Hemistropharia subalbocrenulata Z.B. Zhao & E.J. Tian, 2019

Zhao, Zhengbo & Tian, Enjing, 2019, Hemistropharia subalbocrenulata (Strophariaceae, Agaricales), a new species with pleurocystidia and unique basidiospores from China, Phytotaxa 395 (3), pp. 219-226 : 221-225

Hemistropharia subalbocrenulata Z.B. Zhao & E.J. Tian , sp. nov. ( FIGURE 2 , 3 , 4 )

MycoBank: MB 827193

Diagnosis:—Differs from Hemistropharia albocrenulata in having pleurocystidia, some unusually larger basidiospores, smaller basidiomata, as well as a whitish stipe.

Type:— CHINA. Jilin Province: Jiaohe city, Shasong mountain, saprotrophic, scattered on rotten stumps of Ulmus pumila L. in conifer-broadleaf mixed forest, 43°32′8′′N, 127°1′21′′E, elev. 660 m, 9 August 2017, Zhengbo Zhao & Enjing Tian ( HMJAU 46957 , holotype!) (GenBank: ITS: MH697850 and LSU: MH712739 ).

Etymology:—The epithet subalbocrenulata refers to the similarity to Hemistropharia albocrenulata .

Description:— Pileus 2.2–3.9 cm in diameter, dark reddish orange to dark brown (10.0R 5/8-5/10), viscid, convex to hemispherical when young, becoming broadly convex to nearly plane, sometimes with an obtuse umbo, not hygrophanous, no striate, with whitish to pale brownish yellow (7.5Y 9/2), fibrillose squamules formed by remnants of the veil; margin slightly involute to deflexed, frequently decorated with veil fragments. Context slightly thick, whitish to pale yellow (5.0Y 9/2); odor and taste not distinctive. Lamellae whitish to pale purplish gray (2.5PB 9/2), adnate to sinuate, close, broad; edges white and crenulate. Stipe 4.2–5.5 cm long, 0.5–0.9 cm thick, whitish to yellowish (7.5Y 9/2), central, equal to slightly enlarged at base, stuffed; surface dry, decorated with yellowish brown (2.5YR 6/8), subfloccose to recurved scales below the floccose-cottony evanescent annulus, pruinose to silky at the apex. Spore print dark rusty brown (5.0YR 3/8).

Basidiospores 10.5–14(–24) × 5.5–7(–10) μm, [Q = 1.75–2.82], some spores are unusually large (18–24 ×8–10μm), wide-fusoid, fusoid to subfusoid, wall appreciably thickened, smooth, with a distinct germ pore, content homogeneous to inhomogeneous with some amorphous, refractive, oily inclusion, brown in KOH at maturity, unchanged in Melzer’s reagent. Basidia 24.0–35.0 × 5.0–7.0 μm, 2-, or 4-spored, clavate, hyaline in KOH. Cheilocystidia abundant, 25– 55 × 5–9 μm, narrowly clavate, cylindric-capitate to flexuous with an apical capitellum, rarely subglobose with a short pedicel, thin-walled, smooth, hyaline, with homogeneous contents. Pleurocystida 40–50 × 7–10 μm, clavate-rostrate, the long neck, sometimes flexuous, apex acute to obtuse, content hyaline to yellow, homogeneous, sometimes with crystalline substance. Caulocystidia not observed. Lamellar trama regular; hyphae hyaline in KOH, smooth. Pileipellis a gelatinous layer of hyaline to light yellow hyphae, ixocutis, 4–9 μm in diam., thin-walled, smooth to slightly roughened. Clamp-connections present in all tissues.

Habitat:—Scattered on rotten hardwood in conifer-broadleaf mixed forest, from summer to autumn.

Additional materials examined:— CHINA. Jilin Province: Jiaohe City, Shasong mountain , elev. 660 m, 43°32′8′′N, 127°1′21′′E scattered on rotten stumps of Ulmus pumila L. in conifer-broadleaf mixed forest, 9 August 2017, Zhengbo Zhao & Enjing Tian ( HMJAU 46957 ) ; same location, 3 September 2017, Zhengbo Zhao ( HMJAU 46956 ) ; Jiaohe City, Shansong mountain , elev. 420 m, 43°33′55′′N, 127°0′23′′E, scattered on litter in conifer-broadleaf mixed forest, 5 September 2016, Zhengbo Zhao ( HMJAU 46958 ) ; Jilin Province, Yanji City, Erdaobaihe Town, Changbai Mountain Academy of Sciences , elev. 780 m, 42°24′12′′N, 128°6′1′′E, scattered on rotten stumps in conifer-broadleaf mixed forest, 7 September 2017, Zhengbo Zhao ( HMJAU 46960 ) ; Jiaohe City, Qianjin township forest school , 43°42′52′′N, 127°21′1′′E, solitary on coniferous wood, 11 September 2017, Shiliang Liu ( HMJAU 46959 ) .

Comments:—This species is readily recognized due to the dark brown pileus with pale brownish yellow fibrillose scales, pale purplish gray lamellae with white and crenulate edge, the stipe with subfloccose to recurved scales, some unusually large subfusoid spores (up to 24 μm long, 10 μm wide), conspicuous clavate-rostrate pleurocystidia with a flexuous neck, as well as cylindric-capitate cheilocystidia.

Hemistropharia subalbocrenulata is similar to the only one known species of this genus, H. albocrenulata , in the color and scales of the pileus. However, we can easily distinguish the former from the latter based on both micromorphological features and other macro-characteristics. The former has conspicuous,clavate-rostrate pleurocystidia with flexuous neck, larger basidiospores, and smaller basidiomata, as well as a whitish stipe; but the latter has no pleurocystidia, comparatively smaller basidiospores (11–14 × 5.5–7 μm), larger basidiomata (pileus, 3–10 cm broad) and darker stipe ( Jacobsson & Larsson, 2007). Furthermore, in our phylogenetic analysis, H. subalbocrenulata clustered with H. albocrenulata forming the Hemistropharia clade with the high statistical support (BPP = 1), but it represented a relatively independent lineage within it ( Figure 1 ). Therefore, it is proposed here as a new species of the genus Hemistropharia .

Figures

FIGURE 1. Consensus Bayesian tree based on combined ITS and LSU sequences data analysis. Bayesian posterior probabilities values (BPP ≥ 0.90) are indicated along nodes. Bold names belong to samples newly sequenced in this study. The new species described here is labelled with ‘*’.

FIGURE 2. Microscopic features of Hemistropharia subalbocrenulata (HMJAU 46957, holotype!) A. Basidiospores; B. Hymenium showing basidia, basidioles and pleurocystidia; C. Cheilocystidia; D. Pileipellis: ixocutis; E. Pleurocystidia. Bars = 10 μm. Drawings by Zhengbo Zhao.

FIGURE 3. Basidiomes of Hemistropharia subalbocrenulata.A. Showing pileus surface; B. showing lamellae and stipe surface. (HMJAU 46957, holotype!). Bars = 1 cm. (Photo by Zhengbo Zhao).

FIGURE 4. Basidiomes of Hemistropharia subalbocrenulata. A, B. Showing pileus and stipe surface. (HMJAU 46956). Bars = 1 cm. (Photo by Zhengbo Zhao).