Shivasia solida
Shivasia solida (Berk.) Vánky, M. Lutz & Piątek 2012, in Lutz et al., IMA fungus, 3, 143-154 (2012).
Diagnosis: Sori in all flowers of an inflorescence, comprising the innermost floral organs, visible between the glumes as black, globose to ovoid bodies, 1–2 mm in diam., rarely also on the stems, then fusiform, at first covered by a thick, whitish brown fungal peridium of thick-walled, sterile hyphae that early flakes away exposing the compact mass of spore balls with spores, powdery on the surface. Spore balls usually irregular or globoid to ellipsoidal, composed of 2–15 spores, loose but rather permanent, 25–55(–70) × 20–40 µm, reddish brown, enclosed by subhyaline mucilaginous layer. Spores subglobose, ovoid, elongate or irregular, flattened on one or two sides, 15–20 × 12–16 µm, yellowish to pale reddish brown; wall uneven, 0.5–1.5 µm thick, smooth to rough, in SEM finely, densely, irregularly verruculose and covered by remnants of the mucilaginous layer which form irregularly warty (pseudo-)ornamentation. Spore balls and spores produced on the surface of host tissues in hyaline, sporogenous fungal tissues in radially arranged, U-shaped pockets. Spore germination (on water, at room temperature, in 3–5 days) results in long, aseptate basidia on which apically elongated, cylindrical basidiospores are produced that germinate by filaments.
Index Fungorum Number: IF800822
Figure 1. Bayesian inference of phylogenetic relationships within the sampled Ustilaginomycetes: Markov chain Monte Carlo analysis of an alignment of LSU sequences using the GTR+I+G model of DNA substitution with gamma distributed substitution rates and an estimated proportion of invariant sites, random starting trees and default starting parameters of the DNA substitution model. A 50 % majority-rule consensus tree is shown computed from 45 000 trees that were sampled after the process had reached stationarity. The topology was rooted with the exobasidiomycetous species Entyloma microsporum, Exobasidium vaccinii, and Tilletia caries. Numbers on branches before slashes are estimates for a posteriori probability, numbers on branches after slashes are ML bootstrap support values. Branch lengths were averaged over the sampled trees. They are scaled in terms of expected numbers of nucleotide substitutions per site. The taxonomic concept used here follows Bauer et al. (2001).
Figure 2. Shivasia solida on Schoenus apogon A Holotype of Ustilago solida [K(M) 171338]. B The habit of infected plants and two enlarged sori (H.U.V. 15059). Bars: A = 1 cm, B = 1 cm and 3 mm, respectively.
Figure 3. Shivasia solida on Schoenus apogon A. Embedded, stained, semi-thin section of a sorus (H.U.V. 17649), sh = sporogenous hyphae, sp = spore balls, p = peridium. B. Fungal cells of the peridium covering the sori, formed of thick-walled, sterile hyphae (H.U.V. 15059). C Spore ball formation in sporogenous fungal layer on the surface of innermost floral organs, in U-shaped pockets, hand sectioned, stained with cotton blue in lactophenol (H.U.V. 15059). D–E. Young spores and spore balls covered by fungal cells of the young peridium, embedded in plastic, sectioned and stained with new fuchsin and cristal violet (H.U.V. 15059). F. Spore balls in different developmental stages, hand sectioned, stained with cotton blue in lactophenol (H.U.V. 15059). G–H. Spore germination in water, at room temperature, in 3–5 days (H.U.V. 15059). Bars: A = 100 μm, B–H = 10 μm.
Figure 4. Shivasia solida on Schoenus apogon (KRAM F-49115). A–C. Spore balls and spores seen in LM, note mucilaginous layer (subhyaline caps) around spores marked by arrows. D–E Spore balls and spores seen in SEM, note that spores are enclosed by remnants of mucilaginous layer that form (pseudo-) ornamentation, while the spore surface is verruculose as marked by arrow. Bars = 10 μm.
References:
Bauer, R., Begerow, D., Oberwinkler, E., Piepenbring, M., & Berbee, M. L. (2001). Ustilaginomycetes. Systematics and evolution, 57-83.
Lutz, M., Vánky, K., & Piątek, M. (2012). Shivasia gen. nov. for the Australasian smut Ustilago solida that historically shifted through five different genera. IMA fungus, 3, 143-154.
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