Im fascinated by the slugs from genus Arion and want to be able to identify them as accurately as possible. Im not just talking about the most popular species, i mean every single one if possible

Welcome to the forum! Like many terrestrial gastropods, differentiating Arion spp. typically requires dissection. It’s probable that some species are only found in certain regions, but if you want to be sure, you will need to dissect them. This is especially true where they have been introduced, as …

That makes sense. I don’t like killing animals unless necessary, but thank you for the links, i think those will come handy in the future.

[image] captainnik: i mean every single one if possible Every single one would probably need DNA analysis for the immatures. And if you mean every single species worldwide, then that is a very big task. You would need a decade or so of experience and lots of discussion with other Arion taxono…

I’m based in Poland and often travel throughout central and eastern Europe, thats the region i want to focus on

Im specifically talking about Arion hortensis, Arion fasciatus, Arion distinctus, Arion fuscus, Arion intermedius and the young of Arion vulgaris and Arion ater. Ive been having trouble with identifying some of these for a while. I also dont euthanise the animals, so dissection and dna analysis won’…

Sounds like you are continuing this thread: https://forum.inaturalist.org/t/how-do-i-distinguish-different-members-of-the-arion-genus/75914 Things like foot color, skirt color, mantle color, and mucus color can help distinguish subgenera. I don’t think there are reliable ways to distinguish specie…

I moved the above two posts to this thread to keep all the discussion in one place.

New classification has split A. fasciatus into 2 species. how do i distinguish between them (if its possible).

The split on iNaturalist is reflecting some disagreement in the literature regarding how many species actually exist in the subgenus. Generally they are distinguished by genitalia, but you can see other details that don’t require dissection in the sources here: https://forum.inaturalist.org/t/how-d…

How do i distinguish different members of the Arion genus

Nature Talk

thomaseverest February 19, 2026, 5:38pm 4

Other features such back color, foot color, mucus color, and shape when contracted are also helpful. But to be absolutely sure, dissection and DNA are best.

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How do i distinguish different members of the Arion genus

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