Macrolepiota velosa
Macrolepiota velosa Vellinga & Zhu L. Yang
Index Fungorum number: 373847
Basidioma large-sized, 14 cm high. Pileus 10 cm in diam., plano-convex, with a wide indistinct, umbo fibrillose, covered with dense, purplish-brown squamules at center, much scarcer near margin. Lamellae free, moderately crowded, white. Stipe purplish brown, slightly paler above annulus, cylindrical, 13 × 0.7–0.9 cm, tapering at apex, slightly enlarged at base. Annulus ascending, white above, purplish-brown below, with margin, irregularly waved. Volva white, limbate, membranous, with white rhizomorphs at the base. Taste and odor are indistinct.
Basidiospores amygdaloid-ellipsoid inside view, ellipsoid in front view, 8–11 × 5.5–7 μm (average =9.2 × 6.2 μm), Q (length/width ratio) 1.28–1.68 (average Q=1.49), smooth, thick-walled, dextrinoid, with api-cal central germ pore. Basidia clavate, without clamp connections at base, mostly 4-spored but sometimes 2-spored, 27–35 (not including sterigma) = 9–11 μm, sterigma 2–4 μm long. Cheilocystidia cylindrical, without clamp connections at base, thin-walled, 52–63 × 6–8.5 μm. Squamules on pileus composed of slightly thick-walled brown hyphae with cylindrical to swollen apex, up to 95 × 24 μm.
Habitat and known distribution in Myanmar: Terrestrial, solitary on the ground in predominantly
evergreen, broad-leaved forests including Dipterocarpaceae, mixed with bamboos and Pinus spp. So far only found in one locality (National Kandawgyi Garden) in Myanmar.
Materials examined: Myanmar: Mandalay Division, Pyin Oo Lwin, National Kandawgyi Garden, alt. 1,100 m, 28 Aug. 2016, K. Hosaka (KH-MYA16-018, deposited as TNS and Forest Research Institute, Myanmar).
Notes: Macrolepicola velosa was first described from Yunnan Province, China (Vellinga and Yang, 2003). It was then recorded from Hainan Province, China (Ge et al., 2010). The available information also indicates that the species is also distributed in Thailand (Chiang Mai), retrieved as a GenBank accession no. KJ524569 and also mentioned by Ge et al. (2010). However, we could not find any other published records (e.g., morphological observation) of the specimen from Thailand. Our morphological observation was consistent with previous descriptions of M. velosa (Vellinga and Yang, 2003; Ge et al., 2010). However, the material from Myanmar possesses slightly longer basidia (27–35 × 9–11 μm) than Chinese materials (25–30 × 9.5–11.5 μm). Furthermore, we have infrequently found 2-spored basidia, which were not observed by previous studies (Vellinga and Yang, 2003; Ge et al., 2010). These differences are likely intraspecific variations, but further studies are warranted.
The BLAST search indicated that the sequences (ITS and LSU) of Myanmar material shares highest similarities with M. velosa from China and Thailand. The top 5 hits of ITS BLAST search were all M. velosa (99.03% or higher similarities), and the next hit was “Macrolepiota sp. 3” (GenBank accession no. KY927722) from Brazil at 93.83% similarity. The top hit of LSU BLAST search (99.89%) was also M. velosa (GenBank accession no. JN940273) from Hainan, China. There was only one CT transition observed between Chinese and Myanmar samples across the whole range of LSU region. Phylogenetic analyses of the ITS region resulted in 6 equally parsimonious trees. The alignment consisted of a total of 680 characters, but 675 characters were parsimony uninformative and therefore excluded from the analyses. The ITS phylogeny was midpoint rooted, and arguably indicated that the materials from Hainan was more diverged from the rest of samples from Myanmar, Thailand and Yunnan, China. All materials were, however, separated only by a few substitutions. We, therefore, conclude that they all represent a single species, M. velosa. Our study revealed a new distribution of M. velosa outside of China and Thailand. The species may be distributed in wider areas in tropical to subtropical regions of Southeast Asia. Whether intraspecific variations observed from morphological and molecular analyses actually represent local populations or distinct species warrant further investigation.
Fig. 1 One of 6 most parsimonious trees of Macrolepiota velosa based on the ITS sequences. The tree was rooted at midpoint. Taxon names are shown as GenBank accession numbers followed by the countries (and more detailed locality, if available) of origin. The number of branch indicates parsimony bootstrap value. The asterisk indicates the node collapsed in the strict consensus.
Fig. 2 Macrolepiota velosa (KH-MYA16-018). A. Basidioma in situ. B. Pileus showing fibrillose surface. C. Basidioma with distinct volva at base of stipe. D. Lamellae and annulus. E. Volva. F. Dried basidioma. Scale Bars=2 cm.
Fig. 3 Light microscopy of Macrolepiota velosa (KH-MYA16-018). A. Basidiospores in Meltzer’s reagent. B. Basidiospores (reddish-brown) with globose lamellar cells (hyaline). C. Basidia showing 4 sterigmata (arrow). D. 2-spored basidia. Scale bars=10 μm.
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