Flora of New Zealand Series

=Collema flaccidum var. γ caerulescens C.Bab. in J.D. Hooker, Fl. Nov. Zel. 2: 309 (1855).

≡Synechoblastus flaccidus var. caerulescens (C.Bab.) Müll.Arg., Bull. Herb. Boissier 2, App. 1: 19 (1894).

≡Collema rupestre var. coerulescens (C.Bab.) Zahlbr., Cat. lich. univ. 3 (1): 60 (1924).

Lectotype: New Zealand. Sine loco [probably Wellington], Charles Knight – BM [fide Degelius (1974: 135)].

Collema flaccidumvar. γcaerulescens. Lectotype: New Zealand. Sine loco, on trees, W. Colenso – BM [fide Degelius (1974: 135)].

Description : Flora (1985: 142–143).

N: Northland to Wellington (Palmerston North, Featherston, Upper Hutt). S: Nelson (Riwaka River), Marlborough (Pelorus Bridge), Westland (Kumara, Otira Gorge), Canterbury (Cass, Port Hills Christchurch, Acland Falls Peel Forest), Southland (Milford Sound, Rowallan Burn). St: A: (Adam's Island Fairchild's Garden, Ranui Cove). C: Widely distributed on both E and W coasts. Mainly corticolous on trees and shrubs in open or shady situations from both coastal and inland habitats, predominantly a lowland species, s.l. to 400 m; very rarely on limestone. Known also from Japan, Australia and Paraguay (Degelius 1974; McCarthy 2003c, 2006).

Western Pacific

Illustrations : Degelius (1974: 137, fig. 40); Kantvilas & Jarman (1999: 60).

Collema subconveniens is characterised by: the corticolous (rarely on basicolous rocks) habit; broadly lobate thallus, generally without isidia, often distinctly bluish in colour reminiscent of Leptogium; young apothecia are clustered together in ±erumpent groups, the thalline margin only slightly raised above the level of the thallus surface; and the muriform ascospores. Verdon (1992a: 178) records "Many past and recent determinations of Leptogium azureum from south-eastern Australia and New Zealand are misidentifications of Collema subconveniens (blue-grey form)". Collema subconveniens is distinguished from Leptogium aucklandicum (L. azureum is a neotropical species and does not occur in New Zealand) by the morphology of the apothecia and by the ascospores. The ascospores of C. subconveniens are longer and more noticeably apiculate at the apices, 20–40(–43) μm, and also broader, 8–10.5(–15) μm, and are distinctly constricted at the transverse septa than are those of L. aucklandicum, and generally have mainly 2 and not 3 longitudinal septa for each transverse septum (Degelius 1974: 137; Galloway 1999: 321).