Physarum flavicomum Berk.

Fructification
Sporocarps scattered, stipitate, depressed globose, only slightly umbilicate below, apically deeply umbilicate (sic!), total height up to ca. 1.5 mm, head diam. up to ca 0.5 mm.

Hypothallus
Dark brown, discoid under individual sporocarps, confluent under ajacent ones.

Stalk
± cylindric, slightly furrowed, dull orange, dark as hypotallus towards base, length ca. 2/3 of total height.

Peridium
Smooth, dull yellowish green on sides of head, bright ochraceous on top and into umbilicus in RL, basically with a brownish circular area around stalk; pale yellowish to almost hyaline in TL, towads apex bright yellow in TL, (yelleow pigment seems to be somewhat water soluble), apparently almost limeless laterally, apically with fine (< 1 µm Ø), bright yellow granular matter.

Columella
Columella not seen; at most with a somwhat thickened base.

Capillitium
Capillitium of hyaline tubules, 1- ca. 6 µm broad, branched whith expanded nodes into a lax net, no lime inclusions observed.

Spores
Spores globose, medium brown in RL, pale greyish brown in TL, with fine, ± regularly distributed warts, slight tendency to coalesce to very short lines, 8-9-11 µm Ø (n=25).

Plasmodium
Phaneroplasmodium, dull greyish yellow.

Ecology
Cultured in moist chamber. Material, twings of Cistus sp., collected primo feb. 2014 by Thomas Læssøe in Cyprus. MC prepared on 7.3.2014, active plasmodia detected 18.3.2004 and mature sporocarps harvested 1.4.2014.

Discussion
The identification of this collection gave me some problems, so I called for suggestions on this page. Initially I focused on the apical umbilicus as a diagnostic character. That eventually turned out to be wrong.

Hans van Hooff (the Netherlands) gave the solution. He reported similar fructifications in moist chamber culture on bark of Juniperus, and added a photograph which clearly shows the same taxon. Hans identified his specimen as Physarum flavicomum berk.

I have afterwards done a more careful check of the literature and found that Gray (1961) reported the variation in P. flavicomum sporocarps in culture depending upon moisture conditions in the chambers. High humidity resulting in less lime in the peridium and somewhat distorted sporocarps, including umbilicate ones.

 


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.

Physarum flavicomum Berk.:
Physarum flavicomum Berk. - Sporocarps
Sporocarps
Physarum flavicomum Berk. - Sporocarps
Sporocarps
Physarum flavicomum Berk. - Spores
Sporocarps
Physarum flavicomum Berk. - Spores and capillitium
Spores and capillitium