(Nicol. & Gerd.) C. Walker & F.E. Sanders
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SPORES single in the soil; formed terminally on a bulbous subtending hypha; pastel yellow (2A4) to dark orange (5A8); globose to subglobose; (160-)214(-260) µm diam; sometimes ovoid; 150-190 x 210-260 µm.
SUBCELLULAR STRUCTURE OF SPORES consists of a spore wall and two inner germination walls.
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In PVLG+Melzer's reagent
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Spore wall composed of two, tightly adherent layers (swl1 and 2).Layer 1 permanent, smooth, hyaline, (0.5-)0.8(-1.0) µm thick.
Layer 2 laminate, pastel yellow (2A4) to dark orange (5A8), (2.9-)7.1(-11.0) µm thick.
Germination wall 1 consists of two flexible, hyaline layers (gwl1 and 2).Layer 1 up to 0.5 µm thick, usually tightly adherent to layer 2.Layer 2 (0.5-)0.7(-1.0) µm thick.
Germination wall 2 comprises two layers (gw2l1 and 2).Layer 1 flexible, coriaceous, hyaline, (0.7-)2.1(-2.9) µm thick, staining dull red (9B4) in Melzer’s reagent.
Layer 2 plastic, hyaline, up to 14 µm thick in PVLG, 1.5-3.0 µm thick and beetroot purple (13D8) in Melzer’s reagent.
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In PVLG |
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Wall of sporogenous cell composed of two layers (scwl1 and 2), continuous with spore wall layers 1 and 2.
Layer 1 hyaline, <0,5 µm thick, very difficult to see.
Layer 2 pastel yellow (2A4) to dark orange (5A8), (1.1-)5.7(-7.5) µm thick at the spore base.
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In PVLG |
GERMINATION SHIELD ellipsoid to irregular; hyaline to pale yellow (1A4); 70-85 x 115-137 µm; with deep folds partitioning 5-7 lobes with smooth margins, formed on germination wall 2.
AUXILIARY CELLS rarely single in the soil, usually in loose clusters of 2-8; hyaline to pale yellow (2A2); pyriform to irregular; 22.5-32.5 x 37.5-47.5 µm; produced on coiled hyphae, 2.5-6.5 µm diam, concolourous with auxiliary cells.
MYCORRHIZAE. Although S. calospora sporulated abundantly in trap cultures, many attempts to initiate this fungus to produce spores in one-species cultures failed. According to Morton (2000), S. calospora formed arbuscular mycorrhizae staining intensively in trypan blue.
DITRIBUTION. Scutellospora calospora has originally been described from spores isolated from a cultivated soil of Scotland (Nicolson and Gerdemann 1968). This fungus has also been recovered from cultivated soils and those with natural vegetation located in many other regions of the world, e. g., in USA (Gemma and Koske 1997; Gerdemann and Trappe 1974; Nicolson and Gerdemann 1968), Canada (Dalpé 1989), Brazil (Trufem et al. 1989), Portugal (Blaszkowski, pers. observ.), Finland (Vestberg 1995), Spain (Blaszkowski, pers. observ.), Italy (Blaszkowski, pers. observ.; Giovannetti 1985; Puppi and Riess 1987), Turkey, Israel (Blaszkowski, pers. observ.), and Australia (Hall and Abbott 1984; Koske 1975).
NOTES. Scutellospora calospora is most similar to S. dipurpurescens J.B. Morton & Koske. The two fungi are indistinguishable when observed under a dissecting microscope: their spores are identical in colour, shape, and size (Blaszkowski 1989; Franke and Morton 1994; Koske and Walker 1986; Morton 2000; Nicolson and Schenck 1979). The spores differ only in the structure of the germination wall 1. In S. dipurpurescens, this wall is 1-layered, whereas the germination wall 1 of S. calospora spores includes two layers.
REFERENCES
Blaszkowski J. 1989. Polish Endogonaceae. I. Acaulospora bireticulata, Entrophospora infrequens, Glomus caledonium, and Scutellispora pellucida. Karstenia 29, 1-10.
Dalpé Y. 1989. Inventaire et repartition de la flore endomycorhizienne de dunes et de rivages maritimes du Quebec, du Nouveau-Brunswick et de la Nouvelle-Ecosse. Naturaliste can. (Rev. Ecol. Syst.) 116, 219-236.
Franke M., Morton J. B. 1994. Ontogenetic comparisons of arbuscular mycorrhizal fungi Scutellospora heterogama and Scutellospora pellucida: revision of taxonomic character concepts, species descriptions, and phylogenetic hypotheses. Can. J. Bot. 72, 122-134.
Gemma J. N., Koske R. E. 1997. Arbuscular mycorrhizae in sand dune plants of the North Atlantic coast of the U.S.: Field and greenhouse studies. J. Environ. Manag. 50, 251-264.
Gerdemann J. W., Trappe J. M. 1974. The Endogonaceae in the Pacific Northwest. Myc. Memoir 5, 1-76.
Giovannetti M. 1985. Seasonal variations of vesicular-arbuscular mycorrhizas and Endogonaceous spores in a maritime sand dunes. Trans. Br. Mycol. Soc. 84, 679-684.
Hall I. R., Abbott L. K. 1984. Some Endogonaceae from south western Australia. Trans. Br. Mycol. Soc. 83, 203-208.
Koske R. E., Walker C. 1986. Species of Scutellospora (Endogonaceae) with smooth-walled spores from maritime sand dunes: two new species and a redescription of the spores of Scutellospora pellucida and Scutellospora calospora. Mycotaxon 27, 219-235.
Morton J. B. 2000. International Culture Collection of Arbuscular and Vesicular-Arbuscular Mycorrhizal Fungi. West Virginia University.
Nicolson T. H., Gerdemann J. W. 1968. Mycorrhizal Endogone species. Mycologia 60, 313-325.
Nicolson T. H., Schenck N. C. 1979. Endogonaceous mycorrhizal endophytes in Florida. Mycologia 71, 178-198.
Puppi G., Riess S. 1987. Role and ecology of VA mycorrhizae in sand dunes. Angew. Botanik 61, 115-126.
Trufem S. F. B., Otomo H. S., Malatinszy S. M. M. 1989. Fungos micorrizicos vesiculo-arbusculares em rhizosferas de plantas em dunes do Parque Estadual da Iiha do Cardoso, Sao Paulo, Brasil. (I) Taxonomia. Acta Bot. Bras. 3, 141-152.
Vestberg M. 1995. Occurrence of some Glomales in Finland. Mycorrhiza 5, 329-336.
