Oligonema fulvum Morgan

Fructification
sporocarps sessile, solitary to gregarious or in groups in groups of up to 10-20, sperical to somewhat angular (in groups), shining bright yellow in RL, ca. 0.2-0.7 mm Ø.

Peridium
Thin, fragile, membranous, medium golden yellow in TL, smooth to very delicately warted or with a faint whirl-pattern on the inside, occasionally with impressions from the spores, splitting irregularily

Capillitium
Sparse, elaters, ± straight to slightly coiled, apices slightly swollen, frequently with a little, blunt spine, with thickend apical wall, ornamentation of 3-4 faint spiral bands on the cylindrical part, 65-109-175 x 4-4.3-5 µm, but elaters down to 10 µm and up to ca. 280 µm is found in the Danish material, pale yellow in TL.

Spores
± globose, bright yellow in RL, medium golden yellow in TL, with up to ca. 0.5 µm high regularly distributed medium sized warts which often coalesce to form comma-shaped structures or short lines, 10.5-11.46-12 µm Ø.

Ecology
Moist board and willow-bark (Salix sp.), and on bark of brach of deciduous tree on the ground, in very moist conditions

Distribution in Denmark
Rare, only 5 collections known.

Global distribution
Reported from Western Europe, Northern Africa, North America and Greenland.

Discussion
The danish collections of O. fulvum deviate from most descriptions by having bright yellow sporocarps instead of olivaceous brown. In all other characters they fall within the nornal variaton af the species. In the family Trichiaceae one finds several other examples of species having more than one colour phase, f.ex. Trichia decipiens og T. lutescens.

O. fulvum is a rather incospicuous species. It was found on rather moist substrates, as is the case of the other species in the genus. From these other species it can only be separated with certainty by microscopical characters (elaters and spores).

Description
Description and discussion partly based on Albertsen & Gøtzsche (1993) and partly on one more recent find (hfg2336)

 


Abbreviations: TL : transmitted light; RL : reflected light; Ø : diameter; TBU : Danish Botanical Topographical District.

Colour-codes refer to: Kornerup, A. & J. H. Wanscher 1974: Farver i farver. 5th reprint. Politikens Forlag, Copenhagen.

When not otherwise indicated spore measurements are given as: min-mean-max or (extreme-)min-mean-max(-extreme). Spore measurements are exclusive of ornamentation.

Line drawings are free hand sketches.

Distribution maps: Maps of Danish distributions are based on material seen by the author. World distributions are based on reports extracted from literature.

Oligonema fulvum:
Oligonema fulvum - Sporocarps
Sporocarps (hfg2336)
Oligonema fulvum - Spores and elater
Spores and elater (hfg2336)