Pusillomyces manuripioides

Pusillomyces manuripioides J.S. Oliveira, in Oliveira et al., Mycological Progress. 18(5): 718 (2019)

Etymology: The epithet is based on the strong similarity to Manuripia bifida Singer, a monotypic genus. The name Manuripia comes from Manuripi (Bolivia), the holotype locality of M. bifida.

Pileus 0.3–1.8 mm diam., orbicular, plano-convex, plane, to plano-infundibuliform or subinfundibuliform, center with a shallow papilla especially when young, some-times depressed, or papilla usually receding in old or larg-er pileus, disc and margin smooth, margin straight to slightly uplifted, edge entire; surface glabrous, dry, dull, papyraceous or subvelutinous; membranous at the margin, a little thicker, tough or coriaceous at the disc towards the center, context thin (< 1 mm), white to whitish cream; with brown to dark brown center or papilla, disc chestnut brown becoming yellowish brown or buff brown towards the margin, or paller , becoming cream when very fresh. Hymenophore smooth (lamellae absent), white to pale cream, papyraceous, dull, dry. Stipe 1–4×0.2–0.3 mm, central, filiform, very thin, equal, cylindrical, insititious, chitinous, hollow, glabrous, smooth, opaque, dark chestnut brown or very dark brown, growing directly from the substrate or more frequently arising from abundant, very elongate, hair-like rhizomorphs, concolorous with the stipes, part glabrous, part densely pubescent or even hirsute, resembling those found in Manuripia bifida, with dark brown to black pubescence.

Basidiospores 6–9 × (2.2)2.8–4.6(5) μm (xrm =6.9–7.4 × 2.8–3.6 μm, xmm =7.3 (± 0.3) × 3.3 (± 0.4) μm, Qrm =2–3.3, Qmm = 2.6 (± 0.7), n = 30, s = 3), obovoid, rarely shortly oblong, usually ellipsoid to subellipsoid, or amygdaliform, lacrymoid to subclavate, smooth, thin-walled, hyaline, inamyloid. Basidia (Fig. 5b) 20–27.5 × 5–7 μm, clavate, smooth, hyaline, thin-walled, inamyloid, 2–4sterigmata. Basidioles (Fig. 5c) 17–26.8 × 3.7–6.4 μm, clavate to broadly clavate, some with tapered apex, smooth, hyaline, thin-walled, inamyloid. Hymenial cystidia absent. Pileus trama inamyloid, irregular, non-gelatinized, packed, but also lacunose in some parts, especially at the central part of the context, forming a gradient, pale brownish near the pileipellis, fading to more hyaline near the hymenial layer, hyphae interwoven, cylindrical, 2–8.2 μm diam., regular in outline, branched, smooth, or more frequently incrusted (irregularly ornamented) towards the pileipellis, hyaline or some more opaque (wall thickness), thin- to more thick-walled next to the pileipellis, clamp connections absent. Pileipellis non-hymeniform, non-gelatinized, formed by a layer of disorganized elements or trichoderm, pale chestnut brown in 3% KOH with abundant and dominant Rameales-structures, some in transition to irregular iccus- or Rotalis-type cells, usually interconnected with smooth or incrusted hyphae of the pileus trama, main body 8.8–29 × 3.3–10.5(− 21) μm, hyphoid, branched, lobed or irregular, but clavate to cylindrical in the Siccus-/Rotalis-type cells, hyaline when isolated, smooth, thin-walled, inamyloid; diverticula apical or divergent to the laterals, generally short, 0.7–2.2 × 0.6–1.2 μm, vesiculose, verruciform, to shortly digitiform, sometimes branched, hyaline, solid, with obtuse and rounded apex. Stipe trama mostly inamyloid, or cortical hyphae apparently dextrinoid (at least in the stipe apex) or only orangish brown in Melzer’s reagent due to pigmentation, parallel, not compact, hyphae easily disassociating, then chestnut brown, losing pigmentation towards the inner trama, cylindrical, 3–8.4 μm diam., generally regular in outline, sep-tate, thick-walled, smooth or with granular incrustations, sometimes very prominent looking like diverticula, clamp connections absent; internal hyphae 2.5–7.4 μm diam.,with thinner walls, hyaline, usually smooth, sometimes rough, clamp-connections absent. Stipitipellis without elements or vesture on the glabrous stipes and rhizomorphs. Rhizomorphs corresponding to the stipe trama for the glabrous segments in micromorphology, but some pubescent segments densely covered by elongate, cylindrical to fusoid (tapered at the apex) conidia, 106–237.2 × 7.4–13.2 μm diam., presenting an apparent apical orifice, body with numerous septa, each short segment slightly inflated, thick-walled (including septa), dark brown, very distinct from the hyphae of the trama, non-fragmentary, but breaking at septal point when compressed, interconnected with one another at the base via connecting, thinner, irregular, sometimes branched, repent, similar segments, the whole structure forming the conidiophores which are immersed in the trama, but do not appear to have originated from the hyphae, reaction in Melzer’s reagent not distinctive due to the dark pigmentation.

Habit and Substrate: Manuripioid to gloiocephaloid (those basidiomata growing on the substrate, tiny, gregarious, epiphytic (about 1.5 m above the ground upward), forming abundant rhizomorphs in hanging living and dead leaves, attaching also on twigs, branches and limbs, specifically or frequently of Eugenia cf. subterminalis DC (Myrtaceae), in “campinarana”, sometimes in transition to “terra-firme”, Amazon Forest.

Index Fungorum number: IF827360

Figure 1. Bayesian 50% majority-rule consesus tree from the single locus (nrLSU) analysis of DATASET 1 [tree length (TL) (mean of the means from two runs), 23.821670; −lnL (mean), − 14,951.21]. Support values at the nodes consist of PP ≥ 0.95 and BS ≥ 70; unsupported nodes un-der PP 0.5 are collapsed. Thicker stems in black represent highly supported nodes, and those in gray are moderately to weakly supported nodes. Major clades are simplified, representing family level groups as depicted in figure. Outgroup consists of members of Clitocybe, Collybia, Entoloma, Lepista, Mycena s. str., and Tricholoma.

Figure 2. Bayesian 50% majority-rule consensus tree from the multilocus (combined nrITS and nrLSU) analysis of DATASET 3 (TL, 35.696274;−lnL, − 14,951.21). Support values at the nodes consist of PP ≥ 0.95 and BS ≥ 70; unsupported nodes under PP 0.5 are collapsed. Thicker stems in black represent highly supported nodes, and those in gray are moderately to weakly supported nodes. Outgroup consists of members of the clade Marasmiaceae.