Hohenbuehelia flabelliformis Phonemany & Raspe, 2023

Phonemany, Monthien, Vadthanarat, Santhiti, Raghoonundon, Bhavesh, Thongklang, Naritsada & Raspe, Olivier, 2023, Additions to Hohenbuehelia (Basidiomycota, Pleurotaceae): two new species and notes on H. tristis from northern Thailand, MycoKeys 99, pp. 109-130 : 109

Hohenbuehelia flabelliformis Phonemany & Raspe sp. nov.

Figs 2 , 3

Diagnosis.

This species is distinguished from other Hohenbuehelia species by large flabelliform basidiomata, yellowish-white pileus that is densely villose with white hairs longer near the point of attachment, and shorter towards the margin, ellipsoid basidiospores, absence of cheilocystidia, and a trichoderm pileipellis.

Holotype.

Thailand, Chiang Mai Province, Mae Taeng District, Pha Daeng Village, 27 May 2019, Monthien Phonemany (MFLU22-0008).

Etymology.

" flabelliformis " refers to the flabelliform shape of basidiomata.

Description.

Pileus 35-45 × 20-40 mm, spathulate when young, expanding to spathuliform, flabelliform, rounded flabelliform or orbicular, white when young, becoming yellowish-white to pale yellow (4A2-4A3) at the centre and cream (2A3-2B3) to slightly darker elsewhere in age; surface densely villose with white hairs that are longer near the attachment and shorter towards the margin, as observed with a lens; margin white, incurved when young, becoming straight when old. Lamellae 1-3 mm wide, decurrent, pale yellow to yellowish-white (4A3-4A2), moderately crowded when mature, with lamellulae in 1-3 tiers; edge concolorous to sides, fimbriate. Stipe absent or as pseudostipe 5-12 mm × 3-8 mm. Context consisting of two layers: 1) non-gelatinous layer, 1 mm thick, soft when young and rather leathery when old, white to dirty white (4A1-4A2); 2) gelatinous layer 0.5 mm thick, soft, sticky, colourless. Odour mild, pleasant. Taste none. Spore print white.

Basidiospores [150/3/2] (5.8-)6-7-8(-8.6) × (3.5-)4-4.2-5(-5.1) µm, Q = (1.3-)1.36-1.67-2.01(-2.03), ellipsoid to elongate (oblong) in side view, smooth, thin-walled, inamyloid. Basidia (21-)21-25.8-35(-37) × (5-)5.3-7.3-10.5(-11) µm, subclavate to clavate, with 4 sterigmata 4-8 µm long, hyaline, smooth, thin-walled. Cheilocystidia absent. Pleurocystidia metuloidal, present on both sides of lamellae and visible with a lens, (34-)34-42-54(-55) × (8.5-)8.5-11-14(-14.5) µm, scattered, narrowly fusiform to fusiform, mucronate at apex, brownish in KOH. Hymenophoral trama irregular, hyphae 2-5 µm wide. Pileipellis a trichoderm, hyaline in KOH, brownish in water, with cylindrical terminal elements 34-86 × 4-7 µm. Pileoleptocystidia absent. Pileus trama consists of two different layers: 1) upper layer gelatinous, composed of horizontally arranged, smooth, colourless encrusted hyphae, 2-5 µm wide; 2) lower layer, non-gelatinous, composed of interwoven, smooth, hyaline hyphae, 2-4 µm wide. Clamp connections present in pileipellis, pileus trama, and hymenophoral trama.

Habitat and distribution.

On dead wood, scattered or fasciculate by 2-4 basidiomata. So far only found in tropical forests of northern Thailand.

Additional specimens examined.

Thailand. Chiang Rai Province, Pa Daed District, Pa Ngae Village , 9 August 2019, Monthien Phonemany (MFLU22-0009) .

Notes.

The basidiomata colour of Hohenbuehelia flabelliformis is similar to H. angustata (Berk.) Singer, H. bonii A.M. Ainsw., H. concentrica Corner, H. carlothornii Consiglio, Setti & Thorn, H. horrida (Boedijn) Corner, H. luteola G. Stev, H. malesiana Corner, H. odorata C.K. Pradeep & Bijeesh, H. olivacea Yu Liu & T. Bau, and H. testudo (Berk.) Pegler. The basidiomata range from white, yellowish-white, yellow-brown, to pinkish-orange, and are spathulate to flabelliform. Hohenbuehelia angustata , originally described from Brazil, differs from H. flabelliformis by its smaller, smooth, greyish-yellow basidiomata, with stipe 4.5 mm long, smaller basidiospores (3.5-5 × 2.5-3.5 µm), smaller cheilocystidia, and the presence of pileocystidia ( Silva-Filho and Cortez 2017). H. horrida and H. odorata differ from H. flabelliformis by smaller basidiospores (5.2-7.6 × 4.8-6.4 µm), lack of cheilocystidia, and presence of pileoleptocystidia ( Bijeesh et al. 2019). Hohenbuehelia testudo differs by smaller basidia (20-25 × 5-6 µm), larger pleurocystidia (44-78 × 12-18 µm) with thick yellowish walls, and the presence of cheilocystidia ( Corner 1994). Hohenbuehelia malesiana , described from Brazil, is different from H. flabelliformis by having longer, subcylindrical basidiospores (7-9 × 3.5-4 µm), pileipellis as an interrupted cutis, and presence of cheilocystidia ( Corner 1994). Hohenbuehelia bonii , from England, has larger yellow-brown basidiomata (20-75 mm diam.), smooth pileus surface, larger basidiospores (7.2-10.4 × 4.5-6.1 µm), larger pleurocystidia (56-103 × 11-19 µm), and an ixotrichoderm or ixocutis pileipellis ( Ainsworth et al. 2016). Hohenbuehelia carlothornii described from Costa Rica, is different by having off-white basidiomata with a large pseudostipe (20-32 × 14-25 mm), presence of cheilocystidia ( Consiglio et al. 2018b). Hohenbuehelia concentrica from Singapore, has larger basidiomata (80 mm wide), larger basidiospores (8-8.5 × 6-6.7 µm), and absence of cheilocystidia ( Corner 1994). Hohenbuehelia incarnata , from the Solomon Islands, differs from H. flabelliformis by subglobose basidiospores and the presence of subcylindrical to submoniliform cheilocystidia ( Corner 1994). Hohenbuehelia olivacea , originally described from China, has reniform basidiomata with dense and long tomentum, light brown to pallid brown in gelatinous zone, and the presence of cheilocystidia ( Liu and Bau 2009).

Phylogenetically, H. flabelliformis was closely related to H. algonquinensis Consiglio, Setti & Thorn. (voucher RGT 870601/12 UWO) with 3.5% (21/599) differences in the ITS sequence, 1.4% (12/839) in the LSU sequence, and 6.66% (35/540) in the tef 1 sequence. Moreover, the morphologies of both species are completely different, with H. algonquinensis having glossy black pileus, ungulate to dimidiate basidiomata and contrasting white or off-white lamellae ( Consiglio et al. 2018b).

Figures

Figure 2. Basidiomata of Hohenbuehelia flabelliformis in the field a, c-e MFLU 22 - 0008 b MFLU 22 - 0009. Scale bars: 1 cm (a-e).

Figure 3. Micromorphology of Hohenbuehelia flabelliformis (MFLU 22 - 0008, MFLU 22 - 0009) a basidiospores b pleurocystidia c basidia and basidioles d pileipellis. Scale bars: 10 µm (a, c); 20 µm (b, d).