Steccherinum amapaense Soares & Ryvarden

MycoBank number: MB 821088 Facesoffungi number: FoF 03641

Etymology: amapaense (Latin) = referring to the state of Amapá in Brazil, where the species was found.

Holotype: URM 89348

Basidiomata resupinate, white to cream (5E to 6F), up to 1 mm thick, soft when dry, separable from the substrate. Margin narrow, entire, white to cream (5E to 6F). Pores entire, round, regular, 6-8 per mm, dissepiment thin and entire, tubes concolorous, up to 1 mm deep. Context white to cream (5E to 6F), about 0,1 mm thick. Basidiospores ellipsoid to oblong-ellipsoid, 4–5 (6.5) × 3–3.5 μm, smooth, thin-walled, IKI-. Basidia clavate, with four sterigmata, 8‒10 (12) × 4–5 μm. Hyphal system “dimitic” (pseudodimitic), hyphae simple septate, septa sparse, thin- to thick-walled to solid, hyaline, 4–5 (6.5) μm in diameter. Cystidia absent.

Material examined: BRAZIL, AMAPÁ: Porto Grande, Floresta Nacional do Amapá, September 2013, A. Soares, AS 888 (URM 89348, holotype; O, isotype). BRAZIL, Amapá: Porto Grande, Floresta Nacional do Amapá, February 2014, A. Soares, M245 (URM 89349). GenBank numbers LSU:KY980666.

Notes: Steccherinum amapaense is recognized by the poroid hymenophore and lack of the pseudocystidia, deviating from the description of Eriksson et al. (1984). However, the new species seems to have the hyphal system described by Eriksson et al. (1984), with thick-walled hyphae and sparse septa. Moreover, Miettinen et al. (2012) stated that the Steccherinum clade is morphologically heterogeneous, including dimitic species with clamps and encrusted skeletocystidia as well as monomitic, simple-septate species without cystidia, and with both poroid and hydnoid hymenophore. Steccherinum amapaense clustered in the Steccherinum clade in our phylogenetic tree (0.60/59%) and seems to belong to Steccherinum sensu lato (Miettinen et al. 2012).

Maximum likelihood phylogenetic tree of the concatenated ITS1, 5.8S, ITS2 and partial 28S rDNA sequences. Bootstrap supporting values (1000 replicates) and posterior probabilities (PP) from Bayesian analysis to each node are shown from left to right. Only bootstrap values above 50% and PP above 0.75 are provided. The new species described in this study are in bold. The tree was rooted with Albatrellus syringae

Steccherinum amapaense (URM 89348, holotype). a Abhymenial surface. b Hyphae context. c Generative hyphae. d Basidiospores. Photos: R.L. Alvarenga. Scale bars a = 1 cm, b, c = 10 um, d = 5 um