Hennediella stanfordensis moving west

Hennediella stanfordensis near Pont Nedd Fechan

On Tuesday afternoon we noted a significant patch of Hennediella stanfordensis under the Pont Nedd Fechan A465 flyover (SN903807476), near to where the Mellte makes a confluence with the Nedd Fechan (and becomes the River Neath). This is new to me and may be new for VC41.
The rather neat rosettes of bluntly-rounded leaves remind me of Syntrichia latifolia, but the teeth on the upper part of the leaf, which can be (just) made out with a hand lens, are very clear under the microscope. The leaf also has a distinct point at the apex.

Teeth on upper margin of Hennediella stanfordensis leaf

Other useful leaf microscopic characters are the border of elongated cells and the clearly papillose cells.

Elongated marginal cells and papillose cells of Hennediella stanfordensis leaf

First recored in Britain in 1958, most bryologists regard H. stanfordensis as an alien although Smith made an argument for it being native. It certainly shows a distribution pattern that is typical of founder populations. This Neath Valley record certainly looks a bit disjunct from the concentration of records on the English-Welsh borders but I suspect that there is more of it in suitable areas elsewhere in Glamorgan.