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

Fig. 9

GenBank accession numbers.

PQ 685930 (SSU).

Etymology.

Helvus (Latin) light yellowish-brown, tawny, pale ochre, referring to the color of the outer surface of the peridium.

Diagnosis.

Differs from L. aggregatum by yellow with ochraceous undertones or darker peridium, larger peridial vesicles (109 –) 132–159 (– 185) μm in diameter, and capillitium decorated with dense reticulum.

Description.

Sporocarps scattered, more or less spherical, 1.6–2.3 mm in diameter. Peridium relatively thick and hard, yellow with ochraceous undertones or darker, covered with vesicle aggregates that form small spines as seen from the side. The inner surface of the peridium decorated with unevenly distributed small warts. Vesicles (109 –) 132–159 (– 185) μm in diameter, black under RL, deep warm brown or darker under TL, angular from mutual pressure, clustered in rounded, nearly opaque aggregates, with 5–7 vesicles across the group, vesicle walls rather indistinct. Crystals and Oil droplets not observed. Capillitium (3.4 –) 4.3–5.6 (– 6.8) μm in diameter, with wavy contour, but no bracelet-like rings, ornamented with dense reticulum of warts and pits, free ends are swallowed. Spore mass in old collections gold or beeswax yellow, hyaline under TL, (4.3 –) 5.5–6.3 (– 6.7) μm in diameter, reticulate, with 5–7 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 • Zhejiang Province: Tianmu Mountain National Nature Reserve , 30.3439°N, 119.4481°E, on rotten wood, 17 Jun 2024, collected by Wen-Long Song and Ya-Jing Chen ( HFNNU 10835 ).

Additional specimens examined.

CHINA • Jiangsu Province: Zijin Mountain National Forest Park , 32.0868°N, 118.8596°E, on rotten wood, 20 Jul 2024, collected by Wen-Long Song, Qian Meng, and Ya-Jing Chen ( HFNNU 10836 ) .

Notes.

The rosette-like aggregation of peridial vesicles, small capillitium diameter, small spore size, and similar density of spore ornamentation place L. helvolum close to L. aggregatum . These two species are also closely related (Fig. 2 ). However, the following characteristics allow us to distinguish them. (i) Peridial vesicles. Lycogala helvolum has larger peridial vesicles, (109 –) 132–159 (– 185) μm in diameter, with 5–7 vesicles across clusters. In L. aggregatum the vesicle diameter is 10–100 μm, their groups contain only 1–3 vesicles across diameter. (ii) Capillitium. The capillitium of L. helvolum is ornamented by rounded pits, and possesses bulbous free ends, while the capillitium of L. aggregatum may also be covered by large (1–3 μm) rings. Morphological differences between L. helvolum and Lycogala uviforme are described in Notes for the latter species. From a phylogenetic perspective based on SSU and COI sequences (Fig. 2 ), the two specimens representing L. helvolum form a sister clade to L. aggregatum with strong statistical support (UBS = 100, PP = 1). The interspecific genetic distance between L. helvolum and L. aggregatum , measured based on SSU sequences, is 0.20. The separation of L. helvolum is supported in 8 of 10 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 9. Morphological characteristics of Lycogala helvolum: A, B sporocarp; C the outer surface of the peridium; D peridial vesicles; E the inner surface of the peridium (SEM); F capillitium; G the bulbous free ends of the capillitium (SEM); H the detail of capillitium ornamentation (SEM); I, J spores (LM); K, L spore (SEM). Scale bars: 1 mm (A – C); 100 μm (D); 10 μm (F); 5 μm (E, G – J); 1 μm (K, L).