Amauroderma calcitum Costa-Rezende & Drechsler-Santos, 2016

Costa-Rezende, Diogo Henrique, Gugliotta, Adriana De Mello, Góes-Neto, Aristóteles, Reck, Mateus Arduvino, Robledo, Gerardo L. & Drechsler-Santos, Elisandro Ricardo, 2016, Amauroderma calcitum sp. nov. and notes on taxonomy and distribution of Amauroderma species (Ganodermataceae), Phytotaxa 244 (2), pp. 101-124 : 109-111

Amauroderma calcitum Costa-Rezende & Drechsler-Santos sp. nov. Fig. 3 a–c , 8 c

Mycobank:—812846.

Diagnosis:—Basidiome stipitate, pileus up to 6.0 mm thick, with a reddish brown, slightly shiny pilear surface, pale context, brown and slightly velvety stipe, large lacerate pores, hyphal system dimitic and pale yellowish, broadly ellipsoid to ellipsoid basidiospores [11–14 (15) × (7) 8–10.5 (11) μm]. Similar to A. calcigenum and A. partitum ; differing from A. calcigenum by its narrower basidiospores [(7) 8–10.5 (11) μm vs 10–12 (12.5) μm] and coriaceus pileus, and from A. partitum by presenting a thicker pileus (2.5–6.0 mm vs 0.9–1.1 mm thick).

Etymology:— “ calcitum ” is a neologism referring to its intermediate morphology when compared to A. calcigenum and A. partitum .

Holotype:— BRAZIL. MATO GROSSO: Chapada dos Guimarães, Chapada dos Guimarães National Park , 07 Jan 2013, D.H. Costa-Rezende 105 ( FLOR52230 ) . Isotype in HUEFS.

Basidiomata stipitate, mesopodal, pleuropodal or pseudomesopodal, single to occasionally two fused pilei, with superposed pileus (unusual) on the upper surface; pileus 25–70 mm in diameter, up to 6.0 mm thick, circular, subinfundibuliform or almost flattened to slightly convex, deeply umbilicate at center in younger specimens, coriaceous when fresh, coriaceous to corky when dry; margin acute to obtuse, regular and entire. Pilear surface slightly shiny, dark reddish brown 2.5YR (3/4, 2.5/4) with very dusky red (2.5/2) concentric zonation, slightly sulcate, radially finely strigose (under the lens), glabrous. Context firm, almost white to pale yellow 2.5Y (8/4), with or without one or two brown lines coming from the stipe and a thin dark cuticle, 0.5–1 mm thick. Tubes concolorous with context, up to 5 mm long. Pore surface concolorous to slightly darker than the context in young specimens, to pale brown 10YR (6/3) in fully developed basidiomata; pores circular and regular in young specimens to angular and irregular in older ones, 1–2 (3) per mm, (400) 450–900 (1000) μm in diameter, (ave = 657.9 μm); dissepiment entire or lacerate to almost irpicoid, (50) 60–180 (200) μm, (ave = 127.1 μm). Stipe solid to tubular in some portions, straight to slightly tortuous, up to 100 mm long and 5 mm in diameter; surface velutinose (under the lens), brown 10YR (5/3); context concolorous with pilear context, with two brown bands at least near the pileus; cuticle distinct brown.

Pilear surface composed of clamped generative hyphae, 3–5 μm in diameter, thin to slightly thick-walled and intermixed with solid skeletal hyphae, both parallel to the contextual hyphae. Hyphal system dimitic; context composed of clamped generative hyphae, (2) 3–5 μm in diameter, hyaline, thin-walled; and skeletal hyphae aciculiform or with two terminal branches, 5–6 μm in diameter, up to 900 μm without branches, hyaline to pale yellowish, straight or tortuous, thick-walled to almost solid; trama of tubes composed by clamped generative hyphae, 3–5 μm in diameter, hyaline, thin-walled; and skeletal hyphae aciculiform or with few apical branches (2–4) in variable size, 4.5–6 μm in diameter, up to 700 μm long (basal clamp not observed), some skeletal hyphae with a few lateral aborted branches, both in the main stalk and branches, variably dextrinoid. Hyphal pegs conical, 130 × 20 μm, variably present. Basidia clavate, 35–50 × 15–30 μm. Basidiospores broadly ellipsoid to ellipsoid, 11–14 (15) × (7) 8–10.5 (11) μm, (ave = 12.8 × 9.4 μm), Q = 1.24–1.61, (ave-Q = 1.37), pale yellowish, double-walled with the inner layer finely and regular ornamented, IKI-.

Substrate:—Growing always on the ground associated with roots of undetermined angiosperms.

Distribution:—So far known from the Cerrado, in Mato Grosso state, Brazil.

Other specimens examined:— BRAZIL. Mato Grosso: Barra do Garças, Serra do Roncador, Trail R14 , 31 May 1968, D.M. Vital (SP 102719) ; Chapada dos Guimarães, Parque Nacional da Chapada dos Guimarães , sitio Vale do Rio Claro , 15 May 2011, Costa-Rezende DHCR031 ( FLOR 52168 ) ; 07 January 2013, Costa-Rezende DHCR104 ( FLOR 52226 ) ; Costa-Rezende DHCR 111 ( FLOR 52228 ) ; Costa-Rezende DHCR 106 ( FLOR 52229 ) ; Costa-Rezende DHCR107 ( FLOR 50931 ) ; 12 January 2014, Pereira-Silva LPS007 ( FLOR 52234 ) ; Pereira-Silva LPS009 ( FLOR 52231 ) ; Pereira-Silva LPS 015 ( FLOR 52233 ) ; Pereira-Silva LPS016 ( FLOR 52235 ) ; Pereira-Silva LPS019 ( FLOR 52236 ) ; Pereira-Silva LPS069 ( FLOR 52232 ) ; Pereira-Silva LPS081 ( FLOR 52237 ) ; Sitio Véu da Noiva , 27 November 2012, Alves-Silva GAS071 ( FLOR 52238 ) ; Alves-Silva GAS072 ( FLOR 52239 ) ; Alves-Silva GAS074 ( FLOR 52240 ) ; Primavera do Leste, near to Lagoa Vô Pedro Piana , 27 March 2013, Costa-Rezende DHCR 130 ( FLOR 52243 ) ; APP Instituto Matogrossense do Algodão, near to Córrego Alminhas , 22 December 2013, Alves-Silva GAS549 ( FLOR 52241 ) .

Comments:— Amauroderma calcitum is macroscopically characterized by its robust basidiomata (pileus 2.5– 6.0 mm thick) with a reddish brown, slightly shiny pilear surface, a pale context with or without brown bands, a brown, robust (in mature specimens) and slightly velvety stipe up to 5 mm in diameter, and large pores with lacerate dissepiments in mature specimens. Microscopically, it has a dimitic hyphal system with skeletal hyphae variably dextrinoid and broadly ellipsoid to ellipsoid, pale yellowish, double-walled basidiospores, with the inner layer fine and regularly ornamented. It could be compared with A. calcigenum ( Fig. 3g ) and A. partitum ( Fig. 3d–f ). A. calcigenum differs from A. calcitum by having a softer pileus and larger basidiospores [(12) 13.5–16 × 10–12 (12.5) μm, (ave = 14.2 × 10.9 μm)] ( Table 3, Figs. 4 , 5 ). A. partitum differs mainly by having thin and pliable basidiomata (up to 1.1 mm thick) and slightly smaller basidiospores [10–13 (13.5) × 8–10 (10.5) μm (ave = 11.6 × 8.9 μm)] ( Table 3, Figs. 4 , 5 ).

Ryvarden (2004) describe the basidiospores of A. calcigenum with a slight difference in length and width from our measurements (12–15 x 9–12 μm). In relation to the spore measurements of A. partitum , our data agree with the the description given by Gomes-Si lva e t al (2010) [10–13 × 7–9.5(10) μm], but Ryvarden (2004) describes the spores as being a little longer [(10) 12–15 x 8–10]. The specimens studied by Corner (1983) and identified as A. calcigenum , collected at Mato Grosso and possibly Manaus (Amazon state), should be re-evaluated, since they have basidiospores similar in length and width to A. calcitum (12–14.5 x 8.5–10). These specimens also possess strongly dextrinoid skeletal hyphae. However, in Corner’s description of a variety (collections from Rio de Janeiro and Manaus) with a minor difference in basidiospore measurement that he called A. calcigenum var. A, he suggested that the dextrinoidity of hyphae may not even be specific ( Corner 1983).

Figures

FIGURE 3. Macroscopic view of A. calcitum and related species. a–c A. calcitum: a—general view (FLOR52230, holotype); b—detail of hymenophore (FLOR52230); c—section of basidioma (FLOR 52232). d–f A. partitum: d—general view (K180681 type); e—detail of context and tubes (FLOR 48461); f—detail of hymenophore (FLOR 48461). g—general view of Polyporus torrendi = A. calcigenum (US 307270, holotype). Scale bar 1 cm. Photos by: D.H. Costa-Rezende

FIGURE 4. Boxplot graphic based on length of basidiospores from A. calcigenum, A. calcitum and A. partitum. For each taxon 25–75 percent quartiles are drawn using a box, median is shown with a horizontal line inside the box. The intervals represented by a line corresponding to the largest value less than 1.5 times the box height and the smallest value less than 1.5 times the box height. Values outside these intervals are considered outliers and are represented as circles.

FIGURE 5. Boxplot graphic based on width of basidiospores from A. calcigenum, A. calcitum and A. partitum. For each taxon 25–75 percent quartiles are drawn using a box, median is shown with a horizontal line inside the box. The intervals represented by a line corresponding to the largest value less than 1.5 times the box height and the smallest value less than 1.5 times the box height. Values outside these intervals are considered outliers and are represented as circles.

FIGURE 8. Spores of Amauroderma species from the Cerrado. a—A. aurantiacum (FLOR 52199). b—A. brasiliense (FLOR 50932). c— A. calcitum (FLOR52230, holotype) d—A. omphalodes (FLOR 52221). e—A. praetervisum (FLOR 52208). f—A. schomburgkii (FLOR 52176). g—A. sprucei (FLOR 52184). Scale bar: 5 μm. Photos by: D.H. Costa-Rezende.