Ambispora gerdemannii and Glomus badium , two species of arbuscular fungi (Glomeromycota) new for Europe and Poland, respectively

and Glomus badium, two species of arbuscular fungi (Glomeromycota) new for Europe and Poland, morphological characters of spores, as well as sporocarps and spores of Ambispora gerdemannii and Glomus badium , respectively, arbuscular fungi of the phylum Glomeromycota, are described and illustrated. additionally, the known distribution of these species in both Poland and the other regions of the world is presented. Ambispora gerdemannii was not earlier reported from europe, and G. badium is a new fungus for Poland.

materials anD methoDs the methods of collection of soil samples, establishment of trap and one-species cultures, growth conditions, isolation and preparation of spores and the determination of properties of their subcellular structure, as well as the terminology of spore structure and colours, the nomenclature of plants and fungi, and the authors of the fungal names used are as those presented previously (Błaszkowski, Czerniawska 2005).microphotographs were recorded on a sony 3CDD color video camera coupled to an olympus BX 50 compound microscope equipped with nomarski differential interference contrast optics.
Voucher specimens were mounted in polyvinyl alcohol/lactic acid/glycerol (PVlG; omar, Bollan and heather 1979) and a mixture of PVlG and melzer's reagent (1:1, v/v) on slides and deposited in the Department of Plant Pathology (DPP).
distribution and habitat. in Poland, spores of Ambispora gerdemannii were found in 19 samples of roots and rhizosphere soils of 14 species of uncultivated plants.none of the almost 1500 root and soil mixtures coming from cultivated sites of Poland contained spores of this fungus.
the average abundance of Am. gerdemannii spores in the samples examined was 4.7 and ranged from 1 to 29 in 100 g dry soil.the proportion of spores of this species in spore populations of all the arbuscular fungi recovered averaged 11.8% in a range of 2.1-66.7%. the average abundance of species of arbuscular fungi in samples in which spores of Am. gerdemannii occurred was 2.7 and ranged from 1 to 6 in 100 g dry soil.
the arbuscular fungi accompanying Am. gerdemannii in the field were Acaulospora bireticulata f.m. rothwell et trappe, A. capsicula Błaszk., A. koskei Błaszk., A. lacunosa J.B. although Am. gerdemannii probably has a worldwide distribution, this species has been infrequently reported.most reports of Am. gerdemannii come from the united states of america (allen, macmahon 1985;an et al. 1990, 1993;an, Guo and hendrix 1993a;an, Quo and hendrix 1993b;Bever et al. 1996;koske, Gemma and Jackson 1977;nicolson, schenck 1979;rose, Daniels and trappe 1979).additionally, spores of this fungus have been isolated in Brazil (moreira-souza et al. 2003), Colombia (Dodd et al. 1990), andaustralia (morton, redecker 2001). in southern Poland, turnau et al. (2001) recovered spores of a morphotype named Glomus sp.hm-Cl4 of molecular properties close (71%) to those of G. gerdemannii, the basionym of Am. gerdemannii (walker et al. 2007).however, the authors did not show any morphological characters of the spores isolated and did not determine which of the two morphotypes of this fungus was found.
myCorrhizal assoCiations.spores of Am. gerdemannii occurred among vesicular-arbuscular mycorrhizal roots of the plant species listed in the section "Collection examined".additionally, they were recovered from some trap cultures established from mixtures of roots and rhizosphere soils of these plants and with P. lanceolata as the plant host.unfortunately, many attempts to produce one-species cultures of Am. gerdemannii failed.
according to morton (2002) and morton & redecker (2001), mycorrhizae of Am. gerdemannii consisted of only arbuscules and intraradical hyphae; no vesicles were found.all the structures were patchily distributed along roots and stained weakly or not at all in trypan blue.Percentage mycorrhizal colonization always was very low, below 10%.
notes.Ambispora gerdemannii has originally been described as Glomus gerdemanii s.l.rose, B.a. Daniels et trappe from spores isolated from soils of Cascade range and siskiyou mountains of oregon, usa (rose et al. 1979). spain et al. (2006) transferred G. gerdemannii to the genus Appendicispora spain, oehl et sieverd. gen. nov., and walker et al. (2007) to the genus Ambispora C. walker, Vestberg et schuessler gen.nov. in the newly erected family Ambisporaceae C. walker, Vestberg et schuessler.the genus Appendicispora has been excluded because a nomenclatural error (walker et al. 2007).
the distinctive morphological properties of Am. gerdemannii are the fragile bilayered inner wall 1 and the mode of differentiation of spores of this fungus.additionally, Am. gerdemannii is a dimorphic fungus producing two morphotypes, acaulosporioid (as in Acaulospora spp.) and glomoid (as in Glomus spp.), a phenomenon rarely occurring in other species of arbuscular fungi.
inner wall 1 of Am. gerdemannii resembles a hardened glass. in slightly crushed spores, linear cracks appear on the surface of this wall.however, in spores vigorously crushed, this wall almost always breaks into small pieces.another characteristic of this wall is its glittering when seen in a polarized light.
when observed under a dissecting microscope, Am. gerdemannii spores may easily be confused with those of A. spinosa, A. thomii, Am. appendicula and Am.fennica.all the fungi form yellow brown and dull spores of a similar size range.spores of Am. appendicula, Am. fennica, and Am.gerdemannii differ mainly in the properties of layers of inner wall 1. in the latter two species, both layers of this wall are smooth on both sides (spain et al. 2006; walker et al. 2007). in contrast, in the former fungus, the lower surface of layer 1 is ornamented with hemispherical protuberances, which impress hemispherical concave depressions on the upper surface of layer 2 during its differentiation (morton, redecker 2001; spain et al. 2006).additionally, in vigorously crushed spores, inner wall 1 of Am. fennica and Am.gerdemannii usually disintegrates, and that of Am. appendicula remains its integrity.as concluded above (see comments on Am. fennica), Am. fennica and Am.gerdemannii probably are congeneric.
the subcellular structure readily separating Am. gerdemannii from A. spinosa and A. thomii is the beaded outer layer and the flexible to plastic, dextrinoid inner layer present in the innermost wall of spores of the latter two species (vs.no such structures have been found in spores of Ambispora spp.).additionally, in Am. gerdemannii the sporiferous saccule wall is continuous with spore wall layers 1-3 and layer 1 of inner wall 1, whereas in all known Acaulospora spp. the sporiferous saccule wall is continuous with only spore wall layer 1. finally, only Am. gerdemannii is a dimorphic fungus, forming both acaulosporioid and glomoid spores.the glomoid morphotype of Am. gerdemannii has not so far been found in Poland and the only report of its existence is that of morton and redecker (2001).
the most distinguishing characters of G. badium are its small sporocarps lacking a peridium and composed of many, brownish orange to reddish brown, relatively small spores (fig.9). the innermost flexible to semi-flexible and coloured layer of the threelayered spore wall also is a diagnostic property of this species (figs 13 and 14).
Glomus badium probably forms spores only in multispored sporocarps, and single spores occasionally recovered from field-collected soil samples represented their fragments.examination of the ontogenesis of this species is needed to confirm this supposition.unfortunately, all attempts to produce one-species cultures of G. badium made by the authors of this paper and by oehl et al. ( 2005) failed.
the interspore mycelium of the specimens of G. badium found by the authors of this paper morphologically corresponds to that characterized by oehl et al. (2005).however, the original description of this fungus does not inform of the cystidiumlike structures occurring between spores of the Polish sporocarps of this fungus.the function of the cystidia-like structures in sporocarps of G. badium probably is similar to that of cystida of agaricales, in which they appear to serve as spacers between basidia (ulloa, hanlin 2000).
of the three wall layers of spores of G. badium, the two outer ones are typical of most species of the genus Glomus, in which the outermost layer sloughs with age and adheres to a laminate structural layer (figs 13 and 14).spore wall layer 3 of G. badium is thin, pale yellow (4a3) to light brown (6D8), and usually tightly adheres to the lower surface of the brownish orange (6C8) to reddish brown (8e8) layer 2 in even vigorously crushed spores (figs 13 and 14).hence, it is difficult to see, especially in young and freshly matured spores. in older spores, this layer usually is slightly thicker and more frequently separates from the middle laminate layer.additionally, this layer is most visible at the spore base where it forms a straight or curved septum of the subtending hypha continuous with its part adherent to the laminate spore wall layer 2 (fig.14).
Apart from G. badium, species of the genus Glomus forming small and compact sporocarps with small, brownish orange to reddish brown spores are G. cuneatum mcGee et Cooper, G. fuegianum (speg.)trappe et Gerd., G. invermaium i.r.hall, and G. rubiforme (Gerd.et trappe) r.t.almeida et n.C. schenck.Compared with G. badium, sporocarps of G. cuneatum are much larger (2-12 mm vs. 200-500 × 290-680 μm in G. badium) and have a peridium (fig.9; vs. no peridium in G. badium; mcGee and trappe 2002).additionally, the spore wall of the latter species consists of only one laminate layer lightening from black to hyaline towards their inside, whereas the spore wall of the former fungus comprises three layers, of which the laminate layer is dark-and uniform-coloured (figs 10, 12 and 16).according to thaxter (1922), G. fuegianum spores coming from spegazzini's original collection were reddish brown as are those of G. badium. in contrast, all G. fuegianum spores found by one of the authors (J.B.) of this paper in Poland, those loaned from kew, united kingdom (Błaszkowski, madej and tadych 1998), and those revealed in australia by mcGee and trappe (2002) were pale yellow to yellow brown.moreover, the spores were frequently surrounded by branched and convoluted hyphae (Błaszkowski 2003) that never occur on G. badium spores (Błaszkowski, pers. observ.;oehl et al. 2005).finally, the radial arrangement of spores in sporocarps of G. fuegianum is regular, and irregular in G. badium sporocarps.
Glomus badium differs from G. invermaium in the formation of smaller (200-500 × 290-680 μm vs. up to 1 mm across) and more compact sporocarps with regularly distributed spores (fig.9; vs. loose sporocarps with randomly distributed spores in G. invermaium; Błaszkowski, pers. observ.;hall 1977).other differences are the number and the phenotypic properties of the spore wall layers of these fungi.the spore wall of G. badium comprises three layers, of which the outermost one sloughs with age (figs 13 and 14). in contrast, the outermost spore wall layer of G. invermaium spores is persistent and the spore wall of this species lacks spore wall layer 3 of G. badium.
the main difference between G. badium and G. rubiforme resides in the wall structure of their spores.the spore wall of G. rubiforme comprises only two layers similar in colour and phenotypic properties to layers 1 and 2 of the spore wall of G. badium (Błaszkowski 2003;Gerdemann, trappe 1974).