The Caspian turtle (''Mauremys caspica''), also known as the striped-neck terrapin, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Geoemydidae The Geoemydidae (formerly known as Bataguridae) are one of the largest and most diverse families in the order Testudines (turtles), with about 70 species A species () is often defined as the largest group of organisms in which any two in ...

(=Bataguridae). It is found in west Asia, in Iran and central Turkey, northward to the Republic of Georgia, Azerbaijan, Russia (Dagestan), eastward to southwestern Turkmenistan, and in Iraq, Saudi Arabia, and Bahrain.

Description

''Mauremys caspica'' is a tan to blackish, medium-sized, semiaquatic turtle, which may attain a

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

length of . Its low, oval carapace has a slight medial keel (better developed in juveniles) and a smooth, unserrated marginal border, which is slightly upturned and tapered above the tail. A pair of low lateral keels are present on the pleural

scute A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of Bird anatomy#Scales, birds. The ter ...

s of hatchlings, but these become lower with age and disappear completely in adults. The carapace is tan to olive or black with yellow to cream-colored reticulations patterning the scutes, and some individuals have yellow vertebral stripes. These light lines fade with age, but the pleural seam borders become darker. The well-developed

plastron The turtle shell is a shield for the ventral and dorsal parts of turtles (the Order (biology), order Testudines), completely enclosing all the turtle's vital organs and in some cases even the head. It is constructed of modified bony elements such ...

is notched posteriorly. The plastral formulae are given in the subspecies descriptions under Geographic Variation. The plastron is either yellow with variable reddish to dark-brown blotches, or dark brown or black with a yellow blotch along the lateral scute borders. The bridge is either yellow with dark seam borders and dark spots on the corresponding marginals, or almost totally black with a few small yellow marks. The head is not enlarged, and is olive to dark brown with yellow or pale cream-colored stripes. Some stripes extend anteriorly from the neck onto the head. One of these on each side passes above the eye and onto the snout where it meets the stripe from the other side. Several others extend across the tympanum to contact the posterior rim of the orbit, and two additional stripes continue across the snout and pass ventral to the orbit. The neck, limbs, and tail are tan gray to olive or black with yellow, cream, or gray stripes or reticulations. ''M. caspica'' has 52 chromosomes; (Killebrew, 1977a; Bickham and Carr, 1983). Females are generally larger than males, have flat plastra and shorter tails with the vent under the rim of the carapace. The smaller males have concave plastra and longer, thicker tails with a vent beyond the rim of the carapace.

Systematics

Three

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

are recognized: The eastern Caspian turtle, Siebenrock's Caspian turtle, and the spotted-bellied Caspian turtle. The western Caspian turtle was formerly treated as a subspecies but is now recognized as its own species. The eastern Caspian turtle (''Mauremys caspica caspica'') was recently split into three forms.Wischuf and Fritz, 1996.Fritz and Wischuf, 1997. The

nominate subspecies In biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. ...

occurs in central Turkey and northern Iran, northward to the Republic of Georgia and eastward to southwestern

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 ...

. It has wider reticulations on its carapace than ''M. c. rivulata'', and a yellow-to-tan plastron with a regularly shaped, large, dark blotch on each scute. These more-or-less symmetrically arranged plastral spots may merge to one dark central spot, but a yellow border to the plastron often remains. The soft parts are mainly dark, and the bridge is mainly yellow with some dark lines or spots (but may be dark in old melanistic individuals). Its plastral formula is ' for males, and ' for females. Siebenrock's Caspian turtle (''M. c. siebenrocki'' ) occurs in Iran and Iraq, with

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

populations in Saudi Arabia and on the island of Bahrain; it intergrades with ''M. c. caspica'' in

Mesopotamia Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent. Today, Mesopotamia is known as present-day Iraq and forms the eastern geographic boundary of ...

. This light form with contrasting colors resembles ''M. c. caspica'', but has a yellow-to-orange plastron with a small to medium-sized, regularly shaped dark blotch on each scute. The soft parts are lighter than in ''M. c. caspica'', and, unlike in other subspecies, age-related melanism does not occur in this subspecies. The spotted-bellied Caspian turtle (''M. c. ventrimaculata'') is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the highlands of the Kor and Maharloo basins in southern Iran. It is distinguished from the ''M. c. caspica'' and ''M. c. siebenrocki'' subspecies by a yellow plastron with one or several irregularly shaped black spots on each scute. In older individuals this results in a complex plastral pattern of irregular dark markings. The western Caspian turtle, formerly ''M. c. rivulata'' and now recognized as its own species ''

Mauremys rivulata The Balkan terrapin or western Caspian terrapin (''Mauremys rivulata'') is a species of terrapin in the family Geoemydidae. It is found in the eastern Mediterranean region. While technically omnivorous, the terrapins are known to prefer meat. Th ...

'', ranges throughout southeastern Europe (former

Yugoslavia , common_name = Yugoslavia , life_span = 1918–19921941–1945: World War II in Yugoslavia#Axis invasion and dismemberment of Yugoslavia, Axis occupation , p1 = Kingdom of SerbiaSerbia , flag_p ...

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 ...

, the

Ionian Islands The Ionian Islands (Modern Greek: , ; Ancient Greek, Katharevousa: , ) are a archipelago, group of islands in the Ionian Sea, west of mainland Greece. They are traditionally called the Heptanese ("Seven Islands"; , ''Heptanēsa'' or , ''Heptanē ...

, Crete, and Cyprus), Bulgaria, eastern to south-central Turkey, coastal

Syria Syria, officially the Syrian Arab Republic, is a country in West Asia located in the Eastern Mediterranean and the Levant. It borders the Mediterranean Sea to the west, Turkey to Syria–Turkey border, the north, Iraq to Iraq–Syria border, t ...

, Lebanon, and Israel; records from the vicinity of

Ankara Ankara is the capital city of Turkey and List of national capitals by area, the largest capital by area in the world. Located in the Central Anatolia Region, central part of Anatolia, the city has a population of 5,290,822 in its urban center ( ...

and from Lake Emir are questioned by Fritz. This species has narrow or fine reticulations on its carapace (which may be lost with age), and a totally black plastron and bridge. Age-related flavism may occur, resulting in a mainly yellow plastron with black reduced to the seams. This species can be separated from melanistic ''M. c. caspica'' by differences in head, neck, and foreleg patterns. Its plastral formula usually is ' in both sexes, but variations of this have been described in

İzmir İzmir is the List of largest cities and towns in Turkey, third most populous city in Turkey, after Istanbul and Ankara. It is on the Aegean Sea, Aegean coast of Anatolia, and is the capital of İzmir Province. In 2024, the city of İzmir had ...

populations. According to Fritz and Wischuf, ''M. c. caspica sensu lato'' (''caspica'', ''siebenrocki'' and ''ventrimaculata'') and ''M. c. rivulata'' only

intergrade In zoology, intergradation is the way in which two distinct subspecies are connected via areas where populations are found that have the characteristics of both. There are two types of intergradation: primary and secondary intergradation. Primary ...

in two populations near the Turkish-Syrian border; no wide intergradation belt between these two forms exists. Therefore, they proposed that ''rivulata'' be separated as a "monotypic semi-species". ''Rivulata'' and members of the main ''caspica'' group are known to produce (presumably fertile) hybrids, so they should never be housed together in captivity The Spanish pond turtle (''Mauremys leprosa'') was formerly considered a subspecies of ''M. caspica'', but studies of the electrophoretic properties of its proteins, and studies of its morphology have shown it to be a separate species.

Etymology

The subspecific name, ''siebenrocki'', is in honor of Austrian

herpetologist Herpetology (from Ancient Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (in ...

Friedrich Siebenrock Friedrich Siebenrock (20 January 1853, Schörfling am Attersee – 28 January 1925, Vienna) was an Austrian herpetologist. Biography He studied zoology at the Universities of Innsbruck and Vienna, afterwards serving as a demonstrator under ...

Ecology

''Mauremys caspica'' occurs in large numbers in almost any permanent

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

body within its range. It also lives in irrigation canals and is quite tolerant of

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

water. The turtles at one Iraq site lacked the ability to swim.Reed. Instead, they would crawl out of the water periodically to breathe and then slide back in again. A captive from there could not be induced to swim. Reed thought this behavior to be an adaptation to the extreme variability in the supply of surface water in the area. Breeding usually takes place in early spring, but may also occur in the fall.Anderson, 1979. The courtship behavior has not been described, but must be similar to that in captivity. Nesting occurs in June and July. A typical clutch is four to six, elongated 20-30 x 35–40 mm (1.0 x 1.5 in), brittle-shelled, white eggs. Hatchlings have round carapaces about in length, and are brighter colored than the adults. The Caspian turtle may occur in large populations in certain areas, especially in permanent water bodies. In temporary waters, it is forced to aestivate in the mud in summer, and the more northern populations hibernate during winter. It often basks, but disappears at the least disturbance. Many are killed each year by humans who obtain their eggs to use in treating ubiquitous eye ailments. Storks and vultures also take a heavy toll of juveniles and adults, respectively. It is carnivorous as juveniles with a shift towards being omnivorous as adults; larger individuals were observed to be more herbivorous. It feeds on small

invertebrates Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordate subphylum ...

, aquatic

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

amphibians Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

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 ...

, as well as a variety of aquatic and terrestrial plants.

References

External links

An introduction to the ''Mauremys'' turtles of the Mediterranean
{{Taxonbar, from=Q848321 Mauremys Turtles of Asia Turtles of Europe Turtle, Caspian Reptiles described in 1774 Taxa named by Johann Friedrich Gmelin Habitats Directive species