ARACHNIDA > OPILIONES > Phalangiidae > Leiobuninae

There are a number of similarities between this species and Leiobunum blackwalli, which is not surprising given that they are close relatives. They're both long-legged and of very similar size, so the important thing is to know how they can be distinguished.

The female is said to be a little darker than Leiobunum blackwalli, described as brown with gold and silver patches rather than pale silvery-brown. Personally, I can't see much difference, which is why the shape of the saddle is important. Admittedly it will vary from one individual to another but, looking at the photos below, Leiobunum rotundum's saddle is more oblong or rectangular than triangular. It widens slightly towards the rear, but nowhere near as much as in Leiobunum blackwalli, plus it gently terminates in a narrower band as opposed to a sharp truncated cut-off.

There's virtually no difference between the males as both species are uniformly orange-brown although, if the two were side by side, rotundum is slightly broader and chunkier. But, as we know from the previous account, these species can be easily distinguished by the colour of their eye rings, as Leiobunum rotundum has dark eye rings separated by a narrow pale mid-line, whereas Leiobunum blackwalli has pale eye rings separated by a dark mid-line.

The write-up for Leiobunum blackwalli made note of the general appearance and body shape of the female compared with the male, but unfortunately there wasn't a photo to show the difference. Below though, there are photos of both females and males, and one that shows the two together.

It's also worth mentioning again that the trochanters are dark, albeit with some pale areas, which helps separate both Leiobunum blackwalli and rotundum from the not dissimilar Opilio canestrinii, which has orange trochanters contrasting with dark legs.

Leiobunum rotundum is a very common, frequently recorded species that can be found in a variety of habitats, but perhaps favouring shady woodlands rather than grasslands or similar open areas. It also occurs in gardens and other environments where there are plenty of bushes and trees, or even in places where there are hard surfaces such as rocks, walls or under bridges. As with all the long-legged harvestmen, Leiobunum rotundum can move easily and surprisingly quickly both horizontally and vertically, which allows it to hunt a much wider range of prey than some of the shorter legged or ground-dwelling species.

Adults are most likely to be seen during the summer months from July to September, but could be encountered a month or two earlier or later.