Hygrocybe solis Ralaiv., Liimat., A.M. Ainsw., Niskanen sp. nov.
Index Fungorum number: IF 902408; Mycobank number: MB 902408; Facesoffungi number: FoF 16069; Figs. 1d–e, 2d, 3d, 4d
Etymology – Solis (Latin) means sun and refers to the colour of the basidiomata.
Holotype – K-M000251894
Pileus 1.5–2.5 cm in diam., convex and depressed in the centre, yellow to orange yellow. Lamellae adnexed to emarginate with a decurrent tooth, subdistant, thick, yellow. Stipe 4.5–8.5 cm, 4–5 mm thick at the apex, yellow to orange yellow, cylindrical. Odour not recorded. Basidiospores 9.5–12 × 6–8 µm, ellipsoid to ovoid, smooth, hyaline in Melzer’s, monomorphic. Basidia 34–61 × 6–15 µm, sterigmata 5–9.5 µm long, subclavate to clavate, (2-)4-spored, clamped, monomorphic. Ratio of basidial to basidiospore length ≤ 5. Lamellar trama subregular. Pileipellis cutis, some clamps seen, hyphae 3.5–6.5 µm wide. ITS sequences (GenBank OR785991, holotype): the two sequences are identical and form a well-supported clade (99% BS) with Hygrocybe macambrarensis from São Tomé and Príncipe and differing from it by 6.1% (39 indels and substitutions).
Habitat – Humid, tropical, evergreen primary forest with no disturbance, on organic soil, dominated by 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 000251894 (K-M, holotype), MAF18-254. Madagascar. Toamasina, Andasibe, Mantadia Nature Reserve, tropical humid forest, 23 Feb 2018, T. Niskanen 000252075 (K-M), MAF18-179.
GenBank numbers – OR785991
Notes – The yellow to orange-yellow basidiomata and large spores (9.5–12×6–8 µm) are typical for the species. Based on our phylogenetic analysis the species clusters together with species from Hygrocybe subgenus Pseudohygrocybe, but the mean ratio of basidial to basidiospore length is<5 like in the species of H. subgenus Hygrocybe. The species differs from its closest Hygrocybe macambrarensis by 39 indels and substitutions (6.1% interspecific differences).
gure 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