Funneliformis verruculosum

(reference accession PL117B)

Spheres yellow orange opaque shiny

Whole Spores

Size distribution graph approximately normal COLOR: Bright yellowish orange (0-10-60-0) to dark brownish orange (0-40-100-0), with many bright orange (0-20-100-0)

SHAPE: Globose, subglobose, occasionally ovoid

SIZE DISTRIBUTION: 100-240 µm, mean = 171 µm, n = 110

Subcellular Structure of Spores

SPORE WALL: Consisting of two layers (L1 and L2) that differentiate consecutively as spores develop.

Smashed Spores
In PVLG	In PVLG	In PVLG & Melzer’s reagent

L1: A semiflexible, hyaline layer, 1-2 µm thick; usually sloughing and therefore absent in field-collected specimens and many spores in a mature pot culture..

Smashed spore L2 L3 with warts

L2: A rigid layer consisting of fine adherent sublayers (or laminae), yellow to orange in color, 5-14 µm thick. Evenly distributed warts, 0.8-1.7 µm high in cross view, 0.5-0.7 µm diam in plan view, are reported by Blaszkowski and Tadych (1997) as projecting inward from the innermost sublayer, but these are seen only in a small percentage of spores in this reference culture. Given that variability, this trait is not a taxonomically informative character.

Subtending Hypha

Smashed spores L2 L3 distinct curved lines subtending hypha

SHAPE: Cylindrical to somewhate flared, occasionally recurved.

WIDTH: 15-28 µm (mean = 21 µm).

COMPOSITE WALL THICKNESS: 4.5-7 µm at spore base.

Smashed spore subtending hypha L2

WALL STRUCTURE: Two layers (L1 and L2) continuous with the inner two layers of the spore wall and with the same properties. L2 extends for only 20-25 µm down length of hypha.

OCCLUSION: Recurved septum from the innermost sublayer of L2 of the spore wall.

Notes

Color of the spores is quite distinctive among glomoid species described thus far. The size range of spores in the reference culture is considerably extended at the small end than is published in the protologue (the lower limit reported to be 145 µm).

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