What is the Southern Subpolar Region?

The Southern Subpolar Region is here taken to be the area between the Antarctic Divergence and Subtropical Convergence. This region is often referred to as the Subantarctic, but that name refers to that part of the region south of the Antarctic Convergence, which has colder summers and a complete lack of arboreal vegetation (Øvstadal & Lewis Smith 2001). As trees are present on some of the areas under consideration they should not be considered ‘Subantarctic’ and so the term ‘Southern Subpolar’ is preferred.

The International Working Group on Taxonomic Databases for Plant Sciences (TDWG) (Brummitt 2001) include in their “Subantarctic Islands” region:
Australasia: Macquarie Island.
South Atlantic: Falkland Islands, South Georgia, South Shetland Islands, South Orkney Islands, Bouvetøya (all except the Falkland Islands included in Antarctica by Øvstadal & Lewis Smith 2001).
Indian Ocean: Tristan da Cunha & Gough Island, Prince Edward & Marion Islands, Crozet Island, Kerguelen, Heard & MacDonald Islands, St Paul Island & New Amsterdam.

This is the area used for this investigation (Fig. 1), with the addition of the southern New Zealand Shelf Islands (Auckland Islands and Campbell Island) and the islands at the southern tip of South America: (e.g. Argentina: Tierra del Fuego (Isla Grande, Isla de los Estados); Chile: Cape Horn to Isla Wellington). Brummitt (loc. cit.) included these islands in the ‘New Zealand’ and ‘southern South America’ regions respectively, but I can see no reason to exclude these areas from the "Subantarctic" while including the Falkland Islands, and Tristan da Cunha and Gough Island.

How well known is the lichen mycobiota?
In 1876 the Rev. J. M. Crombie presented a paper to the Linnean Scociety of London on the lichen collections of Professor R. Cunningham from southern South America. In his introduction he said:

“Unfortunately, as is too often the case in collections from the more remote countries, there are but few saxicole lichens present, though there can be no doubt that these are frequent in the regions visited and ……. [their investigation] would unquestionably be of the greatest advancement to this important branch of cryptogramic Botany.” (Crombie 1876).

Very little has changed in the intervening 128 years. The majority of the most recent accounts of lichens of the area deal only with macrolichens (e.g. Adler & Calvelo 2002, Galloway et al.1995, Stenroos 1991, Stenroos & Ahti 1990 & 1992, Stenroos et al. 1992). Some work has been carried out on the Pertusariales (Messuti 2002, Messuti & Archer 1999, Messuti et al. 2003), and recent work by Øvstedal & Gremmen (2001), gives full coverage of crustose species. Only one work in the past 25 years (Hertel 1984) has concentrated on crustose lichens, and that only with a very limited subgroup (i.e. those previously referred to the genus Lecidea). More recently, Fryday has described twelve new crustose saxicolous taxa and reported several species new to the region from the New Zealand islands (Fryday 2000, 2003, 2004), and southern South American (Fryday 2002, Fryday & Common 2001). In fact, in same ways the situation is worse now than in Crombie’s time due to the work of C. W. Dodge who described numerous new species from the “sub-Antarctic” in a series of publications (Dodge & Rudolph 1955, Dodge 1965-1970). Castello & Nimis (1995) investigated 152 of the 186 species described by Dodge and his co-workers from the Antarctic continent and accepted only 31 (ca. 20%) as valid. There is no reason to expect that a greater proportion of the species he described from the ‘sub Antarctic are good species than those he described from the Antarctic. Indeed, 4 of the 5 new species described by Dodge from the Snares Islands (Fineran 1969) are known to be synonyms of previously described species (Galloway 2004)

The Lichen Collection at the Michigan Sate University Herbarium

The extensive lichen collection at MSC was assembled mainly by Dr. Henry Imshaug, who was the curator of the Cryptogamic Herbarium from 1958-1990.

The collection includes important collections from North America, the West Indies and the Canary Islands, but the true gems of the collection are those from the southern subpolar region. Between 1967 and 1973, Dr. Imshaug and his graduate students made around 20,000 lichen collections from southern South America, New Zealand, and Iles Kergulen on six expeditions financed by the National Science Foundation. Over half of these collections are from southern South America (Patagonia/Fuegia and the Falkland Islands), with the remainder from the Auckland Islands and Campbell Island (New Zealand) and Iles Kerguelen (see map below). There are also large collections from the Juan Fernandez Islands (1,624), and South Island, New Zealand (2,319).They are the largest and best collection of southern subpolar lichens in any North American herbarium and in the case of the island groups (e.g. Iles Kerguelen, Falkland Islands, the Auckland Islands and Campbell Island), they are the largest collections in existence.

Fig. 1: The southern subpolar region, with number of lichen collection from each area held in MSC in parentheses. Click on a name for Dr. Imshaug's collecting sites (if available)

Most previous lichen collections from islands and remote areas were made by botanists, not lichenologists, and they collected mainly conspicuous macrolichens and ignored the numerous crustose microlichens. Imshaug was a specialist lichenologist who meticulously collected every lichen species that occurred at a given site, including the microlichens. His superb knowledge of lichens ensured that his collections exhibited all the pertinent features and represented the complete range in variation. Unfortunately, he published few results from these expeditions, and although over 100 species were given working names under which they were accessioned into the herbarium, none were published. Due to two previous NSF Awards (DBI-9808735 & DBI-0103738) the bulk of this important collection is well curated and the label data from the southern subpolar collections entered into a database. Progress is being made towards curating, accessioning, and databasing the remaining collections. Elsewhere in the world, the only comparable collection is that made by Santesson in 1939-41 housed in the Swedish Museum of Natural History, Stockholm. However, this collection was made from only the Argentinian section of Tierra del Fuego and, although details are not readily available, appears to consist largely of macrolichens. For example of the ca 2,500 currently databased, 853 are Pseudocyphellaria spp. whereas only 53 are Rhizocarpon spp. Iles Keruelen was recently visited by Ulrik Søchting & Roar Poulsen from the University of Copenhagen, who are currently preparing an account of the lichen vegetation of the island that incorporates data from MSC, but their collections were not as numerous as those in MSC. The New Zealand subpolar Islands have been visited occasionally by specialist lichenologists (e.g. Fineran, James) and their collections are under investigation by Dr. David Galloway (Dunedin) as part of his continuing investigations into the lichen mycobiota of New Zealand. However, their visits were rarely for any length of time and no major collections exist other than those in MSC.