Proechimys guyannensis (É. Geoffroy Saint-Hilaire, 1803)

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 : 574

41.

Guyenne Spiny-rat

Proechimys guyannensis

French: Rat-épineux de Guyane / German: Cayenne-Kurzstachelratte / Spanish: Rata espinosa de Cayena

Other common names: Cayenne Spiny-rat

Taxonomy. Mus guyannensis E. Geoffroy Saint-Hilaire, 1803 ,

“Cayenne,” French Guiana.

Proechimys guyannensis is a member of the guyannensisspecies group. It includes cherriei, vacillator, warreni, riparum, and arabupu as synonyms. It is currently regarded as monotypic, but this geographically highly variable taxon requires focused attention to determine its status, at subspecific or specific levels of its formally named taxa and its diversity of karyotypic forms.

Distribution. Amazon Basin in S & E Venezuela, the Guianas, and NE Brazil (E of Rio Negro and N of Amazon River).

Descriptive notes. Head—body 180-230 mm, tail 110-186 mm. No specific data are available for body weight. The Guyenne Spiny-rat is moderately sized, with relatively long tail for a member of the genus (77-87% of head-body length). Samples across the northern Guianan region are light reddish to yellowish brown, lined with black along mid-back, distinctly paler on lowersides, with abrupt pure white venter from chin to inguinal region. White innerthigh stripes are typically continuous across ankle to dorsal surface of hindfoot, which is light colored with only slight brown patch on tarsus below first digit; all digits tend to be white. Plantar pads on hindfeet are only moderately developed, but thenar and hypothenar are present and sub-equal in size. Tail is sharply bicolored, light brown above and cream below. Hairs on tail are sparsely distributed and very short, so that tail appears completely naked to the eye. Tail scales are small, and annuli consequently narrow, ranging 11-14 annuli/cm. Pelage is stiff to the touch, particular along mid-back, with aristiform spines rather short (16-19 mm long) and stout (0-9-1 mm wide); tip is either blunt or terminates with a very short filament. Skull of the Guyenne Spiny-rat conforms to that of virtually all spiny-rats in general shape, but because body size is moderate, skull appears small and rather delicate and lacks heavy ridging that may be present in skulls of larger species of Proechimys . As a result, temporalridges are generally poorly developed,if at all, maximally with just short and weak posterior extensions from supraorbital ledges. Incisive foramina are oval or teardrop in shape, with either no or only weakly developed posterolateral flanges so that anterior palate is typically flat or only very slightly grooved; premaxillary part of septum is short, occupying less than onehalf the opening and usually not in contact with very attenuate and non-keeled maxillary part; anterior palate lacks any medial ridging; and vomeris typically not visible in ventral view. Foraminal shape and structure are especially similar to those of Robert's Spiny-rat ( P. roberti ) and Simons’s Spiny-rat ( P. simonsi ). Floor of infraorbital foramen may either lack evidence of groove or have moderately developed lateral flange indicating passage of infraorbital branch of maxillary nerve. Width of mesopterygoid fossa varies widely among geographical specimens, but it is generally narrow (angle less than 58°); fossa penetrates palate to level of posterior one-half of M? in nearly all specimens. Post-orbital process of zygoma is obsolete or only weakly developed;it is formed entirely by squamosal. Number offolds on upper cheekteeth is relatively constant, with three characterizing dP*, M', and M?, and either three or less (commonly two) on M?; lower cheekteeth are more variable, with dP, having three folds and M, to M,typically only two, occasionally three. Counterfold formula is thus 3-3-3—(2) /3-2(3)-2(3)-2(3). Compared with sympatric Cuvier’s Spiny-rat ( P. cuvieri ), cheekteeth of the Guyenne Spiny-rat are also notably small in size, with tooth row less or equal to 8 mm in length. Baculum is relatively long (length 6-4-8-9 mm) and narrow (proximal width 1-9-2-3 mm; distal width 2-2.4 mm), and shaftis straight with little dorsoventral curvature and only a slight taper distally, and minimal lateral indentations. Proximal end is usually evenly rounded and paddle-shaped; distal tip shows only slight development of apical wings and moderate median depression. Chromosome complementis highly variable: 2n = 46 and FN = 50 from Rio Anaua and Rio Branco, Roraima (Brazil); 2n = 44 and FN = 52 from Manaus (Brazil); 2n = 40 and FN = 54 from Cayenne (French Guiana); 2n = 40 and FN = 50 from Icabaru (Bolivar, Venezuela); and 2n = 38 and FN = 52 from upper Rio Negro to RioJari Basin on the Para~Amapa State boundary (Brazil).

Habitat. Well-drained lowland forests, sometimes in gallery forest in otherwise more open areas from sea level to elevations of ¢.500m. The Guyenne Spiny-rat is more common in primary forests but ranges into secondary forest and other human disturbed communities. It might occur sympatrically with Cuvier’s Spiny-rat.

Food and Feeding. The Guyenne Spiny-rat is mainly frugivorous but also feeds on seeds and fungi.

Breeding. There is no specific information available for this species, but the Guyenne Spiny-rat is reportedly a seasonal breeder.

Activity patterns. There is no specific information available for this species, but anecdotal evidence suggest that the Guyenne Spiny-rat is terrestrial and nocturnal.

Movements, Home range and Social organization. There is no information available for this species.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Guyenne Spiny-rat is widespread and occurs in various forest types, including severely disturbed areas. Additional studies on distribution, habitat, abundance, ecology, and conservations threats to Guyenne spiny-rat are needed.

Bibliography. Allen (1899a), Desmarest (1817), Eisenberg & Redford (1999), Emmons (1990, 1997a), Geoffroy Saint-Hilaire (1803), Moojen (1948), Patton (1987), Patton & Leite (2015), Patton & Reig (1989), Reig et al. (1980), Thomas (1899a, 1903b, 1905b), Wagner (1843), 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. Amazon Basin in S & E Venezuela, the Guianas, and NE Brazil (E of Rio Negro and N of Amazon River).