Flora of New Zealand Series

Type : Megalaria grossa (Pers. ex Nyl.) Hafellner [=Lecidea grossa Pers. ex Nyl.]

Description : Flora (1985: 81 – as Catinaria).

Megalaria is a genus of c. 20 species included in the family Megalariaceae within the suborder Lecanorineae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). The genus was described by Hafellner (1984) and for a time it was thought to be monospecific and included in a family of its own, the Megalariaceae, with M. grossa as generitype. However, recent studies on a range of Northern Hemisphere material added M. pulverea (Schreiner & Hafellner 1992) and M. laureri (Hafellner in Nimis 1993: 429), while Ekman and Tønsberg (1996) described M. brodoana and added M. albocincta (Degel.) Tønsberg, and M. columbiana (G.Merr.) S.Ekman to the list of known taxa. In a study of photobionts cultured from New Zealand specimens of M. grossa, Elisabeth Tschermak-Woess (1984) showed that the photobiont belonged not to Trentepohlia as was widely accepted in the literature, but to Dictyochloropsis. European specimens were found to be in agreement with this finding, and subsequently the remaining five taxa of Megalaria are known to be lichenised not with Trentepohlia either, but with a still unidentified chlorococcoid photobiont that may or may not be the same as that of M. grossa (Ekman & Tønsberg 1996).

Ekman & Tønsberg (1996: 38) suggest Megalaria should be circumscribed in a rather wide sense based on current understanding of the taxa included in it and emphasising the similarities between them. Accordingly Megalaria is characterised thus: (1) crustose lichens with biatorine apothecia; (2) proper exciple of radiating hyphae up to 4 μm diam., without enlarged cells in the rim; (3) presence of a ± green or aeruginose, K+ pure green, N+ purple-red pigment in the epithecium; (4) paraphyses simple or sparingly branched in upper parts, but with at least a few anastomoses; (5) 1-septate, ellipsoidal to subglobose (usually not more than twice as long as broad), thick-walled, non-halonate ascospores without surface ornamentation; (6) asci with a low and blunt ocular chamber and with a conic, cylindrical or barrel-shaped (with convex sides) axial body that is usually surrounded by a zone that is more amyloid than the remainder of the tholus, i.e. Biatora -type or Lecanora -type (Malcolm & Galloway 1997: 186), but with a heavily amyloid zone around the axial body. A recent molecular study (Ivanova & Hafellner 2002) has shown that Megalaria might be more closely related to Aspicilia (Hymeneliaceae) than it is to Pertusaria. Eleven species are known in New Zealand, all except two of these being corticolous, with the majority of them being recently transferred from Catillaria (Galloway 2004c). Fryday (2004a) recently described two new saxicolous species from Campbell I. The genus is still very much in need of careful collection and study in New Zealand.