Myxotrichum persicum M. Mehrabi, Asgari & Zare

Mehrabi, Mehdi, Asgari, Bita & Zare, Rasoul, 2024, Myxotrichum persicum sp. nov., and two new combinations in the genus Myxotrichum, Phytotaxa 649 (1), pp. 83-97 : 89

Myxotrichum persicum M. Mehrabi, Asgari & Zare , sp. nov. Fig. 2

MycoBank: MB851580

Etymology: persicum of Persia, present Iran, referring to the country of origin.

Ascomata superficial, discrete, at first dull green to brown, then becoming nearly black, with a white centrum, more or less globose, 100–200 μm diam incl. appendages, maturing in 4 weeks on PCA. Peridial hyphae dark brown, thick-walled, septate, sometimes constricted at the septum, 2–3.5 μm diam., smooth, branched and anastomosed to form a reticulum, ending in spine-like appendages. Appendages dark brown to nearly black, paling towards the apex, 20–45 × 1–2.5 μm (av. = 37 × 1.7 μm, n = 10), straight or somewhat curved, usually unbranched, 1–2 septate at the lower part, smooth, with hyaline pointed or blunt end. Asci ovoid to pyriform, 8-spored, 7–9 × 6–8 μm (av. = 8.2 × 6.3 μm, n = 5), evanescent. Ascospores hyaline, smooth, ellipsoidal to fusiform, 3–4 × 2–2.5 μm (av. = 3.4 × 2 μm, n = 10). Asexual morph undetermined.

Culture characteristics (25 °C, 4 weeks): Vegetative mycelium consisting of hyaline, branched, septate, smooth-walled, 1–2 μm diam hyphae. Ascomatal initials appear as swollen side branches arising from aerial hyphae, which coil and form a compact mass. Colonies on PDA attaining 27 mm diam., flat, at first velvety, then becoming powdery, white, wrinkled, often deeply immersed into the agar; margins irregular; reverse orange (7) in center and buff (45) in margin. Colonies on PCA attaining 30 mm diam., flat, floccose, white; margins irregular; reverse of the same obverse colony color. Colonies on CMA attaining 33 mm diam., flat, floccose, white, often deeply immersed into the agar; margins irregular; reverse of the same obverse colony color. Diffusible rose (1) to orange (7) pigments were produced in all examined media.

Type:— IRAN, Lorestan province, Azna , 33˚27′46.4″ N, 49˚23′14.71″ E, seed endophyte of Aegilops triuncialis L., August 13, 2018, M. Mehrabi & B. Asgari (holotype IRAN 18352 F, preserved in a metabolically inactive state) ; ex-type culture, IRAN 3775C.

Notes: Attempts to stimulate sporulation of our strain on various culture media including CMA, OA, PCA, PDA and SNA were unsuccessful, and only a few ascomata were formed on PCA. Morphologically, M. persicum closely resembles M. deflexum and M. dendromorphum Matsush. However , this new species is primarily distinguished from similar species by the characteristics of ascomata appendages and ascospores. In comparison to M. deflexum ( Currah 1985) , which infrequently produces alternate arthroconidia (malbranchea-like), M. persicum exhibits smaller ascomata (100–200 μm vs. 200–450 μm). Furthermore, M. persicum has shorter (20–45 μm vs. up to 200 μm), less branched appendages with deflexed lateral branches, and ellipsoidal, smooth ascospores. Phylogenetic analyses ( Fig. 1 ) also support the distinction of M. persicum from M. deflexum . Base pair differences further highlight distinctions, revealing 2% (545/554) and 6% (472/502) differences in LSU and ITS regions, respectively, following the guidelines of Jeewon and Hyde (2016). Myxotrichum dendromorphum ( Matsushima 1995) also resembles M. persicum in ascomata size and peridial hyphae characteristics, but it can be differentiated by longer (40–100 μm), tree-like branching appendages and larger (4–5.5 × 2–3 μm), and longitudinally striate ascospores. No sequence data are available for M. dendromorphum to compare its phylogenetic relationship with M. persicum .

Figures

FIGURE 1. Maximum likelihood phylogenetic tree inferred from the combined ITS, LSU, MCM7 and RPB1 sequence alignment of 55 strains of the Myxotrichaceae and Amorphothecaceae. Maximum likelihood bootstrap supports (≥70%) and Bayesian posterior probabilities support (≥0.9) are given above or below the branches, respectively. Dashes replace non-significant values. The branches with full statistical support (ML = 100%; PP = 1.0) are thickened. The scale bar shows the expected number of changes per site. The tree is rooted to Hyphodiscus hyaloscyphoides (NBRC 104869) and Venturiocistella japonica (NBRC 106633).

FIGURE 2. Myxotrichum persicum. a. Colonies morphology (surface and reverse) from left to right on PDA, PCA and CMA at 25 °C, after 4 weeks of incubation. b.Ascoma. c. Peridial hyphae. d, e. Appendages. f. Immature asci (arrow) and peridial hyphae. g. Ascospores. Scale bars: b, f=20 μm, c–e, g=10 μm.