Helicoma Corda, Icon. fung. (Prague) 1: 15 (1837).

Possible synonyms (Index Fungorum 2014, not seen)

Lituaria Riess, Bot. Ztg. 11: 136 (1853)

Helicocoryne Corda 1854, Icon. fung. (Prague) 6: 9 (1854)

Drepanospora Berk. & M.A. Curtis [as ‘Drepanispora’], in Berkeley, Grevillea 3(no. 27): 105 (1875)

Helicopsis P. Karst., Revue mycol., Toulouse 11(no. 42): 96 (1889)

TroposporellaP. Karst., Hedwigia 31: 299 (1892)

HelicosporellaG. Arnaud, Bull. trimest. Soc. mycol. Fr. 69: 292 (1954) [1953]

HelicosporinaG. Arnaud ex Rambelli, Mycopath. Mycol. appl. 13: 110 (1960)

HelicominopsisDeighton, Mycol. Pap. 78: 20 (1960)

MoorellaP.Rag. Rao & D. Rao, Mycopath. Mycol. appl. 22: 51 (1964)

Saprobic on woody substrata. Mycelium partly immersed, pale brown, septate, branched hyphae.Sexual state:Ascomata superficial, solitary, sometimes clustered, gregarious, superficial, subglobose, oval to obovoid, with soft texture, dark brown, pale brown above, with a central papillate ostiole, rarely with setae. Setae up to 80 µm long, dark brown, tapering towards subacute apex, widest at base, septate. Peridium thick-walled, composed of brown to reddish-brown cells oftexturaangularis. Hamathecium comprising numerous, filiform, septate, branched, hyaline pseudoparaphyses. Asci 8-spored, bitunicate, elongate to cylindric-clavate, thickened at apex, pedicellate. Ascospores 2–3-seriate, elongate-fusiform, subcylindrical, tapering towards subacute ends, up to 10-septate, not constricted at septum, hyaline, smooth-walled. Asexual state:Conidiophores superficial, macronematous, crowded, erect, dark brown, septate, rarely branched, darkened and slightly constricted at septum.Conidiogenous cellsmonoblastic to polyblastic, sometimes branched at apex, brown to dark brown, smooth. Conidia tightly coiled 1–1½ times, conidial filament 6–9 µm wide, hyaline to pale brown, tapering towardsthe flattened end with a basal scar, septate, slightly constricted at septum, smooth-walled.

Type species:Helicoma muelleri Corda

Notes: The genus Helicoma was introduced by Corda (1837), with the type species H. muelleri Corda. The genus is distinguished by its relatively short, erect, thick, dark brown, smooth conidiophores, holoblastic conidiogenous cells and helicoid, hyaline, thick-walled, brown to dark brown conidia forming from terminal, denticulate conidiophores (Goos 1986; Seifert et al. 2011). Illustrations presented here are based onBPI 447569considered authentic material of H. muelleri on natural substrate and determined by D. Linder. Various Helicoma species have been connected with sexual taxa in Tubeufiaceae and the links are confused (Tsui et al. 2006, 2007; Zhao et al. 2007; Boonmee et al. 2011).The sexual state is described from Helicoma rugosa (BPI 1104599, dried culture: BER 12 80–4). Putatively named strains of Helicosporium linderi R.T. Moore (NBRC 9207), T. paludosa (P. Crouan & H. Crouan) Rossman (HKUCC 9118, ANM 196, ANM 1169) and Thaxteriella helicoma (W. Phillips & Plowr.) J.L. Crane, Shearer & M.E. Barr (JCM 2739, UBCF 13877) clustered in this clade and we rename them as Helicoma in the phylogenetic tree (Fig. 2), but do not formally synonymize them as we have not seen voucher material. Asexual morphs regarded as Helicoma rugosa formed in cultures ofThaxteriella helicoma (JCM 2739 and UBCF 13877). Tubeufia khunkornensis Boonmee & K.D. Hyde (MFLUCC 10–0119, ex-type strain), T. inthanonensis Boonmee & K.D. Hyde (MFLUCC 11–0003, ex-type strain) and T. miscanthi W.H. Hsieh, Chi Y. Chen & Sivan., epitypified here) are synonymized under Helicoma. Helicoma chiangraiense, H. fagacearum and H. siamense formed distinct groups at the base of Clade A, and we therefore introduce them as new species of Helicoma.

Type species:Helicoma muelleri Corda, Icon. fung. (Prague) 1: 15 (1837).