Flora of New Zealand Series

Type : "Dendriscocaulon umhausense" (Auersw.) Degel. [=Lobaria amplissima (Scop.) Forss.]

Description : Flora (1985: 152–153).

"Dendriscocaulon" was described by Nylander to accommodate distinctly stalked (often with a well-developed holdfast), sterile, shrubby associations of fungi lichenised with a cyanobacterium. Later, these "Dendriscocaulon" associations were shown to involve a fungus typically known to lichenise green algae (Wilson 1891; Dughi 1944; James & Henssen 1976). "Dendriscocaulon" is included in the family Lobariaceae (Galloway 2001e; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). Currently c. 10 "species" are recognised, all from deeply shaded, highly humid habitats in cool temperate forest biomes in both Northern and Southern hemispheres (Galloway 2001e; Tønsberg & Goward 2001; Goffinet et al. 2003) where the "Dendriscocaulon" -type life form is found in the genera Lobaria, Pseudocyphellaria and Sticta. "Dendriscocaulon" populations are generally corticolous, often growing in mats of bryophytes and other lichens, and some also occur on spray-drenched rocks near waterfalls.

The type of "Dendriscocaulon" is now widely accepted as being the cyanobacterial state of the lichen Lobaria amplissima (Scop.) Forss. This has exposed taxonomic problems in the treatment of Southern Hemisphere free-living cyanobacterial states of fungi in the Lobariaceae currently assigned to "Dendriscocaulon" (see Armaleo & Clerc 1991; Jørgensen 1991, 1996b, 1997b, 1998a; Laundon 1995a, 1996; Heiðmarsson et al. 1997; Galloway 2001e; Thomas et al. 2002; Goffinet et al. 2003), where green-algal and cyanobacterial symbioses of the same fungus may show dramatically different morphologies, the green-algal state often being a species of Sticta. Since free-living cyanobacterial states appear to be physiological adaptations of certain lichen-forming fungi (Lobaria, Nephroma, Peltigera, Pseudocyphellaria, Sticta) to low-light, high-humidity habitats, it is not permitted (under the rules of the ICBN) to give separate names to the cyanobacterial states when they are known to form photosymbiodemes with a named green-algal lichen. Laundon (1995a) proposed that cyanobacterial states be treated as forma of the green species, a position opposed by Jørgensen (1997b, 1998a) and Heiðmarsson et al. (1997). Although it is assumed that free-living cyanobacterial states (including those currently referred to "Dendriscocaulon") are facultatively associated with a green-algal species, this is commonly not the case in the field. Until molecular studies, currently in progress, on generic relationships in the Lobariaceae are further advanced, the view of Jørgensen (1998a: 355) is adopted here, i.e. informal names are given to cyanobacterial states, but confer no nomenclatural status, the informal names being cited within quotation marks, e.g. "Dendriscocaulon dendriothamnodes". This seems a reasonable interim solution to this problem of free-living "Dendriscocaulon" states. Two species are known from New Zealand (Galloway 1985: 152–154), but it is likely that all of the caulescent species of Sticta (q.v.), will prove to have "Dendriscocaulon" states.