Incan caenolestid

The Incan caenolestid (Lestoros inca), also known as the Incan shrew opossum or Peruvian caenolestid,[4] is a caenolestid found in the southern Peruvian Andes. It was first described by English zoologist Oldfield Thomas in 1917. The head-and-body length ranges from 9 to 11.5 centimetres (3.5 to 4.5 in), and the weight is between 25 and 32 grams (0.88 and 1.13 oz). 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 and nocturnal. It feeds on small invertebrates and insects. This caenolestid inhabits elfin and secondary forests. The IUCN classifies it as least concern.

Incan caenolestid
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Paucituberculata
Family: Caenolestidae
Genus: Lestoros
Oehser, 1934
Species:
L. inca
Binomial name
Lestoros inca
(Thomas, 1917)
Range of the Incan shrew opossum
Synonyms[2][3]

Caenolestes gracilis (Bublitz, 1987)
Cryptolestes inca Tate, 1934
Orolestes inca Thomas, 1917

Taxonomy

The Incan caenolestid is the sole member of its genus, Lestoros, and is placed in the family Caenolestidae (shrew opossums). It was first described by English zoologist Oldfield Thomas as Orolestes inca in 1917. In 1934, the shrew opossum was given its present binomial name.[2] Caenolestid fossils date to as early as the early Eocene (nearly 55 mya).[5]

In the latter part of 20th century, scientists believed that Lestoros is closely related to Caenolestes (common shrew opossums).[6][7] Over the years, it became clear that Lestoros is morphologically different from Caenolestes.[8] A 2013 morphological and mitochondrial DNA-based phylogenetic study showed that the Incan caenolestid and the long-nosed caenolestid (Rhyncholestes raphanurus) form a clade sister to Caenolestes. The cladogram below is based on this study.[9]

 
 
 

Gray short-tailed opossum (Monodelphis domestica)

 
 

Brown four-eyed opossum (Metachirus nudicaudatus)

 
 
 
 

Incan caenolestid (Lestoros inca)

 
 

Long-nosed caenolestid (Rhyncholestes raphanurus)

 
 
Caenolestes
 

Northern caenolestid (C. convelatus)

 
 
 

Dusky caenolestid (C. fuliginosus)

 
 
 

Andean caenolestid (C. condorensis)

 
 
 

Gray-bellied caenolestid (C. caniventer)

 
 

Eastern caenolestid (C. sangay)

 
 
 
 
 
 
 
 

Description

The Incan caenolestid, like the common shrew opossums, is characterized by a long snout and small eyes.[4] 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 was not prominent. External measurements recorded were as follows: the head-and-body length ranged from 9 to 11.5 centimetres (3.5 to 4.5 in), the tail length ranged from 9.5 to 13.5 centimetres (3.7 to 5.3 in), and ear length was between 1.4 and 1.7 centimetres (0.55 and 0.67 in).[10] Weight ranges from 25 to 32 grams (0.88 to 1.13 oz). Basically dark brown on the back, the caenolestid may have a lighter underbelly.[11]

This caenolestid has a relatively stronger cranium and shorter mandible, suggesting that it can feed on tougher material than can other shrew opossums. The rostrum is not as well-developed as in the long-nosed caenolestid.[10] The dental formula is 4.1.3.43.1.3.4.[11] The long, blade-like structure of the molars and premolars could suggest a diet of soft invertebrates. The pattern of tooth eruption appears to be largely consistent in all caenolestids – the eruption of procumbent (trailing along the surface without spreading out roots) incisors, 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. The study noted several differences in the dentition of the Incan caenolestid and common shrew opossums.[10]

Ecology and behavior

Little is known of the behavior of the Incan caenolestid. Observations suggest it is terrestrial and nocturnal.[4] Like other caenolestids, it feeds on insects and small invertebrates.[4][12] It is known to host several ectoparasites,[8] such as Pterygodermatites.[13]

Distribution and status

The Incan caenolestid is known to occur in elfin forests, secondary forests, Baccharis scrubs, and at altitudes ranging from 2,100 to 3,600 metres (6,900 to 11,800 ft) above the sea level in moist habitats. It is found mainly in the southern Peruvian Andes, and its range extends from southeastern Peru to the extreme west of Bolivia in northwestern South America.[8][11] The Incan caenolestid is classified as least concern by the IUCN 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.[1]

References
  1. Martin, G.M. (2016). "Lestoros inca". IUCN Red List of Threatened Species. IUCN. 2016: e.T41507A22179769. doi:10.2305/IUCN.UK.2016-1.RLTS.T41507A22179769.en. Retrieved 2 December 2019.
  2. Gardner, A.L. (2005). "Order Paucituberculata". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 19. ISBN 978-0-8018-8221-0. OCLC 62265494.
  3. Nowak, R.M. (2005). Walker's Marsupials of the World. Baltimore, US: Johns Hopkins University Press. pp. 87–8. ISBN 978-0-8018-8211-1.
  4. Hunsaker II, D., ed. (1977). The Biology of Marsupials. Oxford, UK: Elsevier. p. 108. ISBN 978-0-323-14620-3.
  5. Patterson, B.D.; Gallardo, M.H. (1987). "Rhyncholestes raphanurus". Mammalian Species. 286: 1–5. doi:10.2307/3503866.
  6. Simpson, G.G. (1970). "The Argyrolagidae, extinct South American marsupials". Bulletin of the Museum of Comparative Zoology. 139: 1–86.
  7. Marshall, L.G. (1980). "Systematics of the South American marsupial family Caenolestidae". Fieldiana: Geology. New Series. 5: 1–145. doi:10.5962/bhl.title.3314.
  8. Gardner, A.L., ed. (2007). Mammals of South America. 1. Chicago, US: University of Chicago Press. pp. 124–6. ISBN 978-0-226-28242-8.
  9. Ojala-Barbour, R.; Pinto, C.M.; Brito M., J.; Albuja V., L.; Lee, T.E.; Patterson, B.D. (2013). "A new species of shrew-opossum (Paucituberculata: Caenolestidae) with a phylogeny of extant caenolestids". Journal of Mammalogy. 94 (5): 967–82. doi:10.1644/13-MAMM-A-018.1.
  10. Martin, G.M. (2013). "Intraspecific variability in Lestoros inca (Paucituberculata, Caenolestidae), with reports on dental anomalies and eruption pattern". Journal of Mammalogy. 94 (3): 601–17. doi:10.1644/12-MAMM-A-180.1.
  11. Eisenberg, J.F.; Redford, K.H. (1999). The Central Neotropics: Ecuador, Peru, Bolivia, Brazil. Chicago, US: University of Chicago Press. p. 83. ISBN 978-0-226-19542-1.
  12. Hume, I.D. (1999). Marsupial Nutrition. Cambridge, UK: Cambridge university press. p. 43. ISBN 978-0-521-59555-1.
  13. Jiménez, F. A.; Patterson, B.D. (2012). "A new species of Pterygodermatites (Nematoda: Rictulariidae) from the Incan shrew opossum, Lestoros inca". Journal of Parasitology. 98 (3): 604–7. doi:10.1645/GE-3014.1. PMID 22236274.
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