Species of the week-3

This weeks species I found for the first time on Wednesday (14/09) at Kennall Vale Wildlife Trust reserve near Ponsanooth in Cornwall. The pseudoscorpion Roncocreagris cambridgei, also known as Cambridge’s Two-eyed Chelifer. Quite a mouthful whichever name you use!

I’m almost ashamed to admit that this wasn’t just the first time that I’d seen this species, but the first time that I’d seen any pseudoscorpion at all. I’ll have to make up for it by finding as many as I can from now on. 

Here is my phone-microscoped specimen of R.cambridgei:


Surprisingly (if you aren’t familiar with pseudoscorpions) this species only reaches around 2.5mm in length, and the largest British pseudoscorpion is only around 5mm. The small size, and habit of living in under stones and in the soil makes R.cambridgei rather under recorded, like all British pseudoscorpions. 

R.cambridgei, like other pseudoscorpions, is highly predatory. It catches its prey simply by running after it, and grabbing it with its enlarged, pincer-like palps. It then chews its prey, and uses digestive juices to liquidise the victim, which can then be ingested. They prey on mites, larvae of various small insects, and very small flies. I found that the pseudoscorpions were quite aggressive when I tried to pick them up, lifting their palps into the air, and actually gripping to my fingertip using the ‘pincer’ when I tried to let go!

This species has a predominantly South-western distribution in the UK, but also occurs in Western Scotland, with isolated records elsewhere. This again seems to imply that it is under recorded, and should occur in many more localities. See the distribution map here: 


I found several R.cambridgei under a stone on dry soil in a mixed woodland, which is classic habitat for this species. The rest of the reserve is much wetter, implying that the population of the site may well be restricted to that one small area. When I next visit I’ll check the wetter areas more thoroughly, to see if the species also occurs there, or whether our current understanding (that this species only occurs in dryer areas) is correct. Other pseudoscorpion species can be found anywhere from under seaweed at the high-tide mark, to high in the treetops in bird nests, and even in dusty corners in houses.

For more information on pseudoscorpions, including how to identify Britain’s 27 species, follow this link to the provisional FSC key: 




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