Hygrocybe rimosa C.Q. Wang & T.H. Li, 2021

Wang, Chao-Qun, Zhang, Ming, Li, Hai-Jiao, Huang, Hao, Deng, Wang-Qiu, Li, Ting, Luo, De- Jun & Li, Tai-Hui, 2021, Hygrocybe rimosa (Hygrophoraceae, Agaricales), a new poisonous species from southern China, Phytotaxa 527 (4), pp. 293-300 : 294-298

Hygrocybe rimosa C.Q. Wang & T.H. Li , sp. nov. ( Figs. 3–4 )

Fungal Names : FN570860

Diagnosis:— Hygrocybe rimosa is characterized by its yellow to reddish pileus with a paler margin, striated pileus with radial fibrils, broad to ventricose lamellae, subglobose to oblong basidiospores measuring (7)7.5–11 × 5–8(8.5) μm. Hygrocybe rimosa differs from H. intermedia in having a smaller pileus, white lamellae, a slenderer stipe, broader basidiospores, and the distribution in southern China.

Etymology:— rimosa (lat.) means cracks or fissures, refers to the cracked pileus surface.

Typification:— Guizhou Province: Duyun City, Doupengshan , 26°22’N, 107°22’E, elev. ca. 1200 m, 10 September 2019, Ming Zhang, Wangqiu Deng and Ting Li ( GDGM78405 , Holotype) .

Gene sequence ex-holotype: MZ825202 (ITS), MZ848472 (LSU).

Description:— Pileus 1.4–4.5 cm, conic with a flat disc when young, becoming convex, plane to depressed when mature, waxy, light yellow to orange-yellow (4A5–7), orange to deep orange (5A6–8), red or vivid red (9A7–8), darker at center, paler and often more or less lemon yellow (3B5–8) towards the margin, usually with streaky radial fibers from about half the radius, tending to split or rimose radially from margin towards disc; margin slightly decurved to revolute and sometimes lacerated when young, gradually extended, arched to uplifted when mature. Context thin, white, unchanging when injured, brittle. Lamellae free, ventricose, up to 0.6 cm broad, subdistant, white, margins concolorous with faces, waxy, thick, fragile, with 1–3 unequal lamellulae between two entire lamellae, eroded at edge. Stipe 2–7 cm long, 0.2–0.6 cm thick, central to slightly eccentric, cylindrical, usually slightly enlarged downwards, white, pale yellow to yellow (3A3–6) when mature, usually white or paler at apex, with inconspicuous longitudinal stripes, waxy, hollow. Taste mild. Odor indistinctive.

Basidiospores (7)7.5–11 × 5–8(8.5) μm, Lm = 9.13 ± 0.93, Wm = 6.66 ± 0.88, Q = (1.13)1.15–1.58(1.73), Qm = 1.38 ± 0.13, subglobose, broadly ellipsoid, ellipsoid to oblong, hyaline, smooth, thin-walled. Basidia 4-spored, (34.5)35–52 × 9.5–13.5 μm, Q = (2.77)3.08–4.52(4.73), Qm = 3.76 ± 0.46, broadly clavate; sterigmata mostly 5–7 μm long. Lamellar trama regular, composed of long, parallel, hyaline, thin-walled, septate hyphae 4–40 μm in width. Pileipellis a cutis, consisting of hyphae 5.5–14.5 μm broad. Stipitipellis a cutis, made up of repent hyphae 3.5–12 μm broad. Clamp connections present in all tissues.

Known distribution:—Occurring in the subtropical regions in China, only known from Guangdong and Guizhou provinces until now.

Habit and habitat:—Scattered to gregarious in semi-natural grasslands or abandoned fields, occurring from May to September.

Additional specimens examined:— CHINA. Guangdong Province: Fengkai County, Heishiding , 23°25’N, 111°53’E, elev. ca. 450 m, 17 May 2013, Hao Huang ( GDGM40048 , GenBank accession numbers: MZ 825203 for ITS, MZ 848469 for LSU) ; Guizhou Province: Duyun City, Doupengshan , 26°22’N, 107°22’E, elev. ca. 1200 m, 10 September 2019, Ming Zhang, Wang-Qiu Deng and Ting Li ( GDGM78767 , GenBank accession numbers: MZ 825204 for ITS, MZ 848470 for LSU) ; Huishui County, Baijin Town, Dahua Village , 26°12’N, 106°77’E, elev. ca. 1050 m, 3 July 2021, De-Jun Luo HS 20210701 ( GDGM85785 , GenBank accession numbers: MZ 825200 for ITS, MZ 848473 for LSU) .

Figures

FIGURE 3. Basidiomata of Hygrocybe rimosa. A: GDGM40048, B–C: GDGM78405, D: 78767. Scale bars: 1 cm. Photos: A by Hao Huang, B–D by Ming Zhang.

FIGURE 4. Microcharacters of Hygrocybe rimosa. A: basidiospores, B: basidia. Drawings by Chao-Qun Wang.