Introduction to mosses
The currently known moss flora of New Zealand consists of 546 moss taxa (523 species and 23 varieties) distributed among 208 genera. The flora is interpreted as predominantly Gondwanan in origin, and it shows strong relationships to the bryofloras of Tasmania, south–eastern Australia, and temperate South America. Less pronounced floristic relationships exist with paleotropical and Polynesian regions, and there is a pronounced bipolar element.
One hundred and eight (c. 20%) moss species and 11 genera are considered endemic to New Zealand. The endemic genera are: Beeveria Fife, Bryobeckettia Fife, Bryodixonia Sainsbury, Cladomnion Hook.f. & Wilson, Crosbya Vitt, Cryptopodium Brid., Dichelodontium Broth., Fifea Crum, Hypnobartlettia Ochyra, Mesotus Mitt., and Tetracoscinodon R.Br.bis. Nearly all these genera occur in lowland forests or forest margins, with a few extending into montane/subalpine vegetation. There are no endemic families.
The geologically diverse mountains of the north–western South Island and the warm–temperate lowlands of the northern North Island have a disproportionate number of endemic species and species with restricted geographic distribution. A third, less pronounced, area of species concentration occurs in the Auckland and Campbell islands.
The study of New Zealand mosses continues to yield a modest but steady stream of taxonomic novelties. These have included, during the past 15 years, newly described taxa in the genera Brachythecium, Calomnion, Camptochaete, Dicnemon, Epipterygium, Fissidens, Pohlia, Racomtrium, and Sphagnum. Similarly, species belonging to various geographic elements continue to be discovered, such as the predominantly South American Ptychomnion densifolium, the Australian Crossidium davidai and Pyrrhobryum paramattense, the paleotropical Cyclodictyon blumeanum and Syrrhopodon armatus, and the bipolar Orthothecium strictum.
Adventive species continue to infiltrate the New Zealand flora. The northern hemisphere Sphagnum subnitens, first documented in New Zealand in 1975, is actively extending its range and is a weed in wetlands on the west coast of the South Island. In 1997 Rhytidiadelphus triquetrus was discovered in New Zealand, in second–growth native forest, and efforts are underway to eradicate this potentially invasive weed. In general, the number of moss adventives appears to be much lower than that among vascular plants and only 14 species are considered to be unquestionably introduced.