Lagidium ahuacaense
Encyclopedia
Lagidium ahuacaense is a rodent
in the mountain viscacha genus (Lagidium) that occurs in southern Ecuador
. First observed in 2005 and formally described in 2009, it occurs more than 500 km (300 mi) north of the nearest previously known population of mountain viscachas in central Peru. It is a medium-sized species with gray-brown upperparts and creamy white underparts. The tail is long and is various shades of brown above and dark brown below. The skull is long, with a wide rostrum (front part) and narrow interorbital region
(between the eyes). The sides of the mesopterygoid fossa (the opening behind the back of the palate
) are strongly divergent.
Only a single population is known, found on rocky habitats on Cerro El Ahuaca, an isolated granite mountain in southern Ecuador, and there may be as little as a few dozen individuals. The species is threatened by fires and grazing cattle, and the discoverers recommended that its conservation status
be assessed as "Critically Endangered
".
(Lagidium) in central Peru. The find was published in a 2006 note by Florian Werner, Karim Ledesma, and Rodrigo Hidalgo, who provisionally identified the population as representing the Peruvian species Lagidium peruanum, but did not discount the possibility that it might represent a distinct species. Three years later, Ledesma, Werner, Ángel Spotorno, and Luis Albuja proceeded to describe the population as a new species, Lagidium ahuacaense, on the basis of morphological and DNA sequence
differences. The specific name, ahuacaense, refers to Cerro de Ahuaca. They suggested the English common name
of "Ecuadorean mountain viscacha".
Lagidium ahuacaense was the fourth species of the genus
Lagidium to be described, after L. peruanum, L. viscacia, and L. wolffsohni of the central and southern Andes, although more species may eventually be recognized within L. peruanum and L. viscacia and L. wolffsohni is poorly differentiated from L. viscacia. Together with the plains viscacha
(Lagostomus maximus) and the chinchilla
s (Chinchilla), Lagidium forms the Chinchillidae
family of rodent
s. Within Lagidium, L. ahuacaense differs by at least 7.9% from all other species in DNA sequence
s of the mitochondrial
cytochrome b
gene. A cladistic analysis placed the Ecuadorian species as the sister group to all other Lagidium, but support for this placement was not strong. Morphometric analysis also confirms that the Ecuadorian population is different from other Lagidium species.
Lagidium ahuacaense is a medium-sized Lagidium with woolly, gray-brown fur and a very long tail. There is a black stripe on the middle of the back. The thick, long mystacial vibrissae (whiskers above the mouth) are mostly dark brown and the few superciliary vibrissae (above the eyes) are also thick and brown. The ears are covered with dark skin. The underparts are creamy white. The forefeet are brown-furred and much shorter than the hindfeet, which are in covered in part by a mixture of brown and cream hairs and in part by dark brown hairs. The fore- and hindfeet both have four digits, which end in small, curved claws, and three black pads. The palms and soles are naked. The tail is hairy with the hairs on the upper side longer than those below. The upper side is gray-brown at the base, light to medium brown intermixed with cream in the middle, and reddish brown at the tip, and the lower side is dark brown. In the single measured specimen, head and body length is 403 mm (15.9 in), tail length is 400 mm (15.8 in), hindfoot length is 85 mm (3.3 in), ear length is 60 mm (2.4 in), and body mass is 2.03 kg (4.5 lb).
The skull is long and compact. The premaxilla
ry bones extend slightly in front of the upper incisor
s and the zygomatic arch
es (cheekbones) are broad. The suture between the premaxillary and frontal bone
s is more strongly curved than in L. peruanum and the rostrum (front part of the skull) is wider and the interorbital region
(between the eyes) is narrower than in L. viscacia and L. wolffsohni. The incisive foramina (openings in the front part of the palate
) are long and narrow. The palate extends back to a point close to the upper third molar
. The sides of the mesopterygoid fossa (the opening behind the back margin of the palate) are more strongly divergent than in other Lagidium. The mandible
(lower jaw) is strong. The dental formula is (one incisor, one premolar
, and three molars on each side of the upper and lower jaws). The incisors are large and white and distinctly grooved. The molars are low-crowned and rootless (continuously growing).
in Loja Province
, southern Ecuador, where it occurs at an altitude of 1950 to 2480 m (6400 to 8140 ft), but only near rocky surfaces. The vegetation is dominated by the molasses grass (Melinis minutiflora
). They eat plants and traces of their feeding are visible on the mountain. Its habitat on Cerro El Ahuaca covers an area of about 120 ha (300 acre), and the total population there may not contain more than a few dozen individuals. Except for some small outcrops close to the Cerro, there is no nearby suitable habitat, but more populations may exist elsewhere in southern Ecuador or nearby northern Peru.
The species is threatened by fires, used to maintain crop fields in the vicinity, which frequently get out of control and destroy part of the viscacha's habitat on the Cerro, and by competition for food with grazing cattle. However, the species is unknown to the local people and is not hunted. In view of its small range and population, Ledesma and colleagues recommended that the species be assessed as "Critically Endangered
" under the IUCN Red List
criteria and recommended immediate conservation action to protect the Cerro El Ahuaca population and further research into its biology.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the mountain viscacha genus (Lagidium) that occurs in southern Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
. First observed in 2005 and formally described in 2009, it occurs more than 500 km (300 mi) north of the nearest previously known population of mountain viscachas in central Peru. It is a medium-sized species with gray-brown upperparts and creamy white underparts. The tail is long and is various shades of brown above and dark brown below. The skull is long, with a wide rostrum (front part) and narrow interorbital region
Interorbital region
The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups....
(between the eyes). The sides of the mesopterygoid fossa (the opening behind the back of the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
) are strongly divergent.
Only a single population is known, found on rocky habitats on Cerro El Ahuaca, an isolated granite mountain in southern Ecuador, and there may be as little as a few dozen individuals. The species is threatened by fires and grazing cattle, and the discoverers recommended that its conservation status
Conservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
be assessed as "Critically Endangered
Critically Endangered
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations....
".
Taxonomy
Lagidium ahuacaense was first observed in July 2005, when the only known population was encountered at Cerro El Ahuaca, Ecuador, over 500 km (300 mi) north of the northernmost previously known population of mountain viscachasLagidium
Lagidium is a genus of rodent in the family Chinchillidae.It contains the following species:* Northern Viscacha * Southern Viscacha * Wolffsohn's Viscacha...
(Lagidium) in central Peru. The find was published in a 2006 note by Florian Werner, Karim Ledesma, and Rodrigo Hidalgo, who provisionally identified the population as representing the Peruvian species Lagidium peruanum, but did not discount the possibility that it might represent a distinct species. Three years later, Ledesma, Werner, Ángel Spotorno, and Luis Albuja proceeded to describe the population as a new species, Lagidium ahuacaense, on the basis of morphological and DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
differences. The specific name, ahuacaense, refers to Cerro de Ahuaca. They suggested the English common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
of "Ecuadorean mountain viscacha".
Lagidium ahuacaense was the fourth species of 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...
Lagidium to be described, after L. peruanum, L. viscacia, and L. wolffsohni of the central and southern Andes, although more species may eventually be recognized within L. peruanum and L. viscacia and L. wolffsohni is poorly differentiated from L. viscacia. Together with the plains viscacha
Plains Viscacha
The Plains Viscacha or plains vizcacha is a species of rodent in the Chinchillidae family. It is the only living species within the genus Lagostomus. It is found in Argentina, Bolivia, and Paraguay. The plains viscacha is the largest species of the family Chinchillidae...
(Lagostomus maximus) and the chinchilla
Chinchilla
Chinchillas are crepuscular rodents, slightly larger and more robust than ground squirrels, and are native to the Andes mountains in South America. Along with their relatives, viscachas, they make up the family Chinchillidae....
s (Chinchilla), Lagidium forms the Chinchillidae
Chinchillidae
The family Chinchillidae contains the chinchillas, viscachas, and their fossil relatives. They are restricted to southern and western South America, often in association with the Andes. They are large rodents, weighing from to , with strong hind legs and large ears...
family of rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s. Within Lagidium, L. ahuacaense differs by at least 7.9% from all other species in DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s of the mitochondrial
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
gene. A cladistic analysis placed the Ecuadorian species as the sister group to all other Lagidium, but support for this placement was not strong. Morphometric analysis also confirms that the Ecuadorian population is different from other Lagidium species.
Description
The skull is long and compact. The 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....
ry bones extend slightly in front of the upper incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s and the zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...
es (cheekbones) are broad. The suture between the premaxillary and 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....
s is more strongly curved than in L. peruanum and the rostrum (front part of the skull) is wider and the interorbital region
Interorbital region
The interorbital region of the skull is located between the eyes, anterior to the braincase. The form of the interorbital region may exhibit significant variation between taxonomic groups....
(between the eyes) is narrower than in L. viscacia and L. wolffsohni. The incisive foramina (openings in the front part of the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
) are long and narrow. The palate extends back to a point close to the upper third molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
. The sides of the mesopterygoid fossa (the opening behind the back margin of the palate) are more strongly divergent than in other Lagidium. The mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
(lower jaw) is strong. The dental formula is (one incisor, one premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
, and three molars on each side of the upper and lower jaws). The incisors are large and white and distinctly grooved. The molars are low-crowned and rootless (continuously growing).
Ecology and conservation status
Lagidium ahuacaense is known only from Cerro El Ahuaca, a steep granite inselberg near CariamangaCariamanga
Cariamanga is a town in the Loja Province of Ecuador. It is the capital of the Calvas Canton.- References :* *...
in Loja Province
Loja Province
Loja Province is one of 24 provinces in Ecuador and shares its southern border on the west by El Oro Province, on the north by El Azuay, and on the east by Zamora-Chinchipe. Founded on its present site in 1548 by Captain Alonso de Mercadillo the site had been previously moved and rebuilt from La...
, southern Ecuador, where it occurs at an altitude of 1950 to 2480 m (6400 to 8140 ft), but only near rocky surfaces. The vegetation is dominated by the molasses grass (Melinis minutiflora
Melinis minutiflora
Melinis minutiflora, commonly known as molasses grass, is a species of grass. It has been weedy in Australia, where it has been introduced....
). They eat plants and traces of their feeding are visible on the mountain. Its habitat on Cerro El Ahuaca covers an area of about 120 ha (300 acre), and the total population there may not contain more than a few dozen individuals. Except for some small outcrops close to the Cerro, there is no nearby suitable habitat, but more populations may exist elsewhere in southern Ecuador or nearby northern Peru.
The species is threatened by fires, used to maintain crop fields in the vicinity, which frequently get out of control and destroy part of the viscacha's habitat on the Cerro, and by competition for food with grazing cattle. However, the species is unknown to the local people and is not hunted. In view of its small range and population, Ledesma and colleagues recommended that the species be assessed as "Critically Endangered
Critically Endangered
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations....
" under the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
criteria and recommended immediate conservation action to protect the Cerro El Ahuaca population and further research into its biology.
Literature cited
- Ledesma, K.J., Werner, F.A., Spotorno, A.E. and Albuja, L.H. 2009. A new species of Mountain Viscacha (Chinchillidae: Lagidium Meyen) from the Ecuadorean Andes (abstract only). Zootaxa 2126:41–57.
- Werner, F.A., Ledesma, K.J. and Hidalgo B., R. 2006. Mountain vizcacha (Lagidium cf. peruanum) in Ecuador – first record of Chinchillidae from the northern Andes. Mastozoología Neotropical 13(2):271–274.