Slug mites

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Slug mites

Although the FSC guide (page 8) says that the mites which run around on slugs are Riccardoella limacum, they are actually Riccardoella (Proriccardoella) oudemansi (Thor, 1932). Dave Gibbs found this paper by Zabludovskaya & Badanin which demonstrates that the mites on slugs are R. oudemansi, not R. limacum:

Dave used this ID paper to check the identity of some mites on a Tandonia budapestensis slug in his garden:

They were R. oudemansi, as expected. Annotated photo here:


Also note that according to Fauna Europaea, R. limacum is absent from Britain. I'm not sure how much weight to give to that - mites on snails in Britain could be either R. oudemansi, R. limacum or other species. Worth checking.

Species category: 

Good Stuff!

That's awesome!

I was looking for the A Fain paper back in 2013 as I found a few of this group on both slugs and snails during Andy's 1kmsq doodah - but failed to find it, and gave up when I figured flagellate setae would be impossible under the compound.

Looking at the Fain images.. I wonder if I was wrong and the flagellate setae of r.limacum might be visible at x600 - I'm guessing Steve's microscope grab is x400, so i'm hoping that these differences would be visible (to the naked eye) dry - however if the bothridia on r.oudesmani don't show as flagellate at x600 then its not a good character... also looks like there are setae differences on the setae on the leg segements on the flip side.

The only other thing to note is that the figure is for females - my French is non-existant - are the differences likely to apply to both sexes?


Matt (soon to be hoovering molluscs)

Has anyone come to a

Has anyone come to a conclusion on the UK slug mites?  I've collected some from our African Land Snails and need a bit of help with an ID...






Very fascinating story, I

Very fascinating story, I rarely met this information, but you opened my eyes 192.168.l.l

Snail mites

I've found the above discussion most useful - and have started looking at mites collected from both slugs and snails. The mites collected from slugs all appear to be Riccardoella (Proriccardoella) oudemansi - with short stubby hairs in 2 rows of 4 down the back. Recently I've collected some mites from snails - most of these have also turned out to be R. oudemansi, but I've just collected a couple from some Garden Snails (Cornu apsersum), which are very different - long fine hairs in 2 rows of 4 down the back of the mite. I assume these to be Riccardoella (Riccardoella) limacum - but I don't have the expertise to be certain. I've put a couple of photos here: and here: I intend to carry on looking and see what I can find - and hopefully get in touch with a mite expert who can confirm this is limacum.