Pluteus glaucotinctus E. Horak, Bull. Jard. Bot. Belg.

Jr, Nelson Menolli, Justo, Alfredo, Arrillaga, Pedro, Pradeep, C. K., Minnis, Andrew M. & Capelari, Marina, 2014, Taxonomy and phylogeny of Pluteus glaucotinctus sensu lato (Agaricales, Basidiomycota), a multicontinental species complex, Phytotaxa 188 (2), pp. 78-90 : 81-82

Pluteus glaucotinctus E. Horak, Bull. Jard. Bot. Belg. 47: 88, 1977 ( Fig. 2 )

Type description: — Pileus up to 80 mm wide, convex, broadly umbonate; surface fibrillose or glabrous, near gray or pale brown to tan, apex turning bluish gray when young. Lamellae free; pinkish. Stipe up to 120 × 8 mm, cylindrical; surface fibrillose, concolorous with the pileus above and bluish gray or greenish blue towards the base. Odor, taste none. Basidiospores [30/1/1] 6.5–9.0 × 5.0–6.5 μm (Q = 1.15–1.55; Qm = 1.33; Lm = 7.6 μm; Wm = 5.7 μm), broadly ellipsoid to ellipsoid, inamyloid, hyaline, smooth, thick-walled. Basidia not observed. Pleurocystidia 50–70 × 15.0–22 μm; lageniform with rounded to truncate apices, colorless, thin-walled; scattered to relatively common. Lamellar edge sterile. Cheilocystidia 45–61 × 12.0–17.0 μm; lageniform with rounded or sometimes with truncate apices, colorless or (a few) with pale brown intracellular pigment, thin-walled; crowded and forming a well-developed strip. Pileipellis a cutis; individual terminal elements 70–90 × 12.0–17.0 μm, cylindrical or fusiform, colorless or with brown intracellular pigment, thin-walled. Stipitipellis a cutis; hyphae 5.0–12.0 μm wide; colorless, thin-walled. Clamp connections not observed.

Distribution: —Africa: Known only from Democratic Republic of the Congo.

Specimen examined: — DEMOCRATIC REPUBLIC OF THE CONGO. Lake Edward and Kivu District: Panzi, May 1953, Goossens-Fontana 5274 (Holotype BR!; nrITS: HM 562131 ) .

Notes: — Pluteus glaucotinctus was described originally based on one African collection ( Horak 1977). A second collection was added in a subsequent description of the species ( Horak & Heinemann 1978). The nrITS sequence from the holotype (Goossens-Fontana 5274) is only 95 to 96 % identical with all other sequences in this species complex, including the other African collection studied by us (Thoen 5546). We could not obtain a tef1 sequence from the holotype, but based on nrITS data we consider the holotype to be the only collection to represent P. glaucotinctus sensu stricto.

Morphologically, the holotype collection is characterized by the broadly ellipsoid to ellipsoid basidiospores (Qm = 1.33), lageniform pleuro- and cheilocystidia with rounded to truncate apices, and the presence of pale brown intracellular pigment in some cheilocystidia. All of these characters should be checked in future collections to evaluate their reliability for morphological identification. Cheilocystidial pigmentation has been shown to be a variable character in other species of Pluteus , e.g., P. eludens E.F. Malysheva, Minnis & Justo ( Justo et al. 2011c) and P. phlebophorus (Ditmar) P. Kumm. ( Justo et al. 2011b), and, thus, it is not reliable for species rank identification.

Figures

FIGURE 2. Pluteus glaucotinctus (holotype). a. Pleurocystidia. b. Cheilocystidia. Scale bars: 10 μm. Line drawings a–b by A. Justo.