I'm sure I'm missing something obvious, but this hook-leaved moss from Merthyr Common last week has me stumped. It was growing in a flush (or near the stream that ran along the bottom of it - I can't quite remember now) which was probably quite acidic.
I was sure this was going to be Warnstorfia exannulata but there is no trace of a nerve on most of the leaves (some have a faint short double nerve), and I can't see anything that fits the bill. Leaves are 2mm long, hooked but not forming complete loops. Suggestions appreciated, thanks.