Arcyria helvetica (Meyl.) H. Neubert, Nowotny & K. Baumann

Fructification
Sporocarps (only 4) in a small group along grass straw, stipitate, ± globose to obpyriform, total height ca. 1.3 mm, sporotheca diam. ca. 0.8 mm, brownish red with copper reflections.

Stalk
short, ca. o.3 mm high, thin, clearly delimited from calyculus, dark reddish brown by RL.

Hypotallus
brownish, confluent under sporocarps.

Peridium
thin, pale brownish red by TL, persistant for some time and then flaking away in small pieces, ± shining.

Columella
None.

Capillitium
of 3-4 µm broad tubules, only fixed at center of calyculus, hardly expanding, medium dense to dense netted, almost smooth towards base, with gradually more prominent ornamentation towards apex, in apical part with rings, halfrings and smaller and less well defined elements, some logitudinally interconnecting lines, ornamentation may be rather high, up to 2-3 µm, occasionally spiny.

Spores
Spores bright dark rose coloured by RL, almost hyaline to faintly greyish yellow by TL, mostly globose to somewhat irregularly shaped, 6.5 - 6.84 - 7.5 µm Ø, by 1000x apparently very delicately warted with scattered small groups of more prominent warts.

Ecology
On grass straw in mixed Calluna-grass heath. Grazed by horses.

Distribution in Denmark
Rare. Known from one find: Jyll., Biowide 001 Råbjerg Kirke, 04-10-2015, On grass straw in dune. Leg. Annegrete Eriksen & Thomas Læssøe

Global distribution
Reported from scattered localities in Europe and Asia, mainly from alpine or subalpine areas.

Discussion
Arcyria helvetica is generally considered a species of cooler climates, temperate to subarctic, in central Europe often in the mountains. The Danish locality is near sea level, but in close connection with the dunes along the North Sea. In Denmark such areas are well known for finds of subalpine species, such as Sarcoletia globosa and Multiclavula vernalis.

Description
Description based on the only, very scarce, Danish collection: SA_TL2015-719192.

 


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.

Arcyria helvetica
SA_TL2015-719192 - Sporocarps
Sporocarps
SA_TL2015-719192 - Capillitium, apical part
Capillitium - apical part
SA_TL2015-719192 - Capillitium, basal part
Capillitium - basal part
SA_TL2015-719192 - Spores, left: suface view, right: optical section
Spores