Luffia at Penrhyngwyn shingle beach

 Yesterday (Friday 25th Feb), after many days mostly indoors, I ventured down to the Penrhyngwyn shingle beach at Machynys, Llanelli, both for some exercise and to see if I could find some noteworthy invertebrates that I recorded there some 35 years ago. I had no luck with the latter but realised, as I searched, that on those previous successful occasions it had been raining heavily, bringing those species (such as the engaging and tiny `bristle millipede` Polyxenus lagurus and the quite colourful woodlouse Cylisticus convexus) closer to the surface. During my quite casual search I noticed various mosses growing on copper slag and thought that it might be worthwhile taking some photos in case some were of interest, intending to send them to Sam even though he had visited the site back in 2001, when he made some useful bryophyte records. During the preparation (cropping) of the photos to be emailed to him, I noticed what appeared to be a Luffia (a `bagworm` species) - something that I had n`t noticed in the field earlier and Sam later agreed that it was indeed a Luffia. Most of the literature states that the commoner Luffia ferchaultella occurs on tree trunks and fencing, though `Wikipedia` states that it can rarely occur on rocks. However there is another species - known from the Channel Islands and Cornwall - Luffia lapidella that does occur on rocks. [Postscript: I read that Luffia ferchaultella has now been synonymised with L. lapidella ie they are just forms of the same species].

This afternoon I revisited Penrhyngwyn to see if I could relocate some more before my spatial awareness of where I had found the Luffia had faded. Whilst my cognitive map failed to take me back to the exact spot, I need n`t have worried, as I found more Luffia with ease, all affixed to micro-overhangs and mini-cavelets within the rounded hollows (vesicles) formed by gas pockets within the copper slag during its formation. The ringed pattern on the Penrhyngwyn individuals suggest ferchaultella. I lugged four lumps of slag (with Luffia on them) back to the car to take home to further study. I can see one individual actually moving, exposing its head as it does so.

I did various `spot checks` all along the shingle beach and found Luffia in all parts of this depositional land form - there must be scores if not hundreds of individuals present. Incidentally, the shingle was originally made of Pennant Sandstone pebbles but dumping of slag and other material from nearby copper works in the 19th and early 20th Century now means that the sandstone forms a minority.

                                       Above: two of the Luffia individuals found.They are about 3mm long.

Above: Two views of Penrhyngwyn shingle beach, looking approximately west in the top photo (note Gower on the horizon - click on pic to enlarge) and looking up the estuary in the lower photo, with Trostre tinplate works and WWT Penclacwydd in the distance.