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Into the Valley of the Millipedes, part 1

It is a tradition of the Telfer family to hold a biennial gathering in the Brecon Beacons. The naturalist in me wishes that this family tradition had come to be based in a hotspot for wildlife like Purbeck or the New Forest. But the pan-species lister in me knows that I can find species I’ve never seen before wherever I go. Last time I tackled the whitebeams of the Brecon Beacons. This time I got in touch with Chris Owen to see if it might be possible to meet up and look for two of his local specialities: the Ghost Slug Selenochlamys ysbryda and the harvestman Sabacon viscayanum. Chris gave it the thumbs up and I’m so glad he did because the three hours we had in the field on Sunday 28th September will be long remembered.

Jo, Bradley and I pulled in to the car park in Bargoed to meet Chris for the first time. Dave Gibbs was there too which was a nice surprise and made it a proper pan-species listers’ gathering. In emails, Chris had mentioned a few other highly desirable species that he might be able to show us and after dropping down the valley into a jungle of Japanese Knotweed we were soon seeing one of them, the flat-back millipede Propolydesmus testaceus, in good numbers. Ghost Slug took a bit more work, turning logs and stones and rummaging in leaf-litter but Dave eventually found a tiny one, before Chris located a couple of adults. They are uncannily like shelled slugs but from an unrelated family, with an extremely reduced shell and with a bizarre narrow foot like a monorail train. Bradley got this one on his “Poked it!” list.

Ghost Slug Selenochlamys ysbryda, the only species with a Welsh scientific name? Described from Wales in 2008 but thought to have been introduced from the Crimea.

Chris is very good on his slugs and also showed us presumed individuals of Arion distinctus, hortensis and oweni which gave Dave and I some dissection work for later. But with no sign of Sabacon, Chris decided to take us on to a nearby woodland where he was more confident of finding it. We just rolled a couple of logs and there it was! It’s one of the more unusual harvestmen and one with a restricted range.

The harvestman Sabacon viscayanum under a log showing the extraordinary pedipalps. They're well camouflaged and they kept absolutely still for a long time after the log was rolled over.

Deeper into the wood, we searched in beech leaf-litter for the Lemon Slug Malacolimax tenellus and the centipede Lithobius tricuspis. We saw both species in some numbers. Dave and I were reeling with all these new species in such a short space of time, and all the while Chris kept mentioning other highly desirable species we might find: the three-pronged bristletail Dilta chateri, the slugs Arion cf. iratii and Arion cf. fagophilus (both recent additions to the British list) and the nemertine worm Argonemertes dendyi. My limited time was running out but I already knew that Chris’s patch was worth a much longer visit and that I’d be back to do it justice.

Driving home, I reckoned Chris had shown me 7 or 8 ticks, and I was well pleased with that. I had a few specimens to confirm or identify but no inkling at this stage that my tubes contained two species new to Britain! Read on in part 2.