Stemonitis amphorocolumella A. Vlasenko, G. Moreno & V. Vlasenko, 2023

Vlasenko, Anastasia V., Moreno, Gabriel H. & Vlasenko, Vyacheslav A., 2023, Stemonitis amphorocolumella (Stemonitidaceae, Myxomycetes), a new species from Western Siberia, Phytotaxa 592 (1), pp. 59-67 : 61-65

Stemonitis amphorocolumella A. Vlasenko, G. Moreno & V. Vlasenko sp. nov. Figs. 1 , 2 .

Mycobank: MB 829603

Description and Diagnosis: —Sporocarps in groups, dark brown, cylindrical, with total height of 6 – 9 mm. Hypothallus is dark brown, shiny, continuous under the colony. Sporotheca is long-cylindrical. The stalk is short, 25 – 40% of the total height, hollow, shiny, dark brown, almost black, reddish brown, in transmitted light orange. Peridium is not completely destroyed, remains in the form of a membranous collar at the base of sporotheca. Columella is cylindrical, similar in color to the stalk, with a bulge of amphora-like or bottle-like shape on top ends, up to 60 µm in diameter in the widest part. Capillitium is well developed, filaments extending from the column, are winding, dark brown, shiny and form a large-mesh network of different diameters (25–200 µm), well noticeable thickenings and/or membranous extensions are found in places of branching. The surface net consists of lighter, sometimes almost hyaline, threads, forming small meshes of 5 – 50 µm in diameter, with separate free endings in the form of spinules up to 12 µm in length. Spores are free, brown in mass, grayish brown in transmitted light, globose, with reticulate ornamentation, 9 – 11 µm in diameter, with 11 – 14 small meshes of reticulum on the visible side of the spore.

Etymology: —Has a columella with an amphora-like extension.

Type: — RUSSIA. Altai Territory, Aleysky district, 5 kilomerts northeast of the village Borovskoye , Lake Bakhmatovskoye , birch forest with Populus tremula , Padus avium , Caragana arborescens , on dead wood of Betula pendula , 52.689067° N, 82.249050° E, 235 m, substrate samples collected 24 August 2018, V.A. Vlasenko (holotype NSK 1026087 ).

Additional specimens examined: — RUSSIA. Altai Territory, Aleysky district, 5 kilomerts northeast of the village Borovskoye , Lake Bakhmatovskoye , dry birch forest, on stump of Betula pendula , 52.687383° N, 82.245250° E, 233 m, substrate samples collected 24 August 2018, V. A . Vlasenko (paratype NSK 1026086 , isoparatype AH 49360 ) .

Ecology: —Dead wood of deciduous trees.

Distribution: —Currently known only from locality of this types: North Asia, southeast of Western Siberia.

GenBank accession numbers: —SSU: OP831185.

Comments: —The new species belongs to Stemonitis and differs from the Comatricha Preuss and Stemonaria Nann. -Bremek., R. Sharma & Y. Yamam. has in the double net of capillitium, forming a very lax internal net and a delicate complete surface net as well as a hollow, horny or fibrous stalk, consisting of faint closely set, longitudinal fibres. Among representatives of the Stemonitis genus, only four species have bulbous or membranous apex of the columella— Stemonitis capillitionodosa G. Moreno, D.W. Mitch., C. Rojas & S.L. Stephenson ( Moreno et al. 2010), Stemonitis flavogenita E. Jahn (Janh 1904) , Stemonitis pseudoflavogenita A. Vlasenko & Novozh. ( Vlasenko et al. 2020) and Stemonitis sichuanensis B. Zhang & Yu Li ( Zhang & Li 2016). Stemonitis amphorocolumella differs from similar species by several morphological features ( Tab. 1 ). In these species, spores have ornamentation, consisting of spines and warts, while Stemonitis amphorocolumella has reticulate ornamented spores. The peridium of Stemonitis amphorocolumella is partially preserved in the form of a filmy collar at the base of sporotheca, whereas the peridium of S. capillitionodosa , S. flavogenita , S. pseudoflavogenita and S. sichuanensis is always fugacious.

Stemonitis amphorocolumella differs from S. capillitionodosa by a well-developed small-mesh delicate complete surface net of capillitium, as well as thickenings in the places of branching of capillary filaments, but not membranous extensions. Stemonitis amphorocolumella differs from S. flavogenit a by the structure and form of the end of columella. The columella of Stemonitis flavogenit a ends with a large filmy extension, while the columella of S. amphorocolumella has a thickened non-filmy ending in the shape of an amphora or bottle. Stemonitis amphorocolumella differs from S. sichuanensis by significantly larger spores, up to 11 μm in diameter, and the presence of spinous free endings on filaments of the capillitium. Stemonitis amphorocolumella differs from S. pseudoflavogenita first of all spores with reticulate ornamentation and also structure and form of the end of columella. Columella of Stemonitis pseudoflavogenita always ending in a funnel-shaped expansion at the apex of the sporotheca in Table 2 .

The ML analysis based on the 18S nrDNA region showed that the new species is closest to Stemonitis fusca . The genetic distance of the “ Stemonitis amphorocolumella ” branch on the SSU tree is 0.166, with 94% bootstrap support ( Fig. 3 ). The genetic distance of the “ Stemonitis fusca ” branch on the SSU tree is 0.276. Comparison of the sequences of Stemonitis amphoracolumella (OP831185) and S. fusca (KP323386) aligned using the MAFFT for a common fragment of 797 base pairs showed their significant difference, including 183 nucleotide substitutions and 10 deletions and/or insertions).

Thus, the conducted comparative morphological and phylogenetic analysis proves the species independence of Stemonitis amphorocolumella .

Figures

FIGURE 1. Stemonitis amphorocolumella (Holotype). A.—Sporocarps. B.—Columella and capillitum (transmitted light). C.—Apex of columella (transmitted light). D.—Apex of columella (transmitted light). E—Apex of columella (transmitted light). F.—Collar at the base of the sporotheca (transmitted light). G.—Collar at the base of the sporotheca (transmitted light). H.—Lower part of the stalk (transmitted light). Scale bars:A = 1 mm, B = 80 µm, C–H = 100 μm.

FIGURE 2. Stemonitis amphorocolumella (Holotype).A.—Columella and capillitum (SEM). B.—Spore (SEM). C.—Collar at the base of the sporotheca (SEM). D.—Collar at the base of the sporotheca (SEM). Scale bars:A = 100 µm, B = 15 µm, C–D = 100 μm.

FIGURE 3. The maximum likelihood tree based on SSU nrDNA sequences shows the phylogenetic relationships between the new species, Stemonitis amphorocolumella, and other closely related Stemonitis species. Numbers on the tree represent branch genetic distances and bootstrap values.