Diacheopsis cinerea A. Vlasenko & V. Vlasenko, 2022

Vlasenko, Anastasia V., Vlasenko, Vyacheslav A. & Kabilov, Marsel R., 2022, A new species of Diacheopsis from Russia, Phytotaxa 541 (2), pp. 193-200 : 195-199

Diacheopsis cinerea A. Vlasenko & V. Vlasenko , sp. nov. ( Figs 1A–E , 2A–J )

Index Fungorum number: IF557664; Facesoffungi number: FoF 08147

Sporocarps sessile, cylindrical, about 0.7–0.9 mm in diam. and 0.9–1.1 mm in total height, gregarious, scattered or in small groups of 2–8, drab grey, beige, densely clustered. Peridium single, membranous, translucent below, more dense at the top, fugacious above, persisting as a deep cup at the base; transparent, very light, with a slight greyish colour (in transmitted light) in the lower and lateral parts of the sporocarps; in the apex of sporotheca it is light-ocher, transparent (in transmitted light); it is often common in adjacent sporocarps, but with preservation of the side walls between adjacent sporocarps. Dehiscence is apical irregular. After the complete destruction of sporocarps, basal rings remain attached to the substrate. Columella absent. Capillitium dark violet-brown, with expanded nodes of dark brown colour, branched and anastomosed, arising from the base and forming a network connected to the peridium and the base of sporotheca by paler tips. Hypothallus continuous under the group (confluent), thin, light-coloured. Spore-mass dark brown to dark. Spores globose, 10.5–13.0 µm diam. including ornamentation, densely and uniformly covered by warts up to 0.4 µm in total height. In SEM, the ornamentation appears as dense, abundant and regularly distributed, well-developed, coralloid projections on the apex of each wart. Plasmodium not seen.

Etymology:— Referring to the colour of sporocarps.

Type:— RUSSIA. Altai Territory: near Losikha railway station, dry pine forest, on a fallen tree of Pinus sylvestris , 8 July 2009, leg. A. Vlasenko and V. Vlasenko, NSK 1030140 (holotype), GenBank SSU: MT 386336 .

Additional specimen examined:— RUSSIA. Altai Territory: near Losikha railway station, pine forest, on dead wood of Pinus sylvestris , 26 August 2019, leg. A. Vlasenko and V. Vlasenko, NSK 1030138 (paratype) .

Ecology:— Xylobiont.

Distribution:— Known only from type locality.

Comments:— Phylogenetically, Diacheopsis cinerea grouped with Lamproderma echinosporum and L. gulielmae . We have received data that other species of Diacheopsis are phylogenetically similar to those of the genus Lamproderma ( Fig. 3 ). Diacheopsis metallica is closest to L. cristatum , while D. pauxilla is closest to L. sauteri and L. ovoideoechinulatum . Similar to Lamproderma , the morphological genus Diacheopsis consists of several separate phylogenetic lines. At the same time, the species that represent different phylogenetic lines demonstrate morphological similarities. Classification of the family Stemonitidaceae is not developed and is based on morphological features. Based on a complex of morphological features, we assigned the new species to the genus Diacheopsis .

Diacheopsis cinerea has a warty ornamentation of spores, which brings it close to the group of species that have spores with warts: D. laxifila , D. minuta , D. mitchellii , D. pieninica , D. rigidifila , D. vermicularis , D. griseobrunnea and D. serpula . Spores of D. mithellii are very large, 20–21 µm in diam., covered with long spines or warted, about 1 mm in length and with tips that appear frayed under SEM. In comparison, the spores of D. cinerea are significantly smaller, 10.5–13.0 µm in diam., densely and uniformly covered with warts that are up to 0.4 µm in total height. By SEM, their ornamentation consists of dense, abundant, regularly distributed and well-developed coralloid projections on the apex of each wart.

Spores of D. pieninica , D. rigidifila , and D. griseobrunnea are less than 9 µm in diam. (spores of D. cinerea are larger than 10 µm in diam.). Spores of D. laxifila are united into clusters while spores of D. cinerea are free. Sporocarps of D. minuta are very small, 0.2–0.4 mm in total height, of bronze colour while sporocarps of D. cinerea are 2–3 mm in total height, and grey-beige in colour.

In D. serpula , elongated plasmodiocarps are predominant in the colony but in D. cinerea , sessile sporangia are predominant. Capillitium of D. serpula is without extensions while that of D. cinerea is with numerous filmy brown extensions.

Capillitial nodes of D. vermicularis are rounded but in D. cinerea they are triangular and quadrilateral. The capillitial threads of D. vermicularis are colorless or grey and in D. cinerea they are dark violet-brown, and only the ends of threads by which they are attached to the base of sporocarp and peridium are light. The spores of D. vermicularis are light brown, with dark areas consisting of groups of warts (in transmitted light); those of D. cinerea are brown, and evenly ornamented with warts.

In shape and size of sporocarps, the new species resembles D. insessa and D. nannengae , but it differs significantly by the structure of capillitium, size of the spores and their ornamentation. Spores of D. insessa are 16–22 µm in diam. and ornamented with long spines while the spores of D. cinerea are less than 14 µm in diam., and ornamented by warts. Spores of D. nannengae are ornamented with short spines while spores of D. cinerea have long warts up to 0.4 µm in total height. The capillitium of D. nannengae arises only from the base of sporotheca but in D. cinerea it arises from the base and forms a network connected by paler tips to the peridium and the base of sporotheca.

Samples of D. cinerea were first found by us in 2009 in dry pine forests in the northern part of the “Verkhneobsky pine forest”, located on the right bank of Priobsky Plateau. Diacheopsis cinerea was collected there again 10 years later, which indicates the existence of a stable community of the species. The fructification of the species was observed after prolonged rains.

Figures

FIGURE 1. Diacheopsis cinerea (holotype). A–D. Sporocarps (DM). E. Basal rings (DM). Scale bars:A–D = 1 mm, E = 2 mm.

FIGURE 2. Diacheopsis cinerea (holotype). A. Peridium, spores (CM). B, C. Capillitium connected to the peridium, spores (CM). D–F. Capillitium, spores (CM). G. Spores on the peridium (SEM). H. Spore (SEM). I. Spore surface ornamentation (SEM). J. Capillitium connected to the peridium, spores (SEM). Scale bars: A–F = 20 μm, G = 4 μm, H = 2 μm, I = 0.4 μm, J = 30 μm.

FIGURE 3. Maximum likelihood tree illustrating the phylogeny of Diacheopsis cinerea (holotype) with related species in Stemonitidales based on SSU sequences.The evolutionary history was inferred by using the maximum likelihood method and Tamura-Nei model (Tamura & Nei 1993). The tree with the highest log likelihood (-3167.40) is shown. Values on the branches represent a percentage of the 1000 bootstrap replicates, and the bootstrap values over 75% are shown on the tree. There was a total of 644 positions in the final dataset. Echinostelium minutum (ATCC22345) in Echinosteliales was selected as an outgroup taxon. Evolutionary analysis was conducted using MEGA X. Outgroup is indicated in bold and black. The novel taxon is indicated in bold and blue.