First record of Arion ater s.l. (Gastropoda: Arionidae) in Ukraine

Slugs in the Arion ater complex have been reliably recorded in Ukraine for the first time. In recent years, large specimens with an intense black colouration and very prominent skin tubercles have been observed in two neighbouring villages of the Bohorodchany district of the Ivano-Frankivsk region, Stara Huta and Huta. Even externally, they were very different from Arion vulgaris, which has already become common in western Ukraine. The structure of the distal genitalia of such slugs collected in Stara Huta in early July 2024 is similar to the older descriptions and images of Arion rufus. However, DNA barcoding classifies them as A. ater s.s. We assume that A. ater s.l. could have been accidentally introduced into the studied area from abroad together with ornamental plants. The initial source of the slug dispersal here could have been the administrative territory of the Syniohora National Nature Park or the presidential residence of the same name located nearby. For comparison, a map of known records of A. vulgaris in Ukraine is shown, only a few of which have been anatomically verified so far.