Pluteus canaliculatus (Pluteaceae: Agaricomycetes), a new species of Pluteus section Celluloderma from Turkey Author Kaygusuz, Oğuzhan Mycology Research Group, Faculty of Biological Sciences, Goethe University Frankfurt am Main, Max-von-Laue-Str. 13, D- 60438 Frankfurt am Main, Germany & Department of Plant and Animal Production, Atabey Vocational School, Isparta University of Applied Sciences, Isparta, Turkey Author Justo, Alfredo New Brunswick Museum, 277 Douglas Ave., Saint John, NB E 2 K 1 E 5, Canada Author Piepenbring, Meike Mycology Research Group, Faculty of Biological Sciences, Goethe University Frankfurt am Main, Max-von-Laue-Str. 13, D- 60438 Frankfurt am Main, Germany text Phytotaxa 2024 2024-07-03 658 2 136 150 http://dx.doi.org/10.11646/phytotaxa.658.2.2 journal article 10.11646/phytotaxa.658.2.2 1179-3163 Pluteus canaliculatus Kaygusuz, Justo & M. Piepenbr. sp. nov. ( Figs. 2–4 ) MycoBank:— MB852797 Holotype :— TURKEY . Burdur Province , Bucak district , in Sweetgum Forest Nature Protection Area , 37°21′41.8″N , 30°50′01.6″E , on decaying wood, in a Mediterranean forest dominated by Liquidambar orientalis Mill. , elev. 210 m a.s.l. , 22 October 2022 , leg. O . Kaygusuz ( OKA-TR2210 !, ISUF ). GenBank nrDNA ITS: PP464019. FIGURE 2. Pluteus canaliculatus : Basidiomata in their natural habitat. a–c. Specimen OKA-TR2210 (holotype). d–f. Specimen OKATR3239. Scale bars: 5 mm. Photos by: O. Kaygusuz. when young, later becoming grooved or channeled from the margin to near the centre as the pileus expands, resulting in streaks where the underlying layer becomes visible between the colored parts, light brown-yellow to reddish brown (7.5YR 7–6/8, 10 R 4/6–10), centre remaining darker. Lamellae free, thin, moderately crowded, ventricose, up to 2.5 mm broad, pale cream when young, soon pinkish brown, with ochre brown margin. Stipe 7.0–15.0 × 0.6–1.0 mm, cylindrical or somewhat broadened at the basis, slender, fragile; surface glabrous, shiny, silvery cream or pale brown, slightly longitudinally striate when old. Context in stipe and pileus, white or white creamy, thin, shiny in pileus. Smell indistinct. Taste not recorded. Basidiospores (n = 190 from 3 collections) 6.5–7.6–9.5 × 5.0–5.6–7.3 µm, Q = 1.13–1.75, Q av = 1.44, the majority ellipsoid, rarely broadly ellipsoid or oblong, guttulate, smooth, hyaline in 5 % KOH, thick-walled. Basidia 30–38 × 8– 10 μm, narrowly clavate to clavate, 4-spored, hyaline, thin-walled. Pleurocystidia (n = 80 from 2 collections) 65–100 × 12–21 µm, predominantly narrowly fusiform to fusiform, with a narrow, long pedicel, usually with a moniliform to flexuose neck up to 30 µm long, sometimes with apical finger-like excrescences, with evenly dissolved or sometimes condensed pale brown to yellowish brown intracellular pigment in 5 % KOH, thin-walled. Cheilocystidia (n = 70 from 2 collections) 30–60 × 7–15 µm, abundant, mostly narrowly clavate to clavate, with evenly dissolved or sometimes condensed pale brown to brown intracellular pigment in 5 % KOH, thin-walled. Pileipellis an euhymeniderm or a transition between a hymeniderm and an epithelium, composed of ellipsoid, subglobose to spheropedunculate to broadly clavate cells, 30–60 × 10–27 µm, and narrowly cylindrical, narrowly clavate to clavate and narrowly utriform cystidioid elements, 50–85 × 7.5–15 µm, usually with a narrow and long pedicel; both types with condensed brownish intracellular pigment in 5 % KOH, thin-walled. Caulocystidia not observed. Stipitipellis a cutis, 4–10 μm thick, made up of narrow, hyaline, thin-walled, cylindrical cells. Clamp connections absent in all parts examined. Habit, habitat, and distribution:— Basidiomata usually solitary, on rotten branches or buried wood of Liquidambar orientalis . To date only known from southwestern Turkey . Additional specimens examined:— TURKEY . Burdur Province , Bucak district , close to Karacaören , in Sweetgum Forest Nature Protection Area , 37°21′24.5″N , 30°50′00.1″E , on decayed wood of Liquidambar orientalis , elev. 274 m a.s.l. , 25 October 2022 , leg. O . Kaygusuz ( OKA-TR2272, GenBank ITS: PP464019) ; ibid., 37°21′28.2″N , 30°50′02.1″E , on decayed branches or logs of L. orientalis , elev. 269 m a.s.l. , 27 November 2022 , leg. O . Kaygusuz ( OKA-TR3238, GenBank ITS: PP464020) ; ibid., 37°21′31.7″N , 30°49′59.5″E , on L. orientalis , elev. 270 m a.s.l. , 28 November 2022 , leg. O . Kaygusuz ( OKA-TR3239 , GenBank ITS: PP464021) .