Proechimys guairae, Thomas, 1901

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

48.

Guaira Spiny-rat

Proechimys guairae

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

Other common names: La Guaira Spiny-rat

Taxonomy. Proechimys guairae Thomas, 1901 ,

“La Guaira,” Vargas, Venezuela .

Proechimys guairae is a member of the innitatisspecies group. It includes ochraceus and poliopus as synonyms. It is highly variable in karyotype and has been divided into regional “races,” three of which correspond to formal taxa (at specific or subspecific levels), but others are yet to be defined and diagnosed. Three subspecies recognized.

Subspecies and Distribution.

P.g.guairaeThomas,1901—N&CVenezuela,inCordilleraCentral,EAndeanfoothills,andWLosLlanos.

P.g.ochraceusOsgood,1912—NEColombiaandNWVenezuela,inNEMaracaiboLakeandSistemaCoriano.

P.g. poliopus Osgood, 1914 — NE Colombia and W Venezuela, in W & S Maracaibo Lake, W Andean foothills, and the upper Los Llanos.

Descriptive notes. Head-body 210-240 mm,tail 170-200 mm; weight 340-400 g. The Guaira Spiny-rat is medium to large-bodied, with absolutely and proportionately long tail for a species of Proechimys (average c¢.85% of head—body length). Dorsum is light reddish brown, lined with black along southern slopes of the Cordillera de Mérida, but distinctly paler and more yellowish brown in drier forests around Lake Maracaibo. Ventral color is white from chin to inguinal region, including white inner thighs where stripe may be continuous across ankles onto dorsal surfaces of hindfeet. As a consequence, hindfeet are pale above but often have lateral light brown stripe extending from ankle to cover digits. Plantar pads of hindfeet are well developed, with thenar and hypothenar pads large and sub-equalin size. Tail is bicolored, light brown above and pale below, lightly haired so that large scales are obvious to the eye; scale annuli average 7-8 annuli/cm. Pelage is coarse but relatively soft to the touch, with long (20-22 mm) and narrow (0-5-0-7 mm) aristiform spines tipped with whip-like extensions. Skull of the Guaira Spiny-rat is unremarkable, sharing conformational shape of most species of Proechimys . Temporal ridges are undeveloped or present only as weak and short posterior extension from supraorbital ledge. Incisive foramina are broad and long, oval to slightly teardrop in shape, and with weakly developed posterolateral flanges that extend onto anterior palate forming slight moderate grooves; premaxillary part of septum is narrow, extends at least to midpoint of opening but may be only weakly connected to maxillary part, or not at all; maxillary part is thin and attenuated, slightly keeled so that medial ridge may be present on anterior palate; and vomeris visible between premaxillary and maxillary septal elements in ventral view. Floor of infraorbital foramen may be either smooth or with slight groove developed by short lateral flange. Mesopterygoid fossa varies from narrow to moderate in width, with an angle 47-55°, butit penetrates typically to at least the posterior margins of M? and commonly even deeper. Post-orbital process of zygoma is moderately developed and comprised ofjugal alone or by equal contributions ofjugal and squamosal. Three folds are uniformly present on dP*, M', and M?, with M?* having either 2-3 folds in about equal proportions within samples. Lower cheekteeth are uniform with three folds on dP, and two folds on molar series. Counterfold formula is 3-3-3—(2)3/3-(2)3-(2)3-(2)3. Baculum has same elongated, narrow shape and generalsize as other species in the trinitatisspecies group, and ¢.10 mm long and 3-4 mm wide, with bulbous base notched at midline and weakly developed apical wings. Chromosome complement is highly variable: 2n = 62 and FN = 72 at Apure, 2n = 48-50 and FN = 72 at Barinas, 2n = 46 and FN = 72 in nominate subspecies guairae , 2n = 44 and FN = 76 in subspecies ocherous, and 2n = 42 and FN = 76 in subspecies poliopus .

Habitat. Primary and secondary dry tropical forests and human agricultural croplands from sea level to elevations of ¢.800 m. Guaira Spiny-rats have been trapped amidst roots of wild pineapple ( Ananas , Bromeliaceae ) in arid forests of the north-eastern slope of Lake Maracaibo.

Food and Feeding. There is no specific information for this species, but the Guaira Spiny-rat probably feeds on seeds, fruits, and other plant parts.

Breeding. At one site in coastal Venezuela, reproductively active adult Guaira Spinyrats were trapped throughout a two-year sampling period, butjuveniles were only present at the beginning of the rainy season and otherwise absent during the dry season. Breeding was thus posited to be year-round. One recaptured female was pregnant at least three times during the year.

Activity patterns. There is no specific information for this species, but the Guaira Spiny-rat is primarily terrestrial and nocturnal.

Movements, Home range and Social organization. In coastal Venezuela, average home ranges of male Guaira Spiny-rats were three times as large as the average female home range. Females had exclusive home ranges, but those of males overlapped broadly with other individuals of both sexes. Overall population densities were 1 ind/ha to nearly 4 ind/ha, with effective density estimates of 3-20 ind/ha. Similar densities have been reported at another Venezuelan site. These overall patterns suggested that female Guaira Spiny-rats were territorial and the social system was promiscuous or polygynous mating system.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Nevertheless, subspecies poliopus is listed as Vulnerable on The IUCN Red List (as P. poliopus ). Although it is relatively abundant in its restricted distribution ofless than 20,000 km?, it is known from fewer than ten localities, and extent and quality of its habitat are apparently declining, even in protected areas that are extractive preserves. Otherwise, the Guaira Spiny-rat is viewed as widespread, occupying broad variety of forest types, including those modified by humans; it occurs in several national parks and is not judged to be declining overall despite human alteration. Additional studies of the Guaira Spiny-rat, particularly the area occupied by poliopus , are needed.

Bibliography. Aguilera (1999), Aguilera et al. (1995), Benado et al. (1979), Eisenberg (1989), Ellerman (1940), Emmons (1990, 1997a), Hershkovitz (1948), Osgood (1912, 1914), Patton & Leite (2015), Reig & Useche (1976), Reig et al. (1980), Thomas (1901b), 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)

Subspecies and Distribution. P.g.guairaeThomas,1901—N&CVenezuela,inCordilleraCentral,EAndeanfoothills,andWLosLlanos. P.g.ochraceusOsgood,1912—NEColombiaandNWVenezuela,inNEMaracaiboLakeandSistemaCoriano. P.g. poliopus Osgood, 1914 — NE Colombia and W Venezuela, in W & S Maracaibo Lake, W Andean foothills, and the upper Los Llanos.