The long-nosed caenolestid, 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 American zoologist Wilfred Hudson Osgood in 1924. The long-nosed caenolestid resembles Caenolestes species in morphology. It is characterized by a long, pointed snout, small eyes and ears, and one claw on a digit of each of the thin limbs. Little is known of its behavior; it appears to be terrestrial, nocturnal and omnivorous. It prefers cool, moist areas, and has a small distribution. It is classified as near threatened by the IUCN.
Taxonomy and etymology
The long-nosed caenolestid is the sole member of its genus, and is classified in the family Caenolestidae. It was first described by American zoologist Wilfred Hudson Osgood in 1924. Two subspecies are recognised:
R. r. continentalis Bublitz, 1987: Occurs in Argentina and Chile.
R. r. raphanurus Osgood, 1924: Occurs in southern Chiloé Island.
A 2013morphological and mitochondrial DNA-based phylogenetic study showed that the Incan caenolestid and the long-nosed caenolestid form a cladesister to Caenolestes. The cladogram below is based on this study. Caenolestid fossils date to as early as the early Eocene. The generic name derives from the Greek words rhynchos and lestes. The specific name comes from the Greek raphanos, referring to the thick tail of this caenolestid. The Spanish name for this caenolestid, comadrejita trompuda, is the combination of comadreja and trompa. Other names for this shrew opossum are Chilean shrew opossum or Chilean caenolestid.
Description
The long-nosed caenolestid resembles Caenolestes species in morphology. In his 1824 account, Osgood recorded external measurements of three specimens. The head-and-body length ranged from, skull length was between and hind feet measured. The smooth coat is dark greyish brown, without countershading. It is characterized by a long, pointed snout, small eyes and ears, and one claw on a digit of each of the thin limbs. This shrew opossum lacks a marsupium and has seven nipples, unlike the four typical of other caenolestids. The tail helps in balancing the body during locomotion; the relatively shorter tail could imply lesser agility in the long-nosed caenolestid in comparison to other caenolestids. Moreover, the tail can be used to store fat, and is reportedly thickest during early winter. A 2007 study recorded dental anomalies such as missing teeth and supernumerary teeth. The rodent-like incisors help in killingvertebrate prey and searching for insects in crevices. The pattern of tooth eruption appears to be largely consistent in all caenolestids – the eruption of procumbent 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.
Ecology and behavior
Little is known of the behavior of the long-nosed caenolestid. It appears to be terrestrial and nocturnal. An omnivore, it feeds on insects and small invertebrates as well as plant material such as fungi. The caenolestid appears to live in burrows and fallen logs; nests may be used temporarily. Lactating females have been reported in May as well as from October to March.
Distribution and status
The long-nosed caenolestid occurs in temperate forests of Argentina and southern Chile, and up to altitudes of above the sea level. It prefers cool, moist areas. Known from less than 25 locations, it has a very small distribution. This shrew opossum also marks the southern limit of the distribution of caenolestids. Though locally abundant, the survival of the caenolestid is threatened by deforestation. Its population has declined by nearly 20% since the 1990s due to deforestation and human settlement. The IUCN classifies the long-nosed caenolestid as near threatened.
