Characterised by yellow to orange-brown pileus, 7–12 × 4–7 μm smooth, thick-walled, ellipsoid basidiospores with cheilocystidia measuring 23–41 × 7–10 μm, clavate, thin-walled.

Holotype. Benin, Borgou Province, Tchaorou, Okpara Forest: 9°15.13'N, 2°43.05'E on soil in Woodland dominated by Isoberlina doka 12 June 2017, leg. AIGNON L.H, Voucher (HLA0367), GenBank accession: ITS (MN096199); LSU (MT536754).

Pileus 28–38 mm diam., umbonate, yellow (5A3) to orange brown (5C5), dark brown in middle, convex when young, plane at maturity, hard, surface rimose, dry. Lamellae emarginated, adnexed and decurrent, yellow brown (5B5). Stipe 27–39 × 5–6 mm, central, cylindrical, uniform; white, equal, solid, hard, base slightly swollen to bulbous, pruinose at the apex. Basidiospores (7.1) 9.2–11.2 (12) × (4.1) 5.7–7 (7.2) μm, avl × avw = 9.2 × 5.7 μm, Q = (1.2) 1.6–2.1 (2.5), avQ = 1.6, smooth, ellipsoid. Basidia 24–40 × 6–14 μm, clavate, 2–4 spored. Cheilocystidia 23–41 × 7–10 μm, clavate, thin walled. Pleurocystidia absent. Pileipellis a cutis thin-walled hyphae 4–16 μm diam., subparallel, compact hyphae, negative reaction of pileus surface in KOH. Stipitipellis a cutis hyphae 5–10 μm diam., septate, filamentous, thick, subparallel, compact. Caulocystidia 23–52 × 9–10 μm, utriform, rare, observed on the upper third of the stipe.

Currently known only from Benin in Soudano-Guinean zone.

Gregarious under Woodland dominated by Isoberlinia doka, I. tomentosa and Monotes kerstingii Gilg.

flavobrunneum referring to yellow to dark brown pileus.

Benin, Tchaorou, Borgou Province, Okpara Forest: 9°15.27'N, 2°43.40'E on soil in Woodland dominated by Isoberlina doka, I. tomentosa 13 June 2017, leg. AIGNON L.H, HLA0372, GenBank accession: ITS (MT534290); LSU (MT536756).

In the phylogenetic tree (Figure 1), Inosperma flavobrunneum is a sister of Inosperma sp. PC96013, an undescribed species from Zambia in Miombo woodland. Morphologically, I. flavobrunneum is similar to I. lanatodiscum by its yellow to orange-brown pileus, but differs from it by the smaller size of the basidiomata, larger basidiospores, ecological association with Fabaceae / Dipterocarpaceae Blume and distribution in West Africa. I. lanatodiscum is associated with a variety of hardwoods and conifers and is widely distributed from Europe to North and Central America (Kropp et al. 2013). The other related taxa are all African taxa not yet described, such as Inosperma sp. BB3233 from Zambia and the Democratic Republic of Congo, as well as Inosperma sp. G1842 distributed in south-eastern Africa, while I. flavobrunneum is distributed in West Africa.