Kombocles bakaiana

Kombocles bakaiana Castellano, T.W. Henkel & Dentinger 2016, in in Castellano et al., IMA Fungus 7(2), 241 (2016).

Etymology: Baka and –iana (L. suffix adj.) = of the Baka; referring to the Baka indigenous people inhabiting the type locality.

Diagnosis: Basidiomata irregularly globose to subglobose, 10–20 mm tall, 15–25 mm broad, firm throughout development; surface pale cream to light yellowish-brown (4A2–5C4), inherently smooth but with numerous adherent soil particles, occasionally with irregularly spaced cracks revealing the underlying gleba, unchanging with handling but drying rugose to ruminate with numerous shades of brown and darker, humic-stained patches. Peridium two-layered in cross-section; outer layer < 0.5 mm thick, concolorous with surface but somewhat mottled due to uneven distribution of humic stains, underlain by an inner, pale yellowish (1A2–1A3) layer up to 1 mm thick that becomes cottony near the gleba. Gleba initially marbled, then with increasingly well-defined locules separated by off-white to bright white veins, with clear exudate centrally when cut in mature specimens; locules initially off-white to yellowish orange (4B7) to brown (7E8–7F8) at maturity; locules nearly filled with hymenial elements and basidiospores, irregularly spherical, up to ±1 mm broad. Dried gleba distinctly loculate; locules circular to irregularly polygonal, variably-sized up to 1.1 mm broad, with a dark, thin (± 20 μm) outline, inner portion mottled yellow-brown to medium brown, often with a paler central core, contiguous to irregularly-spaced. Odour mild, pleasant, somewhat sweet. Taste mild, indistinct. Peridium 220–320 μm thick, two-layered; outer layer ± 20 µm thick but non-uniform in thickness and sometimes absent in small portions of section, of pale yellow-brown tissues that are distinctly and heavily encrusted with minute particles of unknown origin, otherwise of similar structure as underlying inner layer; inner layer 200–300 μm thick, structurally a mix of textura globosa and textura intricata appearing as interwoven tissue with abundant hyaline, elongate, clavate cells, these 26–31 × 13–16(–24) μm, smaller towards peridial surface and larger where the layer adjoins the gleba; walls up to 2 μm thick. Glebal trama similar in structure to the inner peridium but with less elongate hyphae and more clavate or irregularly-shaped cells, variable in thickness to nearly absent, with no apparent color differentiation near the outer locule edge. Basidia elongate, 40–45 × 6–7 μm, hyaline, not rehydrating well; sterigmata four, prominent, 4–8.5 × ± 1μm, hyaline. Basidiospores variably-shaped, fusoid, allantoid to unevenly ellipsoid, asymmetrical in side view, with slight suprahilar depression, smooth under bright field microscopy or faintly roughened with Nomarski imaging, but distinctly rugulose under SEM, in KOH yellow-brown singly and in mass, many distinctly and instantly dextrinoid, particularly those towards the center of some locules, (12.5–)13.5–16.5 × (5–)5.5–6.0 μm (mean 14.3 × 5.7 μm), Q mean = 2.50, range = 1.86–2.67(–3.17) excluding the hilar appendage; hilar appendage prominent, up to 1.5 μm long, hyaline; walls 1.0–1.5 µm thick.

Index Fungorum Number: IF818595

Figure 1. Phylogenetic placement of Kombocles bakaiana within Boletaceae using Maximum Likelihood (ML) analysis of 28S ribosomal gene sequences. Left is the best ML tree from a RAxML search using the GTRGAMMA model of substitution on a PASTA-aligned dataset of 288 Boletaceae sequences and 16 outgroup taxa from other Boletales. The tree is rooted at the node leading to Suillus spp. The putative clade

containing Kombocles bakaiana is highlighted in red and shown on the right as an enlargement. Numbers on branches are percentage support based on 300 nonparametric bootstrap replicates. Terminal labels are composed of the GenBank accession number followed by taxon name and collection code. (Castellano et al., 2016)