Russula japonica Hongo

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 : 52-57

Russula japonica Hongo

Figs 11–13

Material examined

CHINA • Guangdong Province, Zhaoqing City, Dinghushan Biosphere Reserve, on the ground in evergreen broad-leaf forest mainly with Fagaceae trees; 1 Oct. 2017; F. Yuan & Y. Song K17100106 ; GenBank nos: MN275688 (ITS), MK881959 (nLSU), MK882086 (mtSSU), MT085495 (rpb1), MK880686 (rpb2), MT085596 (tef1); GDGM79697 • same data as for preceding; Y. Song K17100104 ; GDGM79709 • same data as for preceding; 26 May 2015; Y. Song K15052631 ; GDGM79700 • same data as for preceding; 13 Sep. 2015; J. B. Zhang & Y. Song K15091301 ; GenBank no: MN275680 (ITS); GDGM79702 • same data as for preceding; 14 Sep. 2015; J. B. Zhang & Y. Song K15091419 ; GDGM79703 • same data as for preceding; 31 May 2016; Y. Song K16053108 ; GDGM79704 • same data as for preceding; 8 Aug. 2016; Y. Song K16080813 ; GDGM79705 • same data as for preceding; Y. Song K16080825 ; GDGM79706 • same data as for preceding; 12 Sep. 2016; Y. Song K16091228 ; GenBank no: MN275685 (ITS); GDGM79707 • same data as for preceding; 5 May 2018; Y. Song K18050528 ; GenBank nos: MN839579 (nLSU), MN839629 (mtSSU), MT085497 (rpb1), MT085656 (rpb2), MT085627 (tef1); GDGM79710 • On the ground in coniferous forest; 2 Sep. 2014; Y. Song Z14090205 ; GDGM79698 • On the ground in broad-leaf and coniferous mixed forest; 8 May 2015; Y. Song H15050805 ; GDGM79699 • same data as for preceding; 6 Jun. 2015; Y. Song H15060608 ; GDGM79701 • same data as for preceding; 12 Jul. 2017; Y. Song H17071211 ; GenBank no: MN275686 (ITS); GDGM79708 .

Description

Basidiomata medium sized to large. Pileus 7–14 cm in diam., hemispherical to convex when young, turning applanate with depressed center to infundibuliform; surface glabrous, dry, jet white to chalk white (#FFFFFF, #FAF9F9), often tinged or stained with reddish brown (#FD863D; #F7BE81) when mature; margin undulate and slightly inrolled, rarely cracked. Lamellae adnate to slightly decurrent, crowded, unequal with multidymous lamellulae, sometimes forked near stipe, interveined, white at first, turning brownish, reddish brown or yellowish brown (#FDBC78; #F5DA81) with maturity, often rust brown (#FAAC58) stained when old; lamellulae frequent. Stipe 2.5–7 × 2.5–4 cm, central, subcylindrical, often slightly tapering towards base, solid at first, turning spongy with age, white, longitudinally rugulose, turning reddish brown (#FDB262) when bruised. Context white, becoming reddish brown (#FDB262) when bruised and brownish in 5% FeSO 4. Odor distinct. Spore print cream (#FCF3CF).

Basidiospores subglobose to broad ellipsoid, (100/5/5) (5.1–)5.8–6.2–6.6(–6.9) × (4.9–)5.3–5.7–6.1(– 6.5) µm, [Q = (1.02–)1.04–1.12–1.20(–1.23)], hyaline in 5% KOH; ornamentation amyloid, composed of verrucous to cylindrical warts less than 1 µm in height, some fused into crest, mostly connected by fine lines forming partial reticulum; suprahilar spot inamyloid. Basidia 23–30–33(–38) × 5–7–9(– 12) µm, clavate, 2- or 4-spored, thin-walled; sterigmata 3.5–5.5 × 1–1.5 µm. Pleurocystidia (34–)38– 52–64(–72) × 4.5–8–10 µm, subcylindrical to fusiform, with mucronate or papillate apices, thin-walled, with refractive contents, negative in SV. Cheilocystidia similar to pleurocystidia in shape, but smaller, 35.5–40–45.5 × 5.5–7.0–8 µm, thin-walled, with refractive contents, negative in SV. Subhymenium pseudoparenchymatous. Lamellar trama composed of numerous sphaerocytes surrounded by connective hyphae, sphaerocytes measuring 6.5–21 × 5–17 µm. Pileipellis divided into two layers, 80–130 µm thick suprapellis composed of ascending to erect hyphae, and 160–240 µm thick subpellis composed of reptant hyphae; hyphae cylindrical, septate, hyaline, thin-walled, 1.5–5 µm wide; terminal cells (8.5–)19–26–35(–44) × 1.5–2–3.5 µm, cylindrical, with obtuse apices. Pileocystidia (26.5–)32–58– 103(–120) × 3–4.5–6.5(–8) µm, frequent, distributed both in suprapellis and subpellis, cylindrical, with obtuse or papillate apices, with granular refractive contents, unchanging in SV. Stipitipellis 100–190 µm thick, composed of cylindrical, septate hyphae measuring 1.5–3.5 µm wide; terminal cells 11.5–17– 24.5×1.3–2–3 µm, cylindrical with obtuse apices, hyaline, thin-walled. Caulocystidia 33–86 × 4–8 µm, cylindrical, obtuse or papillate, with refractive contents. Clamp connections absent in all tissues.

Comments

Russula japonica has been collected 14 times during our survey and it is a frequent species in DHSBR. Our identification is based on detailed macromorphological comparison and a deposited LSU sequence for a Japanese specimen (AB154697). It is characterized in the field by the nearly smooth pileus and crowded polydymous gills and the appearance of brownish tinges with age. The same characters are also found in R. polyphylla Peck of subg. Compactae with which it can easily be confused in the field, but the latter has different microscopic features (see Buyck et al. 2003).

Russula japonica was described ( Hongo 1954) from Japan as a mild endemic species close to R. delica Fr. , which is the type species of subsect. Lactarioideae Maire, now placed in subg. Brevipedum . Both in the field and under the microscope, it is a morphological twin of R. vesicatoria Murrill , notwithstanding several errors in Hongo’s original description that suggest the opposite. Spores of Japanese specimens of R. japonica have ornaments that are minutely interconnected, just as in R. vesicatoria (see Buyck & Adamčík 2013), and do not have isolated warts as mentioned in the original description (Buyck unpubl. data) and both possess nearly identical dermatocystidia and hymenial cystidia.

Hongo’s species was originally described as mild, but was later given as having slightly bitter or slowly acrid components, but was never reported to be sometimes burningly acrid as in R. vesicatoria . Also R. vesicatoria has been described as being very variable in taste, mostly exhibiting a acridity of variable intensity that develops slowly – at least in younger specimens – after an initial mild to bitter sensation. Kibby & Fatto (1990) describe the acridity of R. vesicatoria as “burningly hot, blistering the lips and long lasting”, thus resuming the elaborate paragraph on taste from Burlingham’s original description (1944). Bills (1986), on the other hand, gives the taste as bitter to disagreeable or mild for older specimens, with the acridity limited to younger specimens. Buyck’s collections from New Jersey were completely mild.

Russula vesicatoria is one of the more common and sometimes very abundant associates of pine on deep sandy soil in the eastern United States. It was originally only known from Florida ( Burlingham 1944). In later years, Bills (1986) reexamined this species in detail and extended its distribution with records from Mississippi, New Jersey, South Carolina and Virginia, describing the closely related R. angustispora Bills with very elongate spores and darker spore print. Shaffer (1964) designed a lectotype for R. vesicatoria and described R. cascadensis Shaffer. The latter species is equally assumed to be very closely related, differing principally by the absence of a clear odor and in being a west-coast species in America. Shaffer (1964) also introduced the new R. inopina Shaffer , differing conspicuously, according to Shaffer, by the absence of a strongly acrid-bitter taste and a different smell.

All the above species are conifer associates, principally associated with Pinus , and sometimes highly host-specific as in the case of R. angustispora , apparently a strictly associate of Pinus virginiana Mill. in its entire range of distribution ( Bills 1986). Russula vesicatoria associates with various 2–3 needle pines ( Pinus taeda L., P. virginiana , P. palustris Mill. , etc…) always growing in pure sand or sandy soil ( Bills 1986). However, whereas R. japonica was originally described as being associated with Pinus densiflora Siebold & Zucc. ( Hongo 1954) , it has since mostly been found under Castanopsis sp. and Quercus sp. in Japan. Interestingly, a morphologically identical collection to R. vesicatoria has more recently also been collected under Quercus oleoideis in the tropical lowlands of Costa Rica (Buyck unpubl. data), which seems to suggest that both species are not strict conifer associates.

Both R. callainomarginis and R. leucobrunnea nom. nov. (illustrations followed) can be distinguished from R. japonica because of their different spore ornamentation with much less differentiated warts.

Figures

Fig. 11. Fruiting bodies of Russula japonica Hongo. A–B. GDGM79699. C–D. GDGM79710. E. GDGM79706. F. GDGM79704. Scale bars = 1 cm.

Fig. 12. Basidiospores under scanning electron microscope of Russula japonica Hongo. A–C. GDGM79699. D. GDGM79704. E–F. GDGM79706. Scale bars = 1 µm.

Fig. 13. Russula japonica Hongo (GDGM79697). A. Basidia. B. Cheilocystidia. C. Pleurocystidia. D. Pileocystidia. E. Caulocystidia. Scale bars = 10 µm.