Flora of New Zealand Series

Type : * Nesolechia oxyspora (Tul.) A.Massal. [= * Abrothallus oxysporus Tul.]

Description : Lichenicolous on corticolous, lignicolous or saxicolous host taxa (members of Parmeliaceae  s. lat.), inducing ±distinct cecidia. Thallus endokapylic. Ascomata apothecia, rounded to irregular, dispersed to aggregated, sessile to immersed, margins indistinct to rarely prominent. Exciple colourless to brown-black, ±reduced. Hypothecium colourless to brown-black, sometimes hyphae I+ violet. Hymenium hyaline, pale-brownish or pale-olivaceous, I+ faint blue or −. Epithecium pale-brown, brown or olive-brown, always covered with a layer of hyaline gel. Hamathecium of paraphyses, weakly branched or unbranched and ± anastomosing, swollen at apices, often irregularly shaped with dark-brown-pigmented caps. Asci broadly clavate, 8-spored, Lecanora -type, with broad diverging axial body, thin outer amyloid (I+ blue) wall layer, relatively thick non-amyloid wall layer, and lack of an amyloid zone above the axial body. Ascospores colourless, simple, ellipsoidal, broadly ellipsoidal, ovoid, fusiform, citriform, falciform or fabiform, partly curved, occasionally thickened at apices. Conidiomata pycnidia, immersed in host thallus; pycnidial wall pseudoparenchymatous, I+ violet. Conidiophores colourless, phialidic, enteroblastic, acrogenous. Conidia bacillar.

Nesolechia is a genus of obligately lichenicolous fungi distributed worldwide on foliose and fruticose taxa of the lichen family Parmeliaceae. Species of Nesolechia are recognised by their growth habit, especially the subimmersed, shiny, brown to black apothecia that are often found aggregated in galls on the host lichens. Six taxa are recognised worldwide (Alstrup & Hawksworth 1990), being mainly distinguished by ascospore characters, the colour and amyloid reaction of the hypothecium, and the choice of host lichen, with several species causing gall-like deformations of their host lichens. The genus is discussed by Keissler (1930: 119–144). Triebel & Rambold (1988) transferred the generitype of Nesolechia to Phacopsis Tul. (see also Triebel et al. 1995), pointing out similarities in ascus and paraphyses type. However, Alstrup & Hawksworth (1990: 49) considered that the well-developed exciple, the pigmentation of the ascomata, the ascospore shape, the even, unthickened spore-walls, and the development of the infections were sufficient characters to separate this taxon at the generic level, a view supported by Hafellner & Sancho (1990), Peršoh & Rambold (2002) and Hawksworth (2003). However, Diederich (2003: 70–72) suggests that on the basis of his study of ascomatal pigments in Phacopsis sens. lat., this genus should not be split into two genera. Nesolechia is included in the family Parmeliaceae (Peršoh & Rambold 2002; Eriksson et al. 2004) and in the family Acarosporaceae by Lawrey & Diederich (2003). One species occurs in New Zealand.