Harvestman with amazingly long legs

[Bruce Williams]

Have you ever seen longer legs relative to body size? Particularly the second (and forth) pair of legs.

Unfortunately the pic doesn't show much detail in the body because I had to get so far back in order to include all the legs.

Help with id (if possible) appreciated.



Bruce

[NickCantle]

Dead Starfish Bruce? I see what you mean! Oddly proportioned aren't they?

[Wild-Woman]

Originally Posted by Bruce Williams

Have you ever seen longer legs relative to body size? Particularly the second (and forth) pair of legs.

Unfortunately the pic doesn't show much detail in the body because I had to get so far back in order to include all the legs.

Help with id (if possible) appreciated.



Bruce

Sorry can't id this opilione but it does make you wonder what the purpose is of such long legs. Wandering over uneven terrain perhaps?

[Pudding4brains]

Hi Bruce,

From the looks of it I'd say these are two Leiobunum rotundum females (males look quite different), and yes they have extremely long legs.

I guess these had 2nd legs in the 4-6cm range? If you ever come across Harvesters that are a tad darker coloured with 2nd legs (the longest) in the 8-9cm range researchers would very much like to know. There is a new/introduced species about in NW-Europe that is positively huge (9cm 2nd legs make for an 15-18cm diameter of the total animal ) and aggregates in large groups (up to hundreds of 'em sitting together).

Has been around for a few years now and seems to spread quite 'well', but as yet could not be identified 100% - just Leiobunum spec.. Would be interesting to keep a look out for their arrival in the UK!

Cheers, Arp

P.S. Ah, as for the function ... don't really know, but as they can't jump or fly I've observed that it gives them amazing agility in brushes to easily/quickly climb from one plant/twig to the other. What amazes me more is that the juveniles of these live under wood/bark etc on the forest floor - in very secluded/confined spaces ... with those legs!

[Action_Man]

Originally Posted by Wild-Woman

Sorry can't id this opilione but it does make you wonder what the purpose is of such long legs. Wandering over uneven terrain perhaps?

They have a false articulation which accounts for about a third of the leg, its used for grasping the grass as they run through, the one in the image below isent rotundum, but you can see that its like have a bicycle chain on the end of your legs, as it hits the grass, it whips around it ...

[Bruce Williams]

Thanks for your comments everyone.

Arp - Appreciate the id and interesting info re the new super-long-legged Leiobunum sp. - would be exciting to see one (or lots) in the UK.

Action_man - thanks for the info and photo.

Bruce

[Pudding4brains]

Hi Bruce,

Originally Posted by Bruce Williams

Appreciate the id

I didn't specifically mention it, because I figured you know how to 'value' my thoughts on Harvestmen, but of course that wasn't a true ID - just my guestimated 2ct on the matter

Just wanted to clear that up - mainly for other readers too, as this is a public site

Cheers, Arp.

[JennyS]

Hi folks, I haven't much of a clue on insects, but after reading this thread I wondered if this is the same species of Harvestman as in the first post?
Its a bit bigger than the ones that usually hang out in the bath.......





As to function, I was watching one the other day and it almost seemed to be using the ultra-long legs as feelers / sensors before deciding which direction to move in

[Pudding4brains]

Hi Jenny,

With those legs it's certainly a very likely Leiobunum and the second image seems to hint at a very fresh, small-bodied L. rotundum female, but please don't take that as an ID - the images a really a tad to darkish/small (the body that is) for me to feel confident (only a 'beginner' at these myself). If you have a better shot/crop of just the body I might get more confident

Cheers, Arp

[JennyS]

Hi Arp,
I doubt if this is the same one, but it was about the same size and stayed still long enough for a close-up - I'd never realised what amazing looking beasties they are!

[Pudding4brains]

Hi Jenny,

That certainly looks like a Leiobunum rotundum female

Sort-of-kinda confirms the other one too I would think

Cheers! Arp

[Bruce Williams]

Jenny and Arp - Think Jenny's close-up pic confirms my original posting of a long legged harvestman. I took this pic yesterday at the exact same place as my original pic (still quite a few individuals hanging around together). I've seen them there most visits (about 4 times a week).

....and can't they move quickly when they want to!

Here's a close-up pic and it is almost identical to Jenny's pic.



Bruce

[Pudding4brains]

Hi Bruce,

Yes, in my 'world' that'd clearly be a Leiobunum rotundum female, but probably a 'fresh' one (short, small body), what's beginning to worry me a bit however is that neither of you has come up with the distinctive reddish males ... so I'm beginning to wonder ....

[JennyS]

Does the male look very different?
If so would you have a photo or a link you could post so I've a bit of an idea what I'm peering around for!

[Pudding4brains]

Hi Jenny,

Originally Posted by JennyS

Does the male look very different?
If so would you have a photo or a link you could post so I've a bit of an idea what I'm peering around for!

Yes they have smaller, rounder bodies that are almost completely orangy-reddish

There is one on the bottom right in this image:


Also, maybe have a look at this topic, or this fine gallery (select "Leiobunum" in the list top left), or maybe here.

Arp

[Meta menardi]

Originally Posted by Wild-Woman

Sorry can't id this opilione but it does make you wonder what the purpose is of such long legs. Wandering over uneven terrain perhaps?

The 2nd pair of legs is the main sensory organ of Opiliones, they use them to do their equivalent of most of our 5 senses. You will vey often see Opiliones with a leg or two missing, but if they lose both of the second pair, they will not survive long.

I have spent some time watching Dicranopalpus ramosus in it's peregrinations, it has extremely long second pair of legs and it will pivot from side to side on the 1st pair, palpating everything with the second pair, thereby covering a very wide space around it.

[Bruce Williams]

Arp - I think I've just found the missing male Leiobunum rotundum that you were concerned about. There was quite a large group spread along a wooden fence quite close to the location of the original pic. A few (the minority) were noticeably smaller and darker - see these two pics:



Bruce

[Pudding4brains]

Yes, that'd be the one

Found a large colony myself on a riverbank yesterday, hundreds of'em under rocks over some 150 meters of shore line. In that colony the ladies also outnumbered the laddies significantly (maybe almost 10:1 ?) - to the point that, for a short while, I was confused if it even was Leiobunum rotundum (until I found the first males)

Cheers, Arp