Phylloporia pseudoweberiana Decock, 2025

Phylloporia pseudoweberiana Decock , sp. nov. MycoBank MB 851916. Figs 12 View Fig , 13 View Fig .

Etymology: “ pseudoweberiana “ (Latin) is referring to the similarity with P. weberiana .

Typus: Kenya, Western Province, Kakamega Forest National Reserve, N00°17’30”, E034°51’22”, elev. ~ 1500 masl, on the living trunk of the small-stemmed tree, Rawsonia lucida ( Achariaceae ), 16 Feb. 2015, C. Decock, KE-15-02 (holotype MUCL 58350 ; GoogleMaps isotype NMK). GoogleMaps

Diagnosis: Phylloporia pseudoweberiana is similar to P. weberiana sensu Ryvarden & Johansen (1980) , characterised by the combination of sessile, perennial basidiomes emerging solitary, a sulcate pileus covered by a tomentum in brown to dark brown shade, a context absent to very reduced covered by a thin black line subtending a comparatively thicker tomentum, and a dimitic hyphal system but differs in having broadly ellipsoid to obovoid, larger basidiospores (3.0–)3.2–4.0 × (1.8–)2.5–3.0 µm (av. = 3.5 × 2.5 µm) and smaller pores, 9–11 / mm, 80–100 µm diam., and occurring on Rawsonia lucida ( Achariaceae ) in the Eastern edge of the Guineo-Congolian rainforest, in Kenya.

Description: Basidiomes pileate, sessile, solitary, perennial; primordia nodulous, rounded; mature basidiomes dimidiate, attached to the substrate only by a narrow circular area at the back but so close to the substrate that appearing at first sight broadly attached, occasionally pendant, then attached by a small apical/subapical vertex, projecting horizontally 10–45 mm, 20–80 mm wide at the margin, from 8 mm thick at the margin up to 20 mm thick at the base, semicircular to dimidiate in face view, the margin outline regular to slightly lobed, mostly applanate in transversal section, the pores surface slightly concave (slightly incurved inside) or slightly decurrent; overall with a corky consistency when fresh, hard corky to woody on drying; pileus covered by a tomentum in 2–5 concentric, broad, rounded, distant bands separated by well-marked furrows, wearing off from the base with weathering, exposing then a narrowly, finely sulcate pileal surface, overall dark brown (6F7, dark brown, chestnut brown), darker on weathering toward the base when the tomentum wears off, paler toward the margin [6E(6–7), cocoa brown, leather brown]; very margin beneath the pileus, forming a thin, but well-delimited, slightly rounded ring, whitish yellow when fresh, pale cork-coloured on drying; pore surface plane to slightly concave (slightly incurved inside), light brown to brown [6(D–E)4, 6E6, camel, greyish brown, cocoa brown], slightly glancing; pores small, regular, mostly round, 9–11/mm, (80–)85–105(–120) µm diam. (av. = 96 µm diam.); dissepiments thin, (15–)20–60(–75) µm thick (av. = 34 µm), agglutinated; context very reduced to almost absent, up to 0.5 mm thick layer between the tube layer and a thin black line subtending the comparatively thicker tomentum, homogeneous, dense, dark brown (6E6); tomentum 4–15 mm, soft corky when fresh, drying hard corky, light brown (6D6, cinnamon) near the base to brown (6E6, cocoa brown), agglutinating with weathering and wearing off from the base, soft corky when fresh, hard corky on drying; tube layer indistinctly stratified, 0.5–14 mm deep, concolourous with the context (6E6, cocoa brown), gradually paler near the pore surface (6D6, cinnamon). Hyphal system dimitic in the context and hymenophoral trama, monomitic in the tomentum; generative hyphae simple septate, thin- to slightly thick-walled, hyaline to faintly yellowish, scarcely branched, with a constriction at the branching point, 2.0–4.0 µm diam.; lower context, dominated by skeletal hyphae, parallel to black line, tightly packed, arising from a generative hyphae and of limited growth, 2.0–2.5 µm wide at the basal septa, progressively widening to 3.0–4.5 µm wide (av. = 3.6 µm), golden brown, darker (brown) in alkali, thick- to very thick-walled with the lumen wide to narrow, mostly aseptate throughout, or with few secondary septa near the apices; tomentum monomitic with hyphae first disposed parallel to the black-line, then progressively erected, then arranged in a fan-shaped, mostly unbranched or Y-branched, thick-walled with widely open lumen, occasionally locally constricted or inflated, septate with both true and secondary septa, the apices rounded to open, yellowish to brownish, mostly (3.5–)3.8–6.0(–6.5) µm diam. (av. = 4.7 µm); hymenophoral trama dominated by skeletal hyphae, mostly subparallel to the tube main axis, arising from a generative hyphae or a mediate hyphae, mostly terminal, of limited growth, measured from 115 µm to 250 µm long (av. = 185 µm), 2.0–2.5 µm diam. at the basal septa to (2.3–)2.8–3.3(–3.5) μm diam. (av. = 3.30 µm) in the main part, mostly straight in the main part, occasionally locally constricted or inflated (up to 4–5 µm), slightly thick-walled at the basal septa, progressively thickto very thick-walled, the lumen opening then narrow, locally lenticular, ending thin-walled, aseptate throughout but with a few secondary septa near the apices, golden brown, darker brown in alkali. Hymenium: Basidioles slightly pyriform to broadly clavate, 6.0–7.0 × 3.0–4.0 µm; mature basidia few, barrel-shaped to broadly clavate, with four sterigmata; cystidioles absent or very few, fusoid to lageniform, thin-walled; basidiospores (ellipsoid), mostly broadly ellipsoid to slightly ovoid, appearing somewhat angular on drying (oblong), thick-walled, smooth, pale yellowish in KOH, without reaction in Melzer’s reagent, 3.0–3.7(–4.0) × (1.8–)2.2–3.0 μm (av. = 3.4 × 2.5 µm), R = 1.1–1.5(–1.9) (ave Q = 1.4).

Phylogenetic affinities: The species, hitherto, is related to P. rinoreae , P. cinnamomea , and Phylloporia sp. PY-SN6, known from the Guineo-Congolian rainforest in Gabon and Cameroon ( Fig. 1 View Fig ).

Ecology (substrate, host, habitat): On small-stemmed, living trunks and lower branches, Rawsonia lucida ( Achariaceae ), understorey compartment, Lake Victoria transitional rain forest (which is an easternmost relict fragment of the Guineo-Congolian rainforest, White 1983, Kindt et al. 2014).

Geographic distribution: Currently known from the Kakamega Forest National Reserve, in Western Kenya.

Additional specimen examined: Kenya, Western Province, Kakamega Forest National Reserve, N00°17’30”, E34°51’22”, elev. ~ 1500 masl, on the living trunk of a small-stemmed tree (15 cm diam.), Rawsonia lucida Harv. & Sond. ( Achariaceae ), 16 Feb. 2015, C. Decock, KE-15-19 ( MUCL 58351 ). GoogleMaps

Notes: Phylloporia pseudoweberiana is characterised by solitary, perennial, deeply sulcate basidiomes ( Fig. 12 View Fig ) with a very thin context underneath a comparatively thicker tomentum, both separated by a thin black line. The tomentum wears off with age from the base, exposing then the black line. The hyphal system is dimitic in the context and the hymenophoral trama. The basidiomes emerge from trunk and lower branches ( Fig. 12 View Fig ) of the small understory tree Rawsonia lucida ( Achariaceae ), so far the only known and, a priori, exclusive host. Phylloporia pseudoweberiana is known, hitherto, from the Lake Victoria transitional rainforest (sensu Kindt et al. 2014), at Kakamega Forest National Reserve, in Western Kenya. The Lake Victoria transitional rainforest is the easternmost reminiscence in Kenya of the Equatorial rainforest (Guineo-Congolian rainforest) that stretched from the Atlantic Ocean ( Guinea) to the Indian Ocean ( Kenya).

In a phylogenetic perspective, P. pseudoweberiana is closely related to P. rinoreae , P. cinnamomea , and Phylloporia sp. PY-SN6 ( Fig. 1 View Fig ), currently known from the Western edge of Guineo-Congolian rainforest, in Central and Western Gabon ( Jerusalem et al. 2019) and Cameroon.

In tropical Africa, P. pseudoweberiana should be compared to P. weberiana sensu Ryvarden & Johansen (1980) or Ryvarden et al. (2022). However, the very identity of P. weberiana and, a fortiori, of P. weberiana sensu Ryvarden & Johansen (1980) or Ryvarden et al. (2022) was uncertain (Caberroi Hernández et al. 2019). Decock et al. (2024) lectotypified and redefined P. weberiana s.s. In that sense, P. weberiana sensu Ryvarden & Johansen (1980) differs from P. weberiana s.s. and P. pseudoweberiana in having much larger pores, mostly 5–6 / mm ( Ryvarden & Johansen 1980) vs 12–13 / mm ( Decock et al. 2024) and 9–11 / mm, respectively.

Phylloporia rinoreae and P. cinnamomea share with P. pseudoweberiana solitary basidiomes, a pileus covered by a broadly sulcate tomentum, comparatively thicker than the underlying context, and both separated by a thin black line, and small pores (> 9 / mm). Phylloporia rinoreae and P. cinnamomea differ in having smaller basidiomes, not exceeding 20 mm wide, 7 mm thick, and larger basidiospores, respectively, mainly 4.0–4.5 × 2.5–3.0 μm (av. = 4.3 × 2.7 μm) and 3.5–4.0 × 2.2–2.5 (av. = 3.9 × 2.3 μm). Phylloporia rinoreae also has a distinct substrate affinity and host relationship, growing from narrow, apical twigs of the shrubby Violaceae , Rinorea sp. ( Jerusalem et al. 2019). The host tree and substrate of P. cinnamomea are unknown.

Out of Africa, P. weberiana sensu Corner (1991) and P. alyxiae ( Wu et al. 2020a) are comparable, in both a morphological and ecological context; both share with P. pseudoweberiana the basidiome habit and anatomy, the tomentum in deeply sulcate, rounded zones, small pores, a dimitic hyphal system, basidiospores similar in shape and size, and some of their autecological parameters (growing from living understorey trees).

Phylloporia weberiana sensu Corner (1991) differs in having a context comparatively thicker (2.5–18 mm) than the overlying tomentum (4–6 mm, fide Corner 1991), an anatomy which is inverted in P. pseudoweberiana (cf. above), and slightly larger pores, viz. 110–200 µm (fide Corner 1991) vs 85–105 µm (cf. above). Corner (1991) reported four specimens of P. weberiana from Malaysia and the Philippines, but identified the host tree ( Diospyros sp. , Ebenaceae View in CoL ) for only one collection. Phylloporia alyxiae View in CoL differs from P. pseudoweberiana in having larger pores [6–8 (fide Wu et al. 2020a) vs 9–11 pores / mm], its host ( Alyxia insularis View in CoL , an endemic Apocynaceae View in CoL from Taiwan, vs Rawsonia lucida View in CoL , Achariaceae View in CoL ), and distribution range.