By Hook or by Brook

Sanionia uncinata habitat, Eastern Cleddau

Waders on for some otter survey work for NRW around Gweunydd Blaencleddau SAC this week. First a chance to finally find some Sanionia uncinata in the county, which had eluded me thus far. Some good patches on grey willows sprawling across the channel. 

Sanionia uncinata

I'll confess to not being particularly experienced with hook mosses, so I went up to the flushes on Dolau isaf to refresh my memory. The Scorpidium cossonii was easy enough, but there was a Palustriella at the top end below the main calcareous spring that I had to collect. 

Under the microscope, the shape of the stem leaves suggested that it wasn't falcata - the regular species of base-rich springs on Preseli, but commutata. I tried to turn it into decipiens, thinking that I'd found papillae as well as prorate cell ends:

Although they looked tall and conical to me, Sharon concluded that these are still just prorate cells so, unsurprisingly, my speculative attempt at a new species for Wales were quashed.  However, with Palustriella commutata dominant and Cratoneuron filicinum frequent, this represents a small area of an Annex 1 habitat previously overlooked on the site - Petrifying Springs with Tufa formation (Cratoneurion). In common with many Welsh examples it lacks the tufaceous element. It narrowly escaped some channel excavation work done in the name of southern damsefly conservation, which stop just 3m short of the patch. 

I thought that the Pohlia around three of these spring heads might bet wahlenbergii var. glacialis, quite tall and with some mid-leaf cells around 30um wide. Sharon corrected me again - the leaf shape is a better fit for var. wahlenbergii and it's just a tall version of that.

Pohlia wahlenbergii and habitat

Back on the river again, I checked a few willows and rocks for Harpalejeunea molleri which grows in the next valley over, but no joy. Lots of otter spraints to record on the rocks though, and couches amongst the sedge tussocks. Mink evidence too. Willow tits in four places - this is a proper hot-spot for them.