Gyalectidium Müll.Arg.
Type : Gyalectidium filicinum Müll.Arg.
Description : Thallus crustose, effuse or the algiferous patches sharply delimited, sometimes furnished with white hairs, corticate. Cortex of one layer of rectangular to rounded cells, sometimes in radiating rows. Photobiont green, Chlorococcaceae. Ascomata apothecia, immersed in thallus but erumpent. Exciple only slightly developed, prosoplectenchymatous, at upper parts of hymenium becoming paraplectenchymatous. Hymenium I−, epiplasm I+ reddish brown; epithecium containing algal cells. Hamathecium of paraphyses, slightly branched and anastomosing or ±simple. Asci rather thick-walled, 1-spored. Ascospores muriform with numerous cells, colourless. Conidiomata hyphophores producing chains of conidia associating with algal cells and acting as vegetative diaspores.
Gyalectidium is a genus of mainly tropical, foliicolous and corticolous lichens of which 41 species are known (Ferraro & Lücking 2000; Ferraro et al. 2001; Herrera-Campos & Lücking 2003; Lücking et al. 2003, 2005; Lücking 2004b) with seven species known from Valdivian rainforest (Lücking et al. 2003), showing that a distinctive Southern Hemisphere facies is present in this genus, and strongly suggesting that additional species should be found here in New Zealand. It is included in the family Gomphillaceae (Pennycook & Galloway 2004; Eriksson et al. 2004). Within the Gomphillaceae, species of Gyalectidium are easily recognised by: immersed apothecia (when fertile); a rudimentary exciple; 1-spored asci; muriform spores; and the presence of algae in the epithecium (Sérusiaux & De Sloover 1986; Vězda & Poelt 1987; Sérusiaux 1993; Lucking 1999a; Buck & Sérusiaux 2000). The genus is rather homogeneous through its hyphophores, the development of which is discussed in Sérusiaux & De Sloover (1986). Gyalectidium is anatomically similar to Calenia but differs from it in its broadly squamiform hyphophores (Lücking 1992: 105). One species is known from New Zealand where it is abundant in the Nelson area (Malcolm & Vězda 1997a). See also Dennetière & Péroni (1998) and Lücking et al. (2005).
