Metatrichia asiatica A. Vlasenko, 2024

Vlasenko, Anastasia V., Enkhtuya, Ochirbat, Degidmaa, Turmunkh, Enkhjargal, Enkhtaivan, Chelobanov, Boris P. & Vlasenko, Vyacheslav A., 2024, Three new species of bright-spored myxomycetes from Asia and the second world record of Perichaena maculosa, Phytotaxa 663 (4), pp. 205-220 : 211-215

Metatrichia asiatica A. Vlasenko sp. nov. ( Figs 4 , 5 , 6 ).

MycoBank no: 854741

Etymology:— Refers to distribution area.

Sporocarps stalked or rarely sessile, often with united stalks, ovate, sub-cylindrical, conical to subovate, leaning on each other, sometimes single, 0.4–0.7 mm in diam., up to 3.7 mm total high. Stalk folded, dark red, red-brown, greyred, grey, red-orange, from very thin to wide and thick, stalks of neighboring sporangia can grow together, 0.1–1.8 mm high. Hypothallus is brownish-red, olive-red, well developed. Peridium always three-layered; upper layer olive, thin, transparent filmy, iridescent, sometimes brown, often partially destroyed and then middle layer of peridium becomes clearly visible; middle layer very thick, opaque, matte, dark grey, resembles a finely dispersed, compressed, dark grey crumb of clay shale. In SEM, like small (up to 1.5 µm diam.) spherical granules resembling calcium in species of the genus Diderma . Inner layer of peridium shell-shaped, opaque, dense, shiny, glossy, brown in color. Dehiscence occurring along predefined lines to form a lid and a deep cup, sometimes dehiscence irregular. Capillitium red-brown, red-orange, represented by many long, free, sometimes branching, spirally twisted threads 5–7 µm diam., covered with long spikes 2–6 µm long. End of the elaters pointed, often with forked ends, sometimes thickened, bulbous, covered with warts and spines. Spores brownish-red in mass; reddish-orange in transmission light, spherical, densely covered with warts, 9–11 (–12) µm diam. Plasmodium unknown.

Holotype:— RUSSIA. Novosibirsk Region: near Сity of Novosibirsk, Central Siberian Botanical Garden , 54°49’47.6” N, 83°07’19.0” E, 183 m a.s.l., pine-birch-aspen forest, on the slope of a ravine, on fallen trunk of Betula pendula , field sample coll. 13 September 2022, A. V. Vlasenko, ident. A. V. Vlasenko, NSK 1016039 , GenBank No.: OQ622252.

Additional specimens examined:— RUSSIA. Novosibirsk Region: near City of Novosibirsk, Central Siberian Botanical Garden, 54°49’50.3” N, 83°07’19.1” E, 191 m a.s.l., pine-birch-aspen forest, on the slope of a ravine, on fallen trunk of Betula pendula , field sample coll. 5 September 2022, A. V. Vlasenko, ident. A. V. Vlasenko, NSK 1016022, GenBank No.: OQ622251; ibid, 54°49’49.9” N, 83°07’10.1” E, 199 m a.s.l., Tilia sp. and Quercus sp. plantings, on fallen trunk of Tilia sp. , field sample coll. 7 September 2021, A. V. Vlasenko, ident. A. V. Vlasenko, NSK 1016775; Arboretum of the Central Siberian Botanical Garden, 54°49’30.5” N, 83°06’42.5” E, 141 m a.s.l., on bark of living tree of Salix alba , substrate coll. 10 June 2017, sample from moist chamber coll. 30 August 2017, A. V. Vlasenko, cult. and ident. A. V. Vlasenko, NSK 1026453; Iskitimsky district, near the village of Novososedovo, 54°38’51.0” N, 83°57’38.3” E, 218 m a.s.l., birch-aspen forest, on fallen trunk of Populus tremula , substrate coll. 19 August 2020, sample from moist chamber coll. 25 April 2022, A. V. Vlasenko, cult. and ident. A. V. Vlasenko, NSK 1031914, GenBank No.: OQ622253.

Eсology:— Grows as a xylobiont on fallen trunks and rarely as an epiphyte on the bark of living trees.

Comments:— Metatrichia asiatica resembles only M. vesparia (Batsch) Nann. -Bremek. ex G.W. Martin & Alexop. in shape and sporulation colour. The main morphological difference between these two species is the presence of a three-layered peridium in M. asiatica , in which the middle layer is always represented by a grey granular material that is clearly visible under a dissecting microscope. The middle layer of peridium of M. asiatica is very thick, opaque, matte, dark grey, resembles a finely dispersed compressed dark grey crumb of clay shale. In SEM looks like small (up to 1.5 µm diam.) spherical granules resembling calcium in species of the genus Diderma . This unique feature allows M. asiatica to be unmistakably identified among all other species of the genus Metatrichia .

The ML analysis based on the 18S nrDNA region ( Fig. 7 ) showed that Metatrichia asiatica is an independent species, closest to M. vesparia (Batsch) Nann. -Bremek. ex G.W. Martin & Alexop. The genetic distance of the M. asiatica branch on the SSU tree is 0.036, with 98% bootstrap support. Phylogenetically, Metatrichia species belong to two separate groups. Metatrichia asiatica , M. vesparia and M. horrida Ing are united in the group Metatrichia s.str., while M. floriformis (Schwein.) Nann. -Bremek. and M. floripara (Rammeloo) Rammeloo belong to a separate group Metatrichia s.l.

Figures

FIGURE 4. Metatrichia asiatica (holotype). A–I. Sporangia (RL). Scale bars:A–I = 1.5 mm.

FIGURE 5. Metatrichia asiatica (holotype). A–C. Sporangia (RL). D. Three-layered peridium (TL). Arrows: black—outer peridium; blue—middle peridium; white—inner peridium. E. Granules of the middle layer of peridium (TL). F–I. Threads of capillitium and spores (TL). Scale bars: A = 1.5 mm, B = 1 mm, C = 1.5 µm, E = 15 µm, F–I = 15 µm.

FIGURE 6. Metatrichia asiatica (holotype). A–B. Spore (SEM). C. Thread of capillitium (SEM). D. Peridium layers (SEM). Arrows: black—outer peridium; blue—middle peridium; white—inner peridium. E–F. Threads of capillitium and spores (SEM). Scale bars: A–C = 2 µm, D = 5 µm, E = 40 µm, F = 20 µm.

FIGURE 7. Maximum likelihood tree based on 18S nrDNA sequences shows the phylogenetic relationships between Metatrichia asiatica and closely related species of bright-spored myxomycetes. BS values with high support and Bayesian posterior probabilities are shown in the branches. GenBank accession numbers are given after the species name.