Pluteus aureofuscus, Del, Jonathan A. & Perry, Brian A., 2025

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 : 38-44

Pluteus aureofuscus J.A. del Rosario & B.A. Perry, sp. nov. ( Figs. 16 , 17 )

MycoBank no.:—854224

Holotype:— VANUATU. Tafea Province: Aneityum , Nopsjec. 19°12.444′S, 169°25.916′E, elev. 222 m, 11 December 2019, coll. J. A. del Rosario, JAD 344 ( HAY).

Etymology:— aureo ( L.) = golden, fuscus ( L.) = grayish brown; refers to the golden and gray-brown color of the pileus and stipe.

Diagnosis:— Pluteus aureofuscus from Tafea Province is characterized by a golden cream and pinkish brown to pale tan finely fibrillose-flocculose colored pileus with a sulcate margin, and a similarly colored and ornamented stipe with a bulbous base. Microcharacters include globose spores (7.0 × 6.3 µm), clavate cheilocystidia, fusoid-ventricose pleurocystidia with some having median or apical septa and small forms with an apical mucronate appendage, a pileipellis arranged as a euhymeniderm to trichoderm composed of broadly clavate to fusoid-ventricose cells mixed with subglobose to pyriform terminal elements overlaying a cutis subpelllis, and clavate caulocystidia.

Description:— Pileus 14–46 mm diam., hemispherical expanding to convex without or with a slight umbo, margin sulcate; surface dull becoming pellucid-striate in age, hygrophanous, finely appressed-fibrillose to finely flocculose, disc minutely pustulate becoming subtomentose in age; fibrils, floccules, and pustules pallid tan (oac709–oac711) with dull pinkish brown (oac667–oac669) tones becoming off-white in age, surface golden cream-colored, becoming gray to off-white in age. Context up to 1.5 mm, white. Lamellae free, crowded with 4 tiers of lamellulae, thin, cream white initially, turning pale pink (oac633–oac634) in age. Stipe 14–45 × 3–4 mm, central, solid, terete, cylindrical over a subbulbous to bulbous base; surface dull, dry, pallid tan (oac709–oac711) appressed-fibrillose to minutely flocculose over a cream-colored to off-white surface or glabrous in age, context white. Odor indistinct. Taste indistinct.

Basidiospores 6–8 (–9) × 6–8 µm [x mr = 6.78–7.24 × 6.02–6.68 µm, x mm = 7.03 ± 0.23 × 6.32 ± 0.33 µm, Q = 1–1.6, Q mr = 1.09–1.13, Q mm = 1.12 ± 0.08, n = 50, s = 3], globose to subglobose, smooth, hyaline, with a guttule, inamyloid, thick-walled. Basidia 18–36 × 7–11 µm, clavate, 4-spored, hyaline, guttulate, thin-walled, sterigmata 1.5–3 × 0.5–2 µm. Basidioles 18–30 × 6–9 µm, clavate, hyaline, guttulate, thin-walled. Lamellar edge sterile. Cheilocystidia (24–) 31–65 (–90) × (11–) 16–36 µm, narrowly to broadly clavate, fusoid or sphaeropedunculate, obtuse, hyaline, thin-walled. Pleurocystidia 60–92 (–120) × 18–36 (–40), uncommon to common, fusoid-ventricose to narrowly lageniform, obtuse, or (20–) 35–91 × 7–18 (–20) µm, lageniform to fusoid-ventricose, commonly to rarely mucronate (3–12 µm long), occasionally medially or apically septate in some collections or not, hyaline, thin-walled. Pileipellis a fragmented to complete ascending euhymeniderm to trichohymeniderm overlying a cutis subpellis, terminal elements typically 60–160 × 14–32 (–43) µm, scattered or in ascending fascicles, narrowly to broadly clavate, fusoid-ventricose or rarely filiform, obtuse, rarely acute, or capitate or sometimes 42–70 × 21–40 µm, sphaeropedunculate to pyriform, obtuse or occasionally capitate-mucronate, hyaline or with pale brown plasmatic pigment, non-incrusted, non-gelatinous, thin-walled; subpellis a cutis of repent hyphae, composed of hyaline, non-incrusted, non-gelatinous, thin-walled hyphae, 3– 16 µm diam.. Pileus trama interwoven, composed of hyaline, non-gelatinous, thin-walled, clavate to inflated hyphae, 2–25 µm diam.. Lamellar trama inverse, composed of hyaline, non-gelatinous, thin-walled hyphae, 3–12 µm diam.. Stipitipellis a cutis, composed of hyaline or with pale grayish brown plasmatic pigment, non-incrusted, non-gelatinous, thin-walled hyphae, 3–10 µm diam.. Caulocystidia 24–68 (–82) × 7–15 (–18) µm, scarce to abundant in fascicles, cylindro-clavate to broadly clavate, seldom fusoid, obtuse or capitate, with pale grayish brown plasmatic pigment or hyaline, thin-walled. Clamp connections absent in all tissues examined.

Habitat and known distribution:—Solitary to gregarious on decaying wood in subtropical montane primary broadleaf- Araucariaceae / Podocarpaceae rainforest containing Agathis macrophylla ( Araucariaceae ), Balanops pedicellata ( Balanopaceae ), Calophyllum neoebudicum ( Calophyllaceae ), Dendrocnide latifolia ( Urticaceae ), Ficus septica ( Moraceae ), Ficus smithii ( Moraceae ), Garcinia platyphylla ( Clusiaceae ), Geissois denhamii ( Cunoniaceae ), Hernandia moerenhoutiana ( Hernandiaceae ), Macaranga dioica ( Euphorbiaceae ), Podocarpus vanuatuensis ( Podocarpaceae ), Polyscias cissondendron ( Araliaceae ), and Syzygium spp . ( Myrtaceae ), Vanuatu (Tanna, Aneityum).

Material examined:— VANUATU. Tafea Province: Tanna, Lighthouse area . 19°38.387′S, 169°25.923′E, elev. 155 m, 6 December 2018, coll. J. A . del Rosario, JAD 218 ( HAY); Aneityum, Noposjec. 20°12.649′S, 169°46.974′E, elev. 184 m, 11 December 2019, coll. J. A . del Rosario, JAD 342 ( HAY); Aneityum, Nopsjec. 19°12.444′S, 169°25.916′E, elev. 222 m, 11 December 2019, coll. J. A . del Rosario , JAD 344 ( HAY) .

Notes:—The specimens of P. aureofuscus exhibit minor morphological variation. Collection JAD 344 consists of younger basidiomes with an overall golden cream-colored pileus surface and stipe streaked with pallid tan fibrils and floccules. JAD 342 contains more mature basidiomes with the same golden cream-colored pileus and stipe, however the fibrils and floccules turn gray with dull pinkish brown streaks. JAD 218 is well-aged, with the pileus turning entirely gray similar to JAD 342, however the dull pinkish brown tones remain. Microscopically, all three collections are similar with a few notable differences. JAD 218 and JAD 342 share a high frequency of apically mucronate pleurocystidia, while this cystidia type was only observed once in JAD 344. In particular, JAD 342 contains pleurocystidia with distinct singular septa, either towards the apex or at the median. Septate cystidia are rare in Pluteus spp ., with P. septocystidiatus being a well-documented species that produces a fuscous pileus, contains thick-walled pleurocystidia, a cutis pileipellis, with the septate cell type occurring in both pleurocystidia and cheilocystidia ( Ševčíková et al. 2014). Overall, the shared micromorphology between the collections of P. aureofuscus would be clavate or sphaeropedunculate cheilocystidia, a pileipellis consisting of clavate, fusoid-ventricose and subglobose elements, and clavate subcapitate caulocystidia.

The variable appearance of P. aureofuscus suggests comparison to species that physically encompass a similar range or are closer to one of the forms. Pluteus sulcatus Singer in Singer & Digilio (1952: 265) from Argentina is very close, but differs in having a more fuscous pileus, smaller cheilocystidia (21–23 × 12 µm), and lacks pyriform elements in the pileipellis ( Singer 1956, 1958, Singer & Digilio 1952). Another similar Argentinean species, P. hiemalis Singer (1958: 248) , differs microscopically in lacking mucronate pleurocystidia and pyriform pileipellis elements ( Singer 1958). The Sri Lankan P. glyphidiatus (Berkeley & Broome) Saccardo (1887: 673) has a very similar stature, is yellow and translucent to grey and squamulose ( Pegler 1986), but differs microscopically with smaller non-mucronate pleurocystidia, both pleurocystidia and cheilocystidia having incrustations, and the absence of pyriform pileipellis elements ( Pegler 1986, Singer 1956). Pluteus pelinus (Berkeley & Broome) Saccardo (1887: 675) is another similar Sri Lankan species, but differs microscopically by having non-mucronate pleurocystidia, smaller pleurocystidia and cheilocystidia, and an overall repent cutis pileipellis ( Pegler 1986).

Phylogenetic analysis based on ITS data ( Fig. 14b ) places the Vanuatu collections in a moderately supported clade ( BS 89 %, PP 0.99) with weakly supported internal topology containing several unidentified species: P. decoloratus Horak (2008: 24) , P. subroseus E.F. Malysheva (2023: 23) , Vanuatu collection JAD 302, and P. albidus Beeli (1928: 82) . Pluteus decoloratus described from New Zealand is similar macromorphologically to P. aureofuscus , but differs micromorphologically in having non-mucronate pleurocystidia, longer trichodermal pileipellis elements (100–270 × 24–30 µm) and lacking caulocystidia ( Horak 2008). Pluteus albidus is very similar micromorphologically, especially in the clavate-mucronate pleurocystidia, but both the cheilocystidia (32–48 × 11–20 µm) and pleurocystidia (37–54 × 11–20 µm) are much smaller, lack septa, and the basidiome is white overall without contrasting colored fibrils/floccules ( Desjardin & Perry 2018). Pluteus subroseus also shares similar micromorphology, but has smaller cheilocystidia (33–45 × 12–25 µm) and pleurocystidia (56–85 × 14–30 µm), thick-walled pileipellis elements, and an overall paler basidiome with a beige-red pileus disc ( Malysheva et al. 2023).

Pluteus chrysaegis (Berk. & Broome) Petch, Annals of the Royal Botanic Gardens Peradeniya 5: 271 (1912) ( Figs. 18 , 19 )

≡ Agaricus chrysaegis Berk. & Broome , Botanical Journal of the Linnean Society 11: 536 (1871)

≡ Entoloma chrysaeges (Berk. & Broome) Sacc., Sylloge Fungorum 5: 61 (1887)

Reported heterotypic synonym:

= Pluteus conizatus var. africanus E. Horak , Bulletin du Jardin Botanique National de Belgique 47(1–2): 89 (1977)

Diagnosis:—As represented by material from Tafea Province, P. chrysaegis is characterized by a sulfur yellow glabrous pileus with a light brown veined rugose-venose disc, and a tan brown longitudinally fibrillose stipe with a bulbous base. A second morphotype from Tanna Island exists with a pale brown pileus ( Fig. 16b ). Microcharacters include globose spores (6 × 5.4 µm), lageniform, acute, thin to thick-walled cheilocystidia, broadly lageniform, thick-walled pleurocystidia, a hymeniderm pileipellis composed of pyriform cells intermixed with fusoid pileocystidia arising from a cutis subpellis, and clavate to fusoid caulocystidia.

Description:— Pileus 30–60 mm diam., hemispherical expanding to plano-convex, with a slightly depressed broad umbo; surface pellucid-striate up to half-way from margin, dry to viscid, glabrous, disc rugose-venose radiating towards the margin; tan-brown (oac686–oac687) in age, or if not, disc veins and wrinkles light to dark brown (oac690– oac691/oac721–oac722), fading towards margin, surface sulfur to pale yellow (oac896–oac897) turning pale (oac898– 899) towards disc with translucent patches exposing underlying white context tissue. Context up to 3 mm thick, white. Lamellae free, crowded with 4 tiers of lamellulae, thin, pink-brown (oac619–oac620). Stipe 28–65 × 4–6 mm, central, terete, cylindrical with a subbulbous base, solid; surface dull, dry, tannish brown (oac643–oac645) longitudinally fibrillose over an off-white base, context white. Odor indistinct. Taste indistinct.

Basidiospores 5–7 (–8) × 4–6 (–7) µm [x mr = 5.55–6.7 × 4.94–5.38 µm, x mm = 6.11 ± 0.59 × 5.19 ± 0.22 µm, Q = 1–1.6, Q mr = 1.12–1.28, Q mm = 1.18 ± 0.09, n = 50, s = 3], globose to subglobose, smooth, hyaline, with a guttule, inamyloid, thick-walled. Basidia 18–28 × 5–8 µm, clavate, 4-spored, guttulate, hyaline, thin-walled, sterigmata 2–4 × 0.5–1 µm. Basidioles 15–28 × 5–8 µm, clavate, guttulate, hyaline, thin-walled. Lamellar edge sterile. Cheilocystidia 28–62 × 5–18 µm, lageniform or fusoid, acute or capitate, hyaline, thin to thick-walled (up to 2 µm thick) especially at the apex. Pleurocystidia typically 50–110 × 13–34 µm, broadly clavate to narrowly lageniform, obtuse or truncate, hyaline, thin to thick-walled (up to 2 µm thick); rarely 35–56 × 8–18 µm, fusoid to lageniform, obtuse with 2–4 poorly developed apical outgrowths or capitate, hyaline, thin-walled. Pileipellis an epithelioid hymeniderm with pileocystidia over a subpellis, composed of a majority of cells 8–30 × 8–15 µm, subglobose to pyriform or sphaeropedunculate, obtuse, some capitate or mucronate, hyaline or sometimes with pale amber brown plasmatic pigment, non-incrusted, non-gelatinous, thin-walled; pileocystidia 26–75 × 8–22 µm, fusoid to lageniform, acute, capitate or mucronate, hyaline or sometimes with pale amber brown plasmatic pigment, thin-walled; subpellis a cutis of repent hyphae, composed of hyaline, non-incrusted, non-gelatinous, thin-walled hyphae, 3–10 µm diam.. Pileus trama interwoven, composed of hyaline, non-gelatinous, thin-walled, cylindrical to inflated hyphae, 3–18 µm diam.. Lamellar trama inverse, composed of hyaline, non-gelatinous, thin-walled hyphae, 3–20 µm diam.. Stipitipellis a cutis, composed of hyaline or often with pale brown plasmatic pigment, non-incrusted, non-gelatinous, thin-walled hyphae, 3–10 µm diam.. Caulocystidia 14–45 × 8–15 µm, scattered to clustered, clavate or fusoid to lageniform, acute or mucronate, hyaline or sometimes with pale brown plasmatic pigment, thin-walled. Clamp connections absent in all tissues examined.

Habitat and known distribution:—Solitary on decaying wood in subtropical montane primary broadleaf rainforest to cloud forest containing Balanops pedicellata ( Balanopaceae ), Diospyros sp. ( Ebenaceae ), Ficus smithii ( Moraceae ), Garcinia platyphylla ( Clusiaceae ), Ilex vitiensis ( Aquifoliaceae ), Melicope latifolia ( Rutaceae ), Metrosideros collina ( Myrtaceae ), Plerandra actinostigma ( Araliaceae ), Scaevola cylindrica ( Goodeniaceae ), Semecarpus tannaensis ( Anacardiaceae ),and Syzygium spp . ( Myrtaceae ); montane transitionary secondary to primary broadleaf- Podocarpaceae rainforest containing Burckella obovata ( Sapotaceae ), Cryptocarya tannaensis ( Lauraceae ), Dacrycarpus imbricatus ( Podocarpaceae ), Elaeocarpus floridanus ( Elaeocarpaceae ), Ficus smithii ( Moraceae ), Hernandia moerenhoutiana ( Hernandiaceae ), Melicope sp. ( Rutaceae ), Metrosideros vitiensis ( Myrtaceae ), Meryta neoebudica ( Araliaceae ), and Neuburgia corynocarpa ( Loganiaceae ); and montane primary broadleaf cloud forest containing Atractocarpus sezitat ( Rubiaceae ), Claoxylon psilogyne ( Euphorbiaceae ), Eumachia trichostoma ( Rubiaceae ), Geissois denhamii ( Cunoniaceae ), Ficus septica ( Moraceae ), Neonauclea forsteri ( Rubiaceae ), and Schefflera neoebudica ( Araliaceae ), Vanuatu (Tanna, Aneityum, Futuna). Also known from Africa (D.R. Congo, São Tomé) and Asia ( China, India, Sri Lanka, Vietnam).

Material examined:— VANUATU. Tafea Province: Tanna,coastal forest near Kwamera, 19°38.467′S, 169°26.078′E, elev. 110 m, 6 December 2018, coll. J. A . del Rosario, JAD 217 ( HAY); Aneityum, Mount Inhetiji , lowland forest in former taro terraces, 20°12.552′S, 169°51.107′E, elev. 140 m, 12 December 2018, coll. J. A . del Rosario & B . Nasawman, JAD 248 ( HAY); Futuna, Mount Tatafu , upper slopes, 19°31.759′S, 170°12.683′E, elev. 645 m, 22 August 2019, coll. J. A . del Rosario & B. A . Perry, JAD 312 ( HAY) .

Notes:— Pluteus chrysaegis (Berkeley & Broome) Petch (1912: 271) was described and known only from Sri Lanka ( Berkeley & Broome, 1871) until material was collected and re-described from India ( Pradeep et al. 2012, Pradeep & Vrinda 2006). Additional recent reports have expanded its known distribution to include equatorial coastal Central Africa ( Desjardin & Perry 2018), southern China ( Hosen et al. 2018), and Vietnam ( Malysheva et al. 2023). Molecular data retrieved from GenBank ( MF153092 and MH212067 ) of additional material included in ITS phylogenetic analysis suggest the presence of the species in Florida, U.S. A.. The material collected throughout Tafea Province matches well with descriptions from previous regional accounts with minor exceptions being that the basidiospores and pleurocystidia are both slightly larger than previously reported size ranges. One feature observed in the Tafean collections is an additional form of pleurocystidia that differs by being smaller, thin-walled, and with capitate or mucronate apical projections. This pleurocystidia type has not been not observed in other reports until recently reported in a study by Malysheva et al. (2023).

Pluteus conizatus var. africanus Horak (1977: 89) was originally described from the Democratic Republic of the Congo ( Horak & Heinemann 1978) and considered to be a synonym of P. chrysaegis by Pradeep et al. (2012) based on Horak’s basidiome descriptions being identical to their newly collected material. Pradeep et al. (2012) commented on the similarity of the microscopic features from Horak’s description with those of their material, but this is not made immediately obvious as previous authors emphasized different characters when describing the microstructures. Desjardin and Perry (2018) noted in their São Tomé collection, identified as P. chrysaegis , the absence of apically thick-walled, acutely fusiform cheilocystidia seen in P. conizatus var. africanus , a trait that is observed in the Vanuatu material. One notable feature in the Aneityum material is the presence of pale brown plasmatic granular contents found sparsely in pileipellis terminal cells and in patches throughout the stipitipellis, typically at the base of the caulocystidia. Horak is the only author to note the presence of pigments in P. conizatus var. africanus , but this pigmentation was described as ‘yellowish’ and only in the pileipellis terminal cells ( Horak & Heinemann 1978).

Phylogenetic analysis of ITS molecular data ( Fig. 16c ) places the Tafean specimens within a supported clade (BS 91 %, PP 0.99). Sister to this P. chrysaegis clade is a well-supported branch (BS 98 %, PP 1.0) consisting of other Vanuatu collections determined to be P. neochrysaegis Menolli & de Meijer in Menolli, de Meijer & Capelari (2014: 135), with both of these species positioned in the leoninus clade sensu Justo et al. (2011b). Distinction of P. chrysaegis from other yellow pigmented species within the leoninus clade, such as P. leoninus or P. variabilicolor Babos (1973: 38) , is primarily through the prominent brown veins on the pileus, thick-walled cheilocystidia and pleurocystidia, and its distribution being mostly restricted to the tropics ( Lezzi et al. 2014).

The presence of another morphotype of an entirely brown rather than yellow pileus, additional form of pleurocystidia, and varying thickness of the cheilocystidia indicates a broader known morphological variation in P. chrysaegis . The differing observations of pigmentation in the pileipellis and stipitipellis is another example of this variability, but combined with molecular data this also presents a strong case that P. conizatus var. africanus is likely conspecific with P. chrysaegis .

Figures

FIGURE 14. Pluteus wahei. 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.

FIGURE 16. Basidiomes of Pluteus aureofuscus (JAD 344 holotype). Scale bar = 10 mm. Photos by: Jonathan del Rosario.

FIGURE 17. Pluteus aureofuscus. a. Basidiospores. b. Basidia. c. Basidioles. d. Pileipellis terminal elements. e. Cheilocystidia. f. Caulocystidia. g. Pleurocystidia. Scale bar = 10 µm. Drawings by: Jonathan del Rosario.

FIGURE 18. Basidiome morphotypes of Pluteus chrysaegis. a. Typical morphotype basidiome of Pluteus chrysaegis (JAD 248). b. Secondary morphotype basidiomes of Pluteus chrysaegis (JAD 217). Scale bar = 10 mm. Photo by: Jonathan del Rosario.

FIGURE 19. Pluteus chrysaegis. a. Basidiospores. b. Basidia. c. Basidioles. d. Pileipellis terminal elements. e. Cheilocystidia. f. Caulocystidia. g. Pleurocystidia. Scale bar = 10 µm. Drawings by: Jonathan del Rosario.