Lycogala indirubinum W. L. Song & Shuang L. Chen, 2025

Song, Wen-Long, Jiang, Zi-Qiong, Li, Min, Leontyev, Dmytro, Gao, Yang & Chen, Shuang-Lin, 2025, Comprehensive revision of Lycogala (Myxomycetes) in subtropical China: morphological and phylogenetic insights and ten new species, IMA Fungus 16, pp. e 147535-e 147535 : e147535-

Lycogala indirubinum W. L. Song & Shuang L. Chen sp. nov.

Fig. 10

GenBank accession numbers.

PQ 685936 (SSU) and PQ 728393 (COI).

Etymology.

Indigorubin, based on indigo (Greek), blue color from India, and rubinum (Latin) ruby-colored, referring to the indigorubin (bluish-purple) tint of the outer surface of the peridium.

Diagnosis.

Differs from L. aggregatum by almost free thick-walled peridial vesicles and purple tint in pigmentation of sporocarp.

Description.

Sporocarps scattered, spherical, short horizontally oval, or irregular, 2.0–5.0 mm in diameter. Peridium thin, membranous, indigorubin (bluish-purple) or lighter, with dense vesicle cover, making it almost black. The inner surface of the peridium is nearly smooth, with only few small warts. Peridial vesicles appear almost black under RL, muted olive-brown or lighter, (78 –) 106–128 (– 158) μm in diameter, irregularly ovoid, isodiametric, mostly solitary but densely distributed and closely adjoining. Oil droplets in form of amorphous granular matter or large vesicles, which occupy 1 / 3–1 / 2 or vesicle space. Crystals absent. Capillitium (3.7 –) 5.0–10.0 (– 21.8) μm in diameter, variable, either completely smooth, or ornamented with large ring-like islets, or densely covered with small pits, thinner tubules are mainly smooth and significantly enlarged to the end, while thicker tubules are mostly covered with pits and their ends are not swollen. Spore mass in old collections yellow with ochraceous undertones or darker, hyaline under TL, (4.8 –) 5.7–6.3 (– 7.3) μm in diameter, reticulate, with 4–6 meshes across diameter, unornamented area occupies 1 / 4 of the spore surface. Plasmodium unknown.

Distribution.

Currently known only from China.

Habitat.

On rotten wood.

Holotype.

CHINA • Hubei Province: Houhe National Nature Reserve , 30.0893°N, 110.5666°E, on rotten wood, 17 Oct 2019, collected by Min Li ( HFNNU 11270 ).

Additional specimens examined.

CHINA • Chongqing City: Jinfo Mountain National Nature Reserve , 29.0470°N, 107.1529°E, on rotten wood, 14 Aug 223, collected by Shu-Zhen Yan and Shuang-Lin Chen ( HFNNU 11282 ) .

Notes.

Fine and nearly smooth capillitium distinguishes L. indirubinum from most Lycogala species. A similar capillitium also appears in L. exiguum , which, however, has densely aggregated peridial vesicles. Nearly black sporocarps, as well as dark solitary vesicles, make L. indirubinum similar to L. maculatum . However, in the latter species, the capillitium is ornamented with regular bracelet-like thickenings, vesicles do not contain abundant oil, and the peridium lacks the purple indirubin tint. From a phylogenetic perspective (Fig. 2 ), L. indirubinum forms a separate clade (UBS = 100, PP = 1) sister to L. epidendrum , L. maculatum , L. projectum , and L. irregulare (UBS = 86, PP = 1). The interspecific genetic distance between L. indirubinum and L. epidendrum , measured for SSU sequences, is 0.20. The separation of L. indirubinum is supported in all partitions created by ASAP (Suppl. material 7).

Figures

Figure 2. Maximum likelihood tree inferred from the concatenated sequences of SSU and COI, showing the phylogenetic relationship of Lycogala. The members of Reticularia were used to root the tree. Only Maximum likelihood ultrafast bootstrap support (UBS) / Bayesian posterior probabilities (PP) ≥ 70 / 0.7 are shown. The voucher numbers are indicated after the species names. The number of identical genotypes is in parentheses (if present). The ten new species described in this study are indicated in red and bold. The four new species to China are indicated in blue and bold. Other newly obtained sequences are in bold. The scale bar represents the number of substitutions per site.

Figure 10. Morphological characteristics of Lycogala indirubinum: A sporocarp; B the outer surface of the peridium; C, D peridial vesicles; E the inner surface of the peridium (SEM); F capillitium; G the detail of capillitium ornamentation (SEM); H the bulbous free ends of the capillitium; I, J the detail of capillitium ornamentation (SEM); K spores; L spores (SEM). Scale bars: 1 mm (A, B); 100 μm (C, D); 10 μm (E – H, J, K); 5 μm (I, L).