Proechimys echinothrix, 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 : 571

35.

Suff-spined Spiny-rat

Proechimys echinothrix

French: Rat-épineux du Jurua / German: Igel-Kurzstachelratte / Spanish: Rata espinosa de espinas rigidas

Taxonomy. Proechimys echinothrix da Silva, 1998 ,

“Colocacao Viravolta, left bank Rio Jurua on Igarapé Arabidi, affluent of Parana Breu, 66°14°W, 3°17’S, Amazonas, Brazil.”

This species is monotypic.

Distribution. W Amazon Basin of Brazil, on both sides of the Amazon River W of the Rio Negro and Rio Madeira, possibly extending along the upper Rio Negro into Colombia.

Descriptive notes. Head-body 141-245 mm, tail 106-209 mm; weight 240-280 g. The Stiff-spined Spiny-rat is moderately large in overall size; it has distinctly robust body, long ears (24 mm), proportionately short tail (averaging c.77% of head-body length), and large hindfeet (48 mm). Overall, dorsal color is uniformly reddish brown, coarsely streaked on back and sides with varying amounts of black; interspersed heavy, dark brown guard hairs make mid-dorsum appear somewhat darker, but this grades evenly onto brighter and paler sides of body. Aristiform hairs are long (averaging 21 mm) and much broader (1-4-1-6 mm) than those of any other sympatric species, with distinctly strong and blunt tips that are conspicuous to the eye and touch, especially in mid-dorsal region. Venter and inner surface of limbs are pure white. Tail is indistinctly bicolored, dark above and white below. It is well haired, with scales nearly completely obscured from view. Scales are small, with average of 12 annuli/cm at mid-length. Hindfeet are nearly unicolored white on dorsal surfaces. All six pads are present on plantar surface of hindfeet, but hypothenar is weakly developed in relation to thenar pad. Skull of the Stiff-spined Spiny-rat is moderately large, rostrum long and narrow, and well-developed supraorbital ledges extend over orbits but are discontinuous across parietals as weakly developed temporal ridges. Zygoma usually lacks post-orbital process or,if present, is low and rounded with equal contributions by jugal and squamosal. Well-developed groove with lateral flange is present on floor of infraorbital foramen. Incisive foramina are ovate to lyrate in general shape, with posterolateral margins mostly flat or only weakly flanged, and thus with very shallow grooves extending onto anterior palate that lacks median ridge; premaxillary part of septum is long and narrow, extending between one-half to two-thirds the length of opening; maxillary part is typically attenuate and has weak to no contact with premaxillary part; and vomeris visible in most specimens. Mesopterygoid fossa is moderate in depth but broad, with angle of indentation averaging c.70° and penetrating palate to front of M?, Median numberoflateral folds on all upper cheekteeth is three, but M, occasionally only has two. Counterfold formula is thus 3-3-3-3 / 3-3-3—(2) 3. Baculum is massive, relatively short (length 8-3-8-6 mm) but broad (distal width 4-2-5-1 mm; proximal width 4-8-5-4 mm); its shaft is broad with thick and expanded base, and distal end has pair of divergent apical extensions that are separated by shallow median depression. Chromosomal complement is 2n = 32 and FN = 60.

Habitat. Non-flooded, or terra firma, lowland evergreen rainforest, and along margins of flooded varzea and igapo forest.

Food and Feeding. There is no specific information for this species, but the Stiff spined Spiny-rat, as other species of Proechimys , likely feeds on seeds, fruits, and other plant parts.

Breeding. Along the Rio Jurua (W Brazil), pregnant Stiff-spined Spiny-rats were trapped in wet and dry seasons; modal litter size was 2 (range 1-3).

Activity patterns. Trapping data suggest that the Stiff-spined Spiny-rat is primarily 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 Stiff spined Spiny-rat is uncommon at any locality where it has been trapped, butit has a relatively wide distribution over mostly undisturbed forest and occurs in several protected areas (e.g. Amana and Mamiraua sustainable development reserves and Jau National Park). Additional studies on distribution, habitat, abundance, ecology, and conservation threats to Stiffspined 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. W Amazon Basin of Brazil, on both sides of the Amazon River W of the Rio Negro and Rio Madeira, possibly extending along the upper Rio Negro into Colombia.