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

Fig. 3 a – d

Diagnosis.

Melanogaster cyaneus is diagnosed by its blue or bluish gleba, rhizomorphs on the base, thinner peridium (100–400 μm), and longer and wider basidiospores (6.2–15 × 4.6–9.0 μm).

Etymology.

The epithet cyaneus refers to the blue or bluish gleba.

Holotype.

China. Sichuan Province: Panzhihua City, Yanbian County, Shuanglong village , 26 ° 49 ' 12 " N, 101 ° 33 ' 7.1028 " E, elevation 1,970 m, in mainly reddish brown soils under Castanea mollissima Bl. , 16 Aug. 2020, collected by M. Yang ( KUN- HKAS 129200 , holotype; YAAS - TJ 75-1 , isotype) .

Description.

Basidiomata 2.5–4.0 × 1.5–2.5 cm, hypogeous or semi-hypogeous, subglobose to ellipsoidal, occasionally elongate; light brown to yellowish brown, with mycelial strands attached in the base (Fig. 3 a ). Peridium two-layered, outer layer 20–75 μm thick, composed of interwoven hyphae, orange-yellow to reddish, 2–4 μm broad, thick-walled, clamp connections present; inner layer 145–335 μm thick, composed of interwoven, strongly gelatinized hyphae, 2–5 μm broad, pale-yellow, intermixed with massive inflated cells, 6–12 μm broad, with clamp connections present. Gleba solid, gelatinous, milk-white when immature, blue or bluish at mature; trama plates pale-yellow, of gelatinized hyphae (Fig. 3 b ); locules small, filled with black spores (Fig. 3 c ). Basidia exhibit limited revival, appearing clavate, hyaline, 4 - spores, randomly distributed, gelatinized at maturity. Basidiospores subglobose to globose, 6.2–15 × 4.6–9.0 μm (L m × W m = 9.5 ± 3.0 × 7.0 ± 2.0, Q = 1.0–2.0, Q m = 1.4 ± 0.6, n = 75), smooth, hyaline when immature, light yellow to reddish at maturity, surfaces display distinctive spots, and optical microscopy reveals a notable hilar appendage, 0.5–1.0 μm in diam (Fig. 3 d ).

Other material examined.

China, Sichuan province, Panzhihua City, Yanbian County, Shuanglong village , 26 ° 49 ' 12 " N, 101 ° 33 ' 7.1029 " E, elevation 2,000 m, under Castanea mollissima Bl. in evergreen hill forest, in mainly reddish-brown soils, 16 Aug. 2020, collected by M. Yang ( YAAS TJ 75-2 ) .

Notes.

M. broomeanus Berk ( Türkoğlu and Castellano 2013; Uzun et al. 2014), M. shanxiensis and M. obovatisporus ( Liu et al. 1989) , are similar to M. cyaneus in morphology. M. cyaneus (basidiomata light brown to yellowish brown), M. broomeanus (basidiomata yellow-brown to deep brown), M. shanxiensis (basidiomata brown to rust-brown) and M. obovatisporus (basidiomata brown to brownish-black), but the specimens of M. cyaneus clustered in an independent clade with strong support (BS = 100 %, PP = 1.0; Fig. 2 ), supporting it as a distinct species. Additionally, DNA analysis revealed M. cyaneus shared less than 92 % ITS similarity with other Melanogaster 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).