A SYNOPSIS OF THE WOOD-DECAY GENUS LAXITEXTUM (HERICIACEAE, RUSSULALES, BASIDIOMYCOTA) AND A NEW SPECIES FROM CAMEROON

Descriptions of and a key to the globally known species of the genus Laxitextum are provided. A new species from Cameroon, Laxitextum globisporum , is described.

Laxitextum species can be differentiated from those of other stereoid genera with resupinate to bracket-like basidiomata by their smooth, pale-coloured hymenophores, enclosed gloeocystidia, and echinulate amyloid basidiospores. Our recent fieldwork from 2014 to 2019 has focused on ectomycorrhizal fungi associated with monodominant forests of the ectomycorrhizal canopy tree Gilbertiodendron dewevrei (De Wild.) J.Léonard in Cameroon. Wood-decay fungi have also been collected during this time. Here, we provide a global synopsis of known species of Laxtitextum and describe a new Cameroonian species as L. globisporum, based on its globose basidiospores.
Laxitextum, although a species-poor genus as currently known, is well characterised by its combination of stereoid basidiomata with brown trama and a white or pale-coloured subhymenial layer, enclosed or partly projecting gloeocystidia, and amyloid, echinulate basidiospores.
Hyphal system monomitic; hyphae of the brown trama distinct, with thin or somewhat thickened walls, light brown in the microscope, usually 2.5-4 μm wide; subhymenial hyphae thin-walled, in old basidiomata partly collapsed and forming a hyphal net with irregular meshes, penetrated by very thin-walled, cytoplasm-filled generative hyphae, these 1-3 μm wide.
Distribution. Cosmopolitan to 70°N in Norway.
Laxitextum bicolor is rather easy to recognise because of the contrasting brown upper and white lower colours and soft consistency. Hyphal system monomitic; hyphae with clamps; tramal hyphae loosely interwoven, pale yellow, 3-5 μm wide; oleiferous hyphae abundant in subhymenium and trama, yellow, distinctly amyloid, 4-6 μm wide.

Substratum. On decayed tropical hardwood stump.
Distribution. Known only from the type locality in the Dja Biosphere Reserve, Cameroon.

Laxitextum incrustans
Basidiomata resupinate, widely effused, often loosening from substratum along the margin; hymenial surface smooth, cream to ochraceous, more or less cracked in dry condition.
The species is similar to Laxitextum bicolor but differs in its deep yellow upper surface, amyloid gloeocystidia, and smaller basidiospores.