Tandonia spp.




Tandonia budapestensis (Hazay, 1881)

T. sowerbyi (Ferussac, 1823)

T. rustica (Millet, 1843)

Common Name

Tandonia budapestensis: Keeled slug, Budapest slug

Tandonia sowerbyi: None reported.

Tandonia rustica: Bulb-eating slug, Root-eating slug


Tandonia budapestensis: Mature, fully extended members of this species will be between 50-70 mm long. The body color of this species is variable. Typically the animals appears black at fist glance; however, it has a pale cream or orange background with very dense, dark-colored speckling. This species has a distinct olive or pale orange-colored keel that extends from the tip of the tail to the posterior margin of the mantle. The pneumostome is located in the posterior half of the mantle and has a grey border. There is also a horseshoe-shaped groove in the center of the mantle. The sole is tripartite: dark in the middle and pale on either side. The foot mucus is colorless. This slender slug often coils into a 'C' shape when it is not active. Other species in this family will contract their bodies into a dome-shape at rest.

Tandonia sowerbyi: Fully extended specimens of this species will be approximately 60-75 mm. The body of the animal is pale or dark brown. Unlike T. budapestensis this species has dark blotches all over its body. The keel is pale in color, and the grooves between the tubercles are pigmented. The breathing pore has a pale border. The pale sole of this animal produces a contrasting yellow mucus.

Tandonia rustica: This slug can measure up to 100 mm long when fully extended. The color of the bulb-eating slug is variable ranging from off-white to dirty yellow to reddish. All color morphs have multiple black flecks. Similar to the other two species describe in this fact sheet. Typical of the Tandonia genus, this species also has a pale colored (yellowish to white) keel. The very large mantle occupies approximately 40 % of the animal's body length. There is a lateral, black streak in the horseshoe-shaped groove in the mantle. The cream-colored sole of this species produces colorless mucus. When disturbed, this species produces thick, milky mucus.

Native Range

Tandonia budapestensis: Eastern Europe

T. sowerbyi: Western Europe and the Mediterranean region

T. rustica: Central and Southern Europe


North America:

  • U.S.: Pennsylvania, Washington D.C.

Australasia: New Zealand (except Tandonia budapestensis )



These species commonly occurs in greenhouses, gardens, ploughed fields and woods. They have the capability to burrow into the soil at depths of 37 cm. All species are known to eat living plant material. Tandonia budapestensis has been recorded to be a pest of potatoes, other root crops and ornamental plants.


Tandonia budapestensis:

  • Milax gracilis (Leydig, 1876)
  • Limax gracilis Leydig, 1876. Arch. Naturgesch. 62(1): 276 (not Rafinesque, 1820).
  • Amalia budapestensis Hazay, 1881. Die Mollusken-fauna von Budapest, Malakozool. Bl. (n.s.) 3: 37. Type locality Budapest.
  • Amalia cibiniensis Kimakowicz, 1884. Verh. Mitth. siebenb. Ver. Naturwiss. 33: 220.

Tandonia sowerbyi:

  • Milax sowerbyi (Ferussac, 1823)
  • Limax sowerbyi Ferussac, 1823. Histoire nayurelle generale et particuliere des mollusques terrestres et fluviatiles (Nouvelle division de pulmones sans opercule) 2: 96. Type locality London.
  • Limax carinatus Risso, 1826. Nat. Hist. Moll. Medit.: 56.
  • Limax marginatus Jefferies, 1862. Brit. Conchol. I: 132 (not Muller, 1774; not Draparnaud, 1805).
  • Amalia marginata (not Muller, not Draparnaud) var mongianensis Paulucci, 1879. Esc. Scient. Calabria: 23.
  • Amalia tyrrena Lessona & Pollonera, 1882. Monogr. Limacidae Ital.: 56.
  • Amalia maculata Collinge, 1895. Proc. Malac. Soc. Lond. 1(7): 336.
  • Amalia collingei Hesse, 1926. Abh. Arch. Moll. 2(1): 139.

Tandonia rustica:

  • Limax rustica Millet 1843
  • Limax marginatus Draparnaud 1805


Anderson 2005; Barker 1979; Cowie et al. 2009; Horsak 2004; Reise et al, 2006; Wiktor 1996

Posted on