Pluteus presleyi, 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 : 88-90

Pluteus presleyi J.A. del Rosario & B.A. Perry, sp. nov. ( Figs. 44 , 45 )

MycoBank no:—854228

Holotype:— VANUATU. Tafea Province: Aneityum, lowland in former taro terraces, Mount Inhetiji , 20°12.531′S, 169°51.071′E, elev. 116 m, 12 December 2018, coll. J. A. del Rosario, JAD 239 ( HAY).

Etymology:—Named in honor of Presley Dovo for his extensive contributions to the Plants mo Pipol blong Vanuatu project as far back as the earliest 2006 expeditions on the island of Santo.

Diagnosis:— Pluteus presleyi from Aneityum is characterized by a light tan pileus covered with gray fibrils and floccules-spinules at the disc spreading outwards, and a cylindrical white stipe. Microcharacteristics include subglobose basidiospores (5.7 × 5.2 µm), fusoid-ventricose cheilocystidia, fusoid-ventricose pleurocystidia occasionally apically nodulose, a cutis pileipellis with suberect clustering clavate or filiform brown pigmented terminal elements, an absence of caulocystidia, and a lack of clamp connections.

Description:— Pileus 20–30 mm diam., convex with a slight umbo, with or without a slight central depression; surface dull, dry, densely longitudinally appressed-fibrillose turning into erect clusters and splitting to expose the context underneath, disc rugose or pustulate-spinulose to floccose; fibrils and pustules/spinules/floccules pallid gray-brown (oac723–oac725), underlying surface isabelline/grayish brown (oac730–oac732). Context 1 mm thick, white. Lamellae free, subdistant to close with 1–2 tiers of lamellulae, thin, dark tan (oac660/oac667). Stipe 20–40 × 3–4 mm, central, terete, cylindrical, solid; surface pearlescent, dry, silky, white, context white. Odor indistinct. Taste indistinct.

Basidiospores 5–7 × 4–6 µm [x mr = 5.58–5.86 × 5.14–5.28 µm, x mm = 5.72 ± 0.18 × 5.21 ± 0.09 µm, Q = 1.0–1.5, Q mr = 1.08–1.1, Q mm = 1.1 ± 0.02, n = 50, s = 2], globose to subglobose, rarely broadly ellipsoid, smooth, hyaline, with a guttule, inamyloid, thick-walled. Basidia 14–22 × 4–6 µm, clavate, 4-spored, hyaline, guttulate, thin-walled, sterigmata 2–4 × 0.5–1 µm. Basidioles 13–22 × 4–8 µm, clavate, hyaline, guttulate, thin-walled. Cheilocystidia (21–) 28–46 × 8–17 (–24) µm, clavate to fusoid-ventricose, obtuse or rarely capitate (observed once), hyaline, thin-walled. Pleurocystidia 44–70 × 9–18 (–28), common to scattered, lageniform to fusoid-ventricose, obtuse to umbonate or occasionally nodulose-capitate with 1–2 nodules, hyaline, thin-walled. Pileipellis a cutis with ascending terminal elements typically in fascicles, composed of cylindrical, with pale brown plasmatic pigment or sometimes hyaline, non-incrusted, non-gelatinous, thin-walled hyphae, 3–20 µm diam.; terminal elements 24–125 × 2–30 µm, ellipsoid to broadly clavate, cylindro-clavate or occasionally filiform, obtuse to somewhat tapering, seldom subcapitate or with a medial nodule. Pileus trama interwoven, composed of hyaline, non-gelatinous, thin-walled, clavate hyphae, 3–26 µm diam.. Lamellar trama inverse, composed of hyaline, non-gelatinous, thin-walled hyphae, 2–12 µm diam.. Stipitipellis a cutis, composed of hyaline, non-incrusted, non-gelatinous, thin-walled hyphae, 3–16 µm diam.. Caulocystidia absent. 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 ), Vanuatu (Aneityum).

Material examined:— VANUATU. Tafea Province: Aneityum, lowland in former taro terraces, Mount Inhetiji , 20°12.531′S, 169°51.071′E, elev. 116 m, 12 December 2018, coll. J. A . del Rosario, JAD 239 ( HAY); Aneityum, lowland in former taro terraces, Mount Inhetiji , S20 ° 12.567’, E169 ° 51.206, elev. 140 m, 12 December 2018, coll. J. A . del Rosario , JAD 251 ( HAY) .

Notes:— Pluteus presleyi is comparable to several species that are macromorphologically superficially similar. The Sri Lankan P. spilopus tends to be larger in stature (4–10 cm), has non-lageniform pleurocystidia and more obtuse and non-tapering pileipellis terminal elements ( Pegler 1986). Another Sri Lankan species, P. escharites (Berkeley & Broome) Saccardo (1887: 670) is similar in stature, but differs based on lacking pleurocystidia, and having a disrupted trichoderm pileipellis with fundamentally different fusoid terminal elements( Pegler 1986). Pluteus hispidilacteus Horak (2008: 20) from New Zealand has a somewhat similar pileus, but differs in the hispid stipe, absent pleurocystidia, nonovoid and non-capitate pileipellis terminal elements, and the presence of caulocystidia ( Horak 2008). The European species P. hispidulus (Fries) Gillet (1887: 391) is similar in stature with a slightly more squamulose pileus surface, but differs microscopically in rare to absent pleurocystidia, narrowly clavate cheilocystidia, and non-capitate and non-filliform pileipellis terminal elements ( Kühner & Romagnesi 1956, Vellinga & Schreurs 1985). The Chinese P. squarrosus Iqbal Hosen & T.H. Li (2019: 3) has similar pileus coloration, somewhat similar surface characteristics and similarly shaped cheilocystidia and pleurocystidia, but differs in having a more squamose-areolate pileus surface, larger pleurocystidia (45–80 × 13–28 µm), having caulocystidia, and a trichoderm pileipellis ( Hosen et al. 2019).

Phylogenetic analysis of the ITS data ( Fig. 37e ) resolves P. presleyi in a basal grade to sect. Celluloderma . The general cutis pileipellis and non-metuloid lamellar cystidia would conform with the current concept of sect. Celluloderma . Interestingly, among the variable elongated clavate and filiform pileipellis cells there are occasionally terminal elements that are chains consisting of short cylindrical cells, ending in short ellipsoid cells. These chains almost resemble epithelioid cells and are perhaps similar to a kind of intermediate form between the cells typical in a hymeniderm or epithelium. Nevertheless, the morphological differences and phylogenetic placement are enough to recognize this species as new.

Figures

FIGURE 37a–e. Maximum Likelihood phylogeny of sect. Celluloderma based on ITS sequence data (-lnL = 18618.671374). 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. Only values greater than 70/0.70 are shown. Nodes receiving support values greater than 90/0.95 are highlighted in bold.

FIGURE 44. Basidiome of Pluteus presleyi (JAD 239 holotype). Scale bar = 10 mm. Photos by: Jonathan del Rosario.

FIGURE 45.Pluteus presleyi.a. Basidiospores.b.Basidia.c.Basidioles.d.Pileipellisterminal elements.e. Cheilocystidia.f.Pleurocystidia. Scale bar = 10 µm. Drawings by: Jonathan del Rosario.