Glomus macrocarpum Tul. & C. Tul.

SPORES rarely single in the soil, usually in sporocarps containing 2-15 randomly distributed spores. Spores yellow (3A6); globose to subglobose; (110-)115(-120) µm diam; rarely ovoid or pear-shaped; 100-110 x 115-130 µm; mostly with one subtending hypha, sometimes with two. Peridium not found.

SUBCELLULAR STRUCTURE OF SPORES composed of one wall with two layers (swl1 and 2).

In PVLG
In PVLG
Layer 1 semiflexible, hyaline, (1.2-)1.5(-1.7) µm thick, becomes granular and sloughs locally or on the whole spore surface with age.

Layer 2 laminate, smooth, yellow (3A6), (4.7-)6.6(-7.6) µm thick.

Layers 1 and 2 do not react in Melzer’s reagent.
In PVLG
SUBTENDING HYPHA yellow (3A6); straight or curved; cylindrical to flared, rarely constricted at the spore base; (17.5-)20.6(-25.0) µm wide at the spore base.

Wall of subtending hypha yellow (3A6); (4.4-)6.4(-7.8) µm thick at the spore base; composed of two layers (shwl 1 and 2), continuous with spore wall layers 1 and 2; layer 1 extends 7-15 µm down layer 2 of the subtending hypha.

Pore usually gradually narrows due to thickening of layer 2 of the subtending hypha, sometimes closed by a curved septum.

GERMINATION. Not observed.

MYCORRHIZAE. All the specimens of Gl. macrocarpum characterized here come from the field. There is no literature data of properties of Gl. macrocarpum mycorrhizae; probably no one established this fungus in one-species culture.

DISTRIBUTION. Literature data indicate that Gl. macrocarpum is a widely distributed fungus in both Poland and the other regions of the world, although it occurs irregularly (Błaszkowski 1993a, b, 1994, 1995; Błaszkowski et al. 2002; Dalpé 1989; Godfrey 1957; Hall and Abbott 1984; Koske and Tews 1987; Puppi and Riess 1987; Schenck and Smith 1982; Tadych and Błaszkowski 2000a, b).

NOTES. Single spores of Gl. macrocarpum resemble those of Gl. geosporum (Nicol. & Gerd.) C. Walker and Gl. verruculosum Blaszk. They are similar in size and colour (Błaszkowski and Tadych 1997; Morton 2000; Walker 1982). However, spores of Gl. macrocarpum are usually arranged in sporocarps, whereas those of Gl. geosporum and Gl. verruculosum always occur singly in the soil. Additionally, the spore wall structure of Gl. macrocarpum comprises two layers, and that of Gl. geosporum and Gl. verruculosum consists of three layers.

REFERENCES

Błaszkowski J. 1993a. Comparative studies of the occurrence of arbuscular fungi and mycorrhizae (Glomales) in cultivated and uncultivated soils of Poland. Acta Mycol. 28, 93-140.

Błaszkowski J. 1993b. Polish Glomales XII. Glomus macrocarpum Tul. et Tul. and Glomus microcarpum Tul. et Tul. Bull. Pol. Ac. Sci. Biol. Sci. 41, 29-39.

Błaszkowski J. 1994. Arbuscular fungi and mycorrhizae (Glomales) of the Hel Peninsula, Poland. Mycorrhiza 5, 71-88.

Błaszkowski J. 1995. Glomus corymbiforme, a new species in Glomales from Poland. Mycologia 87, 732-737.

Błaszkowski J., Tadych M. 1997. Glomus multiforum and G. verruculosum, two new species from Poland. Mycologia 89, 804-811.

Błaszkowski J., Tadych M., Madej T. 2002. Arbuscular mycorrhizal fungi (Glomales, Zygomycota) of the Bledowska Desert, Poland. Acta Soc. Bot. Pol. 71, 71-85.

Dalpé Y. 1989. Inventaire et repartition de la flore endomycorhizienne de dunes et de rivages maritimes du Québec, du Nouveau-Brunswick et de la Nouvelle-Ecosse. Naturaliste Can. (Rev. Ecol. Syst.) 116, 219-236.

Godfrey R. M. 1957. Studies of British species of Endogone. I. Morphology and taxonomy. Trans. Br. Mycol. Soc. 40, 117-135.

Hall I. R., Abbott L. K. 1984. Some Endogonaceae from south western Australia. Trans. Br. Mycol. Soc. 83, 203-208.

Koske R. E., Tews L. L. 1987. Vesicular-arbuscular mycorrhizal fungi of Wisconsin sandy soils. Mycologia 79, 901-905.

Morton J. B. 2000. International Culture Collection of Arbuscular and Vesicular-Arbuscular Mycorrhizal Fungi. West Virginia University.

Puppi G., Riess S. 1987. Role and ecology of VA mycorrhizae in sand dunes. Angew. Botanik 61, 115-126.

Schenck N. C., Smith G. S. 1982. Additional new and unreported species of mycorrhizal fungi (Endogonaceae) from Florida. Mycologia 74, 77-92.

Tadych M., Błaszkowski J. 2000a. Arbuscular fungi and mycorrhizae (Glomales) of the Slowinski National Park, Poland. Mycotaxon 74, 463-483.

Tadych M., Błaszkowski J. 2000b. Arbuscular mycorrhizal fungi of the Brda river valley in the Tuchola Forests. Acta Mycol. 35, 3-23.

Walker C. 1982. Species in the Endogonaceae: a new species (Glomus occultum) and a new combination (Glomus geosporum). Mycotaxon 15, 49-61.