Steccherinum bononiae Westphalen & Gugliotta sp. nov.

Figs 8 A, 9 A, 11 C

Etymology.

In honor of Dr. Vera Bononi, for her contribution to the knowledge of Steccherinum in Brazil.

Diagnosis.

Distinguished by the combination of resupinate to effused-reflexed basidiomes with waxy spines upon drying, elongated skeletocystidia protruding above the hymenium, aculei measuring up to 0.75 mm, and basidiospores 2.6–3.6 × 1.8–2.5 µm.

Typification.

Brazil. São Paulo: São Luis do Paraitinga, Parque Estadual da Serra do Mar, Núcleo Santa Virgínia, Trilha Poço do Pito, 06 Jun. 2017, M. C. Westphalen 557 / 17 (SP 512686).

Description.

Basidiomes adnate, resupinate to effused-reflexed, easily separable from the substratum and usually detaching upon drying, membranaceous to papery and pliable when fresh, turning corky and somewhat waxy upon drying; pilei when present arising from effused parts of the basidiomes and at the margins, usually imbricate and narrow, up to 8 mm wide, pileus surface cream to beige, fimbriate, faintly zonate; sterile margins entire, smooth, pelliculose, up to 2 mm wide, white to cream. Hymenophore hydnoid, pale salmon to pale yellowish when fresh, turning beige to tan upon drying, aculei 0.25–0.75 × 0.1–0.25 mm, with acute apices, with a pilose appearance from the protruding cystidia, solitary or more rarely laterally fused, somewhat crowded, 6–9 per mm. Subiculum cream to beige, homogeneous, slightly dense, up to 0.8 mm thick.

Hyphal system dimitic; subicular hyphae compact, not agglutinated; aculei tramal hyphae intertwined, parallel; generative hyphae clamped, thin to slightly thick-walled, hyaline, occasionally branched, 2–4 µm wide, more abundant in the base of the subiculum; skeletal hyphae thick-walled to almost solid, hyaline to slightly yellowish, 2–4.5 µm wide. Skeletocystidia abundant, arising from the trama and protruding above the hymenium, somewhat elongated, covered with medium-sized crystals, (20–35 – 65 × 5–9 (– 10) µm; leptocystidia present, often scattered and more abundant at the apical portion of the aculei, clavate to fusoid, smooth to apically encrusted. Basidia clavate, tetrasterigmate, 10–14 × 4–5 µm. Basidiospores broadly ellipsoid, hyaline, thin-walled IKI –, CB –, 2.6–3.6 × 1.8–2.5 µm.

Mating system.

Tetrapolar. Monosporic cultures obtained from specimen NR 71.

Habitat and distribution.

Known from southern, southeastern, and northeastern Brazil. Likely widespread in the Brazilian Atlantic Rainforest.

Specimens examined.

Brazil • Pernambuco: Olinda, 7 GAC - Batalhão do Exército, 16 Jun. 2018, R. S. Chikowski RC 1625 (URM 93107). • Rio Grande do Sul: São Francisco de Paula, FLONA, 12 Mar. 2022, M. C. Westphalen 726 / 22 (ICN 213868); • Dom Pedro de Alcântara, RPPN Mata do Prof. Baptista, 17 Nov. 2022, N. C. Regio NR 71 (ICN 213869). • São Paulo: São Paulo, Parque Estadual das Fontes do Ipiranga, 09 May 2014, A. M. Gugliotta 1615 (SP 512683); • Parque Estadual Cantareira, Núcleo Engordador, Trilha da Cachoeira, 24 Apr. 2017, M. C. Westphalen 547 / 17 (SP 512685); • Ribeirão Grande. Parque Estadual Intervales, Trilha roda d’água, 07 Jul. 2015, V. Motato-Vásquez MV 446 (SP 512675).

Notes.

Basidiomes of S. bononiae exhibit considerable variation, ranging from completely effused to effused-reflexed, and aculei vary in size from 0.25 to 0.75 mm long. The basidiospore size and shape in this species resemble those of S. molle and S. resinaceum. However, S. molle can be distinguished by its softer, membranaceous basidiomes, slightly shorter spines, and wider skeletocystidia, which are more deeply embedded in the trama and covered with larger, chunky crystals. Steccherinum resinaceum, in turn, can be distinguished by its denser basidiomes, laterally fused aculei that are often bifurcated at the apices, and embedded cystidia covered with large crystals. Phylogenetically, S. bononiae forms a sister clade to S. elegantissimum, but the latter can be distinguished by its thinner, shorter aculei and larger basidiospores. Additionally, S. elegantissimum typically grows on thin branches, forming small concrescent patches, whereas S. bononiae usually forms basidiomes as a single patch. Both species share the presence of elongated and projecting cystidia covered with a somewhat organized cap of crystals, but these crystals are slightly larger in S. bononiae (Fig. 9).