Dahl's toad-headed turtle (''Mesoclemmys dahli'') is a medium-sized

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), ...

of side-necked turtle 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 ...

Chelidae Chelidae is one of three living families of the turtle suborder Pleurodira, and are commonly called Austro-South American side-neck turtles. The family is distributed in Australia, New Guinea, parts of Indonesia, and throughout most of South Amer ...

. This

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

freshwater turtle 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 northern

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

, where it lives in small pools, streams, and swamps, but

aestivate Aestivation ( (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered me ...

s on land.Forero-Medina, G.; Castaño-Mora, O.V.; Cárdenas-Arevalo, G.; Medina-Rangel, G.F. (2013). "''Mesoclemmys dahli'' (Zangerl and Medem 1958) – Dahl's Toad-Headed Turtle,''Carranchina, Tortuga Montañera''". ''Chelonian Research Monographs'' (5): 069.1–069.8. doi:10.3854/crm.5.069.dahli. v1.2013

Etymology

The Specific name (zoology), specific name, ''dahli'', is in honor of Swedish-born Colombian

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

George Dahl George Leighton Dahl (May 11, 1894 – July 18, 1987) was a prominent American architect based in Dallas, Texas during the 20th century. His most notable contributions include the Art Deco structures of Fair Park while he oversaw planning and con ...

(1905-1979), who collected the

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (''Mesoclemmys dahli'', p. 64).

Appearance

''M. dahli'' has an olive to brown

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 ...

, which is oval to elliptical (to ) and widest behind the middle with a slightly serrated posterior rim. It is somewhat flattened dorsally, and the lateral marginals are upturned. A poorly developed vertebral keel may be present in juveniles and some adults. The flared 1st vertebral is the largest and broader than long, as is also the flared 5th. The 2nd and 3rd vertebrals are also usually broader than long, but the 4th, the smallest of the series, may be slightly longer or as long as broad. The cervical scute is normally longer than broad. 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. Its fore lobe is longer and broader than the hind lobe; the narrowness of the posterior lobe is particularly noticeable in males, and its breadth is only 36-38% of the plastral length. The bridge is relatively broad. We have seen few specimens of ''Mesoclemmys dahli'', but in those measured the plastral formula was: . The intergular completely separates the gulars. Plastron, bridge, and undersides of the marginals are cream to yellow with gray pigment outlining the seams. The head is large and broad with a slightly projecting snout and slightly notched upper jaw. There are two chin barbels, and the dorsal surface of the head is covered with small to large, irregularly shaped scales. Dorsally, the head is gray to olive brown, but the upper jaw, tympanum, and sides are cream to yellow. Lower jaw, chin, and barbels are yellow. The neck is gray dorsally but lighter ventrally. No horny tubercles are present on the neck. Limbs and tail are gray to olive brown on the outside but lighter beneath. Males have longer, thicker tails, narrower posterior plastral lobes, and narrower heads. The head of the female is swollen behind the eyes..

Genetics

The

karyotype A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...

of ''M. dahli'' is 2n = 58: 22 macrochromosomes, 36 microchromosomes.Bull, J.J.; Legler, J.M. (1980). "Karyotypes of side-necked turtles (Testudines: Pleurodira)". ''Canadian Journal of Zoology'' 58: 828-841. It differs from that of '' M. nasuta'' in having the 8th

chromosome pair A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most importa ...

biarmed.

Distribution

''M. dahli'' is only known from the lower Magdalena and Sinú river basins in the Atlántico, Bolívar,

Córdoba Córdoba most commonly refers to: * Córdoba, Spain, a major city in southern Spain and formerly the imperial capital of Islamic Spain * Córdoba, Argentina, the second largest city in Argentina and the capital of Córdoba Province Córdoba or Cord ...

and

Sucre Department Sucre () is a department in the Caribbean Region of Colombia. The department ranks 27th by area, and it has a population of 904,863, ranking 20th of all the 32 departments of Colombia. Sucre is bordered by the Caribbean on the northwest; by B ...

s in northern

Habitat

Medem (1966) reported that the habitat at the type locality of ''M. dahli'' was originally ponds and small brooks within forests, but with the clearing of the woodlands the entire area around the type locality has been transformed into pastures. There, turtles seem to prefer shallow, quiet water bodies, where they fill a bottom-dwelling niche.

Aestivation Aestivation ( (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered m ...

occurs during dry periods.

Reproduction

Medem (1966)Medem, F. (1966). "''Contribuciones al conocimiento sobre la ecología y distribución geográfica de'' Phrynops (Batrachemys) dahli ''(Testudinata, Pleurodira, Chelidae)'' ". ''Caldasia'' 9 (45): 467–489. (in Spanish). reported the mating season of ''M. dahli'' in Colombia as June and July with nesting occurring mainly in September and October, but it may extend through the year. Apparently several clutches of one to six eggs are laid by each female. The white eggs are ellipsoidal (29-35 x 23–28 mm) with brittle shells, and hatchlings have carapaces about 28–30 mm long.

Diet

''M. dahli'' is predominantly

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

, feeding on snails, aquatic insects, other aquatic

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 ...

, fish, and amphibians;

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 ...

is also eaten.

References

External links

* https://web.archive.org/web/20110608013412/http://nlbif.eti.uva.nl/bis/turtles.php?menuentry=soorten&id=172 * http://www.catalogueoflife.org/show_species_details.php?record_id=4485015 * Tortoise & Freshwater Turtle Specialist Group 1996.
''Phrynops dahli''
{{DEFAULTSORT:Dahl's toad-headed turtle dahli Turtles of South America Reptiles of Colombia Endemic fauna of Colombia Reptiles described in 1958 Taxonomy articles created by Polbot