Cantharellus densifolius Heinem., Bull. Jard. bot. Etat Brux. 28(4): 410. 1958.

Buyck, Bart, W. Henkel, Terry & Hofstetter, Valerie, 2019, Epitypification of the Central African Cantharellusdensifolius and C. luteopunctatus allows for the recognition of two additional species, MycoKeys 49, pp. 49-72 : 49

Cantharellus densifolius Heinem., Bull. Jard. bot. Etat Brux. 28(4): 410. 1958. Figs 2, 3

Original diagnosis.

"Pileus carnosulus, infundibuliformis, lobatus, laete ochraceus, squamulosus. Stipes solidus, pileo concolor. Lamellae confertissimae, angustissimae, furcatae, non intervenatae. Caro ochracea, sapore amaro. Sporae breviter ellipsoidae, 5,6-7 × 3,7-4,5 μm.”

Holotype.

DEMOCRATIC REPUBLIC OF THE CONGO. Binga, dispersed on the soil of the dry forest, Aug. 1929, Mme. Goossens-Fontana 879 (BR).

Iconography.

Heinemann (1958, fig. 45; 1959, pl. XXVI, fig. 11).

Original description.

(freely translated from French) "Pileus ca. 8 cm diam., thin, deeply concave to infundibuliform, with the margin convex to stretched, irregular and wavy; surface ochraceous orange, very finely punctuated with tiny squamules that are easily detached. Stipe ca. 30 × 7 mm, cylindrical, massive, concolorous with the cap. Hymenophore composed of crowded gill-folds, less than 1 mm high, 1-4 times forking, deeply decurrent, with blunt gill edge, not interveined. Context fibrous, bright ochraceous. Taste bitter. Smell of C. cibarius . Spore print white. Exsiccatum with reddish ochre brown color.

Spores hyaline, 5.6-7 × 3.7-4.5 μm, shortly ellipsoid, thin-walled, not amyloid; apiculus small. Basidia slender, 37-48 × 6-8 μm, probably 6-spored. Hymenophoral trama pseudoparenchymatic, slightly bilateral. Pseudoparenchyma very compact. Pileipellis squamulae composed of easily detaching cells that are irregularly cylindrical, often undulating, thick-walled with a very thick yellow wall in ammonium solution; the terminal cells obtusely rounded. Clamp connections rare."

Description of the epitype.

Basidiomata solitary or in small groups. Pileus medium-sized to rather large and up to 100 mm diam., 1-2 mm thick at mid-radius, yet firm and leathery; margin undulating, irregularly waving to strongly lobed, smooth; surface layer remaining more or less continuous in the center, then disrupting toward the margin with expansion of the pileus and forming dark, more or less concentrically arranged squamules or fibres; observed under a hand lens these can be appressed and flat, or forming a woolly-cottony mass of suberect fibers, pale brown (5AB3) to warm chocolate brown or dark brown (5EF7-8, 5F4-8, 5D5-8, 5C5-6) when young, but rapidly tinged with ochraceous orange as a consequence of the exposure of the underlying pileus tissue and the yellowing tendency of the context. Hymenophore composed of very crowded (>30/mm) gill folds, which are very low (<1 mm) and thick, not interveined, often transversely fissuring over their entire height, repeatedly forking, strongly decurrent, off-white when young, then darkening to the color of coffee with copious milk, moderately to strongly yellowing upon handling. Stipe 40-60 × 4-5 mm, widening toward the hymenophore and there up to 8(-17) mm wide; surface smooth, whitish, pale brown just beneath the hymenophore. Context whitish, thin and leathery, fibrous in the stipe, faintly to strongly yellowing upon injury or handling, occasionally turning rusty brown. Odor faint. Taste mild. Spore print off-white.

Basidiospores ellipsoid, (5.8 –)6.0–6.46–6.9(– 7.1) × (3.5 –)3.8–4.19–4.6(– 5.0) µm, Q = (1.3 –)1.4–1.55–1.7(– 1.8), smooth, hyaline. Basidia mostly 35-50 × 7-8 µm, (5 –)6(– 7)-spored; sterigmata stout but rather short. Subhymenium forming a very dense layer, not pseudoparenchymatous, but composed of mostly short cells that are not wider than the basidium base. Cystidia none. Pileipellis of loosely interwoven and much septate hyphal extremities composed of ramifying chains of distinctly thick-walled cells; terminal (but also sometimes subapical) cells subcylindrical, but often more irregularly inflated or sinuous-tortuous in outline, 5 –8(– 10) μm wide, mostly 25-45 µm long, often narrowing or abruptly constricted near the apex. Clamp connections absent.

CENTRAL AFRICAN REPUBLIC. Dzanga-Sangha Forest Reserve, near Bayanga, close to Bai-Hakou base camp, 02.859934N, 16.467492E, in monospecific Gilbertiodendron dewevrei forest, on bare sandy soil, 15 May 2016, 1641/Buyck 16.021 (PC 0142486, epitypus hic designatus). MycoBank MBT 384669.

Additional specimens examined.

CENTRAL AFRICAN REPUBLIC. Dzanga-Sangha Forest Reserve, near Bayanga, in and around Bai-Hakou base camp, 02.859934N, 16.467492E, in monospecific Gilbertiodendron dewevrei forest, on bare sandy soil, 19 May 2016, Buyck 16.081/1656 (PC0142487), Buyck 16.065/1649 (PC0142488); ibid., 24 May 2016, Buyck 16.113/1672 (PC0142490); ibid., 26 May 2016, Buyck 16.137/1681 (PC0142489).

Discussion.

Cantharellus densifolius was originally described by Heinemann (1958) and was one of three rain forest Cantharellus species characterized by crowded gill folds. The other two chanterelles with equally crowded gill folds were the fragile, smaller (pileus <30 mm diam.), bright orange C. pseudofriesii Heinem. and the medium-sized, bright yellow C. luteopunctatus Heinem. Eyssartier (2001) re-examined the holotype of each of these three species, and concluded that C. pseudofriesii was distinctive due to its possession of clamp connections (contrary to the original description, see also Buyck et al. 2016a), and suggested that C. luteopunctatus may be a color variant of C. densifolius because of its similar micromorphological features.

The epitype specimen selected here perfectly agrees with the original description of C. densifolius . Indeed, Heinemann (l.c.) described it as a medium-sized species with an infundibuliform, ochre-orange and finely squamulose pileus measuring ca. 80 mm diam. and ending in an irregular but stretched margin, with strongly decurrent, crowded, frequently forking and very low gill folds (<1 mm high) with blunt edges, lacking any intervenation. Heinemann cited shortly ellipsoid basidiospores of near identical size, more precisely given by Eyssartier (2001), as important microscopic features, along with the pileipellis composed of easily disintegrating, very thick-walled hyphal extremities that are sinuous-undulating in outline (compare Heinemann 1958 fig. 45B with our Fig. 3c).

The typical features appear to be quite constant across all specimens of C. densifolius examined here, including both the size and shape of basidiospores (Table 1), as well as the undulate, thick-walled, often apically tapered or constricted hyphal extremities (although less so in Buyck 16.137). The ochre-orange color of the pileus described for the holotype was also present in the epitype (Fig. 2a, c) but across collections examined here pileus color ranged from ochraceous yellow over orange to pale brown and even dark chocolate brown, but never to bright lemon yellow as described for C. luteopunctatus . This is consistent with the highly variable color within many other Cantharellus species ( Olariaga et al. 2015, Buyck et al. 2016e). For C. densifolius , the general color of the pileus also depends on the degree of yellowing of the context underneath the disrupted surface tomentum, which can vary between or within individual basidiomata.

The form of the hyphal extremities composing the pileal tomentum is very similar to that of various other squamulose species in subg. Rubrinus sect. Isabellinus Eyssart. & Buyck, in particular those of the African C. tanzanicus Buyck & V. Hofst. ( Buyck et al. 2013) and the Malagasy C. eucalyptorum Buyck & V. Hofst. and C. tricolor Buyck & V. Hofst., the latter two species being associates of introduced eucalypts ( Liu et al. 2015). The differences in habitat and basidiospore size allow differentiation of C. densifolius from these species.

Cantharellus densifolius has repeatedly been reported from the surrounding woodland area in Africa (e.g. Heinemann 1966, Buyck 1994, Buyck et al. 2000, Härkönen et al. 2015). Our sequence data have now indicated that such woodland specimens merit recognition as independent species. For example, the morphologically similar C. densilamellatus sp. nov. described below is unrelated to C. densifolius but resolved as sister to C. luteopunctatus (Fig. 1).