Cetrariella
Type : Cetrariella delisei (Bory ex Schaer.) Kärnefelt & Thell Cetraria islandicaδdelisei Bory ex Schaer.]
Description : Thallus erect-foliose, dark- to pale-brown; lobes ±canaliculate or almost subtubular, occasionally becoming markedly expanded towards apices. Cortex paraplectenchymatous comprising 1–3 layers of rather large pachydermatous cells. Pseudocyphellae marginal or laminal on lower surface. Ascomata apothecia, terminal on lobe tips. Asci broadly clavate, 40 × 15 μm (Kärnefelt et al. 1993: 398, fig. 8); tholus moderately small, ocular chamber short and broad, axial body broad, c. 5 μm, maximal tholus thickness c. 3 μm. Ascospores ellipsoidal, 5–10 × 2.5– 5 μm. Hamathecium of paraphyses, straight, sparsely branched with swollen apices. Conidiomata pycnidia, developed on tips of projections, one- or two-layered, non-pigmented, sometimes with cortical tissue beneath. Conidia sublageniform, 7–9 × 0.5–1.5 μm (Kärnefelt et al. 1993: 398, fig. 11).
Chemistry : Gyrophoric and hiascic acids.
Cetrariella is a genus of three species worldwide (Thell et al. 2004), separated from Cetraria, and accommmodated in the family Parmeliaceae (Kärnefelt et al. 1993; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). Apart from differences in the ascus type, Cetrariella is mainly characterised by large, pachydermatous cells arranged in 1–3 layers; sublageniform (bottle-shaped) conidia, and the presence of gyrophoric and hiascic acids in the medulla (Thell et al. 2002). The ascus type in Cetrariella is characteristic and sufficiently distinct from that in Cetraria to warrant formal segregation from the larger genus. It is characterised by the tholus lacking an amyloid (I+ blue) ring, the broad ocular chamber, and the large axial body. This ascus type is dominant in the Parmeliaceae as a whole and is characteristic of most parmelioid genera (Kärnefelt et al. 1993). One species is recorded from New Zealand.
