Flora of New Zealand Series

Description : Thallus irregularly spreading, erect or tufted, 1–3 cm diam., loosely to closely attached, pliable when wet, very brittle and fragile when dry, corticolous and saxicolous. Lobes orbicular, 3–6 mm broad, ±flat, complex–imbricate and densely crowded and ±upright. Margins entire, to irregularly lacerate–incised, dentate or phyllidiate, often ascending. Upper surface dark blue-black when wet, lead-grey to bluish when dry, smooth or roughened, ±crumpled in parts but never wrinkled or wrinkled–striate (×10 lens). Phyllidia granular–flattened at first, becoming coralloid–squamiform to expanded–lobulate, 0.1–0.5 mm tall, laminal and marginal, often densely developed and forming a crowded, diffract crust. Lower surface naked, concolorous with upper surface or paler. Apothecia not seen.

K: (Raoul I.). N: Northland (Kaitaia), Auckland (Domain), to Wellington. S: Nelson to Otago and Fiordland, both E and W of Main Divide (map in Galloway 1999: 336, fig. 10). In humid, shaded habitats in lowland and coastal forest and scrub, on trees and shrubs and on moist soil or rocks in forest, occasionally on maritime rocks, s.l. to 200 m. In the New Zealand region it ranges from the Kermadec Island Group in the north to Stewart I. in the south. It occurs on the following phorophytes: Agathis australis, Blechnum fluviatile, Coprosma parviflora, C. propinqua, Cordyline australis, Corynocarpus laevigatus, Cyathea medullaris, Dacrydium cupressinum, Dysoxylum spectabile, Griselinia littoralis, Kunzea ericoides, Leptospermum scoparium, Melicytus ramiflorus, Metrosideros excelsa, Myoporum laetum, Myrsine australis, Phyllocladus trichomanoides, Pittosporum eugenioides, P. umbellatum, Plagianthus divaricatus, Podocarpus cunninghamii, Prumnopitys ferruginea and Pseudopanax arborea. L. denticulatum was described by Nylander (1867a: 534) for a collection from Colombia. The lichen is widely distributed in the New World tropics and the SW United States and Mexico (Sierk 1964; Jørgensen & Nash 2004) and is present in the palaeotropics and Asia (Wolseley et al. 2002) though is apparently not in East Africa (Swinscow & Krog 1988) or Australia (Verdon 1992a; McCarthy 2003c, 2006).

Pantropical

Leptogium denticulatum is characterised by: the corticolous (rarely terricolous/saxicolous) habit; broad to submicrophylline lobes; a smooth, not wrinkled surface and with well-defined phyllidia (but not terete isidia), developed on the margins and upper surface. It is distinguished from the superficially similar L. cyanescens by the presence of phyllidia (L. cyanescens has terete isidia), and from L. limbatum, which has generally far fewer phyllidia, broad, bluish lobes which are often fertile, and scattered to more generally distributed white tomental hairs on the lower surface.