Cantharellus xanthocyaneus Ndolo Ebika & Buyck, 2020

Buyck, Bart, Ndolo, Sydney T., Ebika, Kesel, André De & Hofstetter, Valérie, 2020, Tropical African Cantharellus Adans.: Fr. (Hydnaceae, Cantharellales) with lilac-purplish tinges revisited, Cryptogamie, Mycologie 20 (10), pp. 161-177 : 169-172

Cantharellus xanthocyaneus Ndolo Ebika & Buyck , sp. nov.

( Figs 4 ; 5 )

MYCOBANK. — MB 835035.

TYPE MATERIAL. — Holotype. Republic of the Congo, Likouala Department ; 3.38 km South from Makao village, Plot 1 in Gilbertiodendron dewevrei forest ( PG1 ); 2°33.84’N, 17°10.12’E; alt. 360 m; 17.XI.2016, S. T. Ndolo Ebika 2353 (holo-, PC [ PC0125128 ]; iso-, HICPC [ HICPC005 ]).

DIAGNOSIS. — Differs from C. cyanoxanthus essentially in the distinctly smaller, particularly narrower basidiospores, measuring (5.7-)6- 7.0 -8.1(-8.8) × 3.2- 3.7 -4.3 µm, Q = (1.46-)1.56- 1.91 - 2.26(-2.39).

ETYMOLOGY. — Composed of two Greek color terms, xanthos (yellow) and cyanos (dark blue), referring to the dominant colors of the fruiting body.

HABITAT. — On the ground in Gilbertiodendron dewevrei forest, on terra firma.

ADDITIONAL EXAMINED AND SEQUENCED MATERIAL. — Republic Of The Congo, Likouala Department; 3.38 km South from Makao village, Plot 1 in Gilbertiodendron dewevrei forest (PG1); 2°33.84’N, 17°10.12’E; alt. 360 m; 14.XI.2016; S. T. Ndolo Ebika 2333 (para-, PC[PC0125127]; iso-, HICPC[HICPC004]).

DESCRIPTION

Basidiomata ( Fig. 4 )

Solitary or in pairs, medium-sized and up to 75 mm high.

Pileus ( Fig. 4A )

Thin-fleshed, 50-63 mm wide, plano-concave to slightly funnel-shaped, mottled with dark purplish-violaceous tinges on a yellowish background, smooth.

Hymenophore ( Fig. 4C )

Composed of well-differentiated, forking gill folds, pale ochraceous with distinct pinkish tinges, strongly interveined towards the cap margin, up to 7 mm high.

Stipe ( Fig. 4B, D )

55-57 × 12-17 mm, cylindrical to fluted and bumpy (when fluted), flushed with purple-violaceous to pinkish tones, particularly in its middle portion, distinctly yellowish at the base which is swollen and hollowing, becoming whitish near the junction with the gill folds.

Context

Off-white, rather thin towards the pileus margin.

Smell

Insignificant.

Taste

Unknown.

Spore print

Not obtained.

Spores ( Fig. 5A )

Ellipsoid to elongated, somewhat concave at the adaxial side and more or less kidney-shaped, (5.7-)6- 7.0 -8.1(-8.8) ×

3.2- 3.7 -4.3 µm {N=58}, Q = (1.46-)1.56- 1.91 -2.26(-2.39), smooth, with a small apiculus.

Basidia ( Fig. 5B )

46-70 × 5.6- 8 -10 µm {N=9}, predominantly six-spored.

Cystidia

Absent.

Subhymenium

Subfilamentous, composed of narrow, cylindrical cells that are sometimes slightly larger than the basis of the basidia.

Pileipellis ( Fig. 5C )

Composed of thin-walled, elongated elements, mostly widening towards the septa or towards the tip, quite a few of the terminal and subterminal cells filled with a distinctly dark lilac-brown pigment. Incrusting pigment present on some particularly narrower, subterminal cells and narrow hyphae in the pileipellis.Terminal cells subcylindrical to faintly clavate, mostly 40-100 µm long and (5)8-15(22) µm diam., with thin to slightly thickened (refringent) cell walls.

Clamp connections

Very distinct on hyphae of all tissues.

NOTES

In the field, Cantharellus xanthocyaneus Ndolo Ebika & Buyck , sp. nov., is very similar to C. cyanoxanthus sensu Heinemann because of its color. However, it cannot be the same species because of the distinctly larger basidiospores of C. cyanoxanthus (see below), albeit with a similar length-width ratio. We have measured the holotype of C. xanthocyaneus Ndolo Ebika & Buyck , sp. nov., twice independently (to exclude subjective approaches) with near identical results [S.T. Ndolo Ebika: (5.7-)6- 7.0 -8.1(-8.8) × (3.2-)3.2- 3.7 -4.2(-4.3) µm, Q = (1.46-)1.56- 1.91 -2.26(-2.39) versus Buyck: (6.0)6.4- 6.81 -7.2(7.7) × (3.3)3.4- 3.67 -3.9(4.1) µm, Q = (1.6)1.7- 1.86 -2.0(2.2)]. Also the paratype shows an identical spore size [(5.8)6.3- 6.73 -7.1(7.3) × (2.9)3.3- 3.55 -3.8(4.0) µm, Q = (1.6)1.7- 1.9 -2.0(2.2)].

Heinemann’s (1958) values for spore length of the Central African C. cyanoxanthus seem a bit too low compared to more recent measurements made by Eyssartier (2001) and A. De Kesel (this study) on the holotype (Goossens-Fontana 2082): P. Heinemann (1958: 7.5-9.3 × 4.4-5.4 µm), G. Eyssartier (2001: (7)8- 8.83 -10 × 4- 4.87 -5.5 (6) µm, Q = 1.45- 1.82 -2.0) and A. De Kesel: (7.6-)8.2- 9.4 -10.5 (-10.6) × (4.4-)4.3- 5 -5.6(-5.9) µm, Q = (1.59-)1.61- 1.89 - 2.17(-2.27), but all these are very different from the Malagasy C. littoralis (Buyck & Randrianjohany) Buyck , comb. et stat. nov. (synonym of C. cyanoxanthus sensu Heim ) which has spores that are very similar to those of C. longisporus ( Buyck et al. 2012: (8.1)8.5- 9.01 -9.5(9.8) × (3.5)3.8- 4.07 - 4.4(4.8) µm, Q = (1.9)2.0- 2.21 -2.4(2.5). Some recent collections made near the type locality all confirm the narrower spores of this Malagasy species for a similar length compared to Central African C. cyanoxanthus , resulting in higher Q values [H. 110: 9.08 × 4.15 µm, Q = 2.20; EJ 107: 9.07 × 4.13 µm, Q = 2.21; EJ 108: 8,81 × 4.06 µm, Q = 2.18; EJ 122: 9.06 × 4.08 µm, Q = 2.14].

Figures

FIG. 4. — Cantharellus xanthocyaneus Ndolo Ebika & Buyck, sp. nov. (holotype; PC0125128): A, pileus; B, D, cylindrical to fluted and bumpy stipe with hymenophore; C, detail of hymenophore. Freshly collected fruiting bodies. Photos: S. T. Ndolo Ebika.

FIG. 5. — Cantharellus xanthocyaneus Ndolo Ebika & Buyck, sp. nov. (holotype;; PC0125128): A, spores; B, basidia and basidiola; C, hyphal endings of the pileipellis. Scale bar: 10 µm, but only 5 µm for spores. Drawings: B. Buyck.