In PVLG
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In PVLG |
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SPORES single in the soil or in aggregates without a peridium. Aggregates 160-520 x 300-700 µm, composed of 2-5 spores. Spores develop laterally on the neck of a sporiferous saccule; brownish orange (6C8) to brown (6E8); globose to subglobose; (150-)185(-240) µm diam.
SUBCELLULAR STRUCTURE OF SPORES consists of a spore wall and two inner germination walls.
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In PVLG |
In PVLG+Melzer's reagent |
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Spore wall composed of three layers (swl1-3).
Layer 1 semipermanent, hyaline, (2.5-)4.4(-6.5) µm thick, continuous with the wall of a sporiferous saccule, usually intact in mature spores.
Layer 2 laminate, smooth, brownish orange (6C8) to brown (6E8), (2.5-)3.3(-4.0) µm thick.
Layer 3 semiflexible, hyaline, (1.3-)1.5(-1.8) µm thick, easily separating from layer 2.
Germination wall 1 composed of two hyaline, tightly adherent layers (gw1l1 and 2), each ca. 0.5 µm thick.
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In PVLG+Melzer's reagent |
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Layer 1 flexible, hyaline, ca. 0.5 µm thick, ornamented with small, <0.5 µm diam, granules.
Layer 2 flexible, hyaline, (0.5-)0.9(-1.0) µm thick, staining beetroot purple (13D8) in Melzer’s reagent.
GERMINATION ORB. Not found.
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In PVLG |
SPORIFEROUS SACCULE hyaline to pale yellow (3A3); globose to subglobose; 170-210 µm diam; neck 70-250 µm long, 35-45 µm wide at the saccule, tapering to 20-38 µm wide at the spore attachment. Saccule usually collapses or falls off in mature spores.
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In PVLG |
CICATRIX. A slightly raised collar when seen in a cross view, circular, 11.5-17.0 µm diam, or ellipsoidal, 11.5-13.0 x 12.0-17.0 µm when observed in a plane view.
MYCORRHIZAE. Acaulospora thomii has been associated in the field with vesicular-arbuscular roots of Triticum aestivum L. Many attempts to establish mycorrhizae of this fungus in one-species cultures with Plantago lanceolata L. failed.
DISTRIBUTION. Acaulospora thomii has been described based on spores isolated from under T. aestivum cultivated in Boleslawice (51o18’N, 15º22’E) in south-western Poland (Blaszkowski 1988). Dr. F. Oehl (pers. comm.) found spores of this fungus in cultivated soils of Switzerland.
NOTES. Acaulospora thomii most resembles Ac. sporocarpia Berch. However, Ac. sporocarpia forms larger sporocarps and the the subcellular structure of its spores is much more simple: it contains only two components (Berch 1985).
REFERENCES
Berch S. M. 1985. Acaulospora sporocarpia , a new sporocarpic species, and emendation of the genus Acaulospora (Endogonaceae, Zygomycotina). Mycotaxon 23, 409-418.
Blaszkowski J. 1988. Four new species of the Endogonaceae (Zygomycotina) from Poland. Karstenia 27, 37-42.