Proechimys gardneri, da Silva, 1998

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 : 576

45.

Gardner’s Spiny-rat

Proechimys gardneri

French: Rat-épineux de Gardner / German: GardnerKurzstachelratte / Spanish: Rata espinosa de Gardner

Taxonomy. Proechimys gardneri da Silva, 1998 ,

“Altamira, right bank Rio Jurua, 68°54’W, 6°35’S, Amazonas, Brazil.”

Proechimys gardneri is a member of the gardnerispecies group. Monotypic.

Distribution. Amazon Basin of W Brazil between Rio Madeira and Rio Jurua and extreme N Bolivia.

Descriptive notes. Head-body 154—

209 mm, tail 88-152 mm; weight 110-180 g. Gardner’s Spiny-rat is one of three small-bodied species of Proechimys from western Amazonia. It has short ears (21 mm), short hindfeet (40 mm), and proportionately mid-length tail (c.70% of head-body length). Overall body color is reddish brown or auburn, coarsely streaked with varying amounts of black on dorsum and sides; compared with most other sympatric species of spiny-rats, dorsum looks darker, especially over rump, due to presence of heavy, dark brown aristiform spines. These spines are short (length 17-18 mm) and moderately wide (0-9-1 mm), terminate with distinctly blunt tip, and provide distinctly coarse, or stiff, texture to dorsal pelage. Venter and chin are pure white, and most specimens have white lips. Inner surfaces of hindlimbs are pure white and extend across ankles onto dorsal surfaces of hindfeet so that ankles do not have complete circular dark bands. Dorsal surfaces of hindfeet are yellowish white, not pure white, often with distal parts of toes brownish. Plantar surfaces of hindfeet have all six tubercles. Tail is sharply bicolored, dark brown above and cream to white below; scales are relatively small (averaging 11 annuli/cm at mid-length) but not completely hidden by hair. Skull of Gardner’s Spiny-rat is small and delicate and has relatively long and narrow rostrum and beaded supraorbital ledge above orbits, which extends posteriorly as weakly developed ridge on anterior parietals. Post-orbital process of zygomais obsolete. Floor of infraorbital foramen is smooth, lacking ventral groove. Incisive foramina are ovate to slightly lyrate in shape, with posterolateral margins lying flat or only weakly flanged, and thus outlining only very shallow groove on anterior palate; maxillary part of septum is dorsoventrally compressed posteriorly and narrowed anteriorly, visible over almost one-half the length of foraminal opening, and fully connected to premaxillary part, which is broad and usually about one-half the length of foramen; and vomeris not visible on ventral margin of septum. Palate is smooth, lacking median ridge. Mesopterygoid fossa is long and moderately narrow, with angle of indentation averaging 61° and penetrating palate to middle of M?. Cheekteeth are remarkably small, with tooth row averaging only 7-5 mm in length. All upper teeth typically have three folds, with two occasionally present on M®. Lower dP, has four (occasionally three) folds, M| and M, consistently have three, and M, might have either two or three. Counterfold formula is 3-3-3—(2)3/(3)4-3-3-2(3). Baculum is massive and relatively long (length 6-5-8-6 mm), especially in relation to overall body size, with short, broad (distal width 3-1-4-2 mm), and distolaterally directed apical extensions separated by shallow median depression. Mid-shaft is relatively broad, and base is thick and expanded (proximal width 4-7-5-1 mm). Chromosomal complement is 2n = 40 and FN = 54 from middle Rio Madeira (Brazil) and 2n = 40 and FN = 56 from Rio Jurua (Brazil).

Habitat. Known only from upland, non-seasonally flooded (terra firma) Amazonian rainforest.

Food and Feeding. There is no specific information available for this species, but Gardner’s Spiny-rat likely feeds on seeds,fruits, and other plant parts.

Breeding. Breeding female Gardner’s Spiny-rats were collected only in the rainy season along the Rio Jurua (W Brazil), but age structure based on tooth wear suggested that breeding extends into the dry season, a likelihood thatis supported by presence ofjuvenile and subadults in July at Bolivian sites. Modallitter size was 2 (range 1-3).

Activity patterns. There is no specific information available for this species, but Gardner’s Spiny-rat is nocturnal and terrestrial.

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

Status and Conservation. Classified as Data Deficient on The IUCN Red List. Gardner’s Spiny-rat is distributed over a reasonably large area of primarily undisturbed primary forest, but it is known from only a few specimens and a few localities, none of which are within protected areas. Additional studies on distribution, habitat, abundance, ecology, and conservation threats to Gardner’s Spiny-rat are needed.

Bibliography. Patton & Leite (2015), Patton et al. (2000), da Silva (1998), 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 of W Brazil between Rio Madeira and Rio Jurua and extreme N Bolivia.