Tandonia budapestensis

Tandonia (Tandonia) budapestensis (Hazay, 1881)

Common Names

Budapest slug

Languages: English


Look Alikes

M. gagates, T. sowerbyi 

Author(s): Paustian, Megan
Rights holder(s): Paustian, Megan


External:  Mantle <1/3 body length; forms a "C" when contracted; gray-brown body with somewhat darker dorsum on preserved specimens, with black spots all over and concentrated on top of dorsum and mantle; dark dorsum, to black or dark brown; gray-yellow or orange keel; dark horseshoe groove in mantle, groove along foot sole, and grooves in dorsum; mantle may be lighter than dorsum; gray edge of pneumostome; keel extends from tail tip to mantle; 3-part sole gray or orange-gray with a dark central section; thick, clear mucus that can form threads, orange to yellow transparent, becoming milky when perturbed (Quick 1960; Kerney & Cameron 1979; Wiktor 1996; Yildirim & Kebapçi 2004).

External:  Internal shell 3 x 1.25 mm, brown; longish epiphallus and penis; club-shaped epiphallus about equal in length to penis; rounded penis; strong penial retractor muscle; oviduct tubular; vagina about width of oviduct and very short; wide, long spermatheca duct, and cylindrical spermatheca; two white, lobular accessory glands attached closely to vagina by multiple ducts; no atrial stimulator; long, thin spermatophore that is twisted, covered with spines, and ~16 mm long (Quick 1960; Kerney & Cameron 1979; Wiktor 1987, 1996).

Differs from - M. gagates and T. sowerbyi as body only partly contracts and forms a "C", no stimulator in atrium, longer spermathecal duct; 16 mm spermatophore thin and twisted (Quick 1960).

Eggs: 2.9 x 2.25 mm; yellow, leathery (Quick 1960).

Juveniles: 4.5 mm long, yellow-gray with keel at hatching (Quick 1960).

Author(s): Paustian, Megan
Rights holder(s): Paustian, Megan


To 70 mm long extended; preserved: to 42 mm long, 5 mm wide, 11 mm long mantle (Wiktor 1987).

Author(s): Paustian, Megan
Rights holder(s): Paustian, Megan

Ecology and Distribution


Native to: central Europe (Austria to Transylvania) (Yildirim & Kebapçi 2004); probably S Alps and N Balkans (Wiktor 1987)

Non-native to: Belgium, Czech Republic, Iceland, Poland, Turkey, UK (Yildirim & Kebapçi 2004), USA (introduced to Washington, DC and Philadelphia urban parks) (Reise et al. 2005). 

Author(s): Paustian, Megan
Rights holder(s): Paustian, Megan


For its defense, T. budapestensis is aposematically-colored (orange line along keel) and toxic to carabid beetle predators (Symondson 1997).

Author(s): Paustian, Megan
Rights holder(s): Paustian, Megan


Occurs in shrubland, cultivated land, gardens, roadsides, wastelands, rocky habitats, and sometimes forest; synanthropic where introduced; to 1500 m in Bulgaria; takes shelter under rocks, leaf litter, and detritus (Quick 1960; Wiktor 1983; Yildirim & Kebapçi 2004).

Author(s): Paustian, Megan
Rights holder(s): Paustian, Megan

Trophic Strategy

T. budapestensis is a pest species (Kerney & Cameron 1979) that consumes roots (Chatfield, 1976).

Author(s): Paustian, Megan
Rights holder(s): Paustian, Megan


  • Limax gracilis Leydig, 1876 (synonym)
  • Amalia budapestensis Hazay, 1881 (synonym)
  • Amalia Cibiniensis Kimakowicz, 1884 (synonym)
  • Milax gracilis valachicus Grossu et Lupu 1961 (synonym)


Chatfield, JE. (1976).  Studies on food and feeding in some European land molluscs. Journal of Conchology. 29, 5-20.
Crawford-Sidebotham, TJ. (1972).  The influence of weather upon the activity of slugs. Oecologia. 9, 141-154.
Hunter, PJ. (1978).  Slugs - a study in applied ecology. (FretterV., PeakeJ., Ed.).Pulmonates: Systematics, Evolution, and Ecology. 2A, 271-286. London: Academic Press.
Kerney, MP., & Cameron RAD. (1979).  Land Snails of Britain and North-West Europe. Hong Kong: Harper Collins Publishers.
Quick, HE. (1960).  British slugs (Pulmonata: Testacellidae, Arionidae, Limacidae). Bulletin of the British Museum (Natural History), Zoology. 6, 103-226.
Reise, H., Hutchinson JMC., & Robinson DG. (2005).  Two introduced pest slugs: Tandonia budapestensis New to the Americas, and Deroceras panormitaum New to the Eastern USA.. The Veliger. 48(2), 110-115.
Symondon, WOC. (1997).  Does Tandonia budapestensis (Mollusca: Pulmonata) contain toxins? Evidence from feeding trials with the slugs predator Pterostichus melanarius (Coleoptera: Carabidae). Journal of Molluscan Studies. 63, 541-545.
Wiktor, A. (1983).  The slugs of Bulgaria (Arionidae, Milacidae, Limacidae, Agriolimacidae - Gastropoda, Stylommatophora). Annales Zoologici. 37(3), 71-205.
Wiktor, A. (1987).  Milacidae (Gastropoda, Pulmonata) - systematic monograph. Annales Zoologici. 41(3), 153-319.
Wiktor, A. (1996).  The slugs of the former Yugoslavia (Gastropoda terrestria nuda - Arionidae, Milacidae, Limacidae, Agriolimacidae). Annales Zoologici . 46, 1-110.
Yildirim, MZ., & Kebapçi U. (2004).  Slugs (Gastropoda: Pulmonata) of the Lakes Region (Göller Bölgesi) in Turkey. Tübitak . 28, 155-160.