Hygrocybe parviholatra Ralaiv., Liimat., A.M. Ainsw., Niskanen sp. nov.
Index Fungorum number: IF902407; Mycobank number: MB902407; Facesoffungi number: FoF 16068; Figs. 122b, 123c, 124c, 125c
Etymology – The name is derived from the Malagasy word holatra meaning a fungus and the Latin word parvus means small and refers to the small size of the basidiomata.
Holotype – K-M000251897.
Pileus 0.4–0.8 cm in diam, convex, red. Lamellae subdecurrent to decurrent, subdistant, thick, white. Stipe 1.3–2.3 cm long, 0.5–2 mm thick at the apex, mostly red and then white to brownish white at the base, cylindrical to somewhat clavate. Odour not recorded. Basidiospores 6–8×3.5–4.5 µm,±ellipsoid, smooth, hyaline in Melzer’s, monomorphic. Basidia 29–38.5×5.5–7 µm, sterigmata 3–4.5 µm long, subcylindrical to clavate, (1-)4-spored, clamped, monomorphic. Ratio of basidial to basidiospore length<5. Lamellar trama subregular. Pileipellis cutis, clamped, hyphae 3.5–5 µm wide. ITS sequences (GenBank OR785989, holotype): distinct from other species of Hygrocybe. Forming a well-supported clade (100% BS) with species from USA and Gabon and deviating from them by>4% (>25 substitutions and indels). They are placed outside as the basal lineage of the genus Hygrocybe with (100% BS).
Habitat – Humid, tropical, evergreen primary forest with no disturbance, on organic soil and with Lauraceae, Monimiliaceae, Cunnoniaceae, Rubiaceae and Euphorbiaceae Distribution: So far only known from Madagascar.
Material examined – Madagascar. Toamasina, Andasibe, Mantadia Nature Reserve, tropical humid forest, 25 Feb 2018, P. Eguia 000251897 (K-M, holotype), MAF18-257. Madagascar. Toamasina, Andasibe, Mantadia Nature Reserve, tropical humid forest, 23 Feb 2018, P. Eguia 000251837 (K-M), MAF18-199.
GenBank numbers – OR785989
Notes – The species can be identified by its small and fleshy basidiomata, red and convex pileus, two coloured-stipe that are mostly red and then white to brownish white at the base, and ellipsoid to ovoid basidiospores (6–8×3.5–4.5 µm). The mean ratio of basidial to basidiospore length<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