Taeniolella
Taeniolella S. Hughes, Can. J. Bot. 36: 816 (1958).
Index Fungorum number: IF 10170; Facesoffungi number: FoF 06570, 60 morphological species (Species Fungorum 2022), 12 species with molecular data.
Pathogenic on host. Sexual morph: Unknown. Asexual morph: Colonies scattered on bark, effuse or more or less restricted to lenticels, reticular, caespitose to velvety, sometimes scattered in small tufts or sometimes dense and narrowly oval, somewhat sooty, confluent, black; bark rarely discolored, reddish brown. Mycelium immersed and partly superficial, composed of flexuous hyphae, branched, septate, not constricted at the septa in narrow hyphae, sparingly to distinctly constricted at the septa in wider hyphae, sub hyaline to dark brown, smooth, wall somewhat thickened. Hyphae sometimes aggregated in scattered, immersed to partly superficial, flattened cell layers 1 to 4 cells thick, forming stromata or penetrating deeply into the tissue and forming a continuous or interrupted, superficial or partly immersed, crust-like stroma composed of brown to dark brown irregularly shaped cells. Conidiophores seldom micronematous, reduced to conidiogenous cells, usually semi-macronematous to macronematous, mononematous, arising from hyphae, terminal or lateral, or from stroma cells, mostly in small caespitose tufts of 3−10 conidiophores, sometimes solitary, erect, straight, unbranched, subcylindrical, conidiophores with attached conidia, 1–11-septate, slightly or distinctly constricted at the septa, dark brown, paler towards the apex, smooth; wall thickened, often thinner towards the apex; granular cell plasma mostly reduced, with a central vacuole-like cavity, surrounding plasma giving the impression of very thick, three-layered walls, up to 3 µm wide, frequently enteroblastically proliferating with obvious sheath-like wall remnants visible as an irregular collar. Conidiogenous cell integrated, terminal, monoblastic, monopodial, determinate, subcylindrical, doliiform, attenuated at the tip; loci truncate to convex, unthickened, lateral wall thickened, forming a small rim. Distinction between conidiophores and conidial chains difficult. Conidia catenate, usually in unbranched chains, up to five conidia per chain, straight to slightly curved, doliiform, subcylindrical to nearly obclavate, (0–)1–7(–13)-euseptate, sometimes also with 1–2 intermixed distosepta, mostly constricted at the septa, brown to dark brown, paler near the apex in secondary conidia, outer wall smooth or seldom roughened, slightly thickened, up to 0.75 µm wide, granular cell plasma mostly reduced, with a central vacuole-like cavity, surrounding plasma giving the impression of very thick, three-layered walls, apex rounded in primary conidia, truncate or often slightly obconically truncate in secondary ones, base truncate, sometimes narrowed towards the base, hila truncate to convex, thickened lateral wall sometimes visible as conspicuous rim, sometimes microcyclic conidiogenesis observed (adapted from Ertz et al. 2016).
Type species: Taeniolella exilis (P. Karst.) S. Hughes
Notes: Taeniolella is an asexual genus characterised by having little discerned (semi-macronematous), typically unbranched conidiophores with integrated, terminal, monoblastic, non-cicatrized conidiogenous cells, and pigmented, 1- to pluriseptate conidia produced in mostly long acropetal, not easily disarticulating chains. Most lichenicolous Taeniolella species are characterised by amero- to phragmosporous conidia. An asexual morph for the ascomycete Mytilinidion gemmigenum was reported by Minter and Holubová-Jechová (1981) whereby Taeniolella was referred as the asexual morph of Glyphium and was placed in Mytilinidiaceae without phylogenetic evidence (Kirk et al. 2008, Hyde et al. 2013). Ertz et al. (2016) provided the first phylogenetic study of Taeniolella and included a number of taxa together with two cultures of the type species of the genus Taeniolella. Taeniolella is strongly polyphyletic with species distributed between Dothideomycetes and Sordariomycetes (Ertz et al. 2016). Recently, Hongsanan et al. (2020b) excluded Taeniolella from Kirschsteiniotheliaceae which is in agreement with previous studies of Heuchert et al. (2018) and Dong et al. (2020) where freshwater species of Taeniolella were not congeneric with Taeniolella sensu lato. The taxonomic placement of Taeniolella is confusing and needs revision. Molecular markers available for Taeniolella are ITS, LSU, SSU and TEF-1.
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