PDD 3614.

Fruiting body a stalked sporangium, crowded and sometimes more-or-less tangled, 2.0–3.5 mm tall. Sporotheca subglobose to subcylindrical, wine-red to dark red but becoming red-brown, 0.5–1.0 mm wide. Stalk cylindrical, erect, up to 1.0 mm long. Hypothallus thin, membranous, colourless. Peridium persisting in mature fruiting bodies only as a rather deep and asymmetrical (or rarely shallow and symmetrical) calyculus. Capillitium consisting of a network of threads 3.5–9.0 µm in diameter and marked with warts, spines, cogs, half-rings and rings, also with a number of ridges that may unite locally to form a reticulum. Spores reddish brown in mass, almost colourless by transmitted light, with a few scattered small warts and sometimes a few groups of larger warts, 7–8 µm in diameter. Plasmodium white.

Reported from Africa (Ukkola 1998), Australia (Mitchell 1995), Europe (Lado & Pando 1997), and South America (Farr 1976), but not always distinguished from A. incarnata. First reported from New Zealand by Cheeseman & Lister (1911), based on a specimen from Bay of Plenty. Also known from Wellington, Nelson, and Southland.

Decaying wood.

Martin & Alexopoulos (1969), Nannenga-Bremekamp (1991), Neubert et al. (1993), Lado & Pando (1997), Ing (1999).

This species has been considered as doubtfully distinct from Arcyria incarnata by some authors, and the two species are certainly very close. The major distinguishing features are differences in the calyculus (deep, funnel-shaped in A. affinis and shallow dish-shaped in A. incarnata) and capillitium (expanding longitudinally to form a long procumbent plume in A. affinis and usually expanding evenly and remaining more or less erect in A. incarnata).