Scutellospora armeniaca Błaszk.

SPORES single in the soil or in roots; formed terminally or laterally on a bulbous sporogenous cell; apricot yellow (5B6) to yellowish brown (5E8); globose to subglobose; (140-)196(-240) µm diam; sometimes ovoid; 140-200 x 220-250 µm.

 

SUBCELLULAR STRUCTURE OF SPORES consists of a spore wall and two inner germinal walls.

In PVLG
In PVLG+Melzer's reagent
Spore wall composed of three layers (swl1-3).

Layer 1 permanent, smooth, greyish orange (5B5), (0.7-)0.9(-1.2) µm thick, usually tightly adherent to layer 2.

Layer 2 laminate, apricot yellow (5B6) to yellowish brown (5E8), (5.4-)8.7(-13.0) µm thick, usually staining garnet red (11E8) in Melzer’s reagent.

Layer 3 flexible, hyaline, (0.4-)0.5(-0.7) µm thick, easily separating from layer 2.

Germinal wall 1 contains two layers (gw1l1 and 2).

Layer 1 flexible, hyaline, (1.0-)1.5(-1.7) µm thick.

Layer 2 flexible, hyaline, (0.7-)1.0(-1.5) µm thick, staining pinkish white (7A2) in Melzer’s reagent.

Germinal wall 2 composed of two layers (gwl2l1 and 2).

In PVLG
In PVLG+Melzer's reagent
Layer 1 flexible, coriaceous, hyaline, (2.2-)3.6(-4.4) µm thick, staining pinkish white (9A2) in Melzer’s reagent.

Layer 2 plastic, hyaline, of a variable thickness in PVLG, 2-4.7 µm thick and beetroot purple (13D8) in Melzer’s reagent.

 

In PVLG
  
In PVLG+Melzer's reagent
SPOROGENOUS CELL formed terminally on a sparsely septate sporophore; ovoid to clavate; (32.0-)38.5(-42.0) µm wide; concolourous with spore wall layer 2.

Wall of sporogenous cell composed of two layers, continuous with spore wall layers 1 and 2.

Layer 1 hyaline, 0.5-0.8 µm thick.

Layer 2 apricot yellow (5B8) to yellowish brown (5E8), (1.0-)2.6(-4.2) µm thick at the spore base.

In PVLG

GERMINATION SHIELD cardioid to irregular; pale yellow (3A3); 45.0-67.5 x 80.0-94.0 µm; with deep folds partitioning 5-11 lobes with nicked margins formed by shallow incisions; formed on germinal wall 2. One to three, hyaline to pale yellow (3A3), 1.8-5.4 µm diam germ tubes emerge from the germination shield.

 

 

In PVLG

AUXILIARY CELLS rarely single in the soil, usually in loose clusters of 2-12; hyaline to pale yellow (3A3); lobed to irregular; 15.0-32.5 x 22.5-32.5 µm; with knobby projections, 2.5-11.0 x 3.0-10.0 µm; produced on coiled hyphae, 3.0-5.5 µm diam, concolorous with auxiliary cells.

 

 

MYCORRHIZAE. Scutellospora armeniaca has originally been described from spores recovered from among vesicular-arbuscular mycorrhizal roots of Artemisia campestris L. colonizing maritime dunes adjacent to Chalupy (54o46’N, 18o31’E) located on the Hel Peninsula in northern Poland (Błaszkowski 1992). Later, this fungus has been found associated with vesicular-arbuscular mycorrhizal roots of many other dune and non-dune plant species (Błaszkowski 1992, 1993; Błaszkowski et al. 2002a, b; Tadych and Błaszkowski 2000a, b).

DISTRIBUTION. In Poland, S. armeniaca has occurred in dune sands of the Vistula Bar (54º21’N, 19º14’E; Błaszkowski et al. 2002a), the Gdansk coast (Błaszkowski 1992, 1993), and the Slowinski National Park (54º45’N, 17º26’E; Tadych and Błaszkowski 2000a). This species has been the most frequently occurring arbuscular fungus in soils of the Bledowska Desert (50º22’N, 19º34’E; Błaszkowski et al. 2002b). Additionally, spores of S. armeniaca have been revealed in soils of the Tuchola Forests (53º46’N, 17º42’E-53º40’N, 17º54’E; Tadych and Błaszkowski 2000b).

No report exists of the finding of S. armeniaca in other regions of the world.

NOTES. Spores of S. armeniaca are most likely to be confused with those of S. arenicola, S. castanea, S. erythropa, and S. hawaiensis. All these species produce spores similar in colour (Koske and Gemma 1995; Koske and Halvorson 1989; Koske and Walker 1984; Morton 2002; Stürmer and Morton 1999; Walker et al. 1993). However, even the smallest spores of S. castanea [(285-)298(310) µm diam when globose; Walker et al. 1993] are larger than the largest spores of S. armeniaca [(140-)196(-240) µm diam; Błaszkowski 1992]. Spores of S. arenicola [(160-)230(-360) x (120-)220(-310) µm; Koske and Halvorson 1989], S. erythropa [(160-)240(-320) µm diam; Morton 2002], and S. havaiensis [(200-)240(-360) x (180-)230(-290) µm; Koske and Gemma 1995] may also be much larger than those of the fungus discussed here.

The main differences between these fungi inhere in the subcellular structure of their spores, especially in the number and the composition of the inner germinal walls. Of the species compared here, a third flexible spore wall layer was revealed only in S. armeniaca. A similar layer was found in the spore wall of, e. g., S. heterogama and S. rubra (Stürmer and Morton 1999). This layer usually is very thin and tightly adheres to a structural laminate spore wall layer, and hence is difficult to see, especially in field-collected spores.

Scutellospora castanea and S. erythropa diverge from the other species considered here in the number of germinal walls. In S. castanea, only one 2-layered germinal wall is present (Walker et al. 1993), and S. erythropa differentiates three germinal walls (Morton 2002; vs. two, 2-layered germinal walls in the other species).

REFERENCES

Błaszkowski J. 1992. Scutellospora armeniaca, a new species in Glomales (Zygomycetes) from Poland. Mycologia 84, 939-944.

Błaszkowski J. 1993. 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.

Błaszkowski J., Adamska I., Czerniawska B. 2002a. Arbuscular mycorrhizal fungi (Glomeromycota) of the Vistula Bar. Acta Mycol. 37, 39-62.

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

Koske R. E., Gemma J. N. 1995. Scutellospora hawaiiensis: a new species of arbuscular mycorrhizal fungus from Hawaii. Mycologia 87, 678-683.

Koske R. E., Halvorson W. L. 1989. Scutellospora arenicola and Glomus trimurales: two new species in the Endogonaceae. Mycologia 81, 927-933.

Koske R. E., Walker C. 1984. Gigaspora erythropa, a new species forming arbuscular mycorrhizae. Mycologia 76, 250-255.

Morton J. B. 2002. International Culture Collection of Arbuscular and Vesicular-Arbuscular Mycorrhizal Fungi. West Virginia University. http://www.invam.caf.wvu.edu/.

Stürmer S. L., Morton J. B. 1999. Scutellospora rubra, a new arbuscular mycorrhizal species from Brazil. Mycol. Res. 103, 949-954.

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., Gianinazzi-Pearson V., Marion-Espinasse H. 1993. Scutellospora castanea, a newly described arbuscular mycorrhizal fungus. Cryptog. Mycol. 14, 279-286.