Leggy

Female Opilio canestrinii

For several days in a row a couple of weeks ago, I found this female harvestman (harvestwoman?) sprawled out on a nettle leaf in the garden. Did she stay there the whole time, digesting a particularly big meal? Or had she made sorties and returned to a favoured spot? So many mysteries! She's an Opilio canestrinii, one of Britain's longer-legged harvestman species. The two rows of alternating dark and light bars on her back (see the picture above), her very long dark legs, and her white operculum (the little turret that her eyes sit in) help to identify her. Males are smaller-bodied, and more uniformly red-orange in colour. This is a newly-arrived species in Great Britain. First recorded in the Thames Valley in 1999, it has spread rapidly and is now found across England and Wales. In 2011, it was found in Scotland, and has since been spreading quickly from that initial location. Intriguingly, it wasn't known in Europe until the mid-1900s, when it was found in Italy; since then, its range has expanded to cover most of western Europe. In some places (i.e. the Netherlands), its arrival has led to the extinction of native Opilio species. Let's hope that doesn't happen here!

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

Harvest(wo)man

Leiobunum rotundum

On my way out to the garage the other morning, I spotted this long-legged girl clinging to the bottom of the swallow nest platform, out of the sun. It's a female harvestman (harvestwoman?) belonging to the species Leiobunum rotundum, which has no common name. Though she looks a bit like a spider, with her eight long legs, she's not. Harvestmen (known as daddy-long-legs in the US) are closely related to spiders, but differ in having only a single body segment, rather than the two segments that spiders do. They have just two eyes, rather than the 6-8 that spiders have. You can just see her eyes near the right edge of the smaller (left hand) dark mark on her body; they sit on a tiny turret (called an ocularium). Click on the picture above to enlarge it, if you're having trouble finding them. The dark stripe down the middle of her body is unique, allowing her to be easily identified. The pale patch between her two dark-rimmed eyes is also a useful ID feature. With a body measuring some 7 mm long (1/4-inch) long, she's about twice the size of a male, which would lack the dark body stripe. 

Like all harvestmen, this is an ambush hunter, chasing down small prey including aphids, leafhoppers, flies, moths, spiders and woodlice. Unlike spiders, harvestmen will also feed on carrion and decaying plant matter. This is a common and widespread species right across the UK, though somewhat less so further north. Elsewhere, it widespread across most of Europe, though not around the Mediterranean. It prefers shady, moist habitats. Adults are found from July through November, so we should be seeing them around for a while yet. Ours is the first record for our part of Norfolk in the national database — woohoo!