
So there are plenty of fungi associated with the marine environment, from shoreline sand-dunes to the open sea. My old Yorkshire mycological mate Jerry Cooper (now doing excellent work in New Zealand) sums up the situation extremely well here: http://www.funnz.org.nz/sites/default/f ... eFungi.pdf.
A Northern Hemisphere equivalent to his Stigmidium apophlaeae is Stigmidium (formerly Mycosphaerella) ascophylli. Every time I have picked up a piece of knotted wrack Ascophyllum nodosum bearing receptacles the fungus is there; it is also found on channelled wrack Pelvetia canaliculata, though I have yet to look for it on that, similarly common, seaweed. More info is available here: http://www.lichens.lastdragon.org/faq/w ... ichen.html (towards the bottom of the webpage).
Here is a recent collection (a bit too early for mature ascospores to have formed, though they do tend to be expelled as soon as they ripen and so are easily missed. Next time you're at the seaside have a (close) look for it - those tiny black dots are the perithecia. This has been recorded for Dorset Jenny - in fact I think that Cotton's type collection may well have been from there . . .
Chris