The Iberian freshwater crab (''Potamon ibericum'') is a

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

n species of

freshwater crab Around 1,300 species of freshwater crabs are distributed throughout the tropics and subtropics, divided among eight family (biology), families. They show direct development and maternal care of a small number of offspring, in contrast to marine c ...

. It is an omnivore that feeds on land, but returns regularly to the water, and can survive short periods of drought in burrows and under stones. Its

natural range Species distribution, or species dispersion, is the manner in which a biological taxon is spatially arranged. The geographic limits of a particular taxon's distribution is its range, often represented as shaded areas on a map. Patterns of distr ...

stretches from north-eastern

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

, around both sides of the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

and to beyond the

Caspian Sea The Caspian Sea is the world's largest inland body of water, described as the List of lakes by area, world's largest lake and usually referred to as a full-fledged sea. An endorheic basin, it lies between Europe and Asia: east of the Caucasus, ...

; populations have also been introduced to southern France. It is included as a

near threatened A near-threatened species is a species which has been Conservation status, categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to Endangered species, endangerment in the ne ...

species on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

, and is included in the ''Red Data Book'' for

Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...

Description

''Potamon ibericum'' differs from other species in the genus in the form of the first

pleopod The anatomy of a decapod consists of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment – often called a somite – may possess one pair of appendages, although in various groups these m ...

of the males – the organ used to transfer

spermatophore A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...

s. In ''P. ibericum'', the flexible zone of this appendage is widest near the middle, rather than V-shaped (as in '' P. fluviatile'' and '' P. rhodium'') or bilobed (as in '' P. potamios'').

Ecology and behaviour

The continued survival of ''P. ibericum'' generally requires a permanent body of water, although the crabs can survive short periods of drought by retreating under stones, or into deep

burrow file:Chipmunk-burrow (exits).jpg, An eastern chipmunk at the entrance of its burrow A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of Animal lo ...

s. These burrows may be several kilometres from the nearest body of water. They only breed in moving water, with copulation occurring in the warmer months, from June to October. ''Potamon ibericum'' is an omnivore, eating

detritus In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

filamentous algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

, and plant matter, as well as a variety of animals, including

worm Worms are many different distantly related bilateria, bilateral animals that typically have a long cylindrical tube-like body, no limb (anatomy), limbs, and usually no eyes. Worms vary in size from microscopic to over in length for marine ...

s, amphipod crustaceans,

aquatic insect Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some ''diving'' insects, such as predatory diving beetles, can hunt for food underwater where land-living insects ...

larvae,

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

s and

tadpole A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

, and

carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...

. It feeds on land during the night, and if the air is humid enough, also during the day. In the areas where it occurs, ''P. ibericum'' is a major food item for the

European otter The Eurasian otter (''Lutra lutra''), also known as the European otter, Eurasian river otter, European river otter, common otter, and Old World otter, is a semiaquatic mammal native to Eurasia and the Maghreb. The most widely distributed member o ...

, ''Lutra lutra'', alongside a variety of fish species.

Distribution

The

of ''P. ibericum'' is wide, but highly fragmented. In Europe, it is present in the

Danube The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...

and its tributaries in

Bulgaria Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...

, as well as rivers in

North Macedonia North Macedonia, officially the Republic of North Macedonia, is a landlocked country in Southeast Europe. It shares land borders with Greece to the south, Albania to the west, Bulgaria to the east, Kosovo to the northwest and Serbia to the n ...

, north-eastern

(east of the

Axios River The Vardar (; , , ) or Axios (, ) is the longest river in North Macedonia and a major river in Greece, where it reaches the Aegean Sea at Thessaloniki. It is long, out of which are in Greece, and drains an area of around . The maximum depth of ...

Cyprus Cyprus (), officially the Republic of Cyprus, is an island country in the eastern Mediterranean Sea. Situated in West Asia, its cultural identity and geopolitical orientation are overwhelmingly Southeast European. Cyprus is the List of isl ...

and the European part of Turkey, and around the coast of the

through

to the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

. Despite the

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

', the species does not occur on the

Iberian Peninsula The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, comprisin ...

, which has no native freshwater crabs, but to

Caucasian Iberia In Greco-Roman geography, Iberia (Ancient Greek: ''Iberia''; ; Parthian language, Parthian: ; Middle Persian: ) was an exonym for the Georgians, Georgian kingdom of Kartli or Iveria ( or ), known after its Kartli, core province. The kingdom exi ...

. The Asian part of its range extends across

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

and

Turkmenistan Turkmenistan is a landlocked country in Central Asia bordered by Kazakhstan to the northwest, Uzbekistan to the north, east and northeast, Afghanistan to the southeast, Iran to the south and southwest and the Caspian Sea to the west. Ash ...

. Some sites that formerly held populations of ''P. ibericum'' have been subject to occasional

desiccation Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. The ...

, and the crab populations have been reduced or

extirpated Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions. Local extinctions mark a chan ...

. The northern limit of the species, like that of its western relative, '' P. fluviatile'' is close to the January isotherm. ''Potamon ibericum'' was introduced to the

Cagne The Cagne () is a river that flows through the Alpes-Maritimes department of southeastern France. Its source is near Coursegoules, and it flows into the Mediterranean Sea in Cagnes-sur-Mer. It is long. The Malvan Malvan (also written as Malw ...

River in southern France between 1975 and 1983, when crayfish of the species ''

Astacus leptodactylus ''Pontastacus leptodactylus'', the Danube crayfish, Galician crayfish, Turkish crayfish or narrow-clawed crayfish, is a relatively large and economically important species of crayfish native to fresh and brackish waters in eastern Europe and wes ...

'' were imported for

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

from Turkey. It is now found some downstream of that site, at the entrance to a series of

gorge A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive activity of a river over geologic time scales. Rivers have a natural tend ...

s, in a part of the river that rarely dries out. A second population was discovered in the 1990s, from the Cagne site, in the Hérault River near

Saint-Guilhem-le-Désert Saint-Guilhem-le-Désert ( or ; ) is a Communes of France, commune in the Hérault Departments of France, department in the Occitania (administrative region), Occitania Regions of France, region in Southern France. Situated where the Gellone rive ...

. Neither population is considered invasive. Another species of ''Potamon'' – '' P. fluviatile'' – has also been introduced to France, in the vicinity of

Nice Nice ( ; ) is a city in and the prefecture of the Alpes-Maritimes department in France. The Nice agglomeration extends far beyond the administrative city limits, with a population of nearly one million

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

crabs assigned to the species "''P. antiquum''" have been discovered in sediments of

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

age in northern

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

. That species was previously thought to represent the ancestor of several extant species, including ''P. fluviatile'' and ''P. ibericum'', but its young age and geographical location suggests that "''P. antiquum''" may represent specimens of ''P. ibericum'' from former populations beyond the species' current northern limit. Fossils assigned to ''P. ibericum'' from

Vallesian The Vallesian age is a period of geologic time (11.6–9.0 Ma) within the Miocene used more specifically with European Land Mammal Ages. It precedes the Turolian age and follows the Astaracian age. The so-called Vallesian Crisis resulted in th ...

sediments at Richardhof in the

Vienna Basin The Vienna Basin (, , , Hungarian: ''Bécsi-medence'') is a geologically young tectonic burial basin and sedimentary basin in the seam area between the Alps, the Carpathians and the Pannonian Plain. Although it topographically separates the Al ...

suggest that the crabs in those sediments were

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s of an extinct snail in the genus ''

Melanopsis ''Melanopsis'' is a genus of freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Melanopsidae.Rosenberg, G. (2014). Melanopsis Férussac, 1807. Accessed through: World Register of Marine Species at http://ww ...

''.

Conservation

Despite its wide geographical range, ''P. ibericum'' is classified as

on the

, as "it is possible that populations of ''P. ibericum'' in parts of its range might be in danger of extirpation in the future, especially those on islands or near centres of human population on the mainland". It may even approach a classification of vulnerable. The species is listed in the ''Red Data Book'' for

References

External links

*
''Potamon ibericum'' (Bieberstein, 1809)
Pan-European Species directories Infrastructure {{Taxonbar, from=Q812783 Potamoidea Freshwater crustaceans of Europe Freshwater crustaceans of Asia Crustaceans described in 1808