Filoboletus pallescens (Boedijn) Maas Geesteranus (1992: 269)

Cooper, Alexandra C., Desjardin, Dennis E. & Perry, Brian A., 2018, The genus Mycena (Basidiomycota, Agaricales, Mycenaceae) and allied genera from Republic of São Tomé and Príncipe, West Africa, Phytotaxa 383 (1), pp. 1-47 : 36-39

16. Filoboletus pallescens (Boedijn) Maas Geesteranus (1992: 269) ( Fig. 28 , 29 )

Basionym:— Poromycena pallescens Boedijn (1940: 398) .

Description:— Pileus 7–20 mm diam, initially parabolic, becoming broadly campanulate to broadly obtusely conical or convex, margins inrolled, pellucid-striate to short-striatulate, pustulate-tesselate; surface moist, glabrous, hygrophanous, disc brown (6–7E4–5) or brownish grey (6–7C–D3), margin grey (7D2), fading overall with moisture loss to brownish grey (6–7C–D3). Context 1 mm thick, watery-white to grey. Lamellae ascending-adnate to adnexed, horizontal, distant (15–18) with 2–3 series of lamellulae, broad (~ 3 mm), reticulate to subporoid, pores round to angular, cross lamellae much shallower, pale greyish white with brown tones in upper portion. Stipe 21–40 × 2–4.5 mm, central, cylindrical, terete or flattened, base enlarged, hollow, pliant; surface dull, dry, appressed-pubescent to minutely white-pruinose overall, ornamentation very dense towards base, white to pale greyish white overall. Odour and taste indistinct. Bioluminescence undetected.

Basidiospores 6.4–8.0 × 4.8–6.4 μm [x mr = 7.0–7.7 × 5.2–5.5 μm, x mm = 7.34 ± 0.5 × 5.38 ± 0.2, Q = 1.1–1.7, Q mr = 1.28–1.47, Q mm = 1.37 ± 0.1, n = 20, s = 2], subglobose to broadly ellipsoid, smooth, hyaline, amyloid, thin-walled. Basidia 25.6–34.4 × 4.8–7.2 μm, clavate, hyaline, inamyloid, thin-walled, 4-spored, sterigmata up to 10.4 μm long.

Basidioles clavate. Lamellar edge sterile. Cheilocystidia 30–102 × 6.4–15.2 μm, fusiform to subclavate, occasionally fusiform-strangulate, rarely with a single apical projection, hyaline, inamyloid, thin-walled. Pleurocystidia absent.

Pileipellis a cutis; hyphae 2.4–9.6 μm diam, repent, cylindrical, rarely diverticulate, hyaline or with a few brown incrustations, inamyloid or weakly dextrinoid, thin-walled, non-gelatinous; diverticula 1.6–7.2 × 0.8–3.2 μm, knoblike. Hypodermium undifferentiated. Pileus trama loosely interwoven; hyphae 3–20 μm diam, non-diverticulate,

hyaline, weakly dextrinoid, thin-walled, non-gelatinous. Lamellar trama regular; hyphae 2.4–24 μm diam, cylindrical to inflated, hyaline, dextrinoid, non-gelatinous, thin-walled. Stipitipellis a cutis; cortical hyphae 2.4–5.6 μm diam, parallel, cylindrical, occasional cylindrical diverticula, hyaline, dextrinoid, thin-walled; medullary hyphae 8.8–26.4 μm diam, smooth, dextrinoid, thin-walled, rare laticiferous hyphae up to 8.8 μm diam with knob-like projections. Caulocystidia abundant; 32.8–105 × 6.4–12.0 μm, fusiform-clavate with obtuse diverticula, hyaline, inamyloid, thin-walled. Clamp connections present in all tissues.

Habitat and known distribution:—Gregarious to scattered or solitary on fallen rotten dicot wood in coastal palm grove. Africa ( Príncipe), Indonesia (Krakatoa).

Material examined:—AFRICA. Príncipe, Bom Bom, N01˚41.559’, E07˚24.171’, 22 April 2008, coll. by D.E. Desjardin, DED 8303 (SFSU). Príncipe, Dois Irmẽos, N01˚35.728’, E07˚25.263’, 23 April 2008, D.E. Desjardin and B.A. Perry, BAP 654 (SFSU).

Notes:— Filoboletus pallescens is characterized by a pustulate-tesselate, brownish grey pileus, subporoid lamellae, a white to pale greyish white, pruinose stipe, subglobose to broadly ellipsoid basidiospores with mean 7.3 × 5.4 μm, fusiform to subclavate cheilocystidia, no pleurocystidia, a cutis-type pileipellis with none to few diverticula, and numerous fusiform-clavate caulocystidia. The original description ( Boedijn 1940) indicates that the pileus is campanulate and in age convex often with a small umbo, pale grey when fresh and white when dried. The material from Príncipe lacks an umbo and is more deeply pigmented, otherwise the basidiomata are similar. The micromorphology reported by Boedijn (1940) matches nicely with our material. Maas Geesteranus (1992) reported that the hymenophore of F. pallescens was luminous. The material from Príncipe was not luminescent.

This species is very closely allied with F. manipularis (Berk.) Singer , a strongly bioluminescent taxon widely distributed in East Asia. The latter differs, however, in forming cheilocystidia with diverticulate projections, and a pileipellis with more densely diverticulate hyphae ( Corner 1954, Pegler 1986). Filoboletus lachiwalensis Maas Geest. , described from India, differs in forming more crowded (16–30), decurrent lamellae, inamyloid lamellar trama, cheilocystidia with numerous apical diverticula, and gelatinized pileipellis and stipitipellis ( Maas Geesteranus 1992). The New World F. gracilis (Klotzsch ex Berk.) Singer differs in forming a light pinkish cinnamon, conical pileus, much narrower lamellar tubes (0.5–1 mm), utriform to lecythiform, subcapitate cheilocystidia, a well-developed hypodermium, and smaller, oblong-ellipsoid to pyriform caulocystidia (Pegler 1983).

Pairwise comparisons of aligned, overlapping ITS sequences of F. pallescens (BAP 654, DED 8303) with the top ten BLAST results show 93.6–94.0% similarity to six sequences of F. manipularis from Vietnam, and is sister to F. manipularis in the ITS phylogeny ( Fig. 2) with 90% BS and 0.93 PP support. No other Filoboletus ITS sequences are available for comparison.

Figures

FIGURE 28. Basidiomata of Filoboletus pallescens a. BAP 654. b. DED 8303 Scale bar = 10 mm.

FIGURE 29. Filoboletus pallescens (DED 8303). a. Basidiospores. b. Basidia. c. Cheilocystidia. d. Caulocystidia. Scale bar = 10 μm.