Flora of New Zealand Series

Description : Lichenicolous. Pycnidia, 125–225 μm diam., immersed at first but becoming erumpent through the surface of the host, about ⅓ exposed at maturity, arising singly, scattered, sometimes arising on the site of a previous pycnidium and then assuming a rimmed appearance from above and a double-walled structure in vertical section, black, ostiolate, the ostiole often conspicuous and c. 25 μm diam., wall of varying numbers of cell layers, mainly 4–8, 15–25 μm thick, thickest around the ostiole in the erumpent part of the pycnidium, dark-brown, pseudoparenchymatous, textura angularis, cells thick-walled, tending to be polyhedral, mainly 3–4 μm diam. Conidiogenous cells holoblastic, ampulliform to lageniform, lining the pycnidial cavity, percurrently proliferating, annellate with up to 4 annellations seen, hyaline, smooth-walled to weakly echinulate, 8–12 × 3–4 μm. Conidia obpyriform, hyaline, collecting in a mucilaginous mass in the pycnidial cavity and extruded as a drop, simple, sometimes 1–3-guttulate, apex rounded, the base abruptly truncated, thin-walled, ±smooth-walled at lower magnifications but with a widely spaced, echinulate ornamentation just discernible by interference-contrast, (7–)7.5–10.5(–11.5) × (5–)5.5–7(–7.5) μm.

Teleomorph : Abrothallus parmeliarum

N: S: St:? Known also from Great Britain, Sweden, Poland and the Canary Is (Hawksworth 1981; Santesson 1993; Hafellner 1995c; Kukwa 2002c; Santesson et al. 2004).

Cosmopolitan

Hosts : Parmelia saxatilis and Platismatia glauca and probably a large number of species of Parmelia  s. lat. (Hawksworth 1981). In early infections the pycnidia arise on almost healthy lobes, with a circle of brownish discoloured tissue around the pycnidia. In more advanced stages of infection the pycnidia occur on gall-like deformations of the host thalli typical of infections due to * Abrothallus parmeliarum.

Illustrations : Hawksworth (1981: 68, fig. 33C–D; 1983a: 39, fig. 138).

* Vouauxiomyces santessonii is characterised by: the lichenicolous habit; pycnidia semi-immersed in * Abrothallus parmeliarum infections of host lichen (Parmelia saxatilis); conidia exuding in a mucilaginous mass around ostiole, (7–)7.5–10.5(–11.5) × (5–)5.5–7(–7.5) μm.