Russula cylindrica Y.Song, 2023

Xie, Xiu-Chao, Buyck, Bart & Song, Yu, 2023, Species of Russula subgenera Archaeae, Compactae and Brevipedum (Russulaceae, Basidiomycota) from Dinghushan Biosphere Reserve, European Journal of Taxonomy 864, pp. 28-63 : 39-42

Russula cylindrica Y.Song sp. nov.

MycoBank: MB837414

Figs 3–4

Diagnosis

Russula cylindrica sp. nov. is mainly characterized by its cream buff to reddish brown pileus with obviously striate and undulate margin, white to cream lamellae becoming rusty brown when old, irregular presence of lamellulae, small spores ornamented with isolated warts and crests, cylindrical basidia and hymenial cystidia, and one-layered, gelatinized pileipellis with subcylindrical pileocystidia.

Etymology

Named after its cylindrical basidia and hymenial cystidia.

Type material

Holotype CHINA • Guangdong Province, Zhaoqing City, Dinghushan Biosphere Reserve , on the ground in evergreen broad-leaf forest mainly with Fagaceae trees; 12 Sep. 2016; Y. Song K16091239 ; GenBank

nos: MN 275533 (ITS), MK 881930 (nLSU), MK 882058 (mtSSU), MT 085523 (rpb1), MK 880657 (rpb2), MT 085571 (tef1); GDGM 79551.

Additional material examined

CHINA • Guangdong Province, Zhaoqing City, Dinghushan Biosphere Reserve , on the ground in evergreen broad-leaf forest mainly with Fagaceae trees; 8 Aug. 2016; Y. Song K16080807 ; GenBank no: MN275534 (ITS); GDGM79552 • same data as for preceding; Y. Song K16080808 ; GenBank nos: MN275535 (ITS), MN839556 (nLSU), MN839604 (mtSSU), MT085516 (rpb1), MT085631 (rpb2), MT085603 (tef1); GDGM79553 • same data as for preceding; Y. Song K16080830 ; GenBank no: MN275536 (ITS); GDGM79554 .

Description

Basidiomata small to medium sized, agaricoid. Pileus 4–7 cm in diam., hemispherical to convex when young, turning applanate with maturity; surface glabrous, gelatinized or waxy, viscid when wet, not easy to peel, white to cream (#FAFAD2) with reddish brown tint (#F4A460, #F1B461), dark rust brown (#DF8E3D, #EA9540) at center when old; margin entire when young, turning irregularly undulate and slightly upward with maturity, obviously striate to sulcate when mature, sometimes cracked. Lamellae adnate, thick, unequal, slightly narrowed near stipe, rarely forked, interveined, white (#FDFEFE) at first, turning cream and then rust brown (#E68320, #D4700D) with maturity; edge entire, concolorous, often with white powder; lamellulae present. Stipe 2.5–4× 1.5–2 cm, central, cylindrical, solid at first, turning spongy with age, white (#FFFAFA), often stained with reddish brown (#FAAA5A), longitudinally rugulose. Context whitish to chalky white (#F8F8FF). Taste mild. Odor indistinct. Spore print white (#FBFCFC).

Basidiospores subglobose to ellipsoid, rarely globose, small, (80/4/2) (4.4–)4.9–5.4–5.9(–6.5) × (4.1–) 4.6–4.8–5.2(–6.1) µm, [Q = (1.03–)1.07–1.23–1.39(–1.54)], hyaline in 5% KOH; ornamentation amyloid, composed of verrucous to subcylindircal warts less than 0.8 µm in height, mostly isolated, rarely fused into short crest or linked by lines, but not reticulate; suprahilar spot inamyloid. Basidia (17–)22–32–40 × 4.5–6–8 µm, subcylindrical to cylindrical, 2- or 4-spored; sterigmata 3.2–4.9 × 1.2– 1.7 µm. Pleurocystidia (17–)25–37–65(–73) × 3–4–6 µm, cylindrical, with obtuse apices, thin-walled, with granular or irregular refractive contents, weakly positive in SV or negative in SV. Cheilocystidia not frequent, similar to pleurocystidia. Lamellar trama composed of numerous sphaerocytes surrounded by connective hyphae, sphaerocytes measuring 10–26 × 7–22 µm. Subhymenium pseudoparenchymatous. Pileipellis an ixo-cutis, 33–120 µm thick, composed of cylindrical, septate and hyaline hyphae 2–5.5 µm wide; cystidioid hyphae present in the trama, 4–6 µm wide; terminal cells (7–)14–25–72 × 1.5–3– 5.5 µm, cylindrical, rarely lageniform, with obtuse or tapering apices, thin-walled, hyaline. Pileocystidia (73–)82–95.5–114 × 3.5–4.5–6 µm, cylindrical, often constricted at upper part, with obtuse apices, with refractive contents, negative in SV. Stipitipellis a cutis, composed of hyphae measuring 1.5–4.5 µm wide, rarely septate, incrusted hyphae frequent; terminal cells 9.5–19–30(–34) × 1.5–2–2.5 µm, cylindrical with obtuse apices, hyaline. Caulocystidia (17–)26–43–70(–81) × 2–3–5 µm, cylindrical, obtuse or papillate, with refractive contents. Clamp connections absent in all tissues.

Comments

The newly described R. cylindrica sp. nov. has all the typical features of the subgenus Archaeae (see introduction). It belongs to sect. Archaeinae R.Heim ex Buyck & Sarnari and differs from all other known species so far especially in its very pale overall color which lacks the dominant yellowish or brownish tones in young stages for the other species. The brownish discoloration ( Fig. 3 ) sets in only at later stages when fruiting bodies start to suffer from age. As in other Archaeinae collected from (sub)tropical climates ( R. pseudoaurantiophylla Buyck & V.Hofst. , R. archaea Heim , R. earlei Peck , R. gossypina Buyck ), it possesses a very thin-fleshed pileus.

The only other Asian species in the subgenus, R. butyroindica , still only known from India, is easily distinguished in the field from R. cylindrica sp. nov. by its yellowish and often cracked pileus, detailed micromorphological characters refer to Das et al. (2018).

Figures

Fig. 3. Russula cylindrica Y.Song sp. nov., holotype GDGM79551(A–B, G–H), specimen GDGM79553 (C–D), specimen GDGM79552 (E–F). A–F. Fruiting bodies. G–H. Basidiospores under scanning electron microscope. Scale bars: A–F = 1 cm; G–H = 1 µm.

Fig. 4. Russula cylindrica Y.Song sp. nov., holotype (GDGM79551). A. Basidia. B. Pleurocystidia. C. Cheilocystidia. D. Pileocystidia. E. Caulocystidia. Scale bars = 10 µm.