368.

Short-tailed Cane Mouse

Zygodontomys brevicauda

French: Petite Souris-des-cannes / German: Kurzschwanz-Zuckermaus / Spanish: Ratén de cana de cola corta

Other common names: Short-tailed Zygodont

Taxonomy. Oryzomys brevicauda J. A. Allen & F. M. Chapman, 1893, Princes Town, Trinidad, Trinidad and Tobago.

Zygodontomys brevicauda is the type species of the genus. A largelist of nominal forms, including microtinus, cherriei, frustrator, sanctaemartae, stellae, tobagu, thomasi, seorsus, ventriosus, griseus, fraterculus, soldadoensis, and reigi, are currently considered under the synonymy of brevicauda after the detailed morphological approach made by R. S. Voss in 1991 who retained three subspecies. Nevertheless, an important amount of molecular and karyologycal data accumulated over the past three decades strongly suggest that Z. brevicauda is a composite of several entities. In any case, the ternary scheme of Voss (subspecies brevicauda, cherrier, and microtinus) is not fully concordant with available evidence. Research in new geographical areas also retrieved deeply divergent lineages, such as one recovered on a Pacific island near Panamanian mainland. New comprehensive taxonomic revision is needed. Monotypic.

Distribution. SW Costa Rica, Panama (including Coiba, Cébaco and Pearl Is), Colombia, Venezuela (including Margarita I), Trinidad and Tobago Is, the Guianas, and N Brazil.

Descriptive notes. Head-body 141-161 mm, tail 101-120 mm, ear 16-19 mm, hindfoot 23-27 mm; weight 57 g. Both species of Zygodontomys are medium-sized sigmodontines, with grizzled brownish dorsal pelage;tails are bicolored and shorter than headbody lengths; mystacial vibrissae are short; hindfeet are small, with second through fourth digits much longer than first and fifth digits; and there are eight mammae in inguinal, abdominal, postaxial, and pectoral pairs. When sympatric, the Short-tailed Cane Mouse is conspicuously smaller than the Colombian Cane Mouse (Z. brunneus); cranial characters useful to distinguishes the Short-tailed Cane Mouse from the Colombian Cane Mouse are distinctive occlusal morphology ofits brachyodont molars, more opisthodontincisors, deeper zygomatic notches, and more inflated nasolacrimal capsules. Chromosomal complement is 2n = 84-88, FN = 116-118.

Habitat. Always unforested habitats below elevations of ¢.1300 m on the mainland, including savannas, shrublands, pastures, orchards, grassy roadsides, and several anthropogenic landscapes, and in contrast, closed-canopy rainforests on islands. Preferred microhabitats of the Short-tailed Cane Mouse include herbaceous ground cover interspersed with woody plants growing in small thickets, usually on moist soils. It is probably enlarging its distribution because deforestation and clearing areas originally occupied by closed forests create preferred unforested mainland habitat, with documented examples in Costa Rica and Amazonia. In Venezuelan Llanos, the Short-tailed Cane Mouse was captured in all vegetative types, with the highest representation in Paspalum savanna ( Poaceae, 44%), nearly twice that in Trachypogon savanna ( Poaceae) and piedmont savanna; it was also found in peridomestic habitat.

Food and Feeding. The Short-tailed Cane Mouse is omnivorous.

Breeding. The Short-tailed Cane Mouse is a spontaneous ovulator;litters have 1-11 embryos (modes 4-5). Gestation is ¢.25 days. Postpartum estrus occurs, and lactation does not delay implantation. Neonates typically weigh 3—4 g each, are sparsely haired, and appear naked. Eyes open at c.6 days old, molars begin erupting at c.8 days old, and young are weaned by c.16 days old. Females reach sexual maturity at 3-4 weeks old, males at 6-8 weeks old. Reproduction appears to be year-round in wild populations.

Activity patterns. The Short-tailed Cane Mouseis terrestrial and nocturnal; some degree of diurnal activity was reported in Costa Rica.

Movements, Home range and Social organization. The Short-tailed Cane Mouse is pastoral and makes runways and uses those constructed by other species (e.g. Sigmodon spp-). It also uses dens and builds nests of grass. Home range was estimated at ¢.70 m?.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Aguilera (1985), Allen (1897a), Allen & Chapman (1893, 1897c), August (1983, 1984), Baglan & Catzeflis (2016), Bonvicino, Goncalves et al. (2009), Bonvicino, Maroja et al. (2003), Cordeiro & Oliveira (2005), Delgado, Rivas et al. (2008), Dominguez-Bello & Robinson (1991), Fleming (1970b), Giuggioli et al. (2005), Gonzalez et al. (2010), Mattevi et al. (2002), McPherson (1985), O'Connell (1989), Reid (2009), Reig et al. (1990), Utrera et al. (2000), Vivas et al. (1986), Voss (1991a, 2015e), Voss & Marcus (1992), Voss et al. (1992).