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

caenolestid 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 ...

found in the southern Peruvian

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

. 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 on mammals, describing about 2,000 new species and subspecies for the first time. He was appoin ...

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. 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 or near the ground, as opposed to ...

and

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

. It feeds on small

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

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 Secondary may refer to: Science and nature * Secondary emission, of particles ** Secondary electrons, electrons generated as ionization products * The secondary winding, or the electrical or electronic circuit connected to the secondary winding i ...

forests. The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

classifies it as

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

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

(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 Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República ...

'' (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 or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

-based

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

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 A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

sister A sister is a woman or a girl who shares one or more parents 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 refer to ...

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, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is c ...

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 the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

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 is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

and shorter

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

, 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 * 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 ships * Ros ...

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-physiolo ...

is . The long, blade-like structure of the

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

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 mouth ...

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, wh ...

, 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 close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

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 *'' Pterygo ...

Distribution and status

The Incan caenolestid is known to occur in

elfin forest Dwarf forest, elfin forest, or pygmy forest is an uncommon ecosystem featuring miniature trees, inhabited by small species of fauna such as rodents and lizards. They are usually located at high elevations, under conditions of sufficient air humi ...

secondary forest A secondary forest (or second-growth forest) is a forest or woodland area which has re-grown after a timber harvest or clearing for agriculture, until a long enough period has passed so that the effects of the disturbance are no longer evident. ...

s, ''

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

'' 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 , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

to the extreme west of

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

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 Marsupials of South America Mammals of the Andes Mammals of Peru Mammals described in 1917 Taxa named by Oldfield Thomas Taxonomy articles created by Polbot