Dactylomys dactylinus

65. Amazon Bamboo Rat Dactylomys dactylinus French: Coro-coro dAmazonie / German: Amazonas-Fingerratte / Spanish: Rata de bambu del Amazonas Taxonomy. Echimys dactylinus Desmarest, 1817, no type locality given. Restricted by O. Thomas in 1912 “upper Amazon Area.” Dactylomys dactylinus includes typus as a synonym. An adequate review of geographical patterning of extensive morphological variation present across the large distribution of D. dactylinus has not been under-taken. Three subspecies recognized, but ranges poorly known and their validity needs to be properly assessed. Subspecies and Distribution. D. d. dactylinusDesmarest, 1817 — UpperAmazonofSEColombia, SVenezuela, NEPeru, WBrazil, andNWBolivia, butwithundefinedlimits. D. d. canescensThomas, 1912 — LowerAmazonofC & EBrazil. D. d. modestus.onnberg, 1921 — Upper Amazon of E Ecuador. Descriptive notes. Head—body 315 mm, tail 389 mm; weight up to 325 g. The Amazon Bamboo Rat is large, with relatively soft furred, yellowish to olivaceous, and characterized by distinct pale mid-facial stripe over muzzle and extending posteriorly between eyes and ears onto nape of neck. Stripe contrasts sharply with grizzled yellowish to blackish dorsum, which in turn is streaked with black hairs. Sides become progressively more fulvous, with posterior outer thighs and sides of base oftail bright burnt orange. Ventral color is whitish, with hairs white to bases. Dorsal hairs are black or chestnut at roots, with subterminal black and pale or yellow tips. Head stripe is paler than that of the Bolivian Bamboo Rat (D. boliviensis). Long mystacial black vibrissae extend beyond one-half the length of superciliary vibrissae. Apart from its basal part (first 60 mm oftail), tail is naked, not bicolored at base, covered with large pentagonal scales (5 annuli/cm), and overall ¢.150% of head-body length. Scale hairs are colorless and short from furred tail base to tip. Forefeet have four digits, with digits two and three distinctly longer and nails instead of claws. Hindfeet have five digits, with reduced hallux. Skull of the Amazon Bamboo Rat is large and has broad and short rostrum, well-developed subtriangular post-orbital processes, and medium-sized bullae. Post-orbital processes of zygomatic arch are mainly composed ofjugal bone. In contrast to the Bolivian Bamboo Rat, paroccipital processes of the Amazon Bamboo Rat are oriented vertically and do not closely follow bullar curvature. There is no nerve canal in infraorbital canal. Palate forms a shelf that extends well behind M?, and upper molar rows diverge antero-posteriorly, with dP* nearly in contact. Chromosomal complement is 2n = 94 and FN = 144. Habitat. Amazonian lowlands in cane thickets, seasonally inundated (varzea) forests, bamboo stands, and multi-strata tropical evergreen forest from sea level to elevations of ¢.300m. The Amazon Bamboo Rat is found at lower elevations than the Bolivian Bamboo Rat, but they both might co-occur in headwater habitats. Food and Feeding. Field observations of foraging Amazon Bamboo Rats indicate that they eat bamboo parts. Breeding. One female Amazon Bamboo Rat was collected on Rio Jurua (Brazil) during the high-water season in June with two embryos, one with crown—rump length of97 mm. Activity patterns. There is no specific information available for this species, but the Amazon Bamboo Rat is nocturnal. Movements, Home range and Social organization. Vocalizations of Amazon Bamboo Rats recorded along Rio Jurua consisted of series of 5-10 short staccato pulses. In Ecuador, recorded pulses reached a mean of 42, which were produced during 14second calls. Field observations suggest that Amazon Bamboo Rats are social, with family groups foraging together in single bamboo stands. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Amazon Bamboo Ratis widely distributed and is known to occur in a variety of bamboo and riparian forest habitats. It also occurs in several protected areas. Bibliography. Allen (1900, 1914b, 1916a), Aniskin (1993), Anthony (1920), Bezerra et al. (2007), Desmarest (1817), Deville (1852), Didier (1962), Dunnum & Salazar-Bravo (2004), Eisenberg & Redford (1999), Emmons (1981, 1984, 1990, 1997a, 2005), Geoffroy Saint-Hilaire (1838b), Jentink (1891), LaVal (1976), Layne (1960), Linares (1998), Lonnberg (1921), Moraes-Santos et al. (1999), Ojasti et al. (1992), Patton, Pardinas & D'Elia (2015), Patton, da Silva & Malcolm (2000), Silva, J.S. & Nunes (2000), da Silva, M.N.F. & Patton (1993, 1998), Thomas (1912b), Woods (1993), Woods & Kilpatrick (2005).

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