Russula absphaerocellaris X.Y. Sang & L. Fan, 2016

Sang, Xiaoyu, Li, Xuedong, Wang, Yanwei & Fan, Li, 2016, Four new sequestrate species of Russulaceae found in China, Phytotaxa 289 (1), pp. 101-117 : 108-110

Russula absphaerocellaris X.Y. Sang & L. Fan , sp. nov. ( Fig. 4 , Fig. 7B )

Mycobank: MB819369

Type:— CHINA. Yunnan: Kunming City, in soil under mixed woodlands dominated by P. yunnanensis Franch. , 10 Jan 2015, Cao 1566, FAN 492 ( BJTC!), collected by J. Z. Cao (Holotype: BJTC FAN 492).

Basidiomata 13–21 × 11–19 mm, subglobose to irregularly globose, depressed at base. Peridial surface yellow brown, glabrous, with furrows. Gleba ochraceous, labyrinthic or loculate; loculae crowded, sometimes compacted. Stipe absent. Columella absent. Latex absent. Smell unremarkable.

Basidiospores globose, few subglobose, 10–15 ×10–15 μm (x = 12.9 ± 1.4 × 12.5 ± 1.3, n = 30) excluding ornamentation, Q = 1.00–1.25, brown, slightly thick-walled, completely dissociated after maturity; ornamentation strongly amyloid, composed of isolated, spindly spines 1–3 μm long and spines rarely forked at the apex. Hilar appendix usually conspicuous, 2–5 μm long, central, cylindrical or conical, straight. Basidia 20–38 × 5–10 μm, clavate to broadly clavate, broadly cylindrical or ventricose, hyaline, mostly 1- rarely 2-spored, the sterigmata up to 5–7.5 μm long. Pseudocystidia absent. Cystidia absent. Hymenophoral trama 12.5–38 μm wide, composed of interwoven, hyaline hyphae 2.5–5 μm diam., scattered inflated elements 2.5–5 μm diam., sphaerocytes absent; subhymenium 12.5–25 μm wide, composed of pseudoparenchyma with 2–3 tiers of isodiametric cells 7.5–18 × 5–12 μm broad. Peridiopellis only one-layered, 25–87 μm wide, composed of a patchy turf of upright to repent hyphal tips 2.5–5 μm diam., sometimes with a layer of gelatinous matrix. Peridial context 150–400 μm wide, composed of loosely interwoven, hyaline hyphae 2–4 μm diam., sphaerocytes absent.

Diagnosis:— Basidiomata 13–21 × 11–19 mm diam., subglobose. Peridial surface yellow brown, glabrous. Gleba ochraceous, labyrinthic or loculate. Columella absent. Basidiaspores globose, few subglobose, with isolated and curved spines. Basidia mostly 1-spored. Pseudocystidia and cystidia absent. Peridiopellis one-layered. Sphaerocytes absent in peridial context.

Etymology: —Latin, absphaerocellaris = absence of sphaerocytes, in reference to the absence of sphaerocytes in the peridial context.

Habit, habitat and distribution: —hypogeous, gregarious, in soil under mixed woodlands dominated by P. yunnanensis in Yunnan Province, China.

Additional specimen examined (paratypes): — CHINA. Sichuan: Panzhihua, in soil under mixed woodlands dominated by P. yunnanensis , 23 Nov 2014, CJZ 1539, FAN448 (BJTC!), all collected by J.Z. Cao (Paratype: BJTC FAN448).

Commentary: — Russula absphaerocellaris is differentiated from other species of the genus Russula by the combination of the peridiopellis with a patchy turf of hyphal tips, the mostly one-spored basidia and the absence of sphaerocytes in peridial context. Gymnomyces gilkeya e (Zeller & C.W. Dodge) Trappe, T. Lebel & Castellano ( Trappe et al. 2002: 199) (= Martellia gilkeyae ) and G. monosporus E.L. Stewart & Trappe ( Stewart & Trappe 1975: 209) are similar to the new species as both of them also have one-spored basidia normally, and Gymnomyces gilkeya e has been reported in China ( Liu et al. 1998). However, the basidiospores of G. gilkeya e are noticeably large (12–16 × 12–15 μm) and have long prominent spines of simple to forked, or truncated cones (3.4–5 μm in length) ( Singer & Smith 1960). Gymnomyces monosporus has large, subglobose to broadly elliptical basidiospores (15–21 × 12–18 μm), and its peridiopellis composed of interwoven, hyaline hyphae and sphaerocytes ( Stewart & Trappe 1975). By the way, three hypogeous species described from China, G. lactifer , M. ramispina , M. nanjingensis , have similar structure in peridiopellis to R. absphaerocellaris . However, G. lactifer is distinguished from R. absphaerocellaris by its lactiferous basidiomata ( Zhang & Yu 1990), and by which Trappe et al. (2002) transferred it to the genus Zelleromyces as Z. lactifer (B.C. Zhang & Y.N. Yu) Trappe, T. Lebel & Castellano ( Trappe et al. 2002: 204) ; Martellia ramispina has 2–4- spored basidia and spinous ornamentations often with 2- or 4-branched tips ( Zhang & Yu 1990); Martellia nanjingensis have 2-spored basidia and shorter spines (0.5–1.3 μm long) ( Tao et al. 1993).

Figures

FIGURE 4. Russula absphaerocellaris (BJTC FAN492, holotype). A. Basidiomata. B. Basidia. C. Basidiospores. D. Peridiopellis and peridial context. E. Hymenophoral trama and hymenium. Scale bar = 10 mm (A), 10 μm (B–E).

FIGURE 7. Scanning electron micrograph (SEM) of basidiospores. A. Lactarius spinosporus (holotype). B. Russula absphaerocellaris (holotype). C. Russula brevipileocystidiata (holotype). D. Russula megapseudocystidiata (holotype). Scale bar = 5 μm.