Neoburgoa freyi

Neoburgoa freyi Diederich, E. Zimm. & Lawrey, in Lawrey et al., The Bryologist 119 (4): 344 (2016)

Etymology: The species is named after the Swiss lichenologist Eduard Frey (1888–1974), an eminent scholar of alpine lichens and founder of the Swiss Association for Bryology and Lichenology.

Diagnosis: Basidiomata and conidiomata unknown. Colonies appearing as dispersed bulbils overgrowing thalli of Cladonia rangiferina. Mycelium not observed. Bulbils entirely immersed when young, later becoming superficial, pale yellow to orange, without hairs, surface smooth, with no individual cells visible, roundish to ellipsoid or irregular in form, 150–300(–700) µm diam.; bulbils externally without specialized cells, covered by an amorphous layer 3– 15 µm thick; bulbils internally composed of more or less roundish to ellipsoid or polyhedral cells separating rather easily (with pressure on the cover glass), 10–20 µm diam.; cell wall 0.8–1.7 µm thick; clamps not observed; content of cells occasionally yellowish, with yellow oil droplets emerging when observed in lactophenol cotton blue; no crystals visible in polarized light.

Colonies on agar plates showing yellowish aerial hyphae. Basidiomata, conidiomata and bulbils not observed. Mycelium 2.5–3.5 µm diam., septa with clamp connections, frequently producing chains of strongly swollen, elongate to roundish or irregularly constricted cells, 6–33 3 6–15 µm.

Index Fungorum number: IF818612

Distribution and ecology: This species is known from several alpine localities in Switzerland and is certainly much more widespread in the Alps. It is known only from thalli of Cladonia rangiferina. As young bulbils are entirely immersed in the host thallus and soon become superficial, and as they do not visibly damage the host thallus, it is likely that they have evolved together with the host over a long period and that they are confined to this host genus or species. No visible interactions between bulbils and hosts have been observed.

Notes:  Neoburgoa freyi is mainly characterized by the yellow to orange bulbils that are first immersed and then become superficial on the thallus of Cladonia rangiferina. Burgella species are similar in color, but bulbils are much smaller and superficial from the beginning: those of B. flavoparmeliae are honey-colored, 60–110 µm diam. (Diederich & Lawrey 2007), while those of B. lutea are yellow to orange yellow, 50–80 µm diam. (Diederich et al. 2014). Erythricium aurantiacum (Lasch) D.Hawksw. & A.Henrici (syn. Marchandiobasidium aurantiacum Diederich & Schultheis), a species belonging to the Corticiaceae, is distinguished by orange (carrot red) bulbils (Diederich et al. 2003; Diederich & Lawrey 2007). Microscopically, this species is distinguished from most lichenicolous, bulbilliferous fungi by the roundish to ellipsoid or polyhedral cells with a particularly thick wall.

Figure 1. Best-scoring nuLSU RAxML phylogram of species used in the analysis, showing the placement of Neoburgoa freyi. Internal branches in boldface indicate posterior probabilities ≥0.95 and numbers are ML-BS values ≥70. Arrows indicate described bulbilliferous species that are ± lichenicolous.