Helicoma muelleri Corda, Icon. fung. (Prague) 1: 15 (1837).
Saprobic on woody substrates. Mycelium composed of partly immersed and partly superficial, pale brown, septate, branched hyphae. Sexual state: Unknown.Asexual state: Conidiophores(43-)80–153.5 µm long × 7–10 µm wide ( = 106 × 8 µm, n = 20), superficial, macronematous, crowded, erect, dark brown, septate, rarely branched, darkened at septum. Conidiogenous cellsmonoblastic to polyblastic, sometimes branched at apex, brown to dark brown, smooth-walled. Conidia (15-)16–19(-21) µm diam., and conidial filament 6–9 µm wide ( = 17 × 7 µm, n = 20), tightly coiled 1–1½ times, hyaline to pale brown, tapering toward flat end and with a basal scar 4–7(-8) µm wide, septate, slightly constricted at septum, smooth-walled.
Material examined: USA, New Hampshire, Bartlett, on dead wood (undermined substrate), R. Thaxter, April 1901; Detr. D. Linder,BPI 447569.
Notes: The sequence (Helicoma muelleriCBS 964.69) of this species wasused in the molecular analysis of Tsui et al. (2006). We treat this as an authentic specimen but the species needs epitypfiying with a fresh collection.
Fig. 1 Helicoma muelleri (BPI 447569).a Conidiophores with attached apical conidium on natural substrate. b, c Squash mount of conidiophores with conidial development at the apex (arrows). d Conidiophores with detached conidia and minute denticles (arrows). e-g Conidia. Scale bars: a, d-g=20µm, b-c=50µm
