#campylopus

Rickenella fibula in a Campylopus sp.

25-JUL-2025

Once the ground is too hot for even Geothermal Kānuka to grow, Geothermal Moss (C. holomitrium) dominates - although holomitrium is a synonym for capillaceus. The latter means 'hairy', whereas holomitrium refers to the cap on the spore capsule. Holomitrium is also its own genus of mosses, which doesn't help. Campylopus comes from the Greek campylos, meaning curved, and pous, meaning foot, referring to the stalks on the capsules, which curve downwards.

The taxonomic issues seem to be well known, at least in bryology circles - apparently some workers are notorious for naming new NZ species based on trivial differences. Campylopus capillaceus was originally described in 1844, in 'Musci Antarctici; being characters with brief descriptions of the new species of mosses discovered during the voyage of H.M. Discovery ships, Erebus and Terror, in the southern circumpolar regions, together with those of Tasmania and New Zealand. London Journal of Botany 3: 533–556. The type specimens came from the Bay of Islands.

Campylopus is a large genus containing an unknown number of species - taxonomic issues again - but they're found in all parts of the world except polar regions. Most species growing on acidic or nutrient-depleted soil, so the centre of the geothermal fields is ideal.

Various authors put them in the Dicranaceae or the Leucobryaceae.

Originally described as Dicranum introflexum in 1801. Known as tankmos in the Netherlands and Belgium, thanks to the likely role tanks had in spreading the species during WWII.

Native to New Zealand, southern South America, southern Africa, southern and eastern Australia, and various other Atlantic and Pacific islands including New Caledonia and the South Sandwich Islands. However, it's also been introduced to many parts of the Northern Hemisphere, and is invasive in some areas such as Iceland, where it finds geothermal areas quite to its liking. It will sometimes reproduce asexually, with stem tips broken off and distributed by the wind. Once established, they can cover several hundred square meters within ten years.

It is a pioneer species found on bare peat after peat-cutting, on bare soils after burning or ploughing, in decalcified bogs and dunes, on rotting logs and fence posts, and on roadsides, spoil heaps, and roof shingles.

After getting across Cook Strait without being shipwrecked (the weather was actually quite pleasant compared to some of the unholy gales that come through the gap, with the wind merely howling), we started our explorations of Te Waipounamu, the Island of Greenstone Waters. Pounamu is such a beautiful and useful stone that the Māori named the entire island after it.

Europeans called it South Island, or archaically New Munster. It covers 150,437 square kilometres, making it the world's 12th-largest island. We stopped at the Omaka Aviation Museum, which was worth it, but our first night was spent at St. Arnaud, formerly Rotoiti, a tiny alpine village.

It's certainly surrounded by mountains, and shows some really nice alpine geomorphology - hanging valleys left where subsiduary glaciers got cut off by the larger glaciers in the main valley, scree slopes where the greywacke of the mountains is disintigrating, and alpine lakes like Lake Rotoiti itself, formed when the glaciers retreated at the end of the last Ice Age and left behind huge piles of pebbles, gravel, and boulders to dam the meltwater.

On the other hand St. Arnaud has also been built right on top of a considerably larger geological feature - the Alpine Fault. This tectonic boundary between the Australian and Pacific Plates runs for over 600km, and is one of the fastest moving faultlines in the world, moving, on average, almost 40mm a year. Geological formations that originally straddled the fault are now 480km apart. Unfortunately most of that movement happens during huge earthquakes every few hundred years - the last big one on the Alpine Fault happens around 1717, rupturing 400km of the fault at once.

Over the last 12 million years a significant upwards element to the fault movement has been added, creating the Southern Alps. Most of what is now the South Island got pushed 20 kilometers up, whereupon New Zealand's weather promptly ground it 16 kilometers back down again. The assorted rubble forms the plains on the east and southern coast, or got swept north by prevailing currents on the west coast. Exposed basement rock on the South Island is mostly greywacke, or heavily metamorphised rocks such as schist from even deeper. That's where the greenstone originally formed.

Anyway, the next big quake will probably trash St. Arnaud completely, and cut every road across the mountains for months. Happily that didn't happen on this trip - @purrdence had enough problems with a cyclone cutting roads and trainlines last time.

The original forest around St. Arnaud is mostly Antarctic Beech (Nothofagus sp.) and forms the basis of a unique and seriously threatened ecosystem. I'll tell you all about that over the upcoming posts.

Here's some species I've covered before.

One of at least 180 species of moss, from a genus found worldwide. Photo isn't the best but by this point the rain was getting into the cameraphones despite my best efforts.