Flora of New Zealand Series

Type : Degelia gayana (Mont.) Arv. & D.J.Galloway [Parmelia gayana Mont.]

Description : Thallus foliose, lobate to placodioid, ±orbicular, ±loosely attached, occasionally closely appressed. Lobes flat to slightly concave, adjacent, often imbricate, broadly cuneate to flabellate, greyish blue when wet; margins ±entire to incised, sometimes secondarily lobate or isidiate, Upper surface smooth or faintly ridged, occasionally minutely scabrid. Medulla white. Photobiont cyanobacterial, Scytonema, not penetrating hymenium. Lower surface whitish to pale buff-brown, ±covered in white or blue-black rhizohyphae, rarely ±glabrous. Ascomata apothecia, frequent, laminal, sessile, biatorine, with pale proper exciple and sometimes with secondarily developed crown-like thalline exciple not obscuring the proper exciple; disc concave to flat, becoming plane or convex at maturity, matt, not gyrose–contorted, epruinose, reddish brown, sometimes blackened, sometimes with small white hairs at base, often excluded by disc or thalline exciple; thalline exciple present or absent. Hymenium usually I+ persistent blue. Asci with distinct amyloid plug. Ascospores ellipsoidal, simple, colourless, 8 per ascus, surface somewhat roughened. Conidomata pycnidia, laminal or marginal, wart-like, blackish. Conidia rod-shaped.

Degelia is a genus of 16 species of uncertain position, but regarded at present as belonging in the family Pannariaceae (Jørgensen 2003c; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), mostly occurring in the Southern Hemisphere (Jørgensen & Galloway 1992b; Jørgensen et al. 2000; Jørgensen 2001b, 2003c, 2004a, 2004e). Species are found most commonly on bark in humid, lowland forest, more rarely on rocks and occasionally on soil and rocks in alpine regions. It is discussed in Arvidsson & Galloway (1981), Jørgensen & James (1990), Jørgensen & Galloway (1992b), Jørgensen et al. (2000) and Jørgensen (1999a, 2001b). Degelia was divided into three sections by Jørgensen & James (1990) and Jørgensen (2003c: 7; 2004a: 232), sect. Degelia, containing Scytonema as photobiont, with taxa distributed in the Southern Hemisphere, sect. Amphiloma, having Nostoc as photobiont with species predominantly in the Northern Hemisphere, and sect. Frigidae, for subantarctic-alpine, predominantly Southern Hemisphere species. Recent molecular work on the Pannariaceae (Ekman & Jørgensen 2002: 631) indicates that Degelia sect. Amphiloma should not be included within that family and its present position remains unclear. Wiklund & Wedin (2003) and Wedin & Wiklund (2004)showed that Degelia is paraphyletic, since species of Degelia group with Erioderma and Leioderma, but the ranking of this group is still unclear. Degelia rosulans was recently transferred to the newly described genus Degeliella (Jørgensen 2004a) and Degelia neozelandica is now replaced in Steinera where it was originally described. Five species are recorded from New Zealand. D. symptychia (Tuck.) P.M. Jørg., a species known formerly from Juan Fernandez and southern South America, is also present in the Auckland Islands (Dr A.M. Fryday, pers. comm.)