Geoemyda silvatica
Encyclopedia
The Cochin forest cane turtle (Vijayachelys silvatica), also known as Kavalai forest turtle, forest cane turtle or simply cane turtle, is a rare turtle
from the Western Ghats
of India
. Described in 1912, its type locality is given as "Near Kavalai in the Cochin State Forests, inhabiting dense forest, at an elevation of about 1500 feet above sea level". Only two specimens were found at that time, and no scientist saw this turtle in the next 70 years. It was finally rediscovered in 1982, and since then a number of specimens have been found and some studies have been conducted about its affiliation and habits.
Like its relatives, it belongs to the subfamily Geoemydinae
of the family
Geoemydidae
, formerly known as Bataguridae. It was once placed in the genus
Geoemyda
and subsequently moved to Heosemys
. But as it seems, the Cochin forest cane turtle forms a quite distinct lineage closely related to Melanochelys
. Thus, nowadays it is recognized as a monotypic
genus, named Vijayachelys in honor of the famous Indian herpetologist Jaganath Vijaya who rediscovered this species in 1982 and until her death extensively studied it. A diagnosis of the osteology
of Vijayachelys was published in 2006.
is considerably depressed, with a prominent mid-line keel, as well as one less pronounced lateral keel on each side. Its posterior margin is feebly reverted and not or only indistinctly serrated. The nuchal scute
is small. The first vertebral scute is broader in front than behind and larger than the second, third and fourth vertebral shields. These are considerably broader than long, as broad as the costal scutes.
The plastron is sizeable, being nearly as large as the shell opening; it is connected to the carapace by ligament
s and particularly in females there is little ossification
between the shields of the shell. The plastron is angled at the sides and openly emarginate at the forward and aft opening. The width of the plastron bridge is less than the length of the hind lobe; the longest median
suture is between the abdominal scute, the shortest between the gular scute. The axillary and inguinal scutes are very small; one of the latter is even absent.
Its head is rather large, with a truncated snout as long as the sizeable orbit
; the upper jaw is hooked, with small premaxilla
e. The mandibular
symphysis
is very long, exceeding the maximum diameter of the orbit in width. On the hind part of the head, the skin is divided into moderately large shields. The skull
lacks a temporal arch and has the frontal bone
extended to form a considerable part of the orbit. Seen from above, the prootic extends towards the front. The jugal
does not contact the small laterally emarginated and medially constricted pterygoid process
, the bones being separated by the maxilla and a gap. The triturating (chewing) surface of the upper jaw is long and narrow, more than four times as long as it is wide. The lower temporal fossa
is large and strongly concave, providing an attachment for the massive chewing muscle.
The forelegs are covered in enlarged squarish or pointed horny scales, particularly on the front. The hindlimbs are rather club-shaped, the anterior margins and anterior region of their heels bearing enlarged horny scales. The fingers are webbed one-third of their length, while the toes bear rudimentary webbing only. The tail is rather short and becomes very narrow behind the cloaca
in males; it is a mere stub in females.
The carapace of the type specimen was dark bronze; the plastron yellowish with two dark blotches on either side of the bridge. The jaws and upper front part of the head are bright yellow in the living animal, with a red spot on the top of the snout. The hind part of the head and the neck are brown. Limbs and tail are black.
The length of the type specimen's shell is 120 mm, its breadth 83 mm and its depth 45 mm. Females are slightly larger than males, but this smallish turtle does not seem to exceed about 13 cm in carapace length even when fully grown.
The first captive specimens lived entirely upon vegetable food, but subsequently it has turned out that this turtle is omnivorous, eating any suitably sized plant and animal food.
The Cochin forest cane turtle is listed as Endangered (EN B1+2c v2.3) by the IUCN. It is rarely found in the pet trade.
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
from the Western Ghats
Western Ghats
The Western Ghats, Western Ghauts or the Sahyādri is a mountain range along the western side of India. It runs north to south along the western edge of the Deccan Plateau, and separates the plateau from a narrow coastal plain along the Arabian Sea. The Western Ghats block rainfall to the Deccan...
of India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
. Described in 1912, its type locality is given as "Near Kavalai in the Cochin State Forests, inhabiting dense forest, at an elevation of about 1500 feet above sea level". Only two specimens were found at that time, and no scientist saw this turtle in the next 70 years. It was finally rediscovered in 1982, and since then a number of specimens have been found and some studies have been conducted about its affiliation and habits.
Like its relatives, it belongs to the subfamily Geoemydinae
Geoemydinae
Geoemydinae is a subfamily of turtles. The following genera are placed here:* Chinemys * Cuora * Cyclemys * Geoemyda...
of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Geoemydidae
Geoemydidae
Geoemydidae is the largest and most diverse family in the order Testudines with about 70 species. It includes the Eurasian pond and river turtles and Neotropical wood turtles.-Characteristics:...
, formerly known as Bataguridae. It was once placed in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Geoemyda
Geoemyda
Geoemyda is a genus of freshwater turtles in the family Geoemydidae . It contains the following species:* Ryukyu Black-breasted Leaf Turtle, Geoemyda japonica* Black-breasted Hill Turtle, Geoemyda spengleri...
and subsequently moved to Heosemys
Heosemys
Heosemys is a genus of freshwater turtles in the family Geoemydidae . The genus Heosemys was split out of the related genus Geoemyda by McDowell in 1964.-Species:...
. But as it seems, the Cochin forest cane turtle forms a quite distinct lineage closely related to Melanochelys
Melanochelys
Melanochelys is a genus of turtle in the Geoemydidae family. Members are found in India, Myanmar, Bangladesh, Sri Lanka and Nepal.-Species:Melanochelys contain only the following two species:* Indian black turtle...
. Thus, nowadays it is recognized as a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus, named Vijayachelys in honor of the famous Indian herpetologist Jaganath Vijaya who rediscovered this species in 1982 and until her death extensively studied it. A diagnosis of the osteology
Osteology
Osteology is the scientific study of bones. A subdiscipline of anatomy, anthropology, and archeology, osteology is a detailed study of the structure of bones, skeletal elements, teeth, morphology, function, disease, pathology, the process of ossification , the resistance and hardness of bones , etc...
of Vijayachelys was published in 2006.
Description
The carapaceCarapace
A carapace is a dorsal 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 underside is called the plastron.-Crustaceans:In crustaceans, the...
is considerably depressed, with a prominent mid-line keel, as well as one less pronounced lateral keel on each side. Its posterior margin is feebly reverted and not or only indistinctly serrated. The nuchal scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
is small. The first vertebral scute is broader in front than behind and larger than the second, third and fourth vertebral shields. These are considerably broader than long, as broad as the costal scutes.
The plastron is sizeable, being nearly as large as the shell opening; it is connected to the carapace by ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
s and particularly in females there is little ossification
Ossification
Ossification is the process of laying down new bone material by cells called osteoblasts. It is synonymous with bone tissue formation...
between the shields of the shell. The plastron is angled at the sides and openly emarginate at the forward and aft opening. The width of the plastron bridge is less than the length of the hind lobe; the longest median
Median (disambiguation)
Median has different meanings in different contexts:* Median, in statistics, a number that separates the lowest-value half and the highest-value half* Median , in geometry, a line joining a vertex of a triangle to the midpoint of the opposite side...
suture is between the abdominal scute, the shortest between the gular scute. The axillary and inguinal scutes are very small; one of the latter is even absent.
Its head is rather large, with a truncated snout as long as the sizeable orbit
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
; the upper jaw is hooked, with small premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
e. The mandibular
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
symphysis
Symphysis
A symphysis is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint.1.A symphysis is an amphiarthrosis, a slightly movable joint.2.A growing together of parts or structures...
is very long, exceeding the maximum diameter of the orbit in width. On the hind part of the head, the skin is divided into moderately large shields. The skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
lacks a temporal arch and has the frontal bone
Frontal bone
The frontal bone is a bone in the human skull that resembles a cockleshell in form, and consists of two portions:* a vertical portion, the squama frontalis, corresponding with the region of the forehead....
extended to form a considerable part of the orbit. Seen from above, the prootic extends towards the front. The jugal
Jugal
The jugal is a skull bone found in most reptiles, amphibians, and birds. In mammals, the jugal is often called the malar or Zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species....
does not contact the small laterally emarginated and medially constricted pterygoid process
Pterygoid processes of the sphenoid
The pterygoid processes of the sphenoid, one on either side, descend perpendicularly from the regions where the body and great wings unite.Each process consists of a medial pterygoid plate and a lateral pterygoid plate, the upper parts of which are fused anteriorly; a vertical sulcus, the...
, the bones being separated by the maxilla and a gap. The triturating (chewing) surface of the upper jaw is long and narrow, more than four times as long as it is wide. The lower temporal fossa
Temporal fossa
The temporal fossa is a shallow depression on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.-Boundaries:...
is large and strongly concave, providing an attachment for the massive chewing muscle.
The forelegs are covered in enlarged squarish or pointed horny scales, particularly on the front. The hindlimbs are rather club-shaped, the anterior margins and anterior region of their heels bearing enlarged horny scales. The fingers are webbed one-third of their length, while the toes bear rudimentary webbing only. The tail is rather short and becomes very narrow behind the cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
in males; it is a mere stub in females.
The carapace of the type specimen was dark bronze; the plastron yellowish with two dark blotches on either side of the bridge. The jaws and upper front part of the head are bright yellow in the living animal, with a red spot on the top of the snout. The hind part of the head and the neck are brown. Limbs and tail are black.
The length of the type specimen's shell is 120 mm, its breadth 83 mm and its depth 45 mm. Females are slightly larger than males, but this smallish turtle does not seem to exceed about 13 cm in carapace length even when fully grown.
Ecology
This turtle inhabits dense evergreen forest, presumably at lower elevations. According to the natives from whom Dr. Henderson obtained the type, the species inhabits short burrows underground and is indifferent about having water nearby (unlike some of its relatives, which are decidedly aquatic). The type as well as another younger specimen were kept in captivity for six months, and Dr. Henderson remarks that they did not show any special partiality for water and when handled did not emit the offensive odour known from the related Indian Black Turtle (Melanochelys trijuga).The first captive specimens lived entirely upon vegetable food, but subsequently it has turned out that this turtle is omnivorous, eating any suitably sized plant and animal food.
The Cochin forest cane turtle is listed as Endangered (EN B1+2c v2.3) by the IUCN. It is rarely found in the pet trade.