Arcyria affinis Rostaf.

Rostafinski 1875: Slúzowce (Mycetozoa). Monographia and supplement, p. 276
Type loc.: Sweden, Skåne, Lund (first and only collection mentioned by Rostafinski).

Sporocarprs in close groups which may be from ca. 1 cm to several dm across, short-stalked to almost sessile, ovoid or more often short-cylindrical, up to ca. 3 mm high, brick-red (7D7) to brownish red (8E7), fading to greyish brown.

about 0.5 mm high, but sporocarps with stalks up to 1.2 mm observerd, cylindrical, mostly fairly thin, longitudinally furrowed, dark brown to black in RL, orange-brown in TL, filled with spore-like cells.

leaving a shining reddish brown, flattened to funnel-shaped calyculus, on the inside with fine warts coalescing into a fine-meshed net.

forming a wide-meshed net of 2-4(-5) µm broad tubules, which are attached to the base of the calyculus, tubules with rings, transversal half-rings, warts and low spines, occasionally forming an incomplete net, dark greyish- to brownish red in TL.

spherical, almost smooth or with very fine warts (oil immersion) and always with scattered small groups of more prominent, dark warts, pale greyish yellow in TL, 7.2-7.9-8.8 µm in diam.

Rotten wood and bark of (Fagus sylvatica) and (Populus tremula).

Global distribution
Distrbuted throughout Europe, scattered finds from Central and East Africa, India, New Zealand and the Galapagos Islands.

Distribution in Denmark
Occasional. Approximately 50 collections known.

Arcyria affinis is a very variable species or perhaps a complex of species. It is segragated from other red Arcyria-species by the dark, rather wide-meshed capillitial net (typical size of meshes 100 µm), which is loosely attached at the base of the calyculus. The sporocarps often so closely gathered in groups that their capillitia unite into one big mass of tubules upon expansion.

Description and discussion based on Albertsen & Gøtzsche (1993).


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.