Cladophora rupestris

David Fenwick Snr Wondering if people would agree with Limapontia senestra for these; found on the lowershore today at Penzance, Cornwall on Cladophora rupestris. Thanks.

David Fenwick Snr Sorry I meant agree with L. capitata not L. senestra

Ian Smith Hi David. Agree. Typical L. capitata with very well developed head crests. Angle of photograph (dorsal view) makes crests look rather digitiform (as on senestra) but large white metapodium, large pale area uniting crests and eye , and big dorsal pale area leave no doubt it is capitata. Nice images.

David Fenwick Snr Thanks Ian, I'd not have found the species if I hadn't collected a sample of Cladophora to take home. Even on looking at the weed in water in a container, nothing could be seen, not even on agitating the container a little. On taking the container of weed home and putting it in the dark, about 5 of them were seen after an hour, two Elysia were also seen. Just goes to show how easy missed the species can be and from a sample of weed that may or may not have contained anything. Juvenile isopods and amphipods were also present.

Ian Smith That's the way to do it! Last autumn, it took me three hours to teaze through a marge tub of Cladophora to find eight juvenile L. senestra. My hunch is that L. senestra are more frequent on Cladophera in pools high up the shore (Pelvetia zone) on exposed coasts. If you test the idea, watch out for occasional vanes in front of digitiform tentacles on senestra that can be mistaken for head crests. Other features need consideration to get reliable id. Descriptions of all 3 Limapontia spp. at http://www.conchsoc.org/groupbrowser/Marine%20slug