Pluteus aff. vanuatuensis

Del, Jonathan A. & Perry, Brian A., 2025, The genus Pluteus (Basidiomycota, Agaricales, Pluteaceae) from Tafea Province, Republic of Vanuatu, Phytotaxa 709 (1), pp. 1-104 : 29-30

Pluteus aff. vanuatuensis ( Figs. 11 , 12 )

Diagnosis:— Pluteus aff. vanuatuensis from Tanna is characterized by a brown, glabrous pileus with a black squamulose disc and a white stipe with a subbulbous base. When disrupted, the tissues bruise bluish gray. Microcharacters include subglobose spores (7.2 × 5.8 µm), fusoid, thick-walled pleurocystidia with blunt conical protrusions at the apex, similar intermediate pleurocystidia with lesser developed apices, clavate cheilocystidia, a cutis pileipellis, an absence of caulocystidia, and clamp connections present in all tissues. Subtle differences compared to P. vanuatuensis are having a paler, glabrous, entirely pellucid-striate pileus and a more intense bruising reaction.

Description:— Pileus 50–58 µm diam., hemispherical to plano-convex, with a slight umbo, disc pustulate/rugose; surface pellucid-striate, dry to somewhat viscid, glabrous overall, disc pustulate to minutely appressed-fibrillose towards margin; squamules/fibrils dark chocolate brown, surface pale brown overall (oac720–oac722). Context up to 4 mm thick, white. Lamellae free, crowded with many tiers of lamellulae, thin, blush pink (oac695–oac697). Stipe 55–65 × 5–6 mm, central, cylindrical above a subbulbous base, hollow; surface pearlescent, dry, fibrous, white overall, context white. Tissues turning blue-gray (oac317–oac319) when damaged or handled. Odor indistinct. Taste indistinct.

Basidiospores 6–8 (–9) × (5–) 6–7 µm [x m = 7.32 ± 0.68 × 5.78 ± 0.64 µm, Q = 1–1.3 (–1.7), Q m =1.28 ± 0.18, n = 50, s = 1], subglobose, seldom globose or broadly ellipsoid, smooth, hyaline, with a guttule, inamyloid, thick-walled. Basidia 16–32 × 6–11 µm, clavate, 4-spored, guttulate, hyaline, thin-walled, sterigmata 1.5–3 × 0.5–1 µm. Basidioles 15–26 × 5–11 µm, clavate, guttulate, hyaline, thin-walled. Lamellar edge sterile. Cheilocystidia (25–) 32–52 × 10– 18 µm, clavate, fusoid or utriform, obtuse or subcapitate-umbonate, hyaline, thin-walled. Pleurocystidia; primary pleurocystidia 55–100 × 13–24 µm, narrowly lageniform to fusoid, corniculate with 2–6 whole to bifid, blunt, poorly developed apical hooks, most with a guttule, hyaline, thick-walled (up to 3 µm thick); intermediate pleurocystidia (36–) 46–63 × 11–20 µm, similar to primary but smaller and thinner-walled, narrowly lageniform to fusoid, obtuse or corniculate with 1–4 blunt, poorly developed apical hooks, hyaline, thin to thick-walled. Pileipellis a cutis of repent hyphae, composed of hyaline or with brown plasmatic pigment, non-incrusted, non-gelatinous, thin-walled, cylindrical hyphae, 3–10 µm diam.; terminal cells 52–138 × 9–18 µm, repent or becoming suberect to erect towards disc, clavate to filiform, obtuse, flexuose or tapered. Pileus trama interwoven, composed of hyaline, non-gelatinous, thin-walled, clavate to inflated hyphae, 3–28 µm diam.. Lamellar trama inverse, composed of hyaline, non-gelatinous, thin-walled hyphae, 3–10 µm diam.. Stipitipellis a cutis, composed of hyaline, non-incrusted, non-gelatinous, thin-walled hyphae, 3-12 µm diam.. Caulocystidia absent. Clamp connections present in all tissues examined.

Habitat and known distribution:—Gregarious on decayed wood in subtropical lowland mixed-use agro tree garden and disturbed secondary broadleaf rainforest containing Cocos nucifera ( Arecaceae ), Cordia subcordata ( Boraginaceae ), Leucaena leucocephala ( Fabaceae ), Macaranga dioica ( Euphorbiaceae ), and Syzygium malaccense ( Myrtaceae ), Vanuatu (Tanna).

Material examined:— VANUATU. Tafea Province: Tanna, Yakuwan , 19°32.230′S, 169°28.911′E, elev. 84 m, 15 August 2019, coll. J. A . del Rosario & B. A . Perry , JAD 285 ( HAY) .

Notes:—Phylogenetic analysis sampling the albostipitatus / salicinus clade based on ITS ( Fig. 6b ) places JAD 285 sister to all collections of the P. vanuatuensis clade with strong support. Pairwise analysis of overlapping ITS sequences shows JAD 285 to have 87.12–90.75 % similarity to all collections of P. vanuatuensis . The identically sampled analysis based on tef1 data retrieves the same relationship with moderate support (BS 85 %, PP 0.97). A concatenated analysis using both genes and expanded sampling of the albostipitatus / salicinus clade ( Fig. 6a ) places JAD 285 sister to a clade comprised of sequences of P. harrisii Murrill (1911: 277) and P. puttemansii Menolli Jr. & Capelari (2010: 701) . It should be noted that tef1 data is missing for many of the taxa in the expanded sampling. In the ITS analysis sampling all of sect. Pluteus, JAD 285 appears in a clade nested with P. saupei and P. vanuatuensis , however this is weakly supported ( Fig. 1c ). Morphologically, JAD 285 has both primary and intermediate pleurocystidia that appear to have a higher frequency of apices with lesser developed, more rounded corniculate outgrowths, rather than the more pointed hooks typically observed in P. vanuatuensis . However, P. vanuatuensis shows extensive pleurocystidia apex variability including this type found in JAD 285, thus hardly enough of a feature that can be used to distinguish between these taxa. JAD 285 can be distinguished from P. vanuatuensis f. ramacystidiatus by the lack of a rugose disc, lack of pleurocystidia with elongated branching apices, and the presence of intermediate pleurocystidia without lateral hooks. Based on molecular data, JAD 285 appears to be a phylogenetically distinct species, despite its morphological similarities to common forms of P. vanuatuensis . As this is based on a single collection, the identity of P. aff. vanuatuensis is maintained until additional material can be collected to clearly separate this taxon from P. vanuatuensis .

Figures

FIGURE 1a–d. Maximum Likelihood phylogeny of sect. Pluteus based on ITS sequence data (-lnL = 6609.645735). Sequences of specimens from Vanuatu are indicated in bold type. Stars indicate type specimens. Values separated by / refer to ML bootstrap proportions and Bayesian posterior probabilities, respectively. Only values greater than 70/0.70 are shown. Nodes receiving support values greater than 90/0.95 are highlighted in bold.

FIGURE 6a–c. Maximum Likelihood phylogenies of the albostipitatus/salicinus clade based on combined (Fig. 6a; -lnL = 4927.663337), ITS (Fig. 6b; -lnL 2206.25101), and tef1 (Fig. 6c; -lnL = 2099.291416) sequence data. Sequences of specimens from Vanuatu are indicated in bold type. Stars indicate type specimens. Values separated by / refer to ML bootstrap proportions and Bayesian posterior probabilities, respectively. Only values greater than 70/0.70 are shown. Nodes receiving support values greater than 90/0.95 are highlighted in bold.

FIGURE 11. Basidiomes of Pluteus aff. vanuatuensis (JAD 285). Scale bar = 10 mm. Photo by: Brian Perry.

FIGURE 12. Pluteus aff. vanuatuensis. a. Basidiospores. b. Basidia. c. Basidioles. d. Pileipellis terminal elements. e. Cheilocystidia. f. Intermediate pleurocystidia. g. Primary pleurocystidia. Scale bar = 10 µm. Drawings by: Jonathan del Rosario.