A new and unusual species of Hericium (Basidiomycota: Russulales, Hericiaceae) from the Dja Biosphere Reserve, Cameroon

Abstract

Tropical rainforests form the most species-rich biome on the earth. The Dja Biosphere Reserve (DBR) in Cameroon is a biodiverse tropical forest characterized in part by upland monodominant stands of the ectomycorrhizal (ECM) Gilbertiodendron dewevrei and ECM Uapaca spp. scattered along river banks. This mostly primary Guineo-Congolian evergreen forest harbors natural populations of large megafauna and numerous plant and fungal species. Studies have indicated that some ECM fungal groups of the large order Russulales are abundant in certain localities in the tropics, including the DBR. However, currently, other predominantly wood-decaying families of Russulales are poorly represented in Africa. For example, only three records of the saprotrophic genus Hericium (Russulales, Hericiaceae) are known from the African continent. Here, we describe a new species of Hericium recently collected from the DBR. Morphological characteristics and molecular phylogenetic analyses support placement of the Cameroonian collection in Hericium and its recognition as a new species within a larger H. coralloides species complex. The new species, H. bembedjaense, differs from H. coralloides in its smaller basidiospores (2.6–3.0\u2009×\u20091.7–2.2 μm compared to 3.5–5.0\u2009×\u20092.8–4.2 μm) and longer basidia (up to 27.0 μm compared to 15.0 μm). It differs from all other described Hericium species in the production of pleurocystidia. This is the first species of Hericiaceae known from sub-Saharan lowland tropical evergreen forests. This study highlights the need to increase fungal sampling in species-rich tropical forests such as those of the Congo Basin.