Dulais Valley

Barry's excellent record of Jubula hutchinsiae in the lower Dulais Valley a few weeks ago reaffirmed for me the potential importance of this largely unknown area of NPT. Unfortunately, much of this long valley is flanked by private land and difficult to access. Even where access is possible, navigation is tricky. One stretch of the river at Cefn Coed (near Crynant) provides opportunities for a small amount of exploration. A riverside oak tree here has an interesting assemblage of epiphytes which includes Lejeunea lamacerina and Heterocladium heteropterum. Scattered among the Lejeunea there is a larger liverwort which looks like Jamesoniella autumnalis to me (photos below). Although J. autumnalis is often associated with decaying logs, it does grow on standing oaks in humid valleys (e.g. Nedd Fechan Valley, Brecs). For absolute confirmation I would have liked to have seen some perianths, which I couldn't find. Unfortunately, vegetative J. autumnalis is a bit nondescript and resembles some other liverworts, particularly Jungermannia (or even Saccogyna). The habitat probably rules out Jungermannia and the alternating leaf arrangements looks wrong for Saccogyna (and there are no underleaves). But I might be missing something obvious. Comments appreciated.