Pulchrocladia retipora
Pulchrocladia retipora, most commonly known as the coral lichen, is a species of fruticose lichen in the family Cladoniaceae. It occurs in Australasia and New Caledonia where it grows in coastal and alpine heathlands. The lichen features coral-like branches and subbranches with numerous netlike perforations. It is known by multiple names, with some sources referring to it by its former synonym Cladia retipora, or the common names of snow lichen or lace lichen. First collected by Jacques Labillardière on board the Bruni d'Entrecasteaux expeditions in 1792. Labillardière had erroneously classified it as an alga rather than a  lichen. "Pulchrocladia retipora" was the first Australian lichen to be described in a scientific publication. Taxonomy. The species was first formally described by Jacques Labillardière in 1806, as "Baeomyces reteporus". The type specimen was collected from Tasmania. This collection was made as part of the botanical collections he made during his 1791 voyage to the South Seas with French explorer Antoine Bruni d'Entrecasteaux in an unsuccessful search for Jean-François de Galaup, comte de Lapérouse. He had first collected the lichen in 1792, and published the description in "Novae Hollandiae Plantarum Specimen", erroneously describing the lichen as an alga. According  to Rex Filson, the lichen is the first that was described for Australia. In its taxonomic history, it has been shuffled to several genera, some of which are no longer used or have been synonymized with other genera. These include "Cenomyce" (Acharius, 1814), "Pycnothelia" (Fée, 1825), "Cladonia" (Fries, 1826), "Cladina" (Nylander, 1868), "Cladia" (Nylander, 1876), and "Clathrina" (Johann Müller, 1883). It is now the type species of genus "Pulchrocladia", which was circumscribed in 2018 by Soili Stenroos, Raquel Pino-Bodas, Helge Thorsten Lumbsch, and Teuvo Ahti following a large-scale molecular phylogenetic analysis of the family Cladoniaceae. It is commonly  known as the coral lichen, lace lichen, or the snow lichen. Description. The pseudopodetia are up to tall, white to pale grey in colour, sometimes tinged pinkish or yellowing or superficially blackening at tips. They are rigid when dry, irregularly or dichoromously branched, forming cushiony clumps. The wall is highly perforated, with large, round to ellipsoidal holes. The surface of the pseudopodetia continuously corticate and lacking soredia. The inner medulla is made of twisted strands of hyphae. The conidiomata are terminal, and convered with translucent slime. The colour of the hymenium ranges from dark reddish-brown to black. Specimens collected  in Australia tend to have a brownish tinge, while New Zealand specimens range from pure white to grey, to grayish-green, or slightly yellowish. The photobiont partner is green algae from the "Trebouxia". Occasionally, free-living algae become trapped in the irregularly intertwined hyphae of the medulla. Usnic acid and atranorin are the major secondary compounds present in "Pulchrocladia retipora". Other compounds occurring in lesser quantity, and detectable using thin-layer chromatography, include protolichesterinic acid and ursolic acids, and, often also additional rangiformic acid and norrangiformic acids. It is usnic acid that is thought to be responsible for the antimicrobial , antiviral and cytotoxic biological activity of "Pulchrocladia retipora" lichen extracts tested in "in vitro" experiments. "Pulchrocladia retipora" grows in cushion-like growths ranging in diameter from to . William Martin remarked finding square meter sized cushions in the area of Lewis Pass in Canterbury, New Zealand. A separate description describes cushions the size of a football in Australia's Grampians National Park. According to Martin, coral lichen forming massive cushion growths only occur in subalpine zones, with lowland forms being only in size. Habitat and distribution. "Pulchrocladia retipora" is widely distributed in Australasia. In Australia, it has been recorded from the  Australian Capital Territory, New South Wales, Queensland, Victoria, and Tasmania. In New Zealand, it is known from both the North and South Islands as well as Antipodes Island, Auckland Islands, Campbell Island, and Chatham Islands. In the Pacific, it occurs in New Caledonia. The coral lichen is particularly common in subalpine peat bogs, it is often found in association with the lichens "Cladonia confusa", "Rexiella sullivani", and "Stereocaulon ramulosum". It is found on peaty soils, found among tussocks or in heaths composing of "Dracophyllum" and "Leptospermum", at the margins of "Nothofagus" forests, in fellfield, or rarely on surfaces such as  rocks, logs, and sand dunes. In the moorlands of the Meredith Range area in Tasmania, it is found in "better drained, elevated sites, such as near rotting, dead buttongrass hummocks." The lichen replicates vegetatively when new podetia grow from fragments of old podetia. It has highly variable growth rates, ranging from less than 1 mm per year to up to a few centimetres per year. It has been noted to grow in clusters, sometimes up a metre in diameter. Research. The appearance of the lichen has been described as "of considerable beauty resembling lace or coral". As a result, it  has found use in floral decoration and architectural design. Resynthesis. The "Pulchrocladia retipora" lichen thallus has been successfully resynthesized from isolated mycobiont and photobiont under laboratory conditions. Biomonitoring. The Baseline Air Pollution Station in Tasmania (part of the World Meteorological Organization-Global Atmosphere Watch network) has used "Pulchrocladia retipora" has used as a bioindicator to identify how atmospheric nitrogen and sulphur deposition in Tasmania is affected by human pollution.