Glomus pansihalos S.M. Berch & Koske
SUBCELLULAR STRUCTURE OF SPORES composed of one wall with three layers ( swl1-3).
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Spores in PVLG+Melzer's
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Layer 1 flexible, hyaline, (0.5-)1.0(-1.5) µm thick, staining yellowish white (4A2) to pastel yellow (3A4) in Melzer’s reagent. This layer expands in PVLG into a halo with radiate columns that disappear with time. When present, this structure resembles a corona. The distance between the outer surface of the expanded layer 1 and that of the laminate layer 2 is up to 40 µm.
Layer 2 laminate, pale yellow (3A3) to dark yellow (4C8), (2.0-)8.5(-16.0) µm thick, ornamented with evenly distributed hemispherical warts, 0.6-1.0 µm wide at their base and 0.5-1.0 µm high; layer 2 stains burnt Sienna (7D8) to English red (8D8) in Melzer’s reagent.
Layer 3 flexible to semirigid, hyaline to pale yellow (4A3), ca. 0.8-2.2 µm thick, usually easily separating from layer 2 in crushed spores, nonreactive in Melzer's reagent.
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Wall of subtending hypha pale yellow (3A3) to dark yellow (4C8); composed of three layers (shwl1-3), continuous with spore wall layers 1-3; (3.6-)4.5(-5.5) µm thick at the spore base; layer 1 swells in PVLG.
Pore gradually narrows with age due to thickening of the inner layer of its wall and is closed by a curved septum formed by the innermost layer 3.
GERMINATION. A germ tube emerges from the lumen of the subtending hypha.
MYCORRHIZAE. Many attempts to establish one-species cultures of Gl. pansihalos with different plant hosts failed. No literature data exists of the properties of mycorrhizae of this fungus.
DISTRIBUTION. In Poland, Gl. pansihalos has been found to occur in different dune sites adjacent to the Baltic Sea (Błaszkowski 1993; Tadych and Błaszkowski 2000) and in a calamine spoil mound located near Krakow (50o3'N, 19o57'E; Pawlowska et al. 1996).
Glomus pansihalos probably occurs in the whole world. It has been originally described based on spores found in dune soils of California, New Jersey, and Michigan, and from forest soils of southern Ontario, Canada (Berch and Koske 1986). Later, Koske (1987) isolated this fungus from dunes extending from New Jersey to Virginia. Halvorson and Koske (1987) and Koske and Halvorson (1989) recorded Gl. pansihalos in dunes of San miguel island.
NOTES. When observed under a dissecting microscope, spores of Gl. pansihalos most resemble those of Gl. constrictum Trappe. They are similar in colour and size. Additionally, the thick and colourless outer spore wall layer of the latter species also produces a halo that is reminiscent of the expanding wall layer of spores of the former fungus.
Examination of crushed spores under a light microscope readily separates the two species. The outer spore wall layer of Gl. constrictum is rigid in young and mature spores and does not swell in lactic acid-based mountants. Additionally, the surface of the laminate wall layer of spores of Gl. constrictum is smooth (vs. warty in Gl. pansihalos) and the spore wall lacks the third layer of spores of Gl. pansihalos.
REFERENCES
Berch S. M., Koske R. E. 1986. Glomus pansihalos: a new species in the Endogonaceae, Zygomycetes. Mycologia 78, 838-842.
Koske R. E. 1987. Distribution of VA mycorrhizal fungi along a latitudinal temperature gradient. Mycologia 79, 55-68.
Koske R. E., Halvorson W. L. 1989. Mycorrhizal associations of selected plant species from San Miguel Island, Channel Islands National Park, California. Pacific Sci. 43, 32-40.
Halvorson W. L., Koske R. E. 1987. Mycorrhizae associated with an invasion of Erechtites glomerata (Asteraceae) on San Miguel Island, California. Madrono 34, 260-268.
Pawlowska T. E., Błaszkowski J., Rühling Å. 1996. The mycorrhizal status of plants colonizing a calamine spoil mound in southern Poland. Mycorrhiza 6, 499-505.
Tadych M., Błaszkowski J. 2000. Arbuscular fungi and mycorrhizae (Glomales) of the Slowinski National Park, Poland. Mycotaxon 74, 463-483.