Entoloma sicoense Fachada, Pedreiro, Raimundo, Noordel., Dima & Marques 2023, sp. nov.

Entoloma sicoense Fachada, Pedreiro, Raimundo, Noordel., Dima & Marques sp. nov. (Figs. 2, 3)

MycoBank: 848870

Diagnosis: Entoloma sicoense mostly produces slender basidiomata of a slate gray color, a concolorous smooth stipe, a sterile gill edge rich in brilliant granules and scattered intracellular blue pigment, which is often overtaken by brown pigment in maturation. It inhabits warm temperate broad-leaved forests. This combination of characters, together with the ITS region, sets it apart from other known Entoloma species.

Etymology: Refers to ‘Sico´’, the type locality.

Holotype: — PORTUGAL. Serra de Sico´, Ansia˜o, Santiago da Guarda (WGS84 coordinates: 39.938305, -8.494221, elev. 254 m); 15 November 2020; on Hypnum cupressiforme Hedwig (1801: 291) covering calcareous rocks, in mixed dense forest composed mainly of Arbutus unedo, Quercus faginea and Quercus coccinea; plenty of Ruscus aculeatus Linné (1753: 1041) and Smilax aspera Linné (1753: 1028) also present, on alkaline soil; leg. Vasco Fachada. Holotype PO-F2244!; isotype priv. herb. V.F VF151120ES1!.GenBank ITS: OR026624.

Description:— Basidiomata mycenoid-collybioid. Pileus 10–40 mm convex soon expanding to plano-convex, later applanate, often eventually with wavy margin, with a depressed and somewhat umbilicate center,weakly hygrophanous, clearly translucently striate (often up to the center), frequently pale slate gray (Mu 2.5PB 7/2, 7/4, 6/4 to 2.5B 6/2) with faint dark violaceous tones (Mu 10PB 1/12) (Fig. 2a,b) less commonly dark brownish gray with violaceus brown tinges (10RP 4/2, 2/2) (Fig. 2e), almost always darker in the center, very finely fibrillose at the margin to subsquamulose, especially in the center (Fig. 2b). Lamellae L = 20–30, l = 1–5, adnate-emarginate or with short decurrent tooth, first whitish sometimes with soft blue tinge, soon becoming pinkish beige, edges mostly concolorous, sometimes marginated dark brownish blue, especially at maturity. Stipe 40–65 × 2–4 mm; relatively long and thin, slate gray with bluish tinge, usually rather pale, sometimes maturing to darker violaceus gray, rather concolorous with pileus, polished, sometimes lined dark blue to violaceus at the very apex where the decurrent gill meets the stipe as a continuation of the colored gill edges, base sometimes darker blue with white basal mycelium (Fig. 2c). Context concolorous or slightly paler than stipe surface. Smell pleasant and sweetish, taste not distinctive.

Basidiospores 8.4–12.5 × 5.3–8.7 µm (av. 9.0–10.8 × 6.5–7.4 µm, Q = 1.2–1.8, Qav = 1.3–1.6; with 5–7 (8) rather pronounced and sharp angles in profile view (Fig. 3d, f). Basidia 20–32 × 7.5–13.5 µm), tetrasporic, claviform, clampless, hyaline but often pigmented light blue (Fig. 3c). Lamella edge mostly sterile but occasionally heterogeneous, consisting of clavate, often catenated (usually> 1 septum) cheilocystidia, 27–100 × 8–14 µm, mostly with brown intracellular pigment (especially at maturation), rich in brilliant granules (Figs. 3a,f,g). Hymenophoral trama regular to subregular, made up of cylindrical hyphae, 3–13 µm wide, hyaline but often with very pale brown to light blue intracellular pigment (Fig. 3c). Pileal trama frequently with blue intracellular pigment. Pileipellis a cutis with transition to a trichoderm, composed of clavate to subglobose terminal elements, 40–90 × 10–30 µm, with variable intracellular pigment from blue (Fig. 3b) to strong brown at maturity. Brilliant granules common to abundant, especially in the cheilocystidia (Fig. 3e,g). Clamp connections not observed in any tissue.

Habitat and known distribution:—The two collections of E. sicoense were growing on mossy surfaces, covering large calcareous rocks and occasionally the soil (Fig. 4). This moss, Hypnum cupressi forme, is a species common to forests dominated by A. unedo and Q. faginea in Sicó and west mainland Portugal (Vieira et al. 2012).

Additional Portuguese records were found from environmental sequences (UDB05338481; UDB05338478) originating from the Madeira archipelago, in laurisilva forests dominated by Laurus novoca- nariense Rivas Mart., Lousa˜, Fern.Prieto, E.D´ýas, J.C. Costa & C.Aguiar (2002: 703), Clethra arborea Aiton (1789: 73), Picconia excelsa (Aiton) Candolle. (1844: 288) together with the introduced Quercus rubra Linné (1753: 996).

To date, E. sicoense is only known from Portugal, ranging from the western Iberian Peninsula to southern Macaronesia.

Other material examined: — PORTUGAL. Serra de Sico´, Ansia˜o, Santiago da Guarda (WGS84 coordinates: 39.939767, -8.492875, elev. 250 m); 03 Dec 2022; on Hypnum cupressiforme covering calcareous rocks, in mixed dense forest composed mainly of Arbutus unedo, Quercus faginea and Quercus coccinea; plenty of Ruscus aculeatus and Smilax aspera also present, on alkaline soil, exactly the same ecology as the holotype (Fig. 3d,f); leg. Helder Pedreiro. Paratype PO-F2252!; isoparatype priv. herb. V.F VF031222EM1!. GenBank ITS: OR026625.