Chinchilla chinchilla ( Lichtenstein, 1830 )

F., Pablo Valladares, Spotorno, Ángel E., M., Arturo Cortes & R, Carlos Zuleta, 2018, Chinchilla chinchilla (Rodentia: Chinchillidae), Mammalian Species 50 (960), pp. 51-58 : 51-56

Chinchilla chinchilla ( Lichtenstein, 1830)

Short-tailed Chinchilla

Eriomys chinchilla Lichtenstein, 1830 :plate 28. Type locality unknown; stated as Peru by Prell, 1934a:102 ( Osgood, 1941:410); Allen, 1942:391 states that Lichtenstein “implied that the specimen came from Chile, not Peru.”

Callomys aureus D’Orbigny and I. Geoffroy St. Hilaire, 1830: 289 . Chinchilla in their composite genus Callomys .

Lagostomus laniger: Wagler, 1831:614 . Part, not laniger G. I. Molina.

Lagostomus chinchilla: Meyen, 1833:586 . Name combination.

Chinchilla brevicaudata Waterhouse, 1848:41 . Type locality “ Peru.”

Chinchilla brevicaudata var. major: Trouessart, 1898:628 . Name combination.

Chinchilla boliviana Brass, 1911:613 . Type locality “aus Peruist sehr selten geworden. –Die fiensten Felle kommen aus der Gegend von Tacna und Arica.”

Chinchilla intermedia Dennler, 1939:95 . Holotype probably specimen 13037 from Museo Argentino de Ciencias

mission, by Agustían Iriarte, Nicolas Lagos, and Rodrigo Villalobos. Naturales “Bernardino Rivadavia,” type locality: Abra Pampa, National Breeding from Jujuy.

Chinchilla laniger boliviana: G. M. Allen, 1942:389 . Name combination.

Chinchilla laniger brevicaudata: G. M. Allen, 1942:389 . Name combination.

Chinchilla chinchilla chinchilla: Osgood, 1941:410 . First use of current name combination.

Chinchilla chinchilla boliviana: Osgood, 1943:136 . Name combination.

Chinchilla brevicaudata boliviana: Cabrera, 1960:201 . Name combination.

Chinchilla brevicaudata brevicaudata: Cabrera, 1960:201 . Name combination.

CONTEXT AND CONTENT. Order Rodentia , suborder Hystricomorpha , infraorderHystricognathi, familyChinchillidae, subfamily Chinchillinae . The family Chinchillidae ( Rodentia : Hystricognathi ) contains 3 genera: Chinchilla with 2 species ( C.chinchilla and C. lanigera ), Lagidium with 3 species ( L.ahua - caensis, L. viscacia , and L. wolffsohni ), and Lagostomus with 2 species ( L. crassus and L. maximus —Woods and Kilpatrick 2005; Ledesma et al. 2009; Spotorno and Valladares 2016). Chinchilla chinchilla is monotypic, although several other forms have been described for the high plateau of Perú, Bolivia, and Argentina. However, because C. chinchilla is now extremely rare in the wild and may be extirpated in the greater part of its pre-Columbian distribution, its taxonomic relationship to wild populations of C. chinchilla probably will never be confirmed.

NOMENCLATURAL NOTES. The genus Chinchilla and its species have had a controversial taxonomic history. Opinions differ in the number of species recognized: 1 ( Bennett 1829; Autran 1906; Osgood 1941) or 2 ( Cabrera 1961; Woods 1993; Spotorno et al. 2004a; Woods and Kilpatrick 2005) or 3 ( Bidlingmaier 1937; Prell 1934b), but according to Miller et al. (1983) this taxonomic issue can never be resolved because no wild populations of other putative species or subspecies are known.

Lichtenstein (1830) described Eriomys chinchilla from near Lima, Peru ( Prell 1934a; Osgood 1941, 1943), or probably north of Chile ( Allen 1942). Waterhouse (1848) described Chinchilla brevicaudata from Peru, but according to Osgood (1943), it was based on the same specimens as E. chinchilla Lichtenstein , evidently a renaming to avoid tautonomy. The northern chinchilla has received several names: Callomys aureus d’Orbigny and Geoffroy, 1830 ; Chinchilla major Trouessart, 1898 ; Chinchilla boliviana Brass, 1911 ; Chinchilla intermedia Dennler, 1939 ; Chinchilla lanigera boliviana Allen ; 1942 and Chinchilla lanigera brevicaudata Allen, 1942 ; Chinchilla chinchilla Prell, 1934b and Chinchilla boliviana Prell, 1934b ; Chinchilla c. chinchilla Osgood, 1941 and C. c. boliviana Osgood, 1943 ; Chinchilla brevicaudata brevicaudata Cabrera, 1961 and C. brevicaudata boliviana Cabrera, 1961 but these authors did not designate a type specimen. Cabrera (1960, 1961), Ipinza (1969), Tamayo and Frassinetti (1980), Woods (1993), Redford and Eisenberg (1992), and Spotorno et al. (2004 a, 2004b) recognized C. brevicaudata Waterhouse (1848) , but Anderson (1997) and Valladares (2002) recognized C. chinchilla ( Lichtenstein, 1830) for the “shorttailed” chinchilla species. Spotorno et al. (2004a) recognized 2 species based on molecular divergence in cytochrome- b gene sequences. Tate (1935) recognized Chinchilla as the genus and the species lanigera Molina , but he was not sure about the taxonomic position of C. chinchilla and C. brevicaudata .

Waterhouse (1848) described C. brevicaudata based on 3 specimens identified as E. chinchilla , 1 at the Berlin Museum (not seen by him) and 2 at the Leyden Museum, which he measured himself (C. Smeenk, in litt.). Both specimens were collected or obtained by D’Orbigny and Prévost and described as a new species by Waterhouse. D’Orbigny collected specimens in Bolivia between July 1830 and June 1833 and stayed in La Paz from 19 April to 27 June 1833, during which he arranged and packed his collections amassed during his various expeditions in the country. La Paz may have been only the place where the specimens were acquired or shipped rather than the exact collecting locality. Specimens obtained by Prévost from Chile are not further documented; the Leiden Museum received some mammals from him in 1835 and 1839. According to C. Smeenk (in litt.), both specimens were determined as syntypes (National Natuurhistorisch Museum, Leiden [RMNH.MAM.] 39393 and [RMNH.MAM.] 39394). On other hand, the specimen reviewed by Lichtenstein is deposited in the Museum für Naturkunde, Leibniz Institut for Research on Evolution and Biodiversity at the Humboldt University, Berlin, Germany, with number BZN1878; the label states E. chinchilla , collected by Salmin in Perú. Finally, the specimen reviewed by Bennett (1829) is deposited in the collection of the Department of Zoology (Mammal section) of the Natural History Museum of London (code GMCM 54a1— Valladares et al. 2014b).

In the absence of consensus on the priority of the species name, the matter was referred to the International Commission on Zoological Nomenclature (ICZN-case 3278), appealing to Article 23 of the International Comission on Zoological Nomenclature (1999) to establish the Law of Priority over the most commonly used name. This request was answered on 1 September 2003, stating that the specific epithet chinchilla is the oldest available for the species and is therefore valid (Valladares and Spotorno 2003). It was also suggested to determine a neotype for the Chinchilla genus ( Bennett 1829), for lanigera ( Molina 1782) and for chinchilla ( Lichtenstein 1830) to contribute to taxonomic stability.

DIAGNOSIS

Chinchilla chinchilla can be distinguished from the longtailed chinchilla C. lanigera by larger size (head and body length> 320 mm, shorter ears <32 mm, and tail <100 mm). It is distinguished by number of caudal vertebrae, 20 in C. chinchilla and 23 in C. lanigera ( Cabrera 1960) . The lengths of the humerus and radius (30.4 mm) are the same in both bones in C. lanigera , but are 35.5 and 39.0 mm, respectively, in C. chinchilla ; ulna length is 40.6 mm in C. lanigera , and 48.75 mm in C. chinchilla . Tibia length is almost double (1.92×) that of the radius in C. lanigera , but only 1.75× in C. chinchilla ( Cabrera 1960) . C. chinchilla is distinguishable from Lagostomus and Lagidium by its smaller size, head and body length 530–725 mm in Lagostomus ( Jackson et al. 1996) , and 360–505 in Lagidium ( Ledesma et al. 2009) .

GENERAL CHARACTERS

Chinchilla chinchilla ( Fig. 1 ) is among the smallest chinchillid rodents (means in mm; n = 6; specimens from Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” [specimens MACN-Ma13037, 16267, 16268, 20430–20432, most from Abra Pampa, Jujuy, Argentina]): head and body length, 243.36; length of tail, 73.73; length of hind foot, 127.27. Condylobasal length is 60.86 mm, greatest width of skull across the zygomatic arches is 35.38 mm, interorbital width is 12.44 mm, mastoid width is 33.55 mm, and length of upper molar toothrow is 13.78 mm. Specimens from Abaroa, Region de Antofagasta, Chile (n = 2): length of ear, 31.27 mm, weighing 500–850 g; the female is the larger sex and males rarely weigh over 600 g.

The silky pelage of long soft hairs that are up to 35mm in length is extremely dense ( Grau 1986; Albert 1900) and considered one of the most valuable furs in the world ( Jiménez 1996). The general coloration of the dorsum is bluish, pearl, or brownish gray, and each hair usually has a black tip. The venter is a clear, yellowish white. The furry tail is covered with coarse hairs on the dorsal surface.

The head is broad, with vestigial cheek pouches, and the pinnae, rounded with a covering of tiny hairs ( Waterhouse 1848). The skull ( Fig. 2 ) has greatly expanded auditory bullae. Means (mm) of 4 specimens from Laboratorio de Citogenética de Mamiferos, specimens 2360 and 2338 (Abaroa, Region de Antofagasta, Chile) and specimens 1898 and 1862 (Region de Antofagasta, Chile) were: bullar width, 13.18; bullar height, 24.5; greatest width of skull across the parietals including the external bullae, 31.9. The forefoot is short, with 5 digits and stiff bristles surrounding weak claws and each hind foot has 1 rudimentary and 3 normal digits.

DISTRIBUTION

The former distribution of Chinchilla chinchilla was indeed extensive, including the highlands of Chile, Argentina, Peru, and Bolivia (Chacón 1892; Autran 1906; Walle 1914; House 1953; Grau 1986; Jiménez 1996; Anderson 1997; Parera 2002; Woods and Kilpatrick 2005). But today it is extant only in Chile, specifically near the towns of El Laco (23°44 ′ S and 67°28 ′ W) and Morro Negro (25°00 ′ S and 68°45 ′ W); both are near the Llullaillaco volcano, in the Antofagasta region ( Spotorno et al. 1998; Spotorno et al. 2004b; Tirado et al. 2012) and recently in the vicinity of Nevado Tres Cruces National Park (26°49 ′ 11 ″ S and 69°05 ′ 67 ″ W) in the Atacama region ( Valladares et al. 2012; Fig. 3 ). In the past, wild populations of C. chinchilla were known from northern Chile, for example, the highlands of Arica ( Autran 1906), Mejillones (Phillipi 1860), Licancabur volcano ( Rudolph 1955), and La Ola and Potrerillos ( Schlatter et al. 1987). Grau (1986) suggested that both Chinchilla species may have coexisted in sympatry near Potrerillos (north of Atacama region), which corresponds to the northern limit of the geographic distribution of C. lanigera and the southern limit for C. chinchilla .

In Argentina, historical populations of C. chinchilla are known from near Antofalla, Catamarca ( Autran 1906; Walker et al. 2007), in southwestern Jujuy (Olrog and Lucero 1981; Autran 1906), Salta ( Autran 1906; Ortiz et al. 2010), La Rioja ( Parera 2002), and North of San Juan ( Cajal et al. 1981). In Bolivia, its former distribution reached the districts of La Paz, Oruro, and Potosi ( Anderson 1997), with the last wild specimens being captured by residents of Huachacalla, Sabaya, and Caranga ( Autran 1906; Walle 1914) and Lipez ( Autran 1906). However, a small population was found recently within the National Reserve of Andean Fauna “Eduardo Avaroa,” in the Department of Potosí, specifically in the Laguna Colorada basin ( Delgado et al. 2018).

FORM AND FUNCTION

The relatively broad head of Chinchilla chinchilla has the greatest width of skull across the zygomatic arches (means, n = 4; head with skin include, 36.57 mm; skull, 34.24 mm). The mandible lacks a masseteric crest. The canal of the large lacrimals opens on the side of the rostrum. The short paraoccipital process is attached to the auditory bulla. As in Chinchilla lanigera , each auditory bulla is extremely inflated, having 3 large vesicular protuberances: a nearly hemispherical superior, an oblong posterior, and pyriform inferior protuberance. The dental formula of the hypsodont teeth is i 1/1, c 0/0, p 1/1, m 3/3, total 20. The occlusal surface is composed of 3 closely packed lamellar plates. The laminae of the cheek teeth are widened and fused, with the enamel of each loph being strengthened on the anterior side but weakened on the posterior side in the upper cheek teeth, with the reverse occurring in the lower cheek teeth (Glanz and Anderson 1990). The enamel of the delicate incisors is usually dark yellow.

The well-developed hind limb is longer than the forelimb. Means (mm) of long bones of the limbs include humerus (35.5), radius (39.0), ulna (48.75), femur (58.25), and tibia (68.25— Cabrera 1960). The vertebral formula is 7 C, 13 T, 6 L, 2 S and 20 Ca, total 48 ( Cabrera 1960).

Chinchilla chinchilla has longer dorsal hairs than C. lanigera , up to 35 mm ( Albert 1900). Hairs of the dorsum are bluegray at the root, with a distal broad white tinge and dark gray at the tip, producing a silvery gray tint suffused with black. The venter, inner surfaces of limbs, and feet are whitish. The tail has 2 dark bands on its upper surface ( Waterhouse 1848).

The basal metabolic rate is 0.498 ± 0.068 ml O 2 /g h, equivalent to 67.2% of the predicted value for a mammal of similar size ( Kleiber 1961; Cortés et al. 2003). The lower critical temperature (T lc) is 22°C. In a He–O 2 atmosphere the relationship of metabolic rate versus ambient temperature (T a) was MR (ml O 2 /g h) = 2.28 − 0.0544 T a, during which the thermal conductance (C He) reached 0.0544 ml O 2 /g h. When ambient temperature was lowered to −7.5°C in an artificial atmosphere, metabolic rate fell 16.9% with respect to the maximum metabolic rate of 2.52 ± 0.005 ml O 2 /g h, indicating that the thermoregulatory capability was exceeded. The aerobic metabolic expansivity, calculated as the ratio Maximum Metabolic Rate/Basal Metabolic Rate (MMR/BMR), was 5.1 (Cortés et al. 2003). The relation MMR/ C (thermal conductance) = T b (body temperature) − T LL (calculated theoretical lower lethal temperature) gave a theoretical critical lethal temperature (Bozinovic and Rosenmann 1989) of −67.8°C (Cortés et al. 2003), close to the value of −65.0°C obtained by extrapolating maximum metabolic rate (He–O 2) on the regression curve of metabolic rate versus ambient temperature in normal air (Rosenmann and Morrison 1974; Cortés et al. 2003).

Minimum values of evaporative water loss were 0.498 ± 0.014 mg H 2 O/g h within the ambient temperature range of ≤ 20°C, while the averages of evaporative water loss at 25°C, 30°C, and 32.5°C were 0.604, 0.820, and 1.105 mg H 2 O/g h, representing increases over the minimum of 20%, 65%, and 120%, respectively (Cortés et al. 2003). At the highest experimental temperature, evaporative water loss was equivalent to only 24.6% of the basal rate of heat production (2.39 cal/g h—Cortés et al. 2003). The low cooling capability was reflected in a body temperature increase of 1.1°C above the normothermic condition (38.7°C versus 37.6°C), a value within that expected for xeric rodents (Cortés et al. 2000b). The low evaporative water loss may have unfavourable consequences at high temperatures where evaporative heat loss is important; for example, at an ambient temperature of 32.5°C, C. chinchilla was able to reduce evaporative water loss to only one-fourth that of metabolic heat production, which was reflected by a body temperature increase of 1.1°C. The efficiency index of water regulation for C. chinchilla (T a @) was 10.6°C. Replacing T a = 10.6°C in the regression equation (MR = 1.022 − 0.0239 T a), a value of 3.71 cal/g h is obtained; this is the energetic cost of maintaining water balance in C. chinchilla , indicative of a slightly lower efficiency compared with other Chilean rodents from mesic and xeric habitats (Cortés et al. 2000a; Cortés et al. 2003). Nevertheless, the energetic cost of maintaining water balance, MR-WB = 3.71 cal/g h, was similar to or lower than the values reported for other desert rodent species (Cortés et al. 2003).

Elevated hemoglobin oxygen affinity is a blood property considered an evolutionary adaptation in mammals living at high elevation (Monge and León-Velarde 1991) because hypoxic environments exert strong selective pressures on oxygen levels. Hemoglobin affinity in Chinchilla correlates positively with elevation ( Ostojic et al. 2002). C. chinchilla has a higher hemoglobin oxygen affinity (23.3 ± 0.06 mmHg) than C. lanigera (27.7 ± 0.03 mmHg—Ostojic et al. 2002).

ONTOGENY AND REPRODUCTION

In optimal conditions, wild Chinchilla chinchilla can produce 1 litter in October, January, and April ( Albert 1900). Gestation in chinchillas from Bolivia and northwestern Argentina is 105–111 days ( Dennler 1940). C. chinchilla can become sexually mature as early as 5.5 months, but the average is closer to 8 months ( Chébez 1994). Births take place between February and March, and August to December, with a higher proportion of births in September. The 1st estrus and subsequent copulations occur in April, being more common from mid-May to July, and then between October and December, fully declining in February, when females have given birth ( Dennler 1940). The semi-precocial neonates weigh about 35 g, are fully, have open eyes, and are able to creep under the mother’s body for warmth while she dries them. Females have 1 pair of inguinal and 2 pairs of lateral thoracic mammae. Neonates can eat plant food, which creates a smooth transition during weaning at about 6 weeks ( Cockrum 1962). Experimental breeding in captivity is difficult, resulting in high percentages of sterility ( Genta 1987). Some crosses between C. lanigera and C. chinchilla have been produced during captive breeding ( Grau 1986).

ECOLOGY

Chinchilla chinchilla lives in areas of montane grassland and scrub, habitats similar to those of the viscacha, Lagidium ( Mann 1978) . Its natural habitat is the relatively barren areas of the Andes Mountains at elevations of 3,000 –5,000 m. It usually shelters in crevices and holes among the rocks.

Chinchilla chinchilla in the wild eats similar plants to Lagidium , essentially Festuca and Districhia grasses and Senecio and Parastrephia shrubs ( Mann 1978). Populations of C. chinchilla from the Antofagasta region (Morro Negro, 25°00 ′ S and 68°45 ′ W; El Laco, 23°44 ′ S and 67°28 ′ W) are associated with Parasthrephia lepydophylla, P. quadrangularis , Baccharis incarum, Chuquira gaulicina, and Adesmia horrida ( Spotorno et al. 1998) , Baccharis tola , Adesmia caespitosa , A. erinacea , Fabiana byroides , Stipa chrysophylla , and Cristaria andicola ( Tirado et al. 2012) , with preferences in diets for S. chrysophylla (59.1% of plant consumption). Populations are sympatric with the ashy chinchilla rat— Abrocoma cinerea , yellow-rumped pericote— Phyllotis cf xanthopygus, Andean akodont— Abrothrix andinus dolichonyx , and guanaco— Lama (glama) guanicoe ( Spotorno et al. 1998; Tirado et al. 2012). The habitat for the Atacama populations includes a stream with boulders, mediumsized caves, and sparse scrub vegetation of Stipa frigida and Senecio volckmannii ( Valladares et al. 2012) . Other species of sympatric rodents were the yellow-rumped pericote and Andean akodont. Another population was detected at a northern site, near Santa Rosa lagoon (26°49 ′ 11 ″ S and 69°05 ′ 67 ″ W, 4,000 m), corresponding to the northern area of the National Park where remains of a jaw and feces were found. The principal predator in the 3 recognized populations is Lycalopex culpaeus , the Andean fox.

HUSBANDRY

According to Genta (1978), Chinchilla chinchilla was bred from 1927 in the Andean locality of Jujuy, Argentina, specifically at Estación Zootécnica de Miraflores, Abra Pampa. Founded by 1 wild male and 4 wild females, by 1972 the laboratory colony numbered about 400. The “Atahualpa Breeding of Chinchillas S.A.” program in Cochi Viejo, Chile, begun in 1931, had over 500 animals in 1949. In 1934, Juan Abaroa began breeding C. chinchilla in Calama, Antofagasta region of Chile, with “Atahualpa” specimens. Now named “Abaroa Breeding” this is the only surviving breeding colony. García-Mata (1976) bred C. chinchilla both from the Abra Pampa (Jujuy, Argentina) colony and from a private breeding colony in Coropuna (Arequipa, Perú), with obvious differences between these lineages. The specimens from Abra Pampa were named “de Bolivia ” or “real segunda” and the Peruvian chinchillas were named “indianas.”

GENETICS

Chinchilla chinchilla has a diploid number (2n) of 64 chromosomes, all of which are biarmed ( Vidal et al. 1973). Partial cytochrome- b gene sequences from mitochondrial DNA of C. chinchilla show a substantial molecular divergence with C. lanigera ( Spotorno et al. 2004a) . Mean molecular distances between both species had a mean value of 5.9% (range 4.9– 6.2%). For the 3rd codon position, 8 sites had character states that were exclusive and diagnostic for C. chinchilla . No unique variant associated with C. chinchilla was detected in any of the 5 specimens of domestic C. lanigera . Sequences of the domestic C. chinchilla were similar to those of their wild counterparts. Domestic specimens exhibited the lowest diversity within the sample, with genetic distances of about 0.1%. Both C. lanigera and C. chinchilla emerge as molecularly distinct and geographically divergent species ( Spotorno et al. 2004a), which agrees with previous morphological studies ( Cabrera 1960) and with the reported male sterility of their hybrids ( Grau 1986).

CONSERVATION

The critical conservation status for both Chinchilla species is due to human hunting for the fur trade; at the beginning of the 20th century> 20 million specimens were killed in Chile alone (Iriarte and Jaksic 1986; Albert 1900, 1901). Although both species were considered extinct during the 1960s, C. lanigera populations were rediscovered by Mohlis in 1983, Spotorno et al. (2004a), and Valladares et al. (2014a), and C. chinchilla populations were rediscovered by Spotorno et al. (1998) and Valladares et al. (2012).

A genuine massacre of chinchillas on both sides of the Andes began around 1900 when fur traders demanded large numbers of skins to meet commitments to European furriers. Indians, miners, and others (“chinchilleros”) left their jobs and dedicated themselves to hunting chinchillas ( Albert 1901; Autran 1906). Forms of hunting were diverse, ranging from the use of dogs and a mustelid named “quique” (lesser grisson— Galictis cuja ) to burning thorny shrubs to force them from their burrows. Some hunters used a dead-fall trap, by which a large rock crushed the chinchilla. In the late 19th and early 20th century, one-half million chinchilla skins were exported annually from Chile ( Albert 1901). The carnage was much greater than the export numbers because only one-third of the chinchilla skins were suitable for purchase ( Albert 1901). Skins exported through Buenos Aires included those coming from Bolivia ( Autran 1906). With this level of exploitation, C. chinchilla became commercially extinct in Argentina, Chile, and Bolivia within a few years.

Cofré and Marquet (1999) cataloged C. chinchilla in an “Endangered” category based on a Priority Conservation Index. According to these authors, C. chinchilla has a geographical distribution of 85,000 km 2, with a local abundance of 63.1/km 2, and inhabits 2 countries ( Argentina and Chile). There are still doubts about its current distribution, because only 3 populations are known ( Valladares et al. 2012). For a long time, it was considered extinct in Peru and Bolivia ( Honacki et al. 1982; Bernal and Silva 2003; Tarifa 2009; Anderson 1997), but today Bolivia considers C. chinchilla as “Critically Endangered,” because wild populations were recently documented in the southern region of Potosi ( Delgado et al. 2018). In Perú, it was listed as “Critically Endangered” by Supreme Decree Nº 034-2004- AG, although there were no data supporting its presence. In Argentina, C. chinchilla is listed as “Critically Endangered” by Diaz and Ojeda (2000), Chébez and Oliveras (2008), and Ojeda (2012). Interestingly, no wild specimen has been recently collected in these regions, and C. chinchilla is currently classified as “Endangered” or “Critically Endangered,” but not “Extinct” by Perú and Argentina ( Valladares et al. 2014b).

In Chile, C. chinchilla has been evaluated as “Endangered” by the Regulation of the Law of Hunting (Servicio Agrícola y Ganadero 2012). In 1988, the Corporación Nacional Forestal published the Red Book of Vertebrates in Chile, cataloging C. chinchilla as “Endangered.” For Muñoz-Pedreros and Gil (2009), this species is “Extinguished” in the Tarapacá region, and “Endangered” in the Antofagasta and Atacama regions.

In any case, C. chinchilla is classified as “Critically Endangered” by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (http://cites.org/ eng/resources/species.html), by the International Union for Conservation of Nature and Natural Resources (D’Elia and Ojeda 2008), and by the Evolutionary Distinct and Globally Endangered program (EDGE, www.edgeofexistence.org/mammals/top_100.php). Without urgent conservation actions and further surveys to establish the locations of other wild populations, this species truly is on the edge of extinction. It is noteworthy that in the 100 years since commercial hunting ended the remnant populations have not substantially recovered by expanding into large areas of their former distribution.

Recently discovered populations are small and isolated (Spotorno et al. 2004; Lagos et al. 2012; Valladares et al. 2012; Delgado et al. 2018). Such highly fragmented and small mammalian populations generally have low genetic diversity and a high level of inbreeding, associated with reductions in fitness, further increasing the risk of extinction (Keller and Waller 2002). Currently, the principal threat to the wild C. chinchilla is the relationship between its populations and exploitation and mining prospecting ( Valladares et al. 2014b).

Figures

Fig. 1.—Adult wild Chinchilla chinchilla from Nevado Tres Cruces National Reserve, Atacama region, Chile. Photograph, used with per-

Fig. 2.—Dorsal, ventral, and lateral views of skull and lateral view of mandible of an adult female Chinchilla chinchilla (LCM [Laboratorio de Citogenética de Mamíferos, Facultad de Medicina, Universidad de Chile, Santiago, Chile] 1898) from El Laco, 56 km southeast Socaire, II Región de Antofagasta, Chile. Occipitonasal length is 58.2 mm. Photograph by A. Spotorno O.

Fig. 3.—Past distribution (gray area) of Chinchilla chinchilla according to Grau (1986) and current localities of wild populations according to different authors. 1—Delgado et al. 2018; 2—Rudolph 1955; 3—Spotorno et al. 1998; 4—Spotorno et al. 2004; 5—“Salares 7” from Salares Lithium Company; 6—“Salares Norte Mining” from Golds Fields Salares Norte Company; 7—Schlatter et al. 1987; 8 and 9—Valladares et al. 2012; and 10—Lagos et al. 2012. Open circles correspond to colonies not confirmed by us.