Lycogala annulatum W. L. Song, Z. Q. Jiang & 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 annulatum W. L. Song, Z. Q. Jiang & Shuang L. Chen sp. nov.

Fig. 4

GenBank accession numbers.

PQ 685822 (SSU) and PQ 728321 (COI).

Etymology.

Annulus (Latin) ring, referring to the ring-shaped ornamentation of the capillitium.

Diagnosis.

Differs from L. exiguum by smaller vesicle diameter, and by capillitium tubules decorated by conspicuous visible.

Description.

Sporocarps scattered, spherical to short horizontally ovoid, sometimes deformed by mutual pressure, 1.6–3.7 mm in diameter. Peridium membranous, thin, yellowish brown with olivaceous tones or somewhat darker, with dense vesicles cover on the outer surface; the dehiscence area at the top of sporocarp conspicuous, free of vesicles, irregularly in shape. Inner surface of the peridium smooth or covered by scattered warts. Vesicles polygonal, irregularly ovoid, black under RL, dark brown under TL, (17 –) 18–23 (– 26) μm in diameter, clustered together forming large aggregates with 2–6 vesicles across the group. Vesicles walls smooth, single-layered. Oil droplets large or small, present in the central part of each vesicle. Capillitium tubular, hyaline under TL, with wavy contour and no bracelet-like thickening, (2.1 –) 3.2–5.3 (– 7.6) μm in diameter; the surface of the thread is densely covered by small warts and large rings, the latter visible both under TL and SEM. Spore mass in old collections yellow with ochraceous undertones or darker, hyaline under TL, (5.2 –) 5.5–5.8 (– 6.2) μm in diameter, reticulate, with 6–7 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 , 30.3227°N, 119.4562°E, on rotten wood, 16 Jun 2024, collected by Wen-Long Song and Ya-Jing Chen ( HFNNU 10826 ).

Additional specimens examined.

CHINA • Zhejiang Province: Tianmu Mountain National Nature Reserve , 30.3463°N, 119.4456°E, on rotten wood, 17 Jun 2024, collected by Wen-Long Song and Ya-Jing Chen ( HFNNU 10827 ) ; • Zhejiang Province: Tianmu Mountain National Nature Reserve , 30.3458°N, 119.4436°E, on rotten wood, 18 Jun 2024, collected by Wen-Long Song and Ya-Jing Chen ( HFNNU 10829 ) .

Notes.

The most prominent morphological characteristic of L. annulatum is the surface of the capillitium tubules, which is decorated with large rings visible under TL and SEM. Similar ornamentation of the capillitium is also known in Lycogala aggregatum and Lycogala botrydium , but these two species have different morphologies of peridial vesicles ( Leontyev et al. 2023 b): irregularly grouped and clustered in smooth aggregates with individual vesicles nearly indistinguishable, respectively. The structure of the peridium makes L. annulatum a member of the L. exiguum complex. However, L. annulatum differs from the type material of L. exiguum ( Leontyev and Schnittler 2023) by the following morphological differences: (i) sporocarps of L. exiguum form very large groups (> 50), while those of L. annulatum is scattered; (ii) the vesicle diameter of L. exiguum is 20–40 μm, while that of L. annulatum is (17 –) 18–23 (– 26) μm; (iii) the capillitium of L. exiguum is ornamented with pits, warts and only scanty rings 1–3 μm in diameter, while in L. annulatum the tubules are richly decorated with rings visible under TL. From a phylogenetic perspective based on SSU and COI sequences (Fig. 2 ), the three specimens representing L. annulatum form a sister clade with L. exiguum HFNNU 11333 , with strong statistical supported (UBS = 100, PP = 1). The separation of L. annulatum as a distinct species is supported in 5 of 10 partitions identified by ASAP (Suppl. material 7). The genetic distance between L. annulatum and L. exiguum HFNNU 11333 , measured based on SSU sequences, is 0.03, which is rather low ( Leontyev et al. 2015; Borg Dahl et al. 2018). Therefore, although we describe L. annulatum on the basis of morphology data, the species boundaries within the L. exiguum complex require further investigation.

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 4. Morphological characteristics of Lycogala annulatum: A – C sporocarp; D sporocarp with cracked top; E, F the outer surface of the peridium; G peridial vesicles; H the inner surface of the peridium (SEM); I, J capillitium; K, L the detail of capillitium ornamentation (SEM); M spores; N – P spore (SEM). Scale bars: 1 mm (A – F); 100 μm (G); 5 μm (H, P); 10 μm (I – M); 1 μm (N, O).