Tandonia serbica is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of keel

Keel

In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...

ed air-breathing land slug

Slug

Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

, a terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 pulmonate gastropod mollusk in the family Milacidae

Milacidae

Milacidae is a family of air-breathing, keeled, land slugs. These are shell-less terrestrial gastropod mollusks in the superfamily Parmacelloidea.This family has no subfamilies ....

.

Distribution

This slug lives in Bulgaria, Serbia, probably introduced to Dubrobnik and other localities.

Description

This slug is brownish or dirty cream in color with a blackish reticulate pattern on the mantle. Additional black spots are present on back and sides, diameter 1-2 mm, resembling ink-stains. The keel is pale; the mantle is darker than the rest; there are 13 indistinct grooves between the keel and the pneumostome

Pneumostome

The pneumostome is a feature of the external body anatomy of an air-breathing land slug or land snail. It is a part of the respiratory system of gastropods....

. The head is blackish. the sole of the foot is a dirty cream in color. The mucus

Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

 is colorless and transparent.

The size of preserved specimens is up to 45 mm in length and 11 mm in width.

Reproductive system

Reproductive system of gastropods

The reproductive system of gastropods varies greatly from one group to another within this very large and diverse taxonomic class of animals...

:
Penis rounded, far wider than epiphallus, epiphallus elongate with peaky end, vas deferens opening symmetrically, spermatheca spherical when empty, with a long tubular duct, vagina very short, accessory glands like adhering lobular formations surrounding vagina, atrium wide and like prolongation of penis.

Tandonia serbica resembles Tandonia kusceri, with which it occurs often sympatrically, Tandonia serbica is smaller and Tandonia kusceri has no ink-stains. Vas deferens of Tamdonia serbica is shorter, delimited from epiphallus, epiphallus shorter, penis larger. Wiktor (1996) pointed out that no spermatophores have ever been observed in Tandonia kusceri, and brought up the hypothesis that Tandonia kusceri and Tandonia serbica could be dimorphic

Sexual dimorphism

Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 forms of the same species in different stages of sexual activity.

Ecology

Almost exclusively at dry slopes, most often in rock rubble sheltered by bushes, usually on limestone, in Bulgaria in up to 1800 m. Synantrope. Life cycle very little known on its biology. Spermathecas present at least in June and October.