Flora of New Zealand Series

Type : Rimularia limborina Nyl.

Description : Thallus crustose, thin, superficial, subareolate to distinctly areolate, on rocks or parasitic on other lichens. Photobiont green, chloroccoid. Ascomata apothecia, immersed to sessile, plane to convex, black; disc umbonate or gyrose. Thalline exciple lacking. Proper exciple persistent, often contorted to gyrose, black. Epithecium olivaceous to brown. Hymenium colourless, I+ blue. Hypothecium dark-brown to black, continuous with proper exciple. Hamathecium of paraphyses, thin, to 1 μm diam., richly branched and anastomosing, septate, apices pigmented, not expanded or capitate. Asci 8-spored, cylindrical-clavate, Rimularia -type or Trapelia -type (Malcolm & Galloway 1997: 187; Coppins & Kantvilas 2001: 35). Ascospores ellipsoidal, simple, smooth, thin-walled, colourless at first becoming brown with age, non-halonate. Conidiomata pycnidia, immersed. Conidia bacillar, simple, colourless.

Rimularia is included in the family Agyriaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). The family is characterised by asci of Rimularia - or Trapelia -type having characteristic amyloid structures in the apical tholus (Hafellner 1984: 332, fig. 77; Rambold 1989: 23, fig. 2G; Hertel & Rambold 1990: 153, fig. 1I; Malcolm & Galloway 1997: 187), highly anastomosing moniliform paraphyses and a well-developed exciple of pseudoparenchymatous cells. Rimularia is distinguished from related genera, such as Porpidia (q.v.), by the distinctive iodine reaction of the ascus apex; the richly branched and anastomosing paraphyses; by the large, non-halonate ascospores that are colourless at first but become brownish with age; and the umbonate to gyrose apothecia lacking a thalline exciple (David 1992b). Some 23 species are known worldwide (Kainz & Rambold 2004b; Dr Alan Fryday, pers. comm.), being known from siliceous rocks, bryophytes, bark, and as lichen parasites (Muhr & Tønsberg 1989; Hertel & Rambold 1990; Aptroot & Sipman 1991; Rambold & Printzen 1992; Coppins & Kantvilas 2001; Timdal 2002d; Fryday 2003; Kainz & Rambold 2004b), of which four are known from New Zealand.