Micropsalliota inflata D.D. Ivanova & O.V. Morozova, 2023

Ivanova, Daria, Morozova, Olga & Pham, Thi Ha Giang, 2023, Three new species of Micropsalliota (Agaricaceae, Basidiomycota) from central and southern Vietnam, Phytotaxa 626 (4), pp. 247-258 : 253-254

Micropsalliota inflata D.D. Ivanova & O.V. Morozova , sp. nov. ( Fig. 4 )

Mycobank: MB849327

Type:— VIETNAM, Dong Nai Province, Vinh Cuu District, Dong Nai National Park , on a destroyed termite mound on roadside in a tropical polydominant mixed forest, 14 June 2011, coll. O. V. Morozova (holotype: LE F-315912!, isotype: VRTC 285 VN 11!)

Etymology—Referring to inflated hyphae of the pileipellis.

Diagnosis:—Differs from other small species with red pileus by having basidiospores up to 8 µm long, and oval, inflated, allantoid cells of pileipellis hyphae.

Description: Basidiomata small and fragile, red or cerise (12C8) when fresh, discoloring to dark ruby (12F4–6) when dried. Pileus 3–4 mm in diameter, first campanulate, convex when mature; surface dry, reddish white (11A2) with appressed fine squamules of burgundy, violet brown colors (11D5– 7, 11E 6–8), squamules denser towards the center, the surface reddish brown (8E4) in KOH. Lamellae free, close, 0.4–0.9 mm broad, intercalated with lamellulae, white or cream, with paler edge. Stipe 7–10 × 0.4–1 mm, cylindrical, white or pale burgundy, surface covered with dull red (11B3–4, 11C3–4) tiny fibrillose scales. Annulus fugacious, membranous, dirty white and pale pink, with darker margins.

Basidiospores 6.4–8 × 3.6–4.8 µm, Q = 1.7–1.93, Q m = 1.67 (n = 21), amygdaliform in side view, ellipsoid in frontal view, with apical endosporal thickening. Basidia 16.1–19.0 × 6.5–7.6 µm, clavate, 2- and 4-spored, hyaline. Cheilocystidia 23.2–32.3 × 8.8–11.9 µm, utriform and lageniform, not capitate. Pleurocystidia absent. Pileipellis a cutis, composed of hyphae 7–20 µm, constricted at the septa, incrusted with reddish brown pigment; cells of the hyphae allantoid, almost oval and easy to be separated from each other. Stipitipellis a cutis, composed of hyphae up to 10 µm wide, constricted at the septa; terminal cells often allantoid, up to 17 µm wide, incrusted with reddish brown pigment.

Habitat and distribution: On a destroyed termite mound on roadside in a tropical polydominant mixed forest. Known only from the type locality in southern Vietnam.

Notes: Micropsalliota inflata has small, fragile basidiomata with red pileus and pale burgundy stipe, allantoid hyphae of pileipellis, and large amygdaliform spores (up to 8 µm long). This species is similar to others with squamulose pileus of red shades, but M. inflata can be distinguished from them by inflated and oval-shaped cells of pileipellis hyphae and smaller basidiomata. Micropsalliota cardinalis Heinem. possesses a pileus of approx. 10 mm, white stipe without a ring, lesser spores (5.2–6.8 × 3.1–3.6 μm) and subcapitate elongated cheilocystidia ( Heinemann 1989: 459). Micropsalliota cymbispora Heinem. & Little Flower possesses pileus 5–7 mm diam., smaller cymbiform spores (4.4–5.8 × 3–3.6 μm), and narrow elongated cheilocystidia ( Heinemann & Little Flower 1983: 78). Micropsalliota roseipes Heinem. differs by its pinkish-purple pileus (becoming dirty-purple-brown), deep pink stipe, wider ellipsoid spores (5.3–7.4 × 4.0–4.8 μm) and utriform, capitate cheilocystidia ( Heinemann 1980: 65). Micropsalliota avellanea Heinem. & Little Flower has a reddish-brown pileus 10–14 mm diam., stipe without annulus, smaller cymbiform spores (5–5.8 × 2.8–3.6μm), capitate cheilocystidia with a long sinuous neck ( Heinemann & Little Flower 1983: 77). Micropsalliota laeta Heinem. is characterized by a pileus 8–22 mm in diameter of lighter shades of red, smaller spores (6.3–7.1 × 3.6–4 μm), and fusiform, capitate cheilocystidia ( Heinemann 1980: 58). Micropsalliota suthepensis R. L. Zhao, Desjardin, K. Soytong & K. D. Hyde has more robust basidiomata, brownish violet (11D6) pileus up to 20 mm in diameter, white or brownish violet stipe, clavate cheilocystidia and smaller spores up to 6 mm long ( Zhao et al. 2010: 73). Micropsalliota gracilis Heinemann has larger basidiomata (up to 22 mm in diameter), smaller spores 5.5– 6.5 × 3–4 μm, a white gracile stipe, and elongated subcapitate cheilocystidia ( Heinemann 1980: 60). Micropsalliota wuyishanensis J. Q. Yan possesses a pileus 6.0– 10 mm, white stipe, smaller basidiospores (5.0–6.5 × 3.0–3.5 μm) and branched or forked cheilocystidia ( Yan et al. 2022: 15).

Figures

FIGURE 4. Micropsalliota inflata (LE F-315912, holotype): (a) basidiomata in situ: (b) basidiospores, (c) basidia, (d) cheilocystidia, (e) pileipellis hyphae. Bars: a = 1cm; b–d = 10μm; e = 20μm.