Entrophospora infrequens

(I.R. Hall) R.N. Ames & R.W. Schneid.

SPORES single in the soil; develop inside the neck of a sporiferous saccule; golden yellow (5B8) to brownish orange (7C7); globose to subglobose; (95-)135(-175) µm diam.



SUBCELLULAR STRUCTURE OF SPORES composed of a spore wall and one germination wall.

Tooth-shaped outgrowths of swl3 (SEM)

Spore wall contains three layers (swl1-3).

Layer 1 evanescent, hyaline, (1.5-)2.5(-4.5) µm thick, continuous with the wall of a sporiferous saccule, absent or highly sloughed in mature and older spores, staining crayfish red (9B8) to cerise (12C8) in Melzer's reagent.

Layer 2 semipermanent, smooth, 2.8-6.0 µm thick, slowly degrades with age.

Layer 3 laminate, golden yellow (5B8) to brownish orange (7C7); (1,5-)2,5(-4,5) µm thick, ornamented with tooth-shaped outgrowths, 1.8-3.8 x 1.0-3.0 µm, with a central depression in the upper surface.

Germination wall consists of two layers (gwl1 and 2).

Layer 1 flexible, hyaline, <0.5 µm thick, usually tightly adherent to layer 2, and, hence, very difficult to see.

Layer 2 flexible, coriaceous, hyaline, (5.5-)7.8(-10.0) µm thick.



CICATRIX. Two scars showing the region of contact between spore and saccule neck are present. A scar proximal to the saccule is a slightly depressed area, circular, 13.5-27.0 µm diam, to ellipsoidal, 13.5-23.0 x 16.0-27.0 µm, when seen in a plane view. A scar distal to the saccule is circular, 11.0-14.5 µm diam when observed in a plane view.



In PVLG+Melzer's

SPORIFEROUS SACCULE hyaline, 100-170 x 130-190 µm, usually becomes detached in mature spores.

Wall of sporiferous saccule composed of three layers continuous with layers 1-3 of the spore wall.

In PVLG+Melzer's reagent

Layers 1 and 2 hyaline; layer 3 pale orange (5A3). Layer 1 stains crayfish red (9B8) to cerise (12C8) in Melzer's reagent. Layer 3 usually forms a funnel-shaped stalk projecting inward the sporiferous saccule. It is present only in the part of the saccule wall neighbouring with the spore wall.

GERMINATION. Not observed.

MYCORRHIZAE. Many attempts to establish mycorrhizae of E. infrequens in one-species cultures failed.

The only report of E. infrequens mycorrhizae established in a one-species culture probably is that of Sieverding and Toro (1986). According to these authors, E. infrequens formed typical vesicular-arbuscular mycorrhizae in roots of Pueraria phaseoloides Benth.

DISTRIBUTION. Entrophospora infrequens has originally been described as Gl. infrequens Hall from spores found in New Zealand. Ames and Schneider (1979) concluded that Gl. infrequens was incompletely described and based on spores wet sieved from a celery field soil of California transferred this fungus to a newly established genus, Entrophospora Ames & Schneider.

In Poland, E. infrequens has been found in different both cultivated soils and those with natural vegetation (Blaszkowski 1993a, b; Iwaniuk and Blaszkowski, unpubl.). However, this fungus occurred rarely and in low abundances.

As literature data and the observations of one of the authors of this website, J. Blaszkowski, indicate, E. infrequens has a worldwide distribution. It has been encountered in, e. g., Canada (Dalpé 1989), U. S. A. (Ames and Schneider 1979; Bloss and Walker 1987; Halvorson and Koske 1987; Hetrick and Bloom 1983; Koske and Halvorson 1989; Pfleger and Steward 1989; Schenck and Smith 1982; Stahl and Christensen 1982), France, Switzerland and Germany (Oehl et al. 2003), Turkey (Blaszkowski, pers. observ.), India (Sridhar and Beena 2001), New Zealand (Hall 1977), and Australia (Hall and Abbott 1984).

NOTES. Entrophospora infrequens is the type of the genus Entrophospora that includes four species at present. Another species of this genus forming spores with a structural wall layer ornamented with outgrowths is E. baltica Blaszk. However, the ornamentation of the latter species consists of small warts (Blaszkowski et al. 1998) rather than tooth-shaped outgrowths as in E. infrequens (Ames and Schneider 1979; Blaszkowski 1989). Additionally, spores of E. baltica are surrounded with a hyphal mantle that is lacking in spores of E. infrequens.


Ames R. N., Schneider R. W. 1979. Entrophospora, a new genus in the Endogonaceae. Mycotaxon 8, 347-352.

Blaszkowski J. 1989. Polish Endogonaceae. I. Acaulospora bireticulata, Entrophospora infrequens, Glomus caledonium, and Scutellispora pellucida. Karstenia 29, 1-10.

Blaszkowski J. 1993a. The occurrence of arbuscular fungi and mycorrhizae (Glomales) in plant communities of maritime dunes and shores of Poland. Bull. Pol. Ac. Sci. Biol. Sci. 41, 377-392.

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

Blaszkowski J., Madej T., Tadych M. 1998. Entrophospora baltica sp. nov. and Glomus fuegianum, two species in the Glomales from Poland. Mycotaxon 68, 165-184.

Bloss H. E., Walker C. 1987. Some endogonaceous mycorrhizal fungi of the Santa Catalina Mountains in Arizona. Mycologia 79, 649-654.

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.

Hall I. R. 1977. Species and mycorrhizal infections of New Zealand Endogonaceae. Trans. Br. Mycol. Soc. 68, 341-356.

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

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.

Hetrick B. A. D., Bloom J. 1983. Vesicular-arbuscular mycorrhizal fungi associated with native tall grass prairie and cultivated winter wheat. Can. J. Bot. 61, 2140-2146.

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.

Oehl F., Sieverding E., Ineichen K., Mader P., Boller T., Wiemken A. 2003. Impact of land use intensity on the species diversity of arbuscular mycorrhizal fungi in agroecosystems of Central Europe. Appl. Environ. Microbiol.69, 2816-2824.

Pfleger F. L., Steward E. L. 1989. Survey of the Endogonaceae in Minnesota with synoptic keys to genera and species. J. Minnesota Ac. Sci. 54, 25-29.

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

Sieverding E., S. Toro T. 1986. The genus Entrophospora in Colombia. In: Gianinazzi-Pearson V., Gianinazzi S. (eds). Physiological and genetical aspects of mycorrhizae. Proc. 1st European Symposioum on Mycorrhizae. Dijon, 1-5 July 1985, 621-626.

Sridhar K. R., Beena K. R. 2001. Arbuscular mycorrhizal research in coastal sand dunes: a review. Proc. Nat. Acad. Sci. India. 71, 179-205.

Stahl P. D., Christensen M. 1982. Mycorrhizal fungi associated with Bouteloua and Agropyron in Wyoming sagebrush-grasslands. Mycologia 74, 877-885.