Phylloporia afropectinata Decock, Jerusalem, Amalfi & Castillo, 2025

Phylloporia afropectinata Decock, Jerusalem, Amalfi & Castillo , sp. nov. MycoBank MB 851871. Figs 2, 3.

Etymology: “ afropectinata ” (Latin) is referring to the morphological resemblance with P. pectinata .

Typus: Kenya, Trans Nzoia Province, Mount Elgon National Park, ~ N1°2’42.30”, E34°47’18.18’’, elev. ~ 2130 masl, trunk of living tree, Turraea cf. holstii ( Meliaceae ), 31 Mar. 2016, C. Decock, KE-16-119 (holotype MUCL 58359 ; GoogleMaps isotype NMK/E). GoogleMaps

Diagnosis: Phylloporia afropectinata resemble P. pectinata sensu Corner (1991) by the combination of sessile, variably sized, compound, merismatoid basidiomes, with downward proliferation of imbricated pilei, but differs in having larger pores, 8–9 / mm vs 10–12 / mm, ellipsoid vs broadly ellipsoid to subglobose basidiospores (3.5–)3.8–4.3(–4.5) × (2.7–)3.0–3.5 µm vs 2.7–3.5 × 2–2.5 µm, host plant ( Turraea cf. holstii , Meliaceae , vs Timonius flavescens , Rubiaceae ), and inhabiting Afromontane middle elevation forest vs Southeast Asian rainforest.

Description: Basidiomes pileate, sessile, perennial, emerging solitary or simultaneously in small number, superposed; individual basidiomata attached by a small dorsal circular point, first semicircular, applanate in section, then becoming compound, merismatoid by successive downward proliferations of new and larger, imbricating pilei, the all compound basidiome triquetrous, triangular in transversal section, then ungulate, projecting mostly downward 3–8(–10) mm, 20–250 mm wide at the last growth, the margin outline of the last formed pileus semicircular to ellipsoid, with a general hard corky consistency; pileus surface slightly concentrically sulcate, shortly velutinous, mainly pale greyish orange, cork-coloured toward the margin, light brown when fresh [(4–5) B6, 6C6, caramel to 6D6, cinnamon], then soon darker brown toward the base [6(E–F)6, cocoa brown];margin entire, whitish when fresh, pale cork-coloured on drying; pore surface plane to mostly slightly concave (incurved inside), greyish orange drying yellowish brown [4F6 to 5(D–E)6, honey yellow, oak brown]; pores small, regular, mostly round to ellipsoid, occasionally fused, 8–9/mm, 90–115(–120) µm diam. (av. = 101 µm diam.); dissepiments thin, 20–65 µm thick (av. = 40 µm); context very thin to almost absent, up to 500 µm thick, homogeneous, dense, greyish brown, with a thin upper black line subtending an upper thin tomentum, up to 2.5 mm thick, tufted near the margin, progressively agglutinating toward the base, golden brown (5D7) to yellowish brown (5E8) in section; tube layer up to 10 mm deep at the base, greyish brown. Hyphal system pseudodimitic (intermediate sensu Pegler 1996); generative hyphae simple septate, thin- to slightly thick-walled, hyaline to faintly yellowish, branched, with a constriction at the branching point, 1.3–2.5 µm diam.; lower context, dominated by thick-walled (sclerified) generative, mostly parallel to long axis, tightly packed, arising from a generative hyphae, 3.0–4.0 µm wide (av. = 3.4 µm), golden brown, darker (brown) in alkali, thick-walled but with the lumen wide, mostly aseptate throughout, or with few secondary septa near the apices; tomentum with prostrate to erected hyphae, mostly unbranched, thick-walled with widely open lumen, septate with both true and secondary septa, the apices rounded to open, yellowish to brown, mostly 3.5–4 µm diam.; hymenophoral trama dominated by thick-walled (sclerified) generative, supporting hyphae, subparallel to the tube main axis, arising from a generative hyphae or a mediate hyphae, mostly terminal of limited growth, ending thin-walled, or intercalary, septate at both ends, apically reversing into slightly thick-walled generative hyphae, measured from 115 µm to 350 µm long, 1.5–2.5 µm diam. at the basal septa to (2.5–)3.0–3.5 μm diam. (av. = 3.2 µm) in the main part, mostly straight, occasionally geniculated, occasionally locally constricted, or inflated (up to 5–7 µm), with a few secondary septa, 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 few, fusoid to lageniform, thin-walled; basidiospores broadly ellipsoid to subglobose, appearing somewhat angular on drying, thick-walled, smooth, pale yellowish in KOH, without reaction in Melzer’s reagent, (3.5)–3.8–4.3(–4.5) × (2.7–)3.0–3.5 μm (av. = 4.0 × 3.2 µm), R = 1.1–1.4 (ave Q = 1.2).

Phylogenetic affinities: The species, hitherto, is related to P. beninensis , known from Benin (Western Africa), and to a specimen of P. cf. pectinata from Australia ( Fig. 1).

Ecology (substrate, host, habitat): On surfacing roots, trunks, and lower branches, small-stemmed Turraea cf. holstii ( Meliaceae ), understory compartment, Afromontane forest (elev. ~ 2000 masl).

Geographic distribution: Currently known from a single spot of Afromontane Forest, at Mount Elgon, Kenya.

Additional specimens examined. Kenya, Trans Nzoia Province, Mount Elgon National Park, ~ N01°2’40.84”, E034°34’9.4”, elev. ~ 2170 masl, on trunks of living trees, Turraea cf. holstii ( Meliaceae ), 31 Mar. 2016, C. Decock, KE-16-105, GoogleMaps KE-16-107 , KE-16-108 , KE-16-109 , KE-16-113 , KE-16-118 , KE-16-119 & KE-16-120 ; ibid., ~ N01°2’25.33”, E034°47’13”, elev. ~ 2160 masl, on trunks of living trees, Turraea cf. holstii ( Meliaceae ), 2 Apr. 2016, C. Decock, KE-16-148 , GoogleMaps KE-16-154 & KE-16-159 ; ibid., ~ N01°2’54.9”, E034°46’22.4”, elev. ~ 2296 masl, on trunk of a living tree, Turraea cf. holstii ( Meliaceae ), 3 Apr 2016, C. Decock KE-16-168 ; GoogleMaps ibid., ~ N01°2’54.9”, E034°46’22.4”, elev. ~ 2296 masl, on trunk of a living tree, Turraea cf. holstii ( Meliaceae ), 4 Apr. 2016, C. Decock, KE-16-187 , GoogleMaps KE-16-191 & KE-16-192 ; ibid., ~ N01°2’54.9”, E034°46’22.4”, elev. ~ 2296 masl, on trunk of a living tree, Turraea cf. holstii ( Meliaceae ), 26 Feb. 2017, C. Decock, M. Jérusalem & G. Castillo, KE-17-212 , GoogleMaps MJ-KE17-002 , MJ-KE17-003 , MJ-KE17-004 , MJ-KE17-005 , MJ-KE17-006 , MJ-KE17-007 , MJ-KE17-008 , MJ-KE17-009 , MJ-KE17-010 , MJ-KE17-011 , MJ-KE17-012 & MJ-KE17-013 ; ibid., ~ N01°2’54.9”, E034°46’22.4”, elev. ~ 2296 masl, on trunk of a living tree, Turraea cf. holstii ( Meliaceae ), 1 Nov. 2017, C. Decock, KE-17-275 . GoogleMaps

Notes: Phylloporia afropectinata is characterised by perennial, merismatoid basidiomes with multiple downward proliferations of imbricated pilei ( Fig. 2), variably sized, and reaching, based on our observations, up to 25 cm wide. It is so far the species producing the largest merismatoid basidiomes in Phylloporia . Corner (1991) provided likely the best modern description of the development of the merismatoid basidiomes in Phylloporia , and our description are, partly, adapted from him.

The hyphal system is of uncertain classification. In the classification scheme of Corner (1991), it would be best described as dimitic of the second degree (d2), with sclerified hyphae, as in P. weberiana and P. chrysites , both sensu Corner (1991). However, dimitism of the d2 degree is not entirely satisfactory by omitting the intercalary, very thick-walled hyphae. The sclerified hyphae of limited length originate from a generative hyphae, occasionally from a mediate hyphae, and are either terminal or intercalary, then reversing to slightly thick-walled, generative hyphae ( Fig. 3). It could be also considered as intermediate dimitic, following Pegler (1996), or with sclerified, supporting hyphae following Clémençon (2012), as adopted by Ferreira Lopes (2018), e.g., in P. pectinata sensu stricto or in P. ribis sensu stricto.

Phylloporia afropectinata , hitherto, is known exclusively from a small-stemmed Meliaceae , Turraea sp. , in a single spot of mid-elevation (~ 2000 masl) Afromontane Forest ( Kindt et al. 2014), at Mount Elgon, Western Kenya. The identification of the host could not be confirmed in situ, nor by DNA sequence data. It is referred to as Turraea cf. holstii . The basidiomes emerge from different tree organs, from surfacing roots to, and predominantly, trunks and the main lower branches ( Fig. 2). Locally, the species is widely distributed, concomitantly to its host; it infects almost every individual tree present in an immediate neighbourhood. This might be linked to the locally gregarious habit of the host, forming small patches. Its distribution range in tropical Africa is still unknown. The species could follow its host over the Eastern Mountain range, where it is widely distributed, although it may depend also on other ad hoc environmental parameters.

In a phylogenetic perspective, the closest relative of P. afropectinata is shown to be, hitherto, the western African P. beninensis , that is only known to date from Benin ( Olou et al. 2021). Both are related to a specimen originating from Australia and tentatively identified as P. pectinata ( Australia, New South Wales, Kurrajong, R. Coveny 113, on Rhodamnia rubescens , Myrtaceae , O, CANB, Wagner & Ryvarden 2002). These three species form a well-supported clade ( Fig. 1).

Phylloporia afropectinata shares with P. beninensis View in CoL the imbricate basidiomes, the substrate, and the host family ( Meliaceae View in CoL ). Phylloporia beninensis ( Olou et al. 2021) View in CoL differs in having an annual (fide Olou et al. 2021) basidiome, more cylindrical oblong basidiospores (mostly 3.3–4.3 × 2.4–3.3 μm, av. 3.8 × 2.8 μm vs 3.8–4.3(–4.5) × 3.0–3.5 μm, av. = 4.0 × 3.2 µm), growing on Trichilia emetica View in CoL (vs Turrea cf. holstii ), and a different habitat.

Phylloporia afropectinata should be compared also to P. pectinata sensu Ryvarden et al. (2022) View in CoL (or under Phellinus pectinatus View in CoL ; Ryvarden & Johansen 1980), reported from East Africa, from Ethiopia Northward, Southward to Malawi. However, the identity of P. pectinata sensu Ryvarden et al. (2022) View in CoL is uncertain. Considering its main characters, including compound basidiomes, small pores (8–10/mm), and a distribution in East Africa, P. afropectinata could be equated, at least pro parte, to P. pectinata sensu Ryvarden & Johansen (1980) View in CoL .

Phylloporia memecyli , P. miomboensis , and P. warneckeicola (cf. below) could be morphologically compared also to P. afropectinata . Phylloporia miomboensis was tentatively identified as P. pectinata View in CoL (identification by L. Ryvarden, herbarium label, O!). They differ in having much smaller basidiomes and a dimitic hyphal system with skeletal hyphae of restricted growth. Phylloporia memecyli and P. warneckeicola also differ in their reproduction strategy, with the simultaneous emergence in dense clusters of multiple basidiomes. Both species inhabit the lowland western edge of the Guineo-Congolian phytochorion and grow from two species of Melastomataceae View in CoL , respectively Memecylon viride View in CoL and Warneckea floribunda View in CoL , both absent from the East African montane range. Phylloporia miomboensis differs also as inhabiting the Lowland Zambezian dry open forest.

Outside Africa, P. pectinata sensu Corner (1991) is the taxon most comparable to P. afropectinata , with respect to its biology, macro- and micromorphology, autecological parameters such as substrate relationships, and local distribution. Both species share the compound, merismatoid basidiomes, reaching up to 15 cm wide in P. pectinata sensu Corner (1991) . They both grow from small-stemmed trunks, and have a very comparable pattern of occurrence at a local scale. While P. pectinata sensu Corner (1991) was found on “almost every tree” of the small-stemmed, understory Timonius flavescens ( Rubiaceae ) at the ridge forest of Gunong Panti (Southeast of Johor, Malaysia), P. afropectinata was emerging from almost every individual of Turraea cf. holstii growing in an immediate neighbourhood at Mount Elgon, Kenya. Phylloporia pectinata sensu Corner (1991) and P. afropectinata differ by their pore size (60–90 µm diam., ~10–12 / mm vs 90–115 µm, 8–9 / mm), ellipsoid vs broadly ellipsoid to subglobose basidiospores (2.7–3.5 × 2–2.5 µm vs 3.8–4.3 × 3.0–3.5 µm), host plant ( Timonius flavescens vs Turraea cf. holstii ), and habitat (Southeast Asian rainforest vs Afromontane middle elevation forest).