Philander opossum (Linnaeus, 1758)

PATTON, JAMES L., DA SILVA, MARIA NAZARETH F. & MALCOLM, JAY R., 2000, Mammals Of The Rio Juruá And The Evolutionary And Ecological Diversification Of Amazonia, Bulletin of the American Museum of Natural History 2000 (244), pp. 1-306 : 79-84

Philander opossum (Linnaeus, 1758)

TYPE LOCALITY: ‘‘America,’’ restricted to

Surinam by J.A. Allen (1900: 195); further

restricted to Paramaribo, Surinam, by Matschie (1916: 268).

DESCRIPTION: This species exhibits considerable geographic variation in coloration and pattern, and no review of this, or other aspects of character variation has yet been undertaken. Specimens from the Rio Juruá are uniformly gray with a creamy white venter a distinct blackened median stripe on the midback, and a naked tail: the proximal two thirds is black with pale blotches and the terminal 20% or less is light. The fur is short even along the midback, and coarse ; the furred base of the tail is short, extending no more than 20% of the tail length. Selected external and cranial measurements are given in table 17. With the small sample available (7 male and 3 female adults, respectively) significant sexual dimorphism is evident only in cranial depth ( CD; p <0.05, one­way AN­ OVA) .

COMPARISONS: This is a smaller animal than P. mcilhennyi , and distinctly different in coloration and pattern (see below). Cranially P. opossum is significantly smaller in overall skull length (condyloincisive length), in measure of the toothrow and palatal length (C to M4 length, M1 to M4 length, and palatal length), and in palatal width (distance between metastyles of M3; see table 17). In external measurements, P. opossum is significantly smaller in total length, length of the tail, and height of the ear (see table 17).

DISTRIBUTION AND HABITAT: In the headwaters localities, P. opossum was truly sympatric (that is, found in adjacent trap stations) with P. mcilhennyi but apparently segregated from it by habitat downriver. Individuals taken in the Upper Central region (from Sacado and Nova Empresa, localities 5 and 8) were collected in várzea; all specimens but one taken in the Headwaters area were from the locally inundated margins of the river. This is in contrast to records of the black foureyed opossum, P. mcilhennyi , from the same areas (see below). We caught all specimens in traps placed on the ground, although Philander individuals were seen to climb on fallen logs and windfalls.

REPRODUCTION: Females with pouch young were collected only during the months of February and March, within the rainy season However, since only one individual (a male)

was taken during dry season months, little can be said about the seasonality of reproduction in this species. The modal number of young was 5 (range 4 to 5, n = 4). Literature reports on litter size vary from a mean of 3.4 (Eisenberg and Wilson, 1981) to 4.5 (Davis, 1947).

KARYOTYPE: 2n = 22, FN = 20 (fig. 40B). All chromosomes are uniarmed and form a graded series from large to small. This karyotype has been described and figured by Reig et al. (1977) and Palma and Yates (1996). Data are available for two specimens MNFS 623 and MNFS 998.

COMMENTS: Hershkovitz (1997: fig. 5) allocates specimens from western Brazil (including the Rio Jurua´, but for which he examined no specimens) to the nominate subspecies, while placing canus Osgood in synonymy with quica Temminck, a subspecies he maps to southeastern Brazil from Rio de Janeiro to Uruguay and northwest through the Paraná basin to eastern Bolivia and Peru´. In part because of cytochrome­b sequence differences between our specimens from the Rio Juruá and those from Guyana, close to the type locality of opossum Linnaeus , we have suggested elsewhere that western and eastern Amazonian P. opossum are distinct and should be recognized as such (Patton and da Silva, 1997). We have also shown that samples from southeastern Brazil are quite different from Amazonian ones (fig. 59; Pat­ ton and da Silva, 1997), and have suggested that quica Temminck, 1824 with its type locality in Estado do Rio de Janeiro, should be considered a synonym of frenata Olfers 1818 (type locality in Estado do Bahia, Brazil). Consequently, we apply the name canus to our samples from the Rio Jurua´.

SPECIMENS EXAMINED (n = 14): (1) 1f — MNFS 1308; (a) 2m, 2f — MNFS 998, 1031, 1047, 1054; (b) 2m, 1f — MNFS 1039–1040, 1053; (3) 1m — MNFS 1579;

(4) 1m, 2f — MNFS 1453, 1465, 1528; (5) 1m — MNFS 623; (8) 1m — JLP 15395 .

Philander mcilhennyi

Gardner and Patton, 1972

TYPE LOCALITY: ‘‘Balta, Río Curanja,’’ Departamento de Ucayali (formerly in Departamento de Loreto), Peru´. DESCRIPTION: This is a larger animal than

P. opossum in virtually all body and cranial measurements (table 17). Both the dorsum and venter are black; the middorsal hair is long and coarse; the haired portion at the base of the tail is long, averaging more than 25% of the tail length; the tail is black and lacks pale blotches, but approximately 47% of the terminal portion is generally paler. The lacrimals are expanded anteriorly, the poste­ rior aspect of the expanded portion of the nasals is distinctly notched, and the labial margin of M3 deeply indented. These characters conform to those presented by Gardner and Patton (1972) in their diagnosis and description of P. mcilhennyi . As with P. opossum , our samples of adult P. mcilhennyi also exhibit little sexual dimorphism, with significant differences between the sexes for only three cranial variables (C­M4, M1­M4, and PW; p <0.05 in each case by one­way AN­ OVA).

COMPARISONS: See section above for P. opossum . Comparisons of the color pattern of the face can be found in Hutterer et al. (1995).

DISTRIBUTION AND HABITAT: All specimens taken at midriver localities came from terrestrial traps in terra firme forest (n = 8); those from the headwaters localities were taken, again all on the ground, in both terra firme (n = 4) and inundated forest along the banks (n = 4). In the latter habitat, this species was truly sympatric with the gray four­eyed opossum, P. opossum .

REPRODUCTION: We recorded females with pouch young in the months of April and June at the type locality in eastern Perú (Gardner and Patton, 1972) and during July and August on the upper Rio Urucu in central Amazonas, Brazil (da Silva, unpubl. data). On the Rio Jurua´, pouch young were found at Penedo in the midriver in August and September and in the headwaters during February and March. The combination of data from these three areas suggests that the species breeds throughout the year. We caught very young independent individuals (age classes 1 and 2 of Gardner, 1982) in September, November, February, and March. Litter size varied from 4 to 7 with a mode of 5 young (n = 8).

KARYOTYPE: 2n = 22, FN = 20 (fig. 40C) The chromosomal complement is identical in every respect in gross chromosome morphology to that of P. opossum (see Reig, et al., 1977). Specimens karyotyped include MNFS 1103, 1410, 1435, JLP 15355, 15677, 15702.

SPECIMENS EXAMINED (n = 22): (1) 1m, 2f

— MNFS 1103, 1196, 1271; (2) 1m, 5f — MNFS 1185–1186, 1255, 1286, 1299, 1410; (3) 2m — MNFS 1599, JUR 208; (4) 1m, 2f — MNFS 1435, 1437, 1496; (6) 2m — JLP 15677, 15702; (7) 2m, 1f — JLP 15355 ; MNFS 383, 402; (9) 1m, 2f — JLP 16057, 16069, 16074 .

SUBFAMILY CALUROMYINAE Kirsch, 1977 CALUROMYS J. A. ALLEN, 1900 Woolly opossums