Euryzygomatomys spinosus (Fischer, 1814)

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Echimyidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 552-604 : 560

13.

Guiara

Euryzygomatomys spinosus

French: Rat-épineux guira / German: Guiara / Spanish: Rata guira

Other common names: Fischer's Guiara

Taxonomy. Rattus spinosus Fischer, 1814 ,

“peuplade d’Atira, un peu plus de huit lieues (44 kilometres), a 1’'Orient de I’Assomption [= Atyra, 44 km E of Asuncion, Cordillera],” Paraguay .

Euryzygomatomys spinosus was formerly classified in the genera Loncheres , Echimys , Hypudaeus, Echinomys, and Mesomys . It includes guiara, brachyurus, and catellus as synonyms. Monotypic.

Distribution. SE & S Brazil (from Minas Gerais and Espirito Santo to Rio Grande do Sul), NE Argentina (Misiones) , and S Paraguay.

Descriptive notes. Head-body 163-205 mm, tail 60-64 mm; weight 180-210 g. The Guiara is medium-sized and is characterized by fusiform body covered, with brown to black spiny dorsal pelage, short limbs, short ears, and short tail—typical of subterranean rodents. Tail is less than 50% of head-body length and is sparsely covered with short hair. Dorsal pelage varies from yellow-brown to dark brown, with black guard hairs. Body sides are lighter in color, and venter varies from white to slightly yellowish, except for more ferruginous throat. Manus has long and powerful claws, probably adapted for digging; pes has shorter claws. Skull is broad, and rostrum is short and wide. Anterior projection of premaxillary bone is truncated. Auditory meatus is medium-sized, with partial contact between ectotympanic and squamosal, restricted to posterior portion of dorsal margin of ectotympanic, and forming cleft between these two bones. Incisive foramina are short and oval. Sphenopalatine foramen and sphenopalatine vacuities are well developed. Incisors are large, heavy, but not grooved. All upper and lower cheekteeth are semicircular in outline. Dentition of the Guiara is unique, characterized by very deep reentrant flexi/flexids, forming elongate fossettes/ fossettids, and by anterior fossette and metafossette sub-equal in size. All upper and lower cheekteeth possess three transverse lophs/lophids. A fourth lophid may be visible on unworn lower teeth.

Habitat. Variety of habitats in the Atlantic Forest, but also in adjacent cerrado, from sea level to elevations of ¢.2300 m. Guiaras are habitat generalists and occur in Pinus taeda ( Pinaceae ) plantations, exotic grasslands ( Melinis minutiflora, Poaceae ), highland forests and grasslands, secondary vegetation, dry grasslands, wet meadows, forest edges, and agriculturalfields..

Food and Feeding. Dentition of the Guiara suggests herbivorous diet. Consumption of P. taeda has been documented in southern Brazil. Leaves of the invasive exotic grass M. minutiflora have been consumed in south-eastern Brazil. Fecal analysis of two specimens collected in cerrado indicated consumption of vegetative parts of plants (leaves and steams) and also insects (Coleoptera, Hymenoptera, and Hemiptera), suggesting omnivorous diet.

Breeding. Pregnant Guiaras carrying 1-3 embryos have been reported in Rio de Janeiro, Brazil. One of them was pregnant in November. Given subterranean habits of the Guiara, it probably nests underground.

Activity patterns. The Guiara is probably nocturnal. It is preyed on by the American barn owl (7yto alba furcata), which is mainly nocturnal.

Movements, Home range and Social organization. The Guiara is semi-fossorial, but little 1s known aboutits ecology and behavior.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Guiara is usually not abundant in mammal surveys, but it is widespread, occurring in wide variety of habitats, including human-impacted areas.

Bibliography. Bonvicino & Bezerra (2015), Goncalves et al. (2007), Loss et al. (2015), Moojen (1952b), Redford & Eisenberg (1992), Woods & Kilpatrick (2005).

Figures

12. Broad-headed Spiny-rat (Clyomys laticeps), 13. Guiara (Euryzygomatomys spinosus), 14. White-spined Spiny-rat (Irinomys albispinus), 15. Elias’s Spiny-rat (Trinomys eliasi), 16. Rigid-spined Atlantic Spiny-rat (Trinomys paratus), 17. Yonenaga’s Spiny-rat (Trinomys yonenagae), 18. Elegant-spined Atlantic Spiny-rat (Trinomys setosus), 19. Moojen’s Spiny-rat (Trinomys moojeni), 20. Pau Brasil Spiny-rat (Trinomys mirapitanga), 21. Rio de Janeiro Spiny-rat (Trinomys dimidiatus), 22. Sao Paulo Spiny-rat (Trinomys thering), 23. Gracile Atlantic Spiny-rat (Trinomys gratiosus), 24. Sao Lourenco Punare (Thrichomys laurentius), 25. Jacobina Punare (Thrichomys inermis), 26. Lagoa Santa Punare (Thrichomys apereoides), 27. Pantanal Punare (Thrichomys pachyurus), 28. Foster’s Punare (Thrichomys fosteri), 29. Painted Tree-rat (Callistomys pictus), 30. Coypu (Myocastor coypus), 31. Armored Rat (Hoplomys gymnurus)

Distribution. SE & S Brazil (from Minas Gerais and Espirito Santo to Rio Grande do Sul), NE Argentina (Misiones) , and S Paraguay.