Acantholichen Marcano, 2022, s.str.
Creators: name: Marcano, Vicente
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Hygrophoraceae
Acantholichen

description: Key to Acantholichen, Cyphellostereum and Dictyonema s.str. in Venezuela
1a. Thallus microsquamulose to microfruticulose, pruinose; squamules densely and dichotomously branched from the tips; photobiont forming clusters of short, irregularly coiled threads (chroococcoid) inside the thallus microsquamulose; soredia absent; upper and lower surfaces in microscope view forming apically thickened, distinctly spiny, pyriform to subglobose, variable in size, sometimes elongate hyphae (acanthohyphidia); clamp connections absent............................................. Acantholichen dendroideus
1b. Thallus composed of distinct fibrils including cyanobacterial filaments (Rhizonema); acanthohyphidia absent; clamp connections present or absent ................................................................................................................................................................................2
2a. Thallus directly on bark of trunks or branches; lobes semicircular and/or hemispherical, variable in color, size and shape; basidiocarp N–; Venezuelan Andes or Guayana Highlands................................................................................................................................ (3)
2b. Thallus on mosses, liverworts or soil, appressed filamentous or loose and not forming semicircular lobes; basidiocarp N+ or N–; Venezuelan Andes (Sierra Nevada de Mérida) ............................................................................................................................... (4)
3a (2). Thallus on tree branches; lobes projecting parallel from the substrate, semicircular and hemispherical, variable in color, size and shape; surface hirsute; clamp connections present; basidiocarp with resupinate patches dispersed on the underside and resembling large, irregular attachment, hapters, margin fibrillose; Venezuelan Andes (Sierra Nevada de Mérida) ..... Dictyonema subsericeum
3b. Thallus on tree trunk, shelf–like filamentous, forming semicircular lobes, projecting upright from the substrate, surface areolate, rugose; clamp connections absent; basidiocarps forming irregular, reticulate, resupinate patches dispersed on the underside, margin entire; Guayana Highlands (Cerro Duida, Alto Orinoco).................................................................................. Dictyonema duidense
4a (2). Hymenophore resupinate; jigsaw-puzzle-shaped hyphal sheath present or absent; prothallus absent; clamp connections present or absent.............................................................................................................................................................................................. (5)
4b. Hymenophore corticioid; jigsaw-puzzle-shaped hyphal sheath present; prothallus present; clamp connections present .............. (6)
5a (4). Jigsaw-puzzle-shaped hyphal sheath absent; fibrils not penetrated by tubular fungal hyphae haustoria, horizontally arranged and closely appressed; cyanobacterial filaments 8–10 μm wide; clamp connections present; basidiocarp surface finely arachnoid, N– ................................................................................................................................................................ Cyphellostereum mucuyense
5b. Jigsaw-puzzle-shaped hyphal sheath present; fibrils penetrated by tubular fungal hyphae haustoria, ascendent and loosely arranged; cyanobacterial filaments> 10 μm wide; clamp connections present or absent; basidiocarp surface smooth, N+ (pink) ......................................................................................................................................................................................................... (7)
6a (4). Fibrils irregularly arranged, ascending or erect; cyanobacterial filaments not divided, 20–25 μm wide; hymenophores forming stereoid-corticioid patches, upper surface smooth, lower surface pruinose, spongy, N+ (red)......................... Dictyonema andinum
6b. Fibrils horizontal or subascending; cyanobacterial filaments divided, 13–17 μm wide hymenophores raised from the thallus, resembling apothecial discs, surface pale yellowish, smooth, margins white, minutely tomentose; N .......... Dictyonema umbricola
7a (5). Thallus developing a mat of interwoven fungal–cyanobacterial fibrils, leaving interspaces; cyanobacterial filaments 12–15 μm wide; clamp connections present; basidiocarp developed as effuse patches, with pruinose surface, margins slightly involute ......... .................................................................................................................................................................... Dictyonema subinvolutum
7b. Thallus forming a thin crust (1.75–2 mm), bordered by a discontinuous, narrow, white margin projecting vertical from the substrate; cyanobacterial filaments 12–17 μm wide; clamp connections absent; basidiocarp hapteriform, with finely reticulate surface ......... ............................................................................................................................................................................... Dictyonema laurae
description: Published as part of Marcano, Vicente, 2022, Eight new species of lichenized Basidiomycota in the genera Acantholichen, Cyphellostereum and Dictyonema s. str. (Agaricales, Hygrophoraceae) from northern South America, pp. 199-225 in Phytotaxa 574 (3) on page 220, DOI: 10.11646/phytotaxa.574.3.1, http://zenodo.org/record/7380966