512.

Brazilian Swamp Rat

Scapteromys meridionalis

French: Akodon méridional / German: Brasilien-Sumpflandratte / Spanish: Rata de ciénaga de Brasil

Other common names: Plateau Swamp Rat

Taxonomy. Scapteromys meridionalis Quintela et al., 2014, “Sao Francisco de Paula municipality (29°29°73” S, 50°13’49”" W; 913 m above sea level), Rio Grande do Sul State, Brazil.”

Type locality of S. meridionalis was poorly defined in the original description because the latitudinal geographic coordinate was erroneous and Sao Francisco de Paula is a municipality that covers ¢.3290 km*. Accordingly, taken into account the original information but also additional publications, type locality of Scapteromys meridionalis is here restricted to 5 km west of Centro de Pesquisas e Conservacao da Natureza Pro-Mata/PUCRS, Rio Grande do Sul State, Brazil. Scapteromys meridionalis presents a marked intraspecific structure according to cytochrome-b data; two strongly supported, reciprocally monophyletic groups were recognized with genetic divergence between clades of ¢.2:8%. Therefore, although it was originally described as monotypic, it probably encompasses two subspecies, one distributed in north-eastern Rio Grande do Sul and southern Santa Catarina states and the other further north in northern Santa Catarina and southern Parana states. Monotypic.

Distribution. S Brazil from S Parana to N Rio Grande do Sulstates.

Descriptive notes. Head-body 114-135 mm, tail 101-125 mm, ear 13-26 mm, hindfoot 32-37 mm; weight 50-91 g. The Brazilian Swamp Rat is medium-sized, characterized by dense and soft pelage, tawny gray on dorsum, darker on top of head and middle and posterior central regions, but without forming a clear banding pattern; venter is whitish gray; longest mystacial vibrissae do not reach bases of pinnae when laid back alongside head; ears are rounded, densely covered by thick hairs; and tail is ¢.90% of head-body length and densely haired. Hindfoot is ¢.25% of head-body length, with undeveloped interdigital webs. There are eight mammae. The Brazilian Swamp Rat differs from the other two living species of Scapteromys by its smaller size and darker and grayer dorsal pelage vs. more tawny in the Argentinean Swamp Rat (S. aquaticus) and the Uruguay Swamp Rat (S. tumidus). Diploid number of the Brazilian Swamp Rat is 2n = 34 or 36 vs. 2n = 32 in the Argentinean Swamp Rat and 2n = 24 in the Uruguay Swamp Rat.

Habitat. Shrub and herbaceous palustrine habitats (swamps and flooded grasslands) in biogeographic domains of Parana State and Araucaria angustifolia (Araucariaceae) forest in highland region called Serra Geral at elevations of 530-1017 m.

Food and Feeding. Based on its dental morphology, the Brazilian Swamp Rat is omnivorous, perhaps with a tendency to eat terrestrial worms.

Breeding. No information.

Activity patterns. Trapping of Brazilian Swamp Rats suggests nocturnal activity. This species is apparently more terrestrial than its congeners.

Movements, Home range and Social organization. No information.

Status and Conservation. Not assessed on The IUCN Red List. Scarcity of information about the Brazilian Swamp Rat would support classification of Data Deficient.

Bibliography. Freitas et al. (1984), Luza, Goncalves, Bolzan & Hartz (2015), Luza, Goncalves & Hartz (2015), Oliveira et al. (1982), Quintela (2014), Quintela et al. (2014).