Flora of New Zealand Series

Holotype: New Zealand. Auckland Is, Port Ross, on [Suttonia] Myrsine australis in Metrosideros umbellata forest, 1927, G. Einar Du Rietz 2277 : 3 – S.

Description : Flora (1985: 410–411).

N: Northland (Te Paki Trig Bush, Mt Tutamoe [where it occurs rarely on twigs of Pinus insignis in a plantation], Kaiwaka Little Barrier I.), Auckland (Piha Gorge, Waitakere Ra. [Bartlett 1988: 20]), South Auckland (King Country), Wellington (Taranaki Falls Tongariro National Park), Wellington (Snake Valley near Turangi). S: Nelson (Denniston, Stillwater), Marlborough (Ship Cove, Resolution Bay), Westland (Kellys Creek, Ross), Canterbury (Peel Forest), Otago (Barrier River), Southland (Dusky Sound). St: A: Both E and W of the Main Divide. On twigs and bark (especially Dracophyllum, Kunzea and Leptospermum) in shaded, humid habitats, lowland to subalpine. Known also from Tasmania (Kantvilas & James 1987; Kantvilas 1994b, 1996b; Filson 1996; McCarthy 2003c, 2006) and recently reported from British Columbia, and Oregon (Brodo & Tønsberg 1994; Brodo 1995b: 160; McCune et al. 1997: 238; Goward 1999: 203; Brodo et al. 2001). There is some doubt, however, as to the North American taxon being conspecific with P. contortum from New Zealand (Goward 1999: 203).

Palaeotropical

Illustrations : Henssen (1963d: 102, fig. 13E–F; pls 29C–D, 30A, 31A); Malcolm & Galloway (1997: 83, 105, 112); Goward (1999: 187, fig. 9B; 202, fig. 2B); Malcolm & Malcolm (2000: 104; 2001: 8, 40); Brodo et al. (2001: 580, pl. 701); Lumbsch et al. (2001: 1).

Polychidium contortum, although not collected frequently, seems characteristic of successional vegetation at the margins of forest in areas of high rainfall, and frequent fog. It sometimes forms impressive, large ball-like thalli on the twigs of isolated Myrsine divaricata in riverflat grassland, where it associates with other cyanobacterial lichens such as Coccocarpia erythroxyli, C. palmicola, Coenogonium implexum, Degelia gayana, Erioderma sorediatum, E. leylandii, Fuscoderma amphibola, Pannaria euphylla, P. fulvescens, Physma chilense and Pseudocyphellaria hookeri.