alcohol) and in the Acarological Collections of Staatliches Museum für Naturkunde Görlitz, Germany (5 specimens in alcohol).

Slovakia

(6) South Slovakia, Stiavnicke rudohori , Zemberovce , (48°15'N, 18°44' E), altitude 450 m, Quercetum, dry litter and humus layer, 12.06.1962 M. Kunst leg. (5 specimens in alcohol); coll. M. Kunst, labelled as “ Gymnodamaeus sensillatus ”. Kunst (1968) refers to both records as “ Gymnodamaeus pussillus ” (see in remarks).

(7) Southeast Slovakia, Slovak Karst National Park, Silická planina Mts., 4 km Southeast of Ardovo village (48°31'N, 20°28'E), forest steppe (extensive pasture) on karstic soil with bushes of Cornus mas , Corylus avellana , Acer campestre , Juniperus communis and Carpinus betulus , dry leaf litter, 13.07.2004 J. Mourek leg. (7 specimens in alcohol, 2 specimens mounted for SEM study).

Austria

(10) Carinthia, Steinkogel, near Voelkermarkt , 46°41'N 14°38'E, knoll with arid meadow, haulm, grass litter moss. Numerous samples 17.06.2005 H. Perlinger and H. Schatz leg. (138 specimens); 08.10.2005 H. Perlinger leg. (38 specimens).

(11) Lower Austria, Hundsheimer Berge near Hundsheim, southern slope with oak forest ( Quercus pubescens ), 350 m a.s.l., in leaf litter, 04.06.2007 H. Schatz leg. (11 specimens).

Some specimens from Steinkogel have been compared by one author (GW), the other material has been checked by H. Schatz. The material from Austria was deposited in coll. H. Schatz (Institut für Zoologie und Limnologie, Universität Innsbruck, Austria) except some specimens from Steinkogel (coll. G. Weigmann, Berlin).

Distribution. Central Europe: Germany, Austria, Czech Republic, Slovakia.

Ecology. The species seems to prefer warm and dry litter layer; habitat of the type series and other collections from south slope of Kyffhäuser Mountain in Germany which is wooded ( Quercus and others), partly with grass; dry organic soil and litter.

Remarks. This species was found in the collection of M. Moritz in the Museum für Naturkunde in Berlin, labelled as “ Allodamaeus pusillus (Berlese, 1910) ”, collected in Eastern Germany. Further specimens of G. barbarossa , labelled as “ Gymnodamaeus pusillus ” and “ Gymnodamaeus sensillatus ”, collected in the Czech Republic and Slovakia (former Czechoslovakia), were found in the collection of M. Kunst (see Material examined). Kunst (1968) referred in his unpublished habilitation thesis to part of this material and wrote that he originally treated the form as a new species. Later he came to the conclusion, that it is most probably conspecific with G. pusillus , based on the comparison with the original description (Berlese, 1910).

Recently, Mahunka & Mahunka-Papp (1995) redescribed Berlese’s species as Arthrodamaeus pusillus basing on specimens of the type series from Italy. Subías (2004) placed this species into the genus Adrodamaeus Paschoal, 1984, which seems to be questionable until a revision with fresh material. Without doubt, G. barbarossa is not conspecific. Main differences of A. pusillus are as characteristic for Arthrodamaeus , articulation of the leg segments with reverse collars ("Crispins ”), genital and anal plates near to each other with a common frame; specific main differences are minute interlamellar setae in posterior position between the bothridia, three pairs of moderately long notogastral setae of the h-row, two pairs of moderately long notogastral setae of the p-row. In consequence, all published records (referred in Mahunka & Mahunka-Papp 1995) need to be confirmed whether they belong to A. pusillus or to G. barbarossa . The literature record of Allodamaeus pusillus (Berlese, 1910) from Slovakia (Stary, 2006) based on Kunst (1968) is G. barbarossa according to our study. Other records from Slovakia based on Miko (1992, 1995) are probably also conspecific with G. barbarossa , because the author used the diagnostic key of Kunst (1968) for identification (Miko, pers. comm.), but the material was not accessible to us.

Two further European Gymnodamaeus species are known from Spain: G. quadriseta Ruiz, Kahwash and Subías, 1990, which is somewhat similar to G. bicostatus and thus is discussed below; G. aprofundatus Mihelcic, 1956, which is similar to G. barbarossa in the general outline and the sensillus, but this species is poorly described (Mihelcic 1956), it differs from G. barbarossa in body size (540-560 µm length) and in the notogastral setation (only two pairs of notogastral setae at the posterior margin, partly on apophyses). Even the genus seems to be uncertain, and in consequence the species is regarded as “ species dubia ” by Perez-Inigo (1997).

Etymology. The species name refers to the Emperor Friedrich I in the middle ages, named Barbarossa, who remained sitting in the Kyffhäuser Mountain, after a popular myth.