Arion lizarrustii Garrido, Castillejo, & Iglesias, 1995
Red List Spain: Sensitive to habitat change (Gómez Moliner et al. 2001).
Copula is static: copulatory organs are everted in the form of a spherical mass which does not fill up the internal space encircled by the partners (contrast with A. subfuscus). At the end of the copula, one partner raises the front part of its body over the other slug, before moving away.
External: Slug dark brown on dorsum with black streaks and dark lateral bands with a yellowish brown line in their upper side, extending to the mantle (the right one arching above the pneuomostome); sides yellowish brown; two rows above foot-fringe white; head grey; tentacles dark; skin tubercles fine; foot-fringe yellowish; sole cream; sole mucus white, body mucus orange.
Internal: Epiphallus slightly longer than vas deferens; epiphallus, spermatheca duct and free oviduct join the atrium on a single line, the epiphallus being in the middle. .
Size: Up to 45 mm long, adults average 36 mm (preserved).
N Spain (Navarra).
Type Locality: Spain: Navarra, Alto de Lizarrusti, UTM 30T-WN75.