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Thursday, 8 October 2020

Missus longlegs

Female Dicranopalpus caudatus
While clearing away some of the branches and fallen Cordyline leaves Mike had piled in one corner of the garden last week, I found this long-legged girl scrabbling around in the compost bin I was filling. I carefully extended my gardening glove (still being a bit of an arachnophobe, despite my best efforts) and she clambered aboard, allowing me to transfer her to safer surroundings. She was clearly different than the harvestman species I'd identified earlier in the autumn, so once I was back inside, I set about figuring out what she was. And it was somewhat more complicated than I'd expected! It turns out that she belongs to a somewhat cryptic taxon that experts have only recently determined is a distinct species. (And indeed, not all of the experts agree.) Females are easier to tell apart than males, thanks to their colouring and the fairly distinctive swelling they have on their back; that of caudatus is considerably more pronounced than that of the similar Dicranopalpus ramosus. Like the Leiobunum rotundum harvestman that I found back in August, this one is small-bodied and very long-legged. Her two eyes are up on a little forward-facing turret called an operculum. And her furry pedipalps are shaped like a tuning fork (you may need to click on the picture to make them big enough to see). Adults are out from late summer into the winter, so we may be seeing her again, out and about. The presence of this species in Great Britain is a bit of a mystery. It has been found in scattered locations across the island since the mid 1950s, but its origin is uncertain. It may have been accidentally introduced; alternately, it may be native. There is some thought that the relatively newly-arrived Dicranopalpus ramosus may have overrun and swamped its smaller cousin in much of southern England. Ours is the first record of this species in all of East Anglia in the national database!
A shot of the distinctive bulge on her back


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