The Incan caenolestid (''Lestoros inca''), also known as the Incan shrew opossum or Peruvian caenolestid, is a caenolestid found in the southern Peruvian

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

. It was first described by English zoologist

Oldfield Thomas Michael Rogers Oldfield Thomas (21 February 1858 – 16 June 1929) was a British zoologist. Career Thomas worked at the Natural History Museum, London, Natural History Museum on mammals, describing about 2,000 new species and subspecies for ...

in 1917. The head-and-body length ranges from , and the weight is between . It is brown on the back, and lighter on the underside. Little is known about the behaviour of the Incan caenolestid; it appears to be

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

and

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

. It feeds on small

invertebrate 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 chordata, chordate s ...

s and insects. This caenolestid inhabits

elfin Elfin may refer to: *ELFIN, a CubeSat developed by University of California, Los Angeles *Elfin (steamboat), a steamboat that ran on Lake Washington from 1891 to 1900 *Elfin of Alt Clut, ruler of Alt Clut, seventh century Scotland *Elfin, a charac ...

and secondary forests. The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

classifies it as

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

Taxonomy

The Incan caenolestid is the sole member of its genus, ''Lestoros'', and is placed in the family

Caenolestidae The family Caenolestidae contains the seven surviving species of shrew opossum: small, shrew-like marsupials that are confined to the Andes mountains of South America. The order is thought to have diverged from the ancestral marsupial line very e ...

(shrew opossums). It was first described by English zoologist

as ''Orolestes inca'' in 1917. In 1934, the shrew opossum was given its present binomial name. Caenolestid fossils date to as early as the early

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

(nearly 55 mya). In the latter part of 20th century, scientists believed that ''Lestoros'' is closely related to ''

Caenolestes The common shrew opossums (genus ''Caenolestes'') are members of the family Caenolestidae. They are found in Colombia, Ecuador, Peru, and Venezuela. The most recently discovered species is ''C. sangay''. Phylogeny See also * List of mammal ...

'' (common shrew opossums). Over the years, it became clear that ''Lestoros'' is morphologically different from ''Caenolestes''. A 2013 morphological and

mitochondrial DNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...

-based

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

study showed that the Incan caenolestid and the

long-nosed caenolestid The long-nosed caenolestid (''Rhyncholestes raphanurus''), also known as the Chilean shrew opossum or long-nosed shrew opossum, is a shrew opossum that occurs in temperate forests of Argentina and southern Chile. It was first described by America ...

(''Rhyncholestes raphanurus'') form a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

sister A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...

to ''Caenolestes''. The cladogram below is based on this study.

Description

The Incan caenolestid, like the common shrew opossums, is characterized by a long

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, Rostrum (anatomy), rostrum, beak or proboscis. The wet furless surface around the nostrils of the n ...

and small eyes. A 2013 study gave a detailed analysis of the morphology of this shrew opossum. The Incan caenolestid appeared to be closer to ''Caenolestes'' than to the long-nosed caenolestid in morphology.

Sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

was not prominent. External measurements recorded were as follows: the head-and-body length ranged from , the tail length ranged from , and ear length was between . Weight ranges from . Basically dark brown on the back, the caenolestid may have a lighter underbelly. This caenolestid has a relatively stronger

cranium The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

and shorter

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

, suggesting that it can feed on tougher material than can other shrew opossums. The

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

is not as well-developed as in the long-nosed caenolestid. The

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

is . The long, blade-like structure of the

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

and

premolars The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mout ...

could suggest a diet of soft

s. The pattern of

tooth eruption Tooth eruption is a process in tooth development in which the teeth enter the mouth and become visible. It is currently believed that the periodontal ligament plays an important role in tooth eruption. The first human teeth to appear, the decidu ...

appears to be largely consistent in all caenolestids – the eruption of procumbent (trailing along the surface without spreading out roots)

incisors Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

, followed by the development of closely spaced incisors that distance from one another as the mandible grows, and then the eruption of molars and premolars. Like most caenolestids, it may have dental anomalies such as missing or

supernumerary teeth Hyperdontia is the condition of having supernumerary teeth, or teeth that appear in addition to the regular number of teeth (32 in the average adult). They can appear in any area of the dental arch and can affect any dental organ. The opposite ...

. The study noted several differences in the dentition of the Incan caenolestid and common shrew opossums.

Ecology and behavior

Little is known of the behavior of the Incan caenolestid. Observations suggest it is

and

. Like other caenolestids, it feeds on insects and small invertebrates. It is known to host several

ectoparasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s, such as ''

Pterygodermatites ''Pterygodermatites'' is a genus of parasitic nematodes in the family Rictulariidae. Their life-cycle is complex. Species include: *'' Pterygodermatites baiomydis'' Lynggaard, García-Prieto, Guzmán-Cornejo & Osorio-Sarabia, 2014 *'' Pterygod ...

Distribution and status

The Incan caenolestid is known to occur in

elfin forest A "natural National Park in the Philippines, a UNESCO World Heritage Site file:Mount Kemiri (8187817161).jpg, An elfin forest in Sumatra's Gunung Leuser National Park Dwarf forest, elfin forest, or pygmy forest is an uncommon ecosystem feat ...

secondary forest A secondary forest (or second-growth forest) is a forest or woodland area which has regenerated through largely natural processes after human-caused Disturbance (ecology), disturbances, such as Logging, timber harvest or agriculture clearing, or ...

s, ''

Baccharis ''Baccharis'' is a genus of perennial plant, perennials and shrubs in the Asteraceae, aster family (Asteraceae). They are commonly known as baccharises but sometimes referred to as "brooms", because many members have small thin leaves resembling ...

'' scrubs, and at altitudes ranging from above the sea level in moist habitats. It is found mainly in the southern Peruvian

, and its range extends from southeastern

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

to the extreme west of

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

in northwestern South America. The Incan caenolestid is classified as

by the

due to its wide distribution in its local habitat, presumably large population, and occurrence across several protected areas. There are no major threats to its survival.

References

External links

* {{Taxonbar, from=Q1343993 Shrew opossums Endemic fauna of Peru Mammals of the Andes Marsupials of Peru Mammals described in 1917 Taxa named by Oldfield Thomas Taxonomy articles created by Polbot