Prototrichia metallica (Berk.) Massee

The genus Prototrichia Rostaf. is monotypic.

Fructification
sporocarps scattered or in small groups, spherical to hemispherical, sessile or with a very short stalk partly hidden in a basal umbilicus, 0.7-1.2 mm in diam., greyish rose fading to beige with a distinct metallic lustre in greenish and purple nuances

Peridium
thin and membranaceous, smoky in transmitted light, on the inner side with scattered warts and low ridges.

Capillitium
of threads arising from the base of the sporocarp, branched several times towards the peridium, basal branches interwined in a rope-like manner gradually splitting into the individual treads which apically are fixed to the peridium, yellowish brown in transmitted light.

Spores
spherical, greyish rose, pale greyish rose in transmitted light, with small but distinct and regularly distributed warts, 10.8-12.1-13.9 µm in diam.

Ecology
On branches of Quercus or Sambucus on the ground.

Distribution
Europe, Noth- and Central Africa, Mexico, USA and Greenland.
About 8 finds from Denmark.

Discussion
Macroscopically P. metallica may be confused with Dianema nivale (Meyl.) G. Lister and Calomyxa metallica (Berk.) Nieuwl., both of which have rounded, greyish rose to beige, distinctly iridescent sporocarps. However, microscopically P. metallica is unique by the branched, rope-like capillitium.

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