Cantharellus citrinus Buyck, R. Ryoo & Antonin, 2020

Buyck, Bart, Hofstetter, Valerie, Ryoo, Rhim, Ka, Kang-Hyeon & Antonin, Vladimir, 2020, New Cantharellus species from South Korea, MycoKeys 76, pp. 31-47 : 31

Cantharellus citrinus Buyck, R. Ryoo & Antonin sp. nov. Figs 3 , 4

Diagnosis.

Differs from its closest Asian and North American relatives in the variously coloured but often bright lemon yellow pileus, similarly tinted stipe and smaller size, as well as in differences in sequence data produced for the transcription elongation factor (tef -1).

Holotype.

South Korea. Geoi-san, Cheong-cheon-myeon, alt. 330 m, 36°37'02.99"N, 127°49'36.56"E, 14 Aug 2013, V. Antonín, R. Ryoo & K.-H. Ka, 1691 / VA 13.156 (holotype: BRNM 825748; isotype: PC 0142457).

Description.

Basidiomata dispersed in small groups or fascicles. Pileus 4-20 mm broad, convex, with involute margin when young, then plane or infundibuliform with depressed centre and inflexed to straight, smooth margin, irregularly undulate when old, hygrophanous, finely tomentose when very young, soon glabrescent and smooth or slightly rugulose, uniformly coloured, light yellow, orange yellow to light orange (3-4A6, 4-5A5-7), sometimes with greyish yellow tinge when old. Hymenophore composed of thick vein-like folds, sometimes strongly decurrent in a reticulate pattern on upper stipe, often not reaching the pileus margin, forking or with rare lamellulae, transversely anastomosed in between, white to whitish (3A2); edges concolorous. Stipe 4-22 × 1-3(-4) mm, slightly tapering towards base when young, then cylindrical, sometimes curved, finely pubescent when young, later glabrescent, smooth, concolorous with pileus or slightly paler. Context thin, yellowish, fibrillose-hollow and yellowish whitish in stipe when old, with a spicy apricot smell and mild taste. Spore print not obtained.

Basidiospores ellipsoid, (7.3-)7.6- 8.24 -8.4(-8.8) × (5.1-)5.4- 5.67 -5.9(-6.1) μm, Q = (1.32-)1.34- 1.42 -1.50(-1.56), smooth, thin-walled. Basidia mostly (42-)66-80 × 8 μm, 4-5(-6)-spored, narrowly clavate; basidiola subcylindrical and slender when young, undulate-wavy in outline, later becoming narrowly clavate, subfusoid, sometimes irregular, rarely submoniliform, thin-walled. Cystidia not observed. Subhymenium composed of narrow, filamentous and cylindrical cells. Pileipellis a cutis composed of cylindrical, ± thin-walled, smooth or minutely incrusted, sparsely septate, (4-)8-12 μm wide hyphae; terminal cells (36-)50-110 × 4.0-15 μm, appressed to suberect, mostly slightly clavate, some with a subapical weak constriction, obtuse, thin-walled. Stipitipellis a cutis of cylindrical, slightly thick-walled, 2.5-6.0(-7.0) μm wide hyphae with isolated terminal cells distinct only in a narrow zone at very top, otherwise rare to absent, 20-51 × 4.0-11 μm, (narrowly) clavate, cylindrical or subfusoid, thin-walled. Clamp connections everywhere and distinct.

Habitat.

On soil near Quercus mongolica Fisch. ex Ledeb., Q. acutissima Carruth., Quercus sp., Castanea crenata Siebold & Zucc., Carpinus laxiflora (Siebold & Zucc.) Blume and Abies koreana E.H. Wilson.

Etymology.

The name refers to the frequent bright lemon yellow colour of pileus and stipe surface of the most common form.

Other specimens examined.

Jinan, Jeongcheon-myeon, Unjangsan Recreational Forest, alt. 390 m, 35°54'01.13"N, 127°24'59.41"E, 7 Sep 2016, V. Antonín, R. Ryoo, K.-H. Wang & Y.-S. Jang, 1710 / VA 16.169 (BRNM 825753, PC 0142467). Ibid., 1711 / VA 16.170 (BRNM 825754, PC 0142468). Yeongdong, Yonghwa-myeon, Minjoojisan Recreational Forest, alt. 540 m, 36°03'14.57"N, 127°49'43.15"E, 26 Aug 2015, V. Antonín, K.-H. Ka, K.S. Kim & J.A. Kang, 1715 / VA 15.93 (PC 0142472).

Remarks.

The description is based on the type specimen, but examination of the other specimens shows that variation of morphological features includes a rather wide amplitude of the overall colour, which seems - based on identical tef1 sequences - to extend from entirely and predominantly pale lemon yellow to an overall deep orange. Collection from Jinan (VA 16.169, BRNM 825753, PC 0142467) differs from other collections of this species by an orange (5-6A7) pileus, light yellow to light orange (4-5A5) lamellae and a stipe more or less concolorous with the pileus.

This new species is here placed in Cantharellus subg. Cinnabarini (Fig. 2 ), a subgenus that comprises several species exhibiting a similarly wide colour range, e.g. the Malagasy C. variabilicolor Buyck & V. Hofst. (in Ariyawansa et al. 2015) or the North American C. cinnabarinus (Schwein.) Schwein. Cantharellus citrinus is here shown to be part of a well-supported clade composed of two other Asian species, the Chinese C. phloginus and Korean C. albovenosus . The latter two species are very different in general aspect, but, except for a single mutation in the coding part, the tef -1 sequences of both species are identical, even including the introns. Yet, their very different general habitus justifies us in our view that we should accept them as a separate species. The clade comprising these Asian species is sister to a clade composed of North American species.

Because of its very small overall size and comparable overall colour, C. citrinus could also easily be mistaken for some species in Cantharellus subg. Parvocantharellus Eyssart. & Buyck, in particular the European C. romagnesianus (= C. pseudominimus Eyssart. & Buyck, see Olariaga et al. 2015). Under the microscope, C. citrinus differs hardly from its Asian relatives and identification relies principally on field characters or sequence data.

Figures

Figure 2. Most likely tree (- ln = 3254.82124) obtained by phylogenetic analyses of 48 tef - 1 Cantharellus sequences. Supported branches are in bold with bootstrap values, when significant (≥ 70 %), indicated along the branches. Sequences newly obtained for this study are in bold and highlighted in blue for the new species described in the present study. Extraction numbers and GenBank accession numbers for tef - 1 sequences are reported before taxon names. Delimitation of Cantharellus subgenera Cinnabarini and Parvocantharellus (sensu lato) are indicated and C. goossensiae Heinem. and C. rubrosalmoneus (Buyck & V. Hofst.) Buyck & V. Hofst. (both in C. subg. Pseudocantharellus) are used as outgroup.

Figure 3. Cantharellus citrinus (holotype) a spores b basidia and basidiola c hyphal extremities of the pileipellis near mid-radius. Scale bar: 10 μm, but only 5 μm for spores. Drawings B. Buyck.

Figure 4. a-c Cantharellus citrinus, yellow, more common form a (VA 13.170) b C. citrinus, reddish orange form (VA 16.169) c (VA 13.156, holotype). Photos V. Antonin.