Mammals Of The Rio Juruá And The Evolutionary And Ecological Diversification Of Amazonia
Author
PATTON, JAMES L.
Author
DA SILVA, MARIA NAZARETH F.
Author
MALCOLM, JAY R.
text
Bulletin of the American Museum of Natural History
2000
2000-01-25
2000
244
1
306
http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1206%2F0003-0090(2000)244%3C0001%3AMOTRJA%3E2.0.CO%3B2
journal article
10.1206/0003-0090(2000)244<0001:MOTRJA>2.0.CO;2
0003-0090
5347311
Marmosops neblina
Gardner 1990
TYPE
LOCALITY: ‘‘Camp VII (
00°50'40''N
,
65°58'10''W
),
1800 m
, Cerro de la Neblina, Territorio Federal
Amazonas
,
Venezuela
.’’
DESCRIPTION: This is a mediumsized, dark brown mouse opossum. The single adult male weighed
44 grams
with a total length of
299 mm
, the condyloincisive length of the skull 34.5 mm, maxillary toothrow 13.7 mm, and molar toothrow 6.7 mm (table 8). The dorsum is a uniform Mummy Brown (Ridgway, 1912) in color from forehead to furred base of tail. The tail is uniformly and darkly colored to its tip. The whitish ventral hair covers the throat and upper chest, but is restricted to the midline through the abdominal and inguinal regions by broad lateral bands of graybased, silvertipped fur (fig. 41, second and third from right). The whitish portion in the abdominal region is less than
1 cm
wide. The skull is delicate, with a relatively smooth interorbital region, with beading only weakly developed even in old adults (fig. 46); the palate has both enlarged anterior and posterior vacuities (fig. 45); the mastoid processes are small; and the paroccipital processes are distinctly enlarged. The upper canine is relatively stout, with the width at its base averaging 61% of its length in unworn specimens. Our specimens match those of the
type
series of
M
.
neblina
, as detailed by Gardner (1989) in his original description in external color and color pattern, particularly in the narrow midventral white stripe bordered laterally by broad areas of darker pelage with paletipped hairs. Our specimens also possess the markedly developed accessory cusps between the paracone and metacone on the third upper molars and, therefore, the shallowly concave labial outline detailed in Gardner’s diagnosis (1989: 414).
COMPARISONS: This species can be distinguished from
M
.
noctivagus
and
M
.
parvidens
in the same way as can
M
.
impavidus
with the exception that the interorbital region of
M
.
neblina
is even smoother with weaker supraorbital beading. For differences between
M
.
neblina
and
M
.
impavidus
, see the section above for
M
.
impavidus
.
COMMENTS: As suggested in the analyses presented by Mustrangi and Patton (1997) we recognize
N
.
neblina
as a species separate from
M
.
impavidus
. With available samples
Fig. 44. Bivariate plots of four cranial measurements against condyloincisive length, a univariate measure of overall size, in four species of slender mouse opossums from the Rio Jurua´:
A
, palatal breadth;
B
, rostral length;
C
, maxillary toothrow length (canine to M4); and
D
, molar toothrow length (M1 to M4). Squares =
M
.
noctivagus
; diamonds =
M
.
neblina
; circles =
M
.
impavidus
; and triangles =
M
.
parvidens
.
although the two species are apparently close phyletic relatives (fig. 43), they are sympatric at two localities and are readily separable by the morphological characters listed above.
DISTRIBUTION AND HABITAT: This taxon is known from a few localities in the Headwaters, Upper, and Lower Central regions of the Rio Jurua´, all from várzea forest or disturbed riveredge areas. Two specimens were taken at approximately 1.5 m; the remainder were taken in traps placed on the ground. Single specimens of both
M
.
neblina
and
M
.
impavidus
were obtained at Igarapé Porongaba (locality
1
) and Altamira (locality
9
), where they were segregated by habitat in both cases.
REPRODUCTION: Specimens were collected in both wet and dry seasons. These include mostly juvenile or subadult individuals (with an incompletely erupted molar series), sug gesting that breeding occurs throughout the year. The single adult female (Nova Empresa, locality
8
) showed no signs of recent past breeding activity.
KARYOTYPE: 2n = 14, FN = 24 (fig. 47B) Chromosomal data are available from two individuals (JLP 15215, from locality h; and MNFS 703, locality
11
). The karyotype appears identical to that described above for
M
.
impavidus
.
SPECIMENS EXAMINED (n = 11): (
1
) 1f — MNFS 1067; (
c
)
1m
— MNFS 994; (
3
)
2 m
— MNFS 1637, JUR 210; (
8
)
1m
— JLP 15450; (h) 1f — JLP 15215; (
9
) 1f — JLP 16052; (
10
)
1m
— MNFS 943; (
11
)
1m
, 2 f — MNFS 703, 718–719.
Marmosops noctivagus
(Tschudi, 1844)
TYPE
LOCALITY: ‘‘Der mittleren und tiefen
Waldregion’’;
restricted by Tate (1933) to
Montaña
de Vitoc
, near Chanchamayo,
Río Perené
drainage,
Departamento de Junín
, Peru´
.
Fig. 45. Palatal views of:
A
,
Marmosops noctivagus
(JLP 15306, Penedo [locality
7
]);
B
,
Marmosops impavidus
(MNFS 760, Barro Vermelho [locality
12
]); and
C
,
Marmosops neblina
(JLP 15450, Nova Empresa [locality
8
]). All specimens are drawn to the same scale.
DESCRIPTION: This is the largest of the four species of
Marmosops
recorded from the Rio Juruá drainage, averaging 321.1 mm in total length, 37.2 mm in condyloincisive length of the skull, and
54 g
in weight (table 8). The dorsal color is paler, more orangishredbrown than that of either
M
.
neblina
or
M
.
parvidens
, but similar to that of
M
.
impavidus
, ranging from CinnamonBrown to Dresden Brown (Ridgway, 1912). The venter is broadly white to cream from chin to inguinal region, either without a lateral band of graybased hairs separating it from the sides and back or, if present, the band is narrow and confined to the abdominal region (fig. 41, left). The skull of
noctivagus
is large, with welldeveloped anterior and posterior pairs of palatal vacuities (fig. 45) and welldeveloped supraorbital beading that forms clearly evident ledges with small postorbital processes in older individuals (fig. 46). The anterior opening of the infraorbital foramen is positioned above the posterior root of PM4 The maxillary toothrow averages 15.7 mm in length, the upper molar series 7.7 mm. The upper canine is relatively short and stout with the width at the base averaging 65.5% of its length.
COMPARISONS:
Marmosops noctivagus
can be readily distinguished from
M
.
neblina
by its larger size, brighter dorsal pelage, pure white venter without a lateral border of graybased hairs (fig. 41), larger molar series and individual teeth, and welldeveloped supraorbital beading with ledges clearly evident in older individuals (fig. 46); it differs from
M
.
impavidus
in the same set of characters, with the exception that the dorsal color of both is quite similar. The large size, supraorbital beading, and presence of posterior palatal vacuities easily distinguish
M
.
noctivagus
from
M
.
parvidens
.
Fig. 46. Views of the interorbital region of crania of sameage specimens of:
A
,
Marmosops noctivagus
(JLP 15306, Penedo [locality
7
]);
B
,
Marmosops impavidus
(MNFS 760, Barro Vermelho [locality
12
]); and
C
,
Marmosops neblina
(JLP 15450, Nova Empresa [locality
8
]). All specimens are drawn to the same scale.
DISTRIBUTION AND HABITAT: This species was found in all four sampling areas along the Rio Juruá except the Lower Central Region. It was very common at Penedo (locality
7
) where
18 specimens
were obtained, mostly in terra firme forest but also in secondgrowth. One specimen was shot at a height of about
10 m
, two were shot at heights of about
2 m
, with all others either trapped or shot while on the ground. Specimens from the Headwaters Region came from both terra firme and várzea forest (lo calities 1 versus 2 and 3); all those from the Upper Central or Mouth regions were taken in terra firme communities.
REPRODUCTION: We found no females with attached young. Specimens taken at localities in the Headwaters Region were collected in the rainy season and were all either juveniles or nulliparous adult females. Only one of the
11 adults
(M1–M4 fully erupted) collected at Penedo (locality
7
) during the height of the dry season in August showed evidence of prior suckling in the form of the discolored orange inguinal region and evident nipples.
KARYOTYPE: 2n = 14, FN = 24 (fig. 47C) Karyotypic data are available from four individuals (MNFS 369, 381, JLP 15566, 15676). The autosomal complement consists of four pairs of large meta and submetacentric and two pairs of small metacentric ele
Fig. 47. Chromosome complements of five species of didelphid marsupials from the Rio Juruá with 2n = 14 karyotypes.
A
,
Marmosops impavidus
(MNFS 1191, Igarapé Porongaba [locality
1
]);
B
,
Marmosops neblina
(MNFS 703, Barro Vermelho [locality
12
]);
C
,
Marmosops noctivagus
(JLP 15676 Condor [locality
6
]);
D
,
Metachirus nudicaudatus
(JUR 399, VaiQuemQuer [locality
15
]);
E
,
Micoureus regina
[MNFS 1417, Igarapé Porongaba [locality
1
]);
F
, and
Caluromys lanatus
(MNFS 796, Barro Vermelho [locality
12
]).
ments; Xchromosome is a small metacentric, and the Y is an even smaller metacentric. This karyotype appears to differ from that of
M
.
impavidus
and
M
.
neblina
by two, versus one, small pairs of metacentric autosomes. Specimens from the Rio Juruá have the same karyotype as do those from eastern
Perú
(Reig et al., 1977) and
Bolivia
(Palma and Yates, 1996).
SPECIMENS EXAMINED (n = 40): (
1
)
3m
, 1f — MNFS 1065, 1066, 1384, 1403; (
2
) 1f — MNFS 1184; (
3
)
4m
— MNFS 1577, 1598, 1674, JUR 226; (
6
) 3f — JLP 15566, 15601, 15676; (
7
)
9m
, 10f, 1 unknown — MNFS 336, 360–361, 369, 371, 381, 398, 403, 414– 418, 495, 522, JLP 15253, 15306, 15313 15353, 15360; (
15
)
5m
, 3f — JUR 251, 283 315–317, 331, 348, 397.