ARTICULOS Y NOTAS

A new northern distribution limit of Abrocoma bennettii (Rodentia, Abrocomidae) in the coastal Atacama desert, Paposo, north of Chile

 

Jonathan A. Guzmán¹ and Walter Sielfeld²

¹ Departamento de Ciencias Básicas, Campus los Ángeles, Universidad de Concepción, Chile [Correspondence: Jonathan Guzmán <jonathanguzman@udec.cl>].
² Laboratorio de Zoología, Universidad Arturo Prat, Casilla 121, Iquique, Chile

 

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ABSTRACT: Abrocoma bennettii is a relatively robust abrocomid rodent endemic to Chile.  It is distributed from approximately 27°18'S - 70°25'W in the north (Atacama) to 36°00'S - 73°7'W in the south (BíoBío). We report the finding of a cranium in excellent conditions, which is the first record of this species in the coastal shrubby Mediterranean desert of the Antofagasta Region.  The record of A. bennettii in the locality of Paposo (25º00'S - 70º27'W; 648 m) represents an extension of about 280 km to the northeast of its previously known distribution in the Atacama Region of Chile.

RESUMEN: Nuevo límite distribucional norte de Abrocoma bennettii (Rodentia, Abracomidae) en el desierto costero de Atacama, Paposo, norte de Chile. Abrocoma bennettii (Abrocomidae) es un roedor relativamente robusto y endémico de Chile. Se distribuye aproximadamente entre los 27°18'S - 70°25'W por el norte (Atacama), a los 36°00'S - 73°7'W por el sur (Bio Bio). A través de un cráneo hallado en excelentes condiciones, se informa por primera vez a la especie en el desierto arbustivo mediterráneo costero de la Región de Antofagasta. El registro de A. bennettii en la localidad de Paposo (25º00'S - 70º27'W; 648 m), representa una extensión cercana a 280 km al noroeste de la distribución previamente conocida en Chile.

Key words. Abrocoma bennettii; Coastal desert; Distribution; Paposo.

Palabras clave. Abrocoma bennettii; Desierto costero; Distribución; Paposo.

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The South American endemic genus Abrocoma (family Abrocomidae) is distributed from Peru, Bolivia and north of Chile to Mendoza Province in central-west Argentina (Braun and Mares, 2002; Musser and Carleton, 2005). In Chile, Abrocoma comprises two currently recognized living species: A. cinerea from the Altiplano highlands of Arica-Parinacota and Antofagasta Regions; and A. bennettii from Copiapó to almost the BioBio River in southern Chile. A. bennettii is a relative big abrocomidae rodent (>80 g) being eaten in central Chile by raptorial birds such as Athene cunicularia and carnivores such as Lycalopex culpaeus (Meserve et al., 1987). Special traits of this species are the prominent ears and a soft, silky, and brandish pelage of general brownish gray color with the underparts being mainly brownish (Osgood, 1943). Under the protection of large rocks, the species constructs large superficial galleries, where it lives in colonies of 2 to 10 individuals (Mann, 1978). It is a nocturnal and mostly herbivorous species which eats the foliage and seeds of a narrow range of species compared to other caviomorphs such as Octodon degus (Meserve, 1981; Meserve et al., 1983). The A. bennettii species complex comprises two currently recognized form: A. bennettii bennettii in central Chile from the Province of Elqui to the Province of Concepción (Coquimbo to Bío-Bío Regions, respectively); and A. bennettii murrayi in the Provinces of Huasco (Atacama Region) and Elqui (Osgood, 1943; Tamayo and Frassinetti, 1980). Both subespecies are distinguishable on the basis of its quality and differences in pelage coloration. The septentrional form is paler and more grayish with its pelage softer and having longer hairs, meanwhile, A. bennettii bennettii is more brownish gray with its underparts mainly brownish rather than whitish gray (Wolffsohn, 1927; Osgood,1943). A. bennettii murrayi was described by Wolffsohn (1916) from Vallenar (Huasco Province, Coquimbo Region) on the basis of a living male adult specimen sent by Sir John Murray, and that Wolffsohn named in his honour. In two studies of 1921 and 1923, Wolffsohn listed more specimens and measurements of Abrocoma bennettii murrayi from Vallenar. Osgood (1943) studied two fragmentary skulls from an owl stomach taken at Ramadilla (west of Copiapó). This finding represents further evidence of the northward extension of the murrayi race. Additionally, Osgood (op. cit.) reported 18 specimens from four localities near of Vallenar (Vallenar and Domeyko) and Coquimbo (Paiguano and Romero) in central Chile. This distribution is confirmed by three specimens taken by Donoso-Barros in 1972 and determinated by Reise from a chañar forest in Los Loros, Copiapó, which are deposited in the Zoology Museum of the Concepción University in Chile (MZUC 5130, MZUC 5131, MZUC 5132). During the last three decades no new localities have been informed from the north of Atacama Region, neither in reviews (e.g. Mann, 1978; Muñoz-Pedreros and Yáñez, 2000; Muñoz-Pedreros et al., 2004; Iriarte, 2008) nor in publications concerning the feeding ecology of carnivors and birds of prey (Simonetti et al., 1984; Marquet et al., 1993; Jaksic et al., 1999; Carmona and Rivadeneira, 2006; Guzmán et al., 2007).

Here, on the basis of a well preserved skull (JG - 311; Fig 1) found in august 1999 near Paposo (25º00'25,88"S / 70º27'04,9"W; altitude 648 m) (Antofagasta Region) and determined as A. bennettii murrayi, we extend the distribution for this form northwards for at least 280 km until the Province of Antofagasta (Fig 2). Thus the Paposo skull represents a new septentrional distribution for this abrocomid species. Skull, mandible, and the characteristic upper and lower molars coincide with specimens deposited in MZUC - UCCC and with published descriptions and figures (Wolffsohn, 1916; Osgood, 1943 figure 11; Mann, 1978, figure 249). Measurements were taken with a digital micrometer and are (in mm): condylobasal length=4.4; breadth across the zygomatic arches= 22.3; length of palate= 25.8; interorbital breadth= 8.5; length of mandible to the condyloidnprocess= 27.9; length of mandible to angular process=30.8; interorbital height= 11.5; length of the maxillary diastema= 13.7; length of the mandibular diastema= 8.4; length of maxillary toothrow= 10.2; length of mandibular toothrow= 9.3.

Fig. 1. Skull of Abrocoma bennettii murrayi (collected by Walter Sielfeld) from Paposo, Región de Antofagasta: (A) dorsal view; (B) ventral view; (C) lateral view; (D) lateral view of left lower jaw. The scale-bar represents 10 mm.

Fig. 2. Localities of record and new locality for Abrocoma bennettii murrayi in Paposo, coastal desert in the north of Chile.

The Bennett´s chinchilla rat inhabits rocky matorral and shrublands from the sea level and coastal canyons to 2000 meters in the Andes (Mann, 1978). The study site, Paposo (50 km N of Taltal), has a shrub cover dominated mostly by cacti (Copiapoa cinerea [Phil.] Britton et Rose, Eulychnia iquiquensis [Schumann] Britton et Rose, Echinopsis deserticola [Werderm] Friedrich et G.D. Rowley and Trichocereus coquimbanus [Mol.] Britton et Rose) and Euphorbia lactiflua Phil., a large succulent shrub. Also there is Puya boliviensis Baker (Bromeliaceae) under which we collected the skull here described. This is the typical vegetation of coastal desert zones in northern Chile, that are influenced by fog whereas yearly precipitation averages 15 mm, being evenly distributed throughout the year (Jaksic et al., 1999). This zone is referred as the "region of matorral" described by Mann (1960) and also named as "Mediterranean coastal desert of Euphorbia lactiflua and Eulychnia iquiquensis" by Luebert and Pliskoff (2006), where Paposo is historically considered the northern limit, while the southern limit is 30°S, coinciding with the limits of A. bennettii murrayii that is replaced by A. bennettii bennettii. However, it has been recently shown by Sielfeld et al. (1995), Muñoz et al. (2001), Pinto (2009) and Pinto and Luebert (2009) that this mediterranean coastal shrub desert extends much far north to Cerro Camaraca (south of Arica), in a discontinous way, restricted to "camanchaca" fog dominated places of the coastal hills.

Other rodent species inhabiting the Paposo area are Thylamys elegans, Abrothix olivaceus and Phyllotis darwini, all typically central Chile species (Meserve and Glanz, 1978; Spotorno et al., 1998).

Our finding shows once more the urgent necessity to intensify the faunistic research of northern Chile's coastal desert.

Acknowledgements. We wish to acknowledge Mr. Simon Pfanzelt and the anonymous referees for critical comments on the manuscript.

LITERATURE CITED

1. BRAUN JK and MA MARES. 2002. Systematics of the Abrocoma cinerea species complex (Rodentia: Abrocomidae), with a description of a new species of Abrocoma. Journal of Mammalogy 83:1-19.         [ Links ]

2. CARMONA ER and MM RIVADENEIRA. 2006. Food habits of the barn owl Tyto alba in the National Reserve Pampa del Tamarugal, Atacama Desert, North Chile. Journal of Natural History 7-8:473-483.         [ Links ]

3. GUZMAN-SANDOVAL J, W SIELFELD, and M FERRU. 2007. Dieta de Lycalopex culpaeus (Mammalia: Canidae) en el extremo norte de Chile (Región de Tarapacá). Gayana (Chile) 71:1-7.         [ Links ]

4. IRIARTE A. 2008. Mamíferos de Chile. Lynx Edicions. Barcelona, España. 420 pp.         [ Links ]

5. JAKSIC FM, JC TORRES-MURA, C CORNELIUS, and PA MARQUET. 1999. Small mammals of the Atacama Desert (Chile). Journal of Arid Environments 42:129-135.         [ Links ]

6. LUEBERT F y P PLISKOFF. 2006. Sinopsis bioclimática y vegetacional de Chile. Editorial Universitaria, Santiago. 316 pp.         [ Links ]

7. MANN G. 1978. Los pequeños mamíferos de Chile. Gayana, Zoología 40:1-342.         [ Links ]

8. MANN G. 1960. Regiones biogeográficas de Chile. Investigaciones Zoológicas de Chile 6:15-49.         [ Links ]

9. MARQUET PA, LC CONTRERAS, JC TORRES-MURA, SI SILVA y FM JAKSIC. 1993. Food habits of Pseudalopex foxes in the Atacama desert, pre-Andean ranges, and the high Andean plateau of northernmost Chile. Mamalia 57:130-135.         [ Links ]

10. MESERVE P. 1981. Trophic Relationships among Small Mammals in a Chilean Semiarid Thorn Scrub Community. Journal of Mammalogy 62:304-314.         [ Links ]

11. MESERVE P, R MARTIN, and J RODRIGUEZ. 1983. Feeding Ecology of Two Chilean Caviomorphs in a Central Mediterranean Savanna. Journal of Mammalogy 64:322-325.         [ Links ]

12. MESERVE P, E SHADRICK, and D KELT. 1987. Diets and selectivity of two Chilean predators. Revista Chilena de Historia Natural. 60:93-99.         [ Links ]

13. MESERVE P. and E, GLANZ. 1978. Geographical Ecology of Small Mammals in the Northern Chilean Arid Zone. Journal of Biogeography 5:135-148.         [ Links ]

14. MUÑOZ-PEDREROS A, and JL YAÑEZ. 2000. Mamíferos de Chile. Ediciones CEA, Valdivia Chile. 464 pp.         [ Links ]

15. MUÑOZ-PEDREROS A, J RAU, and J YÁÑEZ. 2004. Aves Rapaces de Chile. CEA Ediciones. Valdivia, Chile. 387 pp.         [ Links ]

16. MUSSER GG and MD CARLETON. 2005. Superfamily Muroidea. Pp. 894-1531, in: Mammal Species of the World. A taxonomic and geographic reference (DE Wilson and DM Reeder, eds.). Third Edition. 2 vols. Baltimore: The Johns Hopkins University Press, 2141 pp.         [ Links ]

17. MUÑOZ-SCHICK M, R PINTO, A MESA, and A MOREIRA-MUÑOZ. 2001. "Oasis de neblina" en los cerros costeros del sur de Iquique, región de Tarapacá, Chile, durante el evento El Niño 1997-1998. Revista Chilena de Historia Natural 74:389-405.         [ Links ]

18. OSGOOD WH. 1943. The mammals of Chile. Field Museum of Natural History, Zoological Series 30:1-268.         [ Links ]

19. PINTO R and F LEUBERT. 2009. Datos sobre la flora vascular del desierto costero de Arica y Tarapacá, Chile y sus relaciones fitogeográficas con el sur de Perú. Gayana Botánica 66:29-50.         [ Links ]

20. PINTO R. 2009. Cactus del extremo norte de Chile. AMF, Santiago, Chile. 246 pp.         [ Links ]

21. SIELFELD W, E MIRANDA, and J TORRES. 1995. Información preliminar sobre los Oasis de Niebla de la costa de la Primera Región de Tarapacá. Programa de Recursos Hídricos y Naturales Renovables, Informe Técnico, Universidad Arturo Prat, Iquique, 55 pp.         [ Links ]

22. SIMONETTI JA, A POIANI, and KJ READEKE. 1984. Food habits of Dusicyon griseus in northern Chile. Journal of Mammalogy 65:515-517.         [ Links ]

23. SPOTORNO A, C ZULETA, A GANTZ, F SAIZ, J RAU, M ROSENMANN, A COSTES, G RUIZ, L YATES, E COUVE, and J MARIN. 1998. Sistemática y adaptación de mamíferos, aves e insectos fitófagos de la Región de Antofagasta, Chile. Revista Chilena de Historia Natural 71:501-526.         [ Links ]

24. TAMAYO M and D FRASSINETTI. 1980. Catálogo de los mamíferos fósiles y vivientes de Chile. Boletín del Museo Nacional de Historia Natural (Chile) 37:323-399.         [ Links ]

25. WOLFFSOHN JA. 1916. Description of a new rodent from Central Chile. Revista Chilena de Historia Natural 20:6-7.         [ Links ]

26. WOLFFSOHN JA. 1921. Catalogo de cráneos de mamíferos de Chile colectados entre los años 1896 y 1918. Revista Chilena de Historia Natural 25:511-529.         [ Links ]

27. WOLFFSOHN JA. 1923. Medidas máximas y mínimas de algunos mamíferos chilenos colectados entre los años 1896 y 1917. Revista Chilena de Historia Natural 27:159-167.         [ Links ]

28. WOLFFSOHN JA. 1927. Los Octodontidos de Chile. Revista Chilena de Historia Natural 31:97-101.         [ Links ]

Recibido 17 octubre 2010.
Aceptado 3 marzo 2011.
Editor asociado: UFJ Pardiñas