Russula pseudocatillus F. Yuan & Y. Song, 2019

Yuan, Fa, Song, Yu, Buyck, Bart, Li, Jingwei & Qiu, Lihong, 2019, Russula viridicinnamomea F. Yuan & Y. Song, sp. nov. and R. pseudocatillus F. Yuan & Y. Song, sp. nov., two new species from southern China, Cryptogamie, Mycologie 20 (4), pp. 45-56 : 50-54

Russula pseudocatillus F. Yuan & Y. Song , sp. nov.

( Figs 4 , 5 )

SYSTEMATIC POSITION. — Basidiomycota, Agaricomycetes, Russulales , Russulaceae , Russula subg. Heterophyllidia sect. Ingratae .

HOLOTYPE. — China. Guangdong Province, Zhaoqing City, Dinghu Mountain , 14.IX.2016, J.W. Li K16042406, (holo-, GDGM [ GDGM 75338 ]).

ETYMOLOGY. — Named for its resemblance to R. catillus in pileus morphology.

DIAGNOSIS. — R. pseudocatillus F. Yuan & Y. Song , sp. nov. resembles R. catillus in overall pileus morphology, but it differs from the latter by its smaller basidiomata, presence of lamellula, much bigger basidiospores ornamented with higher warts never forming a reticulum, presence of dermatocystidia (pileocystidia and caulocystidia), smaller pleurocystidia and not gelatinized pileipellis.

HABITAT AND DISTRIBUTION. — Gregarious in evergreen broadleaf forest.

ADDITIONAL SPECIMENS EXAMINED. — China. Guangdong Province, Zhaoqing City, Dinghu Mountain, 7.VI.2015, J. B. Zhang K15060706.

DESCRIPTION

Basidiomata

Small, agaricoid.

Pileus

2.5-4 cm in diam., plano-concave or applanate with a depressed center, some slightly decurrent, surface glabrous, slightly viscid when wet, very pale yellow (corn silk, #FFF8DC) at margin, with a pale greyish brown (tan, #D2B48C) center; margin slightly undulate, striate, rarely cracked.

Lamellae

Adnate, subequal, interveined, often forked near stipe, about 2 mm in height, very pale grayish yellow (beige, #F5F5DC), unchanging when bruised; edge entire, concolorous; lamellulae rather frequent, but not polydymous.

Stipe

2.5-4 × 0.6-1 cm, central, cylindrical, sometimes slightly tapering upwards, surface dry, slightly longitudinally rugulose, a pale greenish-grayish yellow (goldenrod, #EEE8AA) in the upper part, burlywood at the bottom, stuffed at first, becoming hollow when old.

Context

Off-white (ivory, #FFFFF0), unchanging when bruised.

Odour

Indistinct.

Taste

Mild.

Spore print

Very pale.

Basidiospores

Broadly ellipsoid to subglobose, [40/2/2] 7.0-7.9-8.6 (-9.2) × (5.1- (5.5-6.1-6.6 (-6.7) µm, Q = (1.19-) 1.22-1.32-1.42, hyaline in 5% KOH; ornamentations amyloid, composed of conical to cylindrical warts up to 1.2 µm, isolated, never forming a reticulum; suprahilar spot unamyloid.

Basidia

33-41.5 × 10.5-13 µm, 4-spored, rarely 2-spored, some containing oil droplets; sterigmata up to 8 µm long.

Lamellar trama

Composed of nested sphaerocytes surrounded by connective hyphae.

Pleurocystidia

32-37.5 × 9.5-11.5 µm, clavate to subcylindrical, rarely fusiform, with obtuse to truncate apices, thin-walled, with abundant refractive granular contents, negative in SV.

Cheilocystidia

33-47.5 × 9-12.5 µm, clavate, with mucronate to rostrate apex, thin-walled, some with refractive granular contents, unchanging in SV. Marginal cells not differentiated.

Pileipellis

Orthochromatic in cresyl blue, divided into two layers: suprapellis trichoderm, composed of ascending to erect hyphae; subpellis a cutis, composed of septate, thin-walled, hyaline hyphae; terminal cells clavate to cylindrical, with obtuse apices; subterminal cells cylindrical or slightly inflated.

Pileocystidia

Abundant, unchanging in SV, mostly 13-33 × 3-6 µm, onecelled, cylindrical, apex obtuse, with granular contents, also present in subpellis.

Stipitipellis

A cutis, orthochromatic in cresyl blue, composed of repent, thin-walled, septate hyphae up to 4.6 µm broad.

Caulocystidia

Frequent, clavate to cylindrical, 16-35 × 3-8 µm, with obtuse or rostrate apex, one-celled, with refractive contents, unchanging in SV.

Stipe trama

Composed of connective hyphae and nested sphaerocytes.

Clamp connections

Absent.

Notes

Russula catillus was reported from Korea, and the name refers to the resemblance of the pileus to a small bowl traditionally used for holding soy sauce. R. pseudocatillus F. Yuan & Y. Song , sp. nov., is sharing similar overall color and shape with R. catillus . Dermatocystidia (both pileocystidia and caulocystidia) are present in our species, but were reported (in Lee et al. 2017) as absent in R. catillus , something that is highly unexpected and should be verified again as all of the presently known species in sect. Ingratae from any part of the world all have abundant dermatocystidia and abundant gloeoplerous elements in all of the tissues. Russula pseudocatillus F. Yuan & Y. Song , sp. nov. is very similar to this R. catillus , but it differs from the latter in its smaller basidiomata, irregular presence of lamellulae, much bigger basidiospores ornamented with higher warts that are never interconnected into a reticulum, and also because of its smaller pleurocystidia and poorly gelatinized pileipellis (see Tables 1 , 2 ).

Figures

FIG. 4. — Russula pseudocatillus F. Yuan & Y. Song, sp. nov.: K16042406 (GDGM 75338, holotype). A, B, fruiting bodies; C, D, Terminal elements of pileipellis; E, F, Scanning electronic micrographs of basidiospores. Scale bars: A, B, 1 cm; C, D, 10 μm; E, F, 1 μm.

FIG. 5. — Russula pseudocatillus F. Yuan & Y. Song, sp. nov.: K16042406 (GDGM 75338, holotype): A, Basidia; B, Pleurocystidia; C, Cheilocystidia; D, Pileocys- tidia; E, Caulocystidia; F, Pileipellis. Scale bars: 10 μm.