Lindtneria borinquensis Miller, Bernicchia & Gorjón, 2025

Lindtneria borinquensis Miller, Bernicchia & Gorjón sp. nov. Figs. 2 View FIGURE 2 , 3 View FIGURE 3

MycoBank no. 858026

Etymology: Borinquen , the name of Puerto Rico in native tongue, which means “the land of the brave lord”.

Holotypus: Puerto Rico, Mayagüez: in suburban yard, encrusting leaves and decaying herbaceous debris at soil level; shaded and made inconspicuous by a dense mat of the vine Mikania micrantha , Albizia procera and Manilkara zapota nearby, 18º13’28” N 67º08’00” W, 60 m. a.s.l, 15-V-2023, coll. Kurt O. Miller MO 519527 (holotype in MAPR number MAPR 29421; isotype in SALA-Fungi 12000).

Macroscopical characteristics: Basidiomata resupinate, effused, pellicular, as small, isolated patches coalescing, very thin up to 5 × 3.5 cm wide and 1 mm thick, encrusting leaves and herbaceous debris, easily removed from the substrate, fragile when dry and breaking into small pieces very easily ( Fig. 2 View FIGURE 2 ). Hymenophore surface furfuraceous to granular, mostly smooth but with scattered isolated small tubercules, emerging 1-2(3) mm, buff to pale salmon when fresh yellowish when dry, paling at the margin. Margin thinning out, consisting of white, cottony, and sterile hyphae. Subiculum with a cottony consistency, cream to ochraceous. Rhizomorphs present, pale to cinnamon buff, made of strands of silky hyphae aggregated into tufts. Odour strong, sickly sweet.

Microscopical characteristics: Hyphal system monomitic, hymenial layer close-packed, with hymenial and subhymenial hyphae hyaline, thin-walled, shortly-celled, 3–4 µm wide, branched, simple-septated but some clamped; subicular hyphae hyaline, long-celled, simple-septated but some with wide clamps, rarely with double clamps, anastomosed, multi branched, very often at right angle and inflated at septa, thin- to somewhat thick-walled, 4–5 µm wide; some forming cordons with encrusted hyphae, and with a peculiar structure made of wide, long, rectangular, thin-walled central hyphae, 126–130 × 13.7–15 µm, and short, thin, lateral hyphae with digitiform appendices, 2.7–5.5 µm long; cystidia and cystidioles absent but some hyphoid hyphae intermingled with basidia are seen; basidia thin-walled, cylindrical-clavate to cylindrical, 3–4 spored, basally clamped, 30–56(–58) × 13–14.5(–16) µm, with numerous small and large globules, better visible in Cotton blue, CB+; basidioles numerous as globose bladders at beginning; 3–4 sterigmata, very prominent and stout, sometimes bent, few up to 18 × 2.8 µm; basidiospores subglobose to widely ellipsoid, IKI–, with one large guttula, at first hyaline and smooth, later yellowish-brown, thin- to thick-walled, strongly cyanophilous, aculeate with numerous stout spines, up to 2 µm long, coalescing and forming continuous and irregular ridges, with the plage area encircled by an evident crown, apiculus prominent, 8.9–10.9 × 7.3–7.7 µm, excluding spines. Rhizomorphs made of very tightly arranged hyphae, the central ones very large, without septa or clamps for a long part of their length, thick-walled and with rounded ends while the lateral hyphae are thin-walled, narrow simple-septated, or frequently clamped, short-celled, sinuous, interwoven with appendices ( Fig. 3 View FIGURE 3 ).

Habitat and distribution: Growing among herbaceous debris in suburban garden near exotic tropical plants, known only from the type location in Puerto Rico. It is likely limited to tropical environments, although its broader distribution is speculative because of limited collections and its association with non-native plant species.

Remarks: Lindtneria borinquensis is one of the tuberculate species of genus Lindtneria . It differs from L. hydnoidea in the presence of clamps, the absence of capitate cystidioles and the globose-subglobose spores, from L. trachyspora in the smooth-tuberculate basidiomes; and from the group of L. leucobryophila (Henn.) Jülich in the differently shaped spores. Phylogenetically it is related to the clade of L. leucobryophyla and L. asiae-orientalis S.L. Liu & S.H. He , in an unresolved group of unnamed species or environmental sequences ( Fig. 1 View FIGURE 1 ).