Gymnopanella nothofagi

Gymnopanella nothofagi Sandoval-Lieva, J.V. McDonald & Thorn, in Sandoval-Leiva et al., Mycologia 108(4): 821 (2016)

Etymology: named for its occurrence on Nothofagus.

Pileus rounded flabelliform to reniform, applanate to convex or conchate, up to 36 × 20 mm, gelatinous when fresh, brittle when dry; light reddish brown to vinaceous red, lighter to translucent to the margin, surface rugulose following outline of lamellae. Hymenophore concolorous to somewhat lighter, anastomosing, up to 13(–22) main veins with interconnecting cross veins at a lower level than the main veins. Stipe lateral, up to 4 × 2.5 mm, dark reddish brown, smooth (rarely rough). Pileipellis a cutis of cylindrical, thick-walled hyphae, 2.5–4.0 µm diam, rarely branched, clamped and coarsely incrusted with ring-like yellowish deposits in the cell walls, hyphal extremities at the surface sometimes aggregated in suberect fascicles, producing a squamulose aspect to pileus. Trama 500– 800 µm deep, a gelatinous matrix, dense, with subparallel to tangled hyphae, 4.5–6.0 µm diam, with abundant clamp connections and fine ring-like incrustations. Subhymenium ramose. Hymenium a palisade of clavate basidioles; basidia clavate, four-spored, 38–44 × 6.5–8.0 µm, hyaline to clear yellow-brown; cheilocystidia present along gill edges, many with a long hook at the apex, hyaline, clavate to broadly fusiform, 35–60 × 5.0–8.0 µm. Basidiospores white in print, ellipsoid, hyaline, smooth, thin-walled, inamyloid, not dextrinoid, (6.0–)6.8–8.0(–9.0) × (4.0–)4.5–5.2(–6.0) µm, Q = 1.3–1.7 (n = 133).

Known distribution: Chile, Region (and Province) of Aisén.

Index fungorum number: IF814816

Notes: This Chilean agaric first was identified tentatively as Resupinatus merulioides (reported from Japan and Australia/New Zealand) because of morphological similarities of basidiome color and the reticulated gill network on the surface of the hymenium. However, it is unrelated to Resupinatus and instead constitutes a new clade within the larger marasmioid, gymnopoid and campanelloid tree. It differs from Resupinatus merulioides and the Resupinateae by the unusual hyphae in the pilea trama that have spirally thickened cell walls, a character not present in any Resupinatus species. Because this species appears to be restricted to Nothofagus forests in South America, more collection effort should be made in areas where this type of forest is prevalent to determine the actual species range.

Figure 1. Simplification of a neighbor-joining tree of the marasmioid-gymnopoid clades based on ITS–5ƍ-28S rDNA, with node support from Bayesian analysis (posterior probabilities out of 100, above nodes) and from 1000 bootstrap replicates in BioNJ (out of 100, below nodes). Width of triangles is proportional to the number of terminal taxa included (see SUPPLEMENTARY FIG. 1). Clades and taxa are labeled according to Wilson and Desjardin (2005). M and O to the right of major nodes refer to Marasmiaceae and Omphalotaceae, respectively.