Distribution of Pseudoryzomys Simplex (Rodentia: Cricetidae) in Argentina

Ulyses F.J. Pardiñas¹, Sebastian Cirignoli² y Carlos A. Galliari³

¹Área Geología y Paleontología, Centro Nacional Patagónico, Casilla de Correo 128, 9120 Puerto Madryn, Chubut, Argentina; <ulyses@cenpat.edu.ar>. ²Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, calles 122 y 60, 1900 La Plata, Argentina. ³Jardín Zoológico y Botánico de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina

ABSTRACT. We report new records for the poorly known sigmodontine rodent Pseudoryzomys simplex in Argentina, totalizing 28 recording localities (Formosa, Chaco, and Santa Fe provinces). The southern limit of the species is about 30ºS and its distribution, in Argentina, is mainly restricted to the Eastern Chaco biome.

Key words: Sigmodontinae, Oryzomyini, Neotropics, biogeography

RESUMEN. Distribución de Pseudoryzomys simplex (Rodentia: Sigmodontinae) en la Argentina. Se presentan nuevos registros para el roedor sigmodontino Pseudoryzomys simplex en Argentina, totalizando 28 localidades conocidas (provincias de Formosa, Chaco y Santa Fe). El límite sur de la especie se encontraría hacia los 30ºS y su distribución, en Argentina, se restringe principalmente al Chaco oriental.

Palabras clave: Sigmodontinae, Oryzomyini, Neotrópico, biogeografía

Pseudoryzomys simplex (Winge, 1887) is an oryzomyne rodent widely distributed in tropical and subtropical lowlands of South America. Following Voss and Myers (1991), collecting localities indicate that P. simplex is distributed in eastern Bolivia, eastern and central Brazil, western Paraguay, and northeastern Argentina. Despite this large distribution, the species is poorly known, and only a few specimens are housed in museum collections (Voss and Myers, 1991).
   Massoia (1976) reviewed the knowledge of this rodent in Argentina mentioning only three localities, one of which was earlier mentioned by Hershkovitz (1959), from the provinces of Formosa and Chaco. Later, Contreras and Berry (1982) reported additional specimens from Chaco province.
   Analyses of Barn Owl (Tyto alba, Tytonidae, Strigiformes) pellets and recent trapping at several localities show an unexpected frequency and wide distribution of P. simplex in northeastern Argentina. The studied specimens can be referred to this species by the following combination of morphological characters: short rostrum, narrow interorbital region, long palate with prominent posterolateral palatal pits, low crowned molars, first upper and second molars with small mesolophs (see Voss and Myers, 1991). Our data plus an extensive bibliographic survey indicate the following geographic distribution of this rodent in Argentina (localities arranged by increasing latitude; the studied material is housed at the Centro Nacional Patagónico Mammal Collection, Puerto Madryn, Argentina [CNP]; Fig. 1):

Fig. 1.Recording localities of Pseudoryzomyssimplex in Argentina (see the main text for identification of numbers).

Localidades de registro para Pseudoryzomys simplex en Argentina (véase el texto para el detalle numérico).

1. Río Porteño, Misión Tacaaglé (24º 56’ S, 58º 46’ W, Department Pilagás, Province of Formosa): one trapped specimen reported by Hershkovitz (1959, 1962; see also Voss and Myers, 1991);
2. Abadie-cué, RíoPilcomayoNational Park (25º 08’ S, 58º 08’ W, Department Pilcomayo, Province of Formosa): several trapped specimens reported by Heinonen Fortabat (in press);
3. Laguna Naick Neck (25º 13’ S, 58º 07’ W, Department Pilcomayo, Province of Formosa): remains from owl pellets reported by Heinonen Fortabat (in press);
4. Estancia Guaycolec (25º 58’ 39” S, 58º 11’ 40” W, Department Formosa, Province of Formosa): remains from owl pellets reported by Massoia et al. (1997);
5. Reserva Ecológica El Bagual (26º 10’ S, 58º 56’ W, Department Laishi, Province of Formosa): several trapped specimens reported by Pardiñas and Teta (in press);
6. Villa Dos Trece (= Kilómetro 213; 26º 10’ S, 59º 21’ W, Department Pirané, Province of Formosa): skulls and mandibles from owl pellets (CNP 763; this study);
7. Zapallar Norte (26º 27’ 17” S, 59º 22’ 24” W, Department Libertador General San Martín, Province of Chaco): skulls and mandibles from owl pellets (CNP 764; this study);
8. Colonia Bermejo (26º 28’ 20” S, 59º 15’ 52” W, Department Libertador General San Martín, Province of Chaco): one trapped specimen reported by Massoia (1976);
9. General San Martín (26º 32’ 01” S, 59º 19’ 17” W, Department Libertador General San Martín, Province of Chaco): skulls and mandibles from owl pellets (CNP 765; this study);
10. 4 km S General San Martín (26º 33’ 06” S, 59º 20’ 02” W, Department Libertador General San Martín, Province of Chaco): skulls and mandibles from owl pellets (CNP 766; this study);
11. Villa Escolar (26º 37’ S, 58º 40’ W, Department Laishi, Province of Formosa): skulls and mandibles from owl pellets (CNP 767; this study);
12. 5 km N Selvas del Río de Oro (26º 47’ 16” S, 58º 57’ 24” W, Department Libertador General San Martín, Province of Chaco): one trapped specimen (see below);
13. Presidencia Roque Sáenz Peña (26º 47’ 17” S, 60º 26’ 43” W, Department Comandante Fernández, Province of Chaco): two trapped specimens reported by Massoia (1976);
14. Capitán Solari (26º 48’ 05” S, 59º 34’ 08” W, Department Sargento Cabral, Province of Chaco): remains from owl pellets reported by Massoia et al. (1995a);
15. Selvas del Río de Oro (26º 48’ 15” S, 58º 57’ 25” W, Department Libertador General San Martín, Province of Chaco): skulls and mandibles from owl pellets (CNP 768; this study);
16. Loma Florida (26º 48’ 55” S, 59º 06’ 50” W, Department Libertador General San Martín, Province of Chaco): skulls and mandibles from owl pellets (CNP 769; this study);
17. La Eduvigis (26º 51’ 42” S, 59º 04’ 48” W, Department Libertador General San Martín, Province of Chaco): skulls and mandibles from owl pellets (CNP 770; this study);
18. Lote 16 (26º 51’ 53” S, 58º 47’ 43” W, Department Bermejo, Province of Chaco): skulls and mandibles from owl pellets (CNP 771; this sudy);
19. 5 km N of General Vedia (26º 54’ 16” S, 58º 37’ 53” W, Department Bermejo, Province of Chaco): skulls and mandibles from owl pellets (CNP 772; this study);
20. General Vedia (26º 55’ 49” S, 58º 39’ 33” W, Department Bermejo, Province of Chaco): skulls and mandibles from owl pellets (CNP 773; this study);
21. Pueblo Viejo, Puerto Bermejo (26º 56’ 04” S, 58º 30’ 06” W, Department Bermejo, Province of Chaco): skulls and mandibles from owl pellets (CNP 774; this study);
22. Las Palmas (27º 03’ 47” S, 58º 42’ 17” W, Department Bermejo, Province of Chaco): skulls and mandibles from owl pellets (CNP 775; this study);
23. Cancha Larga (27º 04’ 37” S, 58º 43’ 51” W, Department Bermejo, Province of Chaco): skulls and mandibles from owl pellets (CNP 776; this study), and remains from owl pellets reported by Massoia et al. (1999);
24. Estancia Las Rosas and Paso Mono (ca. 27º 30’ S, 58º 47’ W, Department Bermejo, Province of Chaco): two trapped specimens reported by Contreras and Berry (1982);
25. Colonia Río Tragadero (27º 22’ S, 58º 57’ W, Department San Fernando, Province of Chaco): one trapped specimen reported by Contreras and Berry (1982);
26. Santa Margarita (28º 18’ 03” S, 61º 33’ 11” W, Department 9 de Julio, Province of Santa Fe): remains from owl pellets reported by Massoia et al. (1995b);
27. Berna (29º 15’ 55” S, 59º 52’ 02” W, Department General Obligado, Province of Santa Fe): two specimens trapped by R. González Ittig housed at CNP (CNP 733 and CNP 734; this study);
28. Pedro Gómez Cello (30º 01’ 59” S, 60º 18’ 08” W, Department San Justo, Province of Santa Fe): skulls and mandibles from owl pellets (CNP 777; this study)

   Pseudoryzomys simplex is often consumed by the owl Tyto alba, being the second commonest prey after Holochiluschacarius Thomas (Rodentia: Cricetidae) in Formosa and Chaco provinces. The absence of P. simplex in an owl pellet sample from Colonia Silva (30º 26’ 59” S, 60º 26’ 15” W, Province of Santa Fe), located 48 km by route south of Pedro Gómez Cello (locality #28), suggests that the southern limit of the species’ distribution may be somewhere between these two localities. The eastern distributional limit of this species may be the río Paraná. Collecting localities (Fig. 1) suggest that, in Argentina, P. simplex is mainly restricted to the Eastern Chaco biome.
   A trapping effort of 1,500 trap-nights (July 2000, winter season) produced one P. simplex from Selvas del Río de Oro (locality #12). This specimen (CNP 735), captured at night, was a subadult male without signals of reproductive activity (measurements [in mm]: Total length, 178; length of tail, 80; length of ear from notch, 15; length of hind foot [with claw/without claw], 28.5/26; weight, 20 g).
   Several authors (Massoia, 1976; Contreras y Berry, 1982; Voss y Myers, 1991) discussed the environmental conditions of the habitats occupied by P. simplex, regarding it as “a creature of open (unforested) tropical and subtropical lowland habitats“ (Voss and Myers, 1991:425). At Selvas del Río de Oro this rat was trapped in a marsh densely covered by palustrine vegetation, with Cyperus giganteus (“pirí”) and Thalia sp. (“pehuajó”) as dominant elements, surrounded by forested areas. Other rodents trapped together with P. simplex were Holochilus chacarius, Scapteromys aquaticus Thomas, Oligoryzomys microtis (Allen), and O. chacoensis (Myers and Carleton).
   Finally, this note points out the importance of the study of owl pellets in mammal surveys. For example, the first mention of P. simplex for the state of São Paulo (Brazil) was made by Mottá Junior (1996) based on T. alba owl pellets, enlarging the known geographic distribution 2,000 km far away from closest earlier records.

ACKNOWLEDGEMENTS

We are grateful to D. Podestá, F. Cremonte, H. Merlo Alvarez, and J. Notarnicola for their help during field-work, to R. González Ittig that kindly sent us two specimens of P. simplex, to P. Teta for drawing the map, and to G. D’Elía for a suggestion on an earlier version of this report. This contribution was funded by the Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina).

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Recibido 14 marzo 2004.
Aceptación final 20 mayo 2004.