Tylopilus pygmaeus A. C. Magnago & R. M. Silveira 2017, sp. nov.
Creators: name: Magnago, Altielys Casale
name: Reck, Mateus Arduvino
name: Dentinger, Bryn T. M.
name: Moncalvo, Jean-Marc
name: Neves, Maria Alice
name: Silveira, Rosa Mara Borges Da
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Boletales
Boletaceae
Tylopilus
Tylopilus pygmaeus

description: Tylopilus pygmaeus A.C. Magnago & R.M. Silveira sp. nov. Fig. 4.   
Mycobank: MB 819524  
 Type: — BRAZIL, Bahia, Itacaré, Parque Estadual da Serra do Conduru, 30 November 2012, Col. Rezende DHC & Montoya CAS, Magnago AC 486 (holotype: FLOR 51612!) GenBank accession: ITS = MF113421, 28S = MF113429.   
 Etymology: — from the Latin pygmaeus = small, short; referring to the small size of the basidiomes.   
 Pileus 11−26 mm broad, at first parabolic, becoming plano-convex with age, brown (OAC 638) to tannish brown (OAC 721), velutinous, dry, becoming dark brown when bruised, margin slightly inrolled and entire when young; context 3−7 mm, cream (OAC 683). Tubes 3−6 mm long, adnate, slightly depressed around stipe, whitish then pale pinkish; pores 2−4 per mm, angular, staining light brown under pressure. Stipe 22−35 × 4−8 mm, central, sub-equal, glabrous to velutinous, cream to light pinkish brown; context cream (OAC 683); extreme base with white mycelium. Basidiospores 7−9 × 4−5 μm (Qm=1.69), ellipsoid in frontal view, the inner side applanate to phaseoliform in side-view, hyaline, inamyloid, smooth, thin walled, hilar appendage 0.5−1 μm long. Basidia 25−35 × 8−10 μm, clavate, thin walled, hyaline, inamyloid; 4-sterigmate, 3−4 μm long. Cystidia abundant on pores (cheilocystidia) and tubes (pleurocystidia), not differentiated from each other, projecting slightly or not, 24−39 × 8−11 μm, ventricose-rostrate to lageniform, the majority with golden brown contents, strongly dextrinoid but some hyaline and without contents. Hymenophoral trama boletoid in a gelatinized matrix, mediostratum of many narrow parallel to interwoven hyphae, 3−5 μm wide, these yellow to light yellow, lateral stratum hyphae 3−11 μm wide, hyaline, strongly divergent. Pileipellis a trichodermium consisting of erect to sub-erect terminal hyphae, cylindrical to fusoid, 28−73 × 8−10 μm, differentiated like pileocystidia, with golden brown contents and dextrinoid. Pileus trama interwoven; hyphae 4−6 μm wide, light yellow, some with granular dextrinoid contents. Stipitipellis hymeniform, terminal hyphae 23−42 × 7−11 μm, clavate to ventricose, with golden brown contents, strongly dextrinoid; caulobasidia present. Stipe trama subparallel to interwoven hyphae, vertically arranged, hyphae 3−10 μm wide, light yellow. Clamp connections absent. Macrochemical reactions: not observed. Spore print pinkish.   
 Habit and habitat: — Gregarious on sandy soil under broadleaf trees in Northeastern Atlantic Forest.   
 Additional specimens examined: — BRAZIL, Amazonas, Tylopilus arenarius Sing. Estrada Manaus-Caracaraí, km 45, 3 February 1978, Singer B 10590 (INPA- type !); Tylopilus potamogeton Sing. Rio Negro, 20 km ca. de São Gabriel da Cachoeira, 20 January 1978, Araujo, I. 938 (INPA!); Tylopilus aquarius var. aquarius, Igarapé do Tarumãzinho, 14 December 1978, Singer B 11433 (INPA- type !).   
 Comments: — Tylopilus potamogeton is morphologically similar to T. pygmaeus by having small basidiomes, a velutinous brownish pileus, and a whitish to pinkish hymenophore. Tylopilus potamogeton differs mainly by its cinnamon to fuscous umber stipe that is densely fibrillose and tomentose at the base, and the hymenophore does not turn brown when bruised. Microscopically the arrangement and appearance of cystidia, pileipellis and stipitipellis are similar, however, T. potamogeton has longer basidiospores (9−12 × 6−8 μm), cystidia that are hyaline, fusoid and mucronate. Tylopilus aquarius var. aquarius can be differed by the dimorphic basidiospores (8−11.5 × 5−7.5 and 11−16 × 5−6 μm), and versiforme cystidia. Tylopilus arenarius differs by the whitish to slightly lilac pileus, reticulation on the upper third of the stipe, larger basidiospores (7−9 × 4−5 μm) and cystidia that are fusoid to ampullaceous (Singer et al. 1983, Barbosa-Silva et al. 2017).
description: Published as part of Magnago, Altielys Casale, Reck, Mateus Arduvino, Dentinger, Bryn T. M., Moncalvo, Jean-Marc, Neves, Maria Alice & Silveira, Rosa Mara Borges Da, 2017, Two new Tylopilus species (Boletaceae) from Northeastern Atlantic Forest, Brazil, pp. 250-260 in Phytotaxa 316 (3) on pages 256-257, DOI: 10.11646/phytotaxa.316.3.4, http://zenodo.org/record/13696207