Proechimys trinitatis (J. A. Allen & Chapman, 1893)

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 : 577-578

49.

Trinidad Spiny-rat

Proechimys trinitatis

French: Rat-épineux de Trinidad / German: Trinidad-Kurzstachelratte / Spanish: Rata espinosa de Trinidad

Taxonomy. Echimys trinitatis |. A. Allen & Chapman, 1893 ,

“Princestown [= Prince Town], Trinidad,” Trinidad and Tobago.

Proechimys trinitatis is a member of the trinitatisspecies group. It includes wurichi as a synonym. Mainland wrichi has often been regarded a species distinct from the nominotypical insular trinitatis . Monotypic.

Distribution. Trinidad I and adjacent coastal lowlands of N Venezuela.

Descriptive notes. Head-body 265-270 mm, tail 200-210 mm; weight 460 g.

The Trinidad Spiny-rat is moderately large, with proportionately long tail (75-80% of head-body length). Dorsum is brownish orange, heavily mixed with black, only slightly paler on sides and contrasting with pure white venter. White inner thigh stripe may continue across ankle to medial side of hindfoot surface, which is otherwise brownish. Plantar pads of hindfoot are well developed, with thenar and hypothenar pads enlarged and sub-equal in size. Tail is covered very sparsely with short hairs so that it appears quite naked to the eye. Tail scales are large, almost oval in shape, and only 6—7 annuli/cm along mid-tail. Pelage is relatively soft to the touch; aristiform spines are long (20-22 mm) and thin (0-:3-0-5 mm) and terminate in extended whip-like tips. Overall shape of skull of the Trinidad Spiny-rat is similar to most other species of Proechimys , relatively narrow and elongated, with long and tapering rostrum. Weak temporal ridges that extend back to mid-parietal from supraorbital ledges are present in older individuals but are less obvious in younger individuals. Incisive foramina are wide and oval in general shape, with only weak posterolateral flanges, if present at all, so that anterior palate is either flat or weakly groove; premaxillary part of septum is variable in size laterally and may extend virtually entire length of opening or only to a point; maxillary part is narrow and weakly developed, barely in contact with premaxilla, and only weakly keeled, typically without extending onto anterior palate as a continuing medial ridge; and vomer part of septum is usually not visible ventral view. Floor of infraorbital foramen is grooved and bordered laterally by moderately developed flange. Mesopterygoid fossa is relatively narrow, forming angle of ¢.53°, and deep, typically penetrating to anterior edge of M? or posterior edge of M*. Post-orbital process of zygoma is weakly to moderately developed and composed entirely of squamosal. Paroccipital processes are distinctly broad, flattened, and tightly appressed to bulla, more so than in any other species of Proechimys . Upper cheekteeth are uniform with three folds on each, except that M’ occasionally has only two; lower cheekteeth all have three folds, less commonly molars may have only two; counterfold pattern is 3-3-3—(2) /3—-(2)—-(2)-(2). Baculum is elongated (length 9-7-10-5 mm) but moderately wide (proximal width 3-1-3-2 mm; distal width 3-1-3-3 mm), with slightly expanded base with median notch, straight sides, and slight apical wings. It is similar to those of other species within the trinitatisspecies group. Chromosomal complement is 2n = 62 and FN = 80 in Venezuela and on Trinidad Island.

Habitat. Open evergreen, seasonal marsh forest with dominant lower canopy of mostly palms ( Arecaceae ) and emergent upper canopy of hardwood trees, interior secondary rainforest on Trinidad, and coastal lowlands and montane areas of north-eastern Venezuela from near sea level to elevations of ¢.1300 m.

Food and Feeding. Diet of the Trinidad Spiny-rat consists primarily of fruit and seeds and opportunistically includes small leaves and even arthropods.

Breeding. Captive breeding of Trinidad Spiny-rats from Trinidad indicated gestation of 62-64 days, mean litter size of 2-4, mean birth weight of 24-7 g, and achievement of reproductive maturity within c¢.5 months of birth.

Activity patterns. Trapping data suggest that the Trinidad Spiny-rat is nocturnal and terrestrial.

Movements, Home range and Social organization. In field studies in marsh forest on Trinidad, monthly average densities were 1-5 ind/ha-2-1 ind/ha; average home range size was 0-17 ha; 95% of all individuals moved less than 95 m over successive trapping events; and home ranges of males and females overlapped ¢.47%. In sum, these data suggest likely polygynous mating system. In captivity, average life spans were 20-41 months. Individuals were also docile when housed alone but became quite aggressive when kept together, often inflicting wounds on one another. This captive observation suggests that Trinidad Spiny-rats are solitary in the wild.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. The Trinidad Spiny-rat was abundant during 1970 surveys in Trinidad, where it occurred in a large protected area. Little is known about the Trinidad Spiny-rat in coastal Venezuela. Therefore, adequate surveys are needed to appropriately assess current conservation status of the Trinidad Spiny-rat in both parts ofits distribution.

Bibliography. Allen & Chapman (1893), Benado et al. (1979), Eisenberg (1989), Emmons (1990, 1997a), Everard & Tikasingh (1973), Patton (1987), Patton & Gardner (1972), Patton & Leite (2015), Patton & Reig (1989), Reig, Barros et al. (1980), Reig, Tranier & Barros (1979), 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. Trinidad I and adjacent coastal lowlands of N Venezuela.