Hygrocybe debilipes C.Q. Wang & T.H. Li, 2020

Wang, Chao-Qun, Zhang, Ming & Li, Tai-Hui, 2020, Three new species from Guangdong Province of China, and a molecular assessment of Hygrocybe subsection Hygrocybe, MycoKeys 75, pp. 145-161 : 145

Hygrocybe debilipes C.Q. Wang & T.H. Li sp. nov. Figures 3A, B , 4

Typification.

China. Guangdong Province, Taishan City, Chuandao Town, Xiachuan Island, on a grassland, elev. ca. 50 m, 21°37'36"N, 112°34'30"E, 17 July 2017, H. Huang, Q.J. Huang & X.R. Zhong (GDGM59314, holotype!).

Sequences ex holotype.

MW001783 (ITS), MW007877 (LSU).

Etymology.

" debili -": not strong, "- pes ": stipe. The species epithet " Hygrocybe debilipes " (Lat.) refers to the fragile stipe of the new species.

Diagnosis.

Hygrocybe debilipes differs from H. singeri in having a smaller pileus, orange red to vivid red pileus before discoloration, pale yellow to light orange lamellae, a fragile and less sticky stipe, ellipsoid to oblong basidiospores, and the distribution in South China Sea islands.

Description.

Pileus 5-12 mm diam., conical with an acute umbo when young, convex to hemispherical in age, inrolled at margin, orange red (8A7-8), red to vivid red (9A7-8, 9B7-8), blackening with injury or aging, sticky when moist, hygrophanous. Lamellae free, pale yellow (4A3) to light orange (5A4) when mature, blackening with injury or aging, up to 4 mm broad, distant, waxy, with 1-3 unequal lamellulae between two entire lamellae, with lighter color at lamellar edge. Stipe 22-45 × 2-5 mm, central, cylindrical, equal or slightly tapered at apex, fistulous, semitranslucent, usually too fragile to obtain a complete stipe base, pale yellow (4A3) to light orange (5A4) with white base, blackening with injury or aging, glabrous to fibrillose, moist.

Basidiospores (7.5)8-11.5(12) × (4.5)5-7(7.5) μm [mean length = 9.4 μm, mean width = 6 μm], Q = 1.3-1.8, Qm = 1.6, ellipsoid to oblong, smooth, thin-walled, hyaline. Basidia 32-53 × 8-13 μm, 4-spored, clavate, with sterigmata up to 7 μm long. Pileipellis a cutis of cylindrical hyphae 2-11 μm diam., thin-walled, hyaline. Stipitipellis a cutis or ixocutis of repent, thin-walled, clamped hyphae 2.5-16 μm diam. Hymenophoral trama regular to subregular, consisting of parallel hyphal cells 4-17 μm diam., thin-walled, hyaline.

Habit, habitat and distribution.

Scattered on grasslands in summer. Known from South China Sea islands.

Additional specimens examined.

China. Guangdong Province, Taishan City, Chuandao Town, Xiachuan Island, elev. ca. 50 m, 17 July 2017, Q.J. Huang, H. Huang & X.R. Zhong (GDGM59131, GDGM59133); Zhuhai City, Dawanshan Island, 28 July 2013, T.H. Li, H. Huang & Y.W. Xia (GDGM57013).

Remarks.

Hygrocybe debilipes is morphologically and genetically a distinct species. Hygrocybe debilipes is characterized by its tiny basidioma, orange red to vivid red pileus, pale yellow to light orange lamellae when mature, fragile and semitranslucent stipe, and ellipsoid to oblong basidiospores measuring (7.5)8-11.5(12) × (4.5)5-7(7.5) μm. Hygrocybe debilipes forms a strongly supported independent clade in both ITS and LSU phylogeny trees (Figs 1 - 2 ).

Hygrocybe cinereifolia , originally described from France, is morphologically similar to H. debilipes in its general appearance. However, H. cinereifolia has larger basidiomata and grayish to gray lamellae ( Courtecuisse 1992, http://www.pharmanatur.com/Mycologie/Hygrocybe%20cinereifolia.htm). Hygrocybe singeri , originally described from northwestern USA, is also morphologically similar to H. debilipes . However, H. singeri is larger (10-50 mm diam.), and possesses a yellow to orange pileus and greenish yellow lamellae ( Hesler and Smith 1963).

Figures

Figure 1. Maximum Likelihood phylogram of genus Hygrocybe based on LSU matrix, rooted with Hygroaster albellus (EF 551314), H. nodulisporus (EF 561625) and H. andersonii (KF 291171). The newly generated sequences in this study are showed in bold. GenBank accession numbers of downloaded sequences or voucher numbers of new sequences are given after the species names. Bootstrap values more than 50 % are shown around the branches.

Figure 2. Maximum-likelihood tree of sect. Hygrocybe based on ITS matrix, rooted with members of subsect. Macrosporae. The newly generated sequences in this study are indicated in bold face. GenBank accession number of downloaded sequence or voucher number of newly generated sequence and place of origin are given after the species name of each sequence. Bootstrap values more than 50 % are shown around the branches.

Figure 3. Basidiomes of Hygrocybe species A Hygrocybe debilipes (GDGM 59314) B Hygrocybe debilipes (GDGM 57013) C Hygrocybe griseonigricans (GDGM 73527) D Hygrocybe griseonigricans (GDGM 81394) E Hygrocybe rubroconica (GDGM 45213) F Hygrocybe rubroconica (GDGM 45214).

Figure 4. Microscopic features Hygrocybe debilipes (GDGM 59314) A basidiospores B basidia C terminal cells of hymenophoral trama D terminal cells of pileipellis.