Melanogaster diqingensis T. J. Yuan, Shu H. Li, & Raspé, 2024

Yuan, Tian-Jun, Luo, Hong-Mei, Su, Kai-Mei, Li, Shu-Hong & Raspé, Olivier, 2024, Three new Melanogaster species (Boletales, Paxillaceae) from southwestern China based on morphological and molecular evidence, MycoKeys 107, pp. 141-160 : 141-160

Melanogaster diqingensis T. J. Yuan, Shu H. Li, & Raspé sp. nov.

Fig. 3 e – h

Diagnosis.

Melanogaster diqingensis is diagnosed by the combination of medium-sized, pale-yellow to orange or brown-yellow basidiomata with scaled, lobed or concave surface, pale yellow gleba, and obovate to subglobose, smooth basidiospores (3.0–5.1 × 2.0–4.0 μm, Q = 1.0–1.8).

Etymology.

The epithet diqingensis refers to the prefecture of the type locality.

Holotype.

China. Yunnan Province: Diqing Autonomous Prefecture, Shangri-La County, Baishuitai village , 27 ° 30 ' 14.2236 " N, 100 ° 2 ' 50.5716 " E, elevation 2,380 m, in brown soil under Quercus aquifolioides Rehd. et Wils. , 25 Sep. 2020, collected by X. H. Wang ( KUN- HKAS 121212 , holotype; YAAS - WXH _ 9068 , isotype) .

Description.

Basidiomata 0.5–2.5 × 0.2–2.2 cm, hypogeous, globose, subglobose or ellipsoidal, pale-yellow to orange or brown-yellow, scaled, lobed or concave in the surface, without visible rhizomorphs (Fig. 3 e ). Odor faint. Peridium two-layered, outer layer 40–80 μm thick, composed of interwoven hyphae, 3.5–7.5 μm broad, with fusoid to cylindrical terminal cells, deeply orange-yellow walls toward surface, with clamp connections; inner layer 150–260 μm thick, composed of interwoven hyphae, 5–10 μm broad, with inflated cells, 7.5–15 μm broad, bright pale yellow, with abundant clamp connections. Gleba solid, milk-white when immature, pale yellow at maturity, hard when dried; trama plates of hyaline or yellowish, gelatinized hyphae (Fig. 3 f ); locules 2–3 mm in diam (Fig. 3 g ). Basidia exhibit limited reviving, appearing clavate, hyaline, 4 – spored. Basidiospores obovate to subglobose, smooth, 3.0–5.1 × 2.0–4.0 μm (L m × W m = 3.8 ± 1.0 × 3.2 ± 0.8, Q = 1.0–1.8, Q m = 1.2 ± 0.6, n = 75), hyaline (immature) to light yellow, dark brown (mature) in KOH 5 %, with truncate-cupped base and very short hilar appendage in optical microscopy, 0.5–1.5 μm in diam (Fig. 3 h ).

Notes.

Six Melanogaster species, namely M. subglobisporus , M. natsii , M. spinisporus ( Wang et al. 1995) , M. rivularis , M. luteus = M. microsporus ( Moreau et al. 2011) , are similar to M. diqingensis in morphology and related by phylogeny. The colors of their basidiomata are similar to M. diqingensis , i. e. rust brown to deep brown in M. subglobisporus , yellow-brown in M. natsii , grayish brown to light brown in M. spinisporus , and bright golden yellow in M. minysporus , but the basidiomata of all of latter species are without scales, lobes or concave area, by which they were easily differentiated from M. diqingensis . M. rivularis (anthracite-black gleba), and M. luteus (club-shaped or cylindro-elliptical to cylindrical basidiospores) also are easily differentiated from M. diqingensis . The thickness of the peridium (≤ 300 μm) is similar among M. subglobisporus , M. ovoidisporus , and M. coccolobae, However , the size of basidiospores provide a clear distinction between these species ( M. subglobisporus 8–11 × 7–9 μm, M. ovoidisporus 5–7 × 3.5–5.8 μm and M. coccolobae 6.2–12 × 5.2–10 μm). Phylogenetically, M. diqingensis and M. subglobisporus formed an independent and strongly supported clade (BS = 78 %, PP = 1.0; Fig. 2 ), but M. diqingensis shared less than 93.2 % ITS similarity with M. subglobisporus , supporting M. diqingensis as a distinct species.

Figures

Figure 2. The ITS phylogram of Melanogaster obtained with RAxML (including ITS 1, ITS 2, and 5.8 S). The six Alpova cessions were chosen as the outgroup. Nodes were annotated with ML BS > 70 %, Bayesian PP > 0.90, or “ - ” in case of non-significant support value. New species are in bold font. The sections are as defined by Moreau et al. 2011 on the basis of basidiospore length.

Figure 3. Photographs of Melanogaster species. Melanogaster cyaneus (YAAS - TJ 75-1, holotype) a basidiomata b LM of Peridium c LM of basidiospores d SEM of basidiospore. Melanogaster diqingensis (YAAS - WXH _ 9068, holotype) e basidiomata f LM of Peridium g LM of basidiospores h SEM of basidiospore. Melanogaster truncatisporus (YAAS - TJ 87, holotype) i basidiomata j LM of peridium k LM of basidiospores l SEM of ascospore. Scale bars: 2 cm (a, e, i); 20 μm (b, f, g); 10 μm (c, g, k); 1 μm (d, h, l).