Flora of New Zealand Series

≡Leptogium cyanescens var. austroamericanum Malme, Ark. Bot. 19 (8): 21 (1924).

Description : Thallus orbicular to irregularly spreading, ±loosely to closely attached, 2–6(–8) cm diam., bluish, lead-grey or ±browned in parts. Lobes rounded, ±ascending, concave or undulate, rarely plicate, 3–8 mm wide, margins entire or lobulate, ±isidiate. Upper surface matt, roughened, delicately wrinkled–striate (×10 lens), isidiate. Isidia granular at first, terete, simple becoming coralloid–branched, to 1 mm tall, often densely crowded and forming a diffract crust, concolorous with thallus, here and there becoming clavate, phyllidiate. Lower surface naked, concolorous with upper surface or paler, wrinkles often more prominent than on upper surface (×10 lens). Apothecia not seen.

K: (Raoul I.). N: Northland (Three Kings Is to Mauitaha I.), Auckland (Piha), South Auckland (Te Aroha to Slipper I.). An epiphyte of northern coastal forest trees and shrubs where it is known from the phorophytes Kunzea ericoides and Melicytus. It is still very poorly collected and understood in the New Zealand region where it occurs between latitudes 29º 16's and 37ºS (map in Galloway 1999: 325, fig. 3). It is also known from Central and South America, the southern United States, Europe, and Australia (Sierk 1964; Verdon 1992a; McCarthy 2003c, 2006; Jørgensen & Nash 2004), and it is common in coastal and lowland areas of Papua New Guinea (Aproot et al. 1995; Aptroot 2002e).

Pantropical

Illustration : Brodo et al. (2001: 402, pl. 450).

Leptogium austroamericanum is characterised by: the corticolous habit; broad lobes having a characteristically wrinkled upper surface (×10 lens) with terete, simple to coralloid isidia. A closely related species is L. propaguliferum, which has a wrinkled upper surface and flattened phyllidia instead of terete isidia. It is discussed in Sierk (1964: 296–297) and Verdon (1992a: 177–178).