Russula pseudocatillus F. Yuan & Y. Song 2019, sp. nov.
Creators: name: Yuan, Fa
name: Song, Yu
name: Buyck, Bart
name: Li, Jingwei
name: Qiu, Lihong
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Russulales
Russulaceae
Russula
Russula pseudocatillus

description: 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).
description: Published as part of 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, pp. 45-56 in Cryptogamie, Mycologie 20 (4) on pages 50-54, DOI: 10.5252/cryptogamie-mycologie2019v40a4, http://zenodo.org/record/7814877