Tyromyces amazonicus Soares & Ryvarden

MycoBank number: MB 821089 Facesoffungi number: FoF 03642

Etymology: the name refers to the locality where it was collected.

Holotype: AS1836

Basidiomata annual, pileate to resupinate, dimidiate to flabelliform when pileate. Pileus 1.5–3.5 cm wide, 1–2 cm long, up to 3 mm thick at base, slightly zonate, woody brown (umber 18). Margin obtuse, brown (snuff brown 12), white in old specimens (4D). Pore surface pale ochraceous to cream (5E−6F), pore round to angular, 2–4 per mm, dissepiment thin and entire, tubes concolorous, up to 1 mm deep. Context white to cream (2B), up to 2 mm. Basidiospores subglobose to broadly ellipsoid and slightly curved, 3.5–5.5 × 1.3–2.0 μm, smooth, thin-walled, with tiny or without apiculus, IKI-. Basidia clavate, with four sterigmata, 10.5–16 × 5–6.5 μm. Hyphal system dimitic, generative hyphae clamped, thin-walled, hyaline, 2.5–3.5 μm diameter; skeletal hyphae thick-walled, hyaline, 4.5–5 μm diameter; trama dominated by interwoven skeletal hyphae (2.0−3.0 mm) with a well-visible lumen, generative hyphae narrow (1.5−2.5 mm). Cystidia absent, but bottle-shaped cystidioles present, 8–16.5 × 5–10.5 μm.

Material examined: BRAZIL, Amapá: Porto Grande, Floresta Nacional do Amapá, on dead hardwood, 00° 58. 25.8 N and 051° 41 73.6 W, October 2014, A. Soares, AS 1836 (URM AS 1836, holotype; O, isotype). GenBank numbers ITS:KY980674; LSU:KY980667.

Notes: Tyromyces amazonicus is easily recognized by the dimidiate to resupinate, brownish basidiomata and the round to angular, 2–4 per mm, pores. The presence of bottle-shaped cystidioles is similar to those of Obba valdiviana (Rajchenb.) Miettinen & Rajchenb., but this species has encrusted tramal hyphae not seen in T. amazonicus. Obba is placed in the “Gelatoporia clade” either as sister group of the clade composed by “Antrodia clade” + “Tyromyces clade” or as sister group of the “core polyporoid clade” (Binder et al. 2013). The new species may represent a new genus in the “Gelatoporia clade”, but for the time being we will keep it in Tyromyces because of the morphological similarities.

Tyromyces amazonicus and other specimens morphologically similar to each other were originally assigned to Antrodiella sensu lato. However, they clustered in Flaviporus, Trulla and Tyromyces.

Flaviporus is a tropical genus characterized by the small and thin basidiomata, small pores, small and ellipsoid spores and the dimitic hyphal system with clamp connections (Ginns 1980). The specimens of this clade were identified as F. liebmanii, which has tramal cystidia, sometimes hard to visualize. Although the main clade of F. liebmanii has high statistical support (0.90/85), the genetic variation among the species is very high and the specimens may represent at least two species. Miettinen et al. (2012) suggested this is caused by parallel evolution, by which basidiomata morphology can remain unchanged while nrDNA undergoes major changes.

Miettinen and Ryvarden (2016) introduced the new genus Trulla based on Miettinen et al. (2012) to accommodate neotropical species of Antrodiella with monomitic context and the dimitic trama, differently from Antrodiella sensu stricto with dimitic context and trama and from the temperate zone. Trulla meridae Miettinen & Ryvarden and T. dentipora (Ryvarden & Iturriaga) Miettinen & Ryvarden are the first records to Brazil and both were previously known only to Venezuela (Ryvarden and Iturriaga 2003; Miettinen and Ryvarden 2016). Additionally, T. meridae was only described morphologically and in this study it is confirmed by molecular data as belonging in this genus.


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

Tyromyces amazonicus (URM AS1836, holotype). a Dried basidiomata. b Hyphal system. c Bottle-shaped cystidioles. d Basidiospores. Photos: A.M. Soares. Scale bars a = 1 cm, b, c = 10 um, d = 5 um