Microthyriales genera incertae sedis » Microthyriales genera incertae sedis

Heliocephala

Heliocephala V. Rao, K.A. Reddy & de Hoog, Persoonia 12(3): 239 (1984)

            Index Fungorum number: IF 11097; Facesoffungi number: FoF xx; 8 morphological species (Species Fungorum 2021), 4 species with molecular data.

Saprobic on leaf. Sexual morph: Unknown. Asexual morph: Colonies effuse, light to dark grey, conidiophores under binocular pinhead-like. Mycelium partly superficial, partly immersed, composed of septate, branched, anastomosing, smooth, sub hyaline to pale brown hyphae, cells later becoming thick-walled. Conidiophores erect, arising singly, terminally or laterally from undifferentiated hyphae, unbranched, stiff, straight or slightly flexuous, septate; the first two septa very close, others distant, last septum formed just below the apex; basal cell swollen, conical, dark brown. Conidiophores ending in large, ovoidal subtending cells up to 3.5 µm diam., from which a number of ampulliform conidiogenous cells arise, or bearing two short, downwardly curved or hooked, 1-2 celled branches, the cells of which transform into conidiogenous cells from which conidiogenous cells of second order are produced in dense, more or less drepanoid arrangement. Conidiogenous cells monoblastic, discrete, ampulliform or ovoidal with short necks, determinate, smooth- and thin-walled, first formed cells are brown to pale brown, later formed cells sub hyaline. Conidia radially arranged in compact heads, dry, obclavate, 2- septate, basal cell minutely verruculose, median and terminal cells smooth-walled, the apical cell drawn into a sharp, straight, subulate or long, continuous, filiform, flexuous or unciform rostrum. Conidia pale brown below, gradually becoming sub hyaline towards apex of rostrum. A few (1–4) conidia from a primary head develop a single septum in the lower part, rostrum remaining continuous, or form a second septum in the middle or near the apex of the rostrum, and then changed into secondary conidiophores which apically form secondary heads of conidiogenous cells (Adapted from Rao et al. 1984).

 

Type species: Heliocephala proliferans V. Rao, K.A. Reddy & de Hoog

 

Notes: Heliocephala was introduced by Rao et al. (1984) with H. proliferans as type species. Heliocephala is characterized by the production of solitary macronematous conidiophores, producing terminal compact clusters of monoblastic conidiogenous cells that can arise more or less radially from short branches (metula-like) and produce obclavate, rostrate, or hooked conidia. Heliocephala was later emended to include species of Holubovaniella based on DNA sequence data and morphological characters by Heredia-Abarca et al. (2011). Holubovaniella was then synonymized as Heliocephala. The placement of Heliocephala is uncertain and is currently accommodated in Microthyriales genera incertae sedis.

 

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