Hygrocybe vintsy Ralaiv., Liimat., A.M. Ainsw., Niskanen sp. nov.

Index Fungorum number: IF 902409; Mycobank number: MB 902409; Facesoffungi number: FoF 16070; Figs. 1f–g, 2e, 3e, 4e

Etymology – Named after the Malagasy magazine and club Vintsy. They specialize in raising awareness of the protection and conservation of the environment and are designed especially for young people. Vintsy is the local name of the Madagascar kingfisher (Corythornis vintsioides).

Holotype – K-M000252026

Pileus 0.7–1.4 cm in diam., plano-convex and depressed in the centre, orange to reddish-orange, yellow towards the margin. Lamellae subdecurrent to decurrent, subdistant, thick, white, becoming orange and whitish with age. Stipe 2.7–3.5 cm long, 2–2.5 mm thick at the apex, yellow-orange at the top, paler and more yellow towards the base, more or less clavate. Odour indistinct. Basidiospores 6.5–7.5(8) × (4–)4.5–5.5 µm, ellipsoid to ovoid, smooth, hyaline in Melzer’s, monomorphic. Basidia 36–55×6–8 µm, sterigmata 3–6 µm long, clavate, (1-)4-spored, clamped or not, monomorphic. The ratio of basidial to basidiospore length > 5. Lamellartrama subregular. Pileipellis cutis, clamped irregularly, hyphae 2–4 µm wide. ITS sequence (GenBank OR785987): Distinct from all other species of Hygrocybe and differing from e.g., H. sp. (GenBank no HM020688) and H. reidii (GenBank no. EU784347), placed in the same clade, by more than 10% (>70 substitutions and indels).

Habitat – Dry, deciduous, tropical forest, on sandy soil with Euphorbiaceae-Cephalocroton, Rubiaceae, Grevia, Salacia madagascariensis and Diospyros.

Distribution – So far only known from Madagascar.

Material examined – Madagascar. Mahajanga, Boeny, Ankarafantsika National Park, tropical dry forest, 13 Feb 2017, Meilinda Sulastri 000252026 (K-M, holotype), MAF17- 091.

GenBank numbers – OR785987

Notes – A plano-convex pileus with a depression in the centre that is orange to reddish-orange and yellow towards the margin as well as two coloured stipe that is paler towards the base and ellipsoid to ovoid spores 6.5–7.5(–8)×(4–)4.5–5.5 µm are typical for this species. It belongs to Hygrocybe subgenus Pseudohygrocybe and has the typical characteristics of that subgenus: the mean ratio of basidial to basidiospore length is>5. In addition, the lamellar trama is subregular and the basidia and spores are monomorphic.

Figure 1 – Basidiomata of the Hygrocybe species: a Hygrocybe minimiholatra 000251949 (holotype, K-M), b Hygrocybe parviholatra 000251897 (holotype, K-M), c Hygrocybe mitsinjoensis 000251832 (holotype, K-M), d Hygrocybe solis 000251894 (holotype, K-M), e Hygrocybe solis 000252075 (K-M), f, g Hygrocybe vintsy 000252026 (K-M). Photographs a Javier Galan, b Paul Eguia, c Tuula Niskanen, d Paul Eguia, e Tuula Niskanen, f, g Meilinda Sulastri. Scale bar 1 cm

Figure 2 – Basidiospores Hygrocybe species in Melzer’s. a Hygrocybe minimiholatra (K-M000251949, holotype). b Hygrocybe mitsinjoensis (K-M000251832, holotype). c Hygrocybe parviholatra (K-M000251897, holotype). d Hygrocybe solis (K-M000251894, holotype). e Hygrocybe vintsy (K-M000252026, holotype). Photographs Anna Ralaiveloarisoa. Scale bar=10 µm

Figure 3 – Basidia of the species of the genus Hygrocybe in Melzer’s. a Hygrocybe minimiholatra (K-M000251949, holotype). b Hygrocybe mitsinjoensis (K-M000251832, holotype). c Hygrocybe parviholatra (K-M000251897, holotype). d Hygrocybe solis (K-M000251894, holotype). e Hygrocybe vintsy (K-M000252026, holotype). Photographs Anna Ralaiveloarisoa. Scale bar=10 µm

Figure 4 – Pileipellis of the species of the genus Hygrocybe in Melzer’s. a Hygrocybe minimiholatra (K-M000251949, holotype). b Hygrocybe mitsinjoensis (K-M000251832, holotype). c Hygrocybe parviholatra (K-M000251897, holotype). d Hygrocybe solis (K-M000252026, holotype). e Hygrocybe vintsy (K-M000251894, holotype). Photographs Anna Ralaiveloarisoa. Scale bar=10 µm