A Revision Of The Didelphid Marsupial Genus Marmosops, Part 1. Species Of The Subgenus Sciophanes
Author
Díaz-Nieto, Juan F.
Author
Voss, Robert S.
text
Bulletin of the American Museum of Natural History
2016
2016-05-11
2016
402
1
72
http://www.bioone.org/doi/10.1206/0003-0090-402.1.1
journal article
10.1206/0003-0090-402.1.1
5f10376b-c1d4-42b7-8ee4-d6c4a3472e1e
0003-0090
4612610
Marmosops pakaraimae
Voss et al., 2013
Figures 11–13
Marmosops pakaraimae
Voss et al., 2013: 6
(original
description).
TYPE MATERIAL
: The
holotype
(by original designation) consists of the skin, skull, postcranial skeleton, and preserved tissues of an adult male (
ROM 115129
; original number
F46739
) collected by
Burton K. Lim
and
Deirdre M. Jafferally
on
26 February 2003
at “Second Camp” on
Mount Roraima
(fig. 10: locality 49),
CuyuniMazaruni Region
,
Guyana
.
The
other seven specimens listed below are all
paratypes
.
DISTRIBUTION, HABITATS, AND SYMPATRY:
Marmosops pakaraimae
is currently known from just five localities, of which three are in the Pakaraima Highlands of western
Guyana
and two are in the adjacent highlands of eastern
Venezuela
. Recorded elevations at these localities range from
800 m
to about
1500 m
above sea level, and recorded habitats are premontane or lower montane rain forest (
Voss et al., 2013
). This species is not definitely known to occur sympatrically with any congeneric species, although it might be expected to come into contact with
M. parvidens
and/or
M. pinheiroi
at lower elevations in western
Guyana
or eastern
Venezuela
.
DESCRIPTION: Body pelage dark brown (near Dark Umber) middorsally, but indistinctly paler laterally, and about
8–9 mm
long at midback; ventral pelage superficially whitish (the ventral coloration contrasting abruptly with the brownish flanks), but hairs of throat, chest, abdomen, and inner surfaces of fore- and hind limbs uniformly gray based (only the apex of the chin, the oral margins, and the scrotum have self-white fur). Manus covered dorsally with uniformly pale hairs in some specimens (e.g., ROM 114698), but metacarpals distinctly darker than digits in others (ROM 115129); lateral carpal tubercles spoon shaped in all examined adult males. Mammary formula unknown (no female specimens examined). Tail much longer than combined length of head and body (mean LT/HBL × 100 = 148%); dorsal caudal surface uniformly dark from base to tip, but ventral surface indistinctly paler (especially near the base of the tail).
FIG. 10. Collecting localities of examined specimens of the Parvidens Group of
Sciophanes
. Numbers are keyed to entries in the gazetteer (appendix 1). Progressively darker shading indicates higher elevations: pale gray ≥500 m, medium gray ≥1000 m, dark gray ≥2000 m, darkest gray ≥3000 m.
Nasal bones long (consistently extending well behind the lacrimals) and much wider posteriorly than anteriorly (laterally expanded at the maxillary-frontal suture). Lacrimal foramina concealed from lateral view inside anterior orbital margin; zygomatic process of squamosal broadly overlapped dorsally by the jugal. Palatine fenestrae absent. Dorsolateral margin of ethmoid foramen formed by the orbitosphenoid.
Upper canine (C1) short, with anterior and posterior accessory cusps in males (female specimens are unknown). Upper third molar (M3) anterolabial cingulum narrowly continuous with preprotocrista (anterior cingulum complete). Lower canine (c1) premolariform (procumbent, with posterior accessory cusp) and small, subequal in height to p1; c1 anterolingual accessory cusp absent. Entoconid of m1 apparently subequal to adjacent m2 paraconid;
3
unworn m4 talonid with three distinct cusps.
COMPARISONS:
Marmosops pakaraimae
averages larger than
M. parvidens
in most measured external dimensions (table 2), and the two species differ strikingly in dorsal pelage coloration (dark brown in
pakaraimae
versus paler and distinctly reddish brown in
M. parvidens
;
Voss et al., 2013
: fig. 2). The difference in ventral
pel3
This character is difficult to evaluate because specimens with unworn molars (juveniles and subadults) are unavailable.
TABLE 2
Measurements (mm) and Weights (g) of Adult Male Specimens of the Parvidens Group
of
Marmosops
(
Sciophanes
)
|
M. pakaraimae
a
|
M. parvidens
b
|
M. pinheiroi
c
|
| HBL |
109 (104–116) 7 |
100 (93–107) 10 |
101 (85–121) 12 |
| LT |
161 (151–169) 7 |
150 (142–160) 10 |
150 (142–160) 12 |
| HF |
18 (17–19) 7 |
16 (15–17) 10 |
17 (16–18) 12 |
| Ear |
22 (22–23) 7 |
22 (21–24) 9 |
22 (20–25) 12 |
| CBL |
30.8 (29.8–31.9) 7 |
28.3 (27.3–29.1) 9 |
29.1 (28.4–29.8) 12 |
| NL |
14.6 (14.2–15.2) 4 |
13.7 (12.7–14.4) 9 |
14.1 (13.2–14.7) 11 |
| NB |
3.8 (3.5–4.0) 7 |
3.4 (2.9–3.6) 12 |
3.7 (3.1–4.2) 12 |
| LIB |
6.0 (5.8–6.2) 7 |
5.3 (4.9–5.5) 11 |
5.4 (5.2–5.7) 12 |
| LPB |
6.2 (6.0–6.6) 7 |
5.5 (5.2–5.7) 11 |
5.6 (5.2–5.9) 11 |
| ZB |
15.2 (14.8–15.7) 7 |
14.5 (13.9–15.0) 10 |
15.1 (14.6–16.0) 12 |
| PL |
17.3 (16.5–17.9) 7 |
16.0 (15.0–16.8) 10 |
16.3 (16.0–16.7) 11 |
| PB |
8.9 (8.2–9.4) 7 |
8.3 (8.0–8.7) 12 |
8.6 (8.2–8.9) 12 |
| MTR |
12.2 (11.9–12.6) 7 |
11.2 (11.0–11.6) 11 |
11.6 (11.3–12.0) 12 |
| LM |
6.1 (6.0–6.3) 7 |
5.5 (5.3–5.7) 12 |
5.7 (5.6–5.9) 12 |
| M1–3 |
5.2 (5.2–5.4) 7 |
4.8 (4.6–5.2) 12 |
5.0 (4.8–5.2) 12 |
| WM3 |
2.0 (2.0–2.1) 7 |
1.9 (1.8–2.0) 12 |
1.9 (1.8–2.0) 12 |
| Weight |
30 (25–33) 6 |
25 (21–31) 9 |
27 (22–33) 12 |
a
The mean, the observed range (in parentheses), and the sample size are provided for each measurement of the type series (ROM 114698, 115129, 115148, 115254, 115841, 115845; USNM 385046).
b
The mean, the observed range (in parentheses), and the sample size are provided for each measurement of the following series: AMNH 93970, 267347, 267348, 267353, 267359, 267361; MNHN 1995-929, 1995-930, 1995-933; ROM 114144, 117348; USNM 579989.
c
The mean, the observed range (in parentheses), and the sample size are provided for each measurement of the following series: AMNH 266423, 267341, 267342, 267345, 267346, 267349, 267352, 267357; CM 63506; FMNH 95320; MNHN 1995-931, 1995-932; ROM 108920, 111558, 111663; USNM 461459, 461460, 461462–461465.
age coloration (op. cit.: fig. 3) is even more striking: whereas
M. pakaraimae
has almost completely gray-based ventral fur, all examined specimens of
M. parvidens
have a continuous streak of self-whitish fur that extends from chin to groin.
Marmosops pakaraimae
is consistently larger than
parvidens
in all measured craniodental dimensions, especially in five variables (CBL, LIB, LPB, MTR, LM) that exhibit nonoverlapping variation between our male samples (no female specimens of
M. pakaraimae
are known). Side-by-side comparisons of representative skulls (figs. 11–13) reveal that
M. pakaraimae
has a visibly broader interorbital region but relatively smaller orbits than
M. parvidens
. In qualitative aspects of craniodental morphology, however, these species are notably similar, both having lacrimal foramina that are mostly concealed from lateral view inside the anterior orbital margin, upper third molars with narrowly complete anterior cingula, and consistently tricuspid m4 talonids.
Marmosops pakaraimae
also averages larger than
M. pinheiroi
in most external dimensions, and the two species differ in dorsal pelage color (dark brown in
M. pakaraimae
versus paler brownish gray in
M. pinheiroi
). The ventral fur of
M. pakaraimae
is also more extensively gray based than the ventral fur of
M. pinheiroi
, which usually includes a narrow, discontinuous midventral streak of selfwhite hairs.
Marmosops pakaraimae
is also larger on average than
M. pinheiroi
in craniodental measurements, especially in three dimensions (LIB, LPB, and LM) that exhibit nonoverlapping variation in our samples. Visual comparisons of representative skulls (figs. 11–13) reveal similar proportional differences between
M. pakaraimae
and
M. pinheiroi
to those previously noted between
M. pakaraimae
and
M. parvidens
, namely that
M. pakaraimae
has a relatively broader interorbit but smaller orbits. Additionally, the lacrimal foramina are more prominently exposed laterally, M3 never has a complete anterior cingulum, and m4 often has a bicuspid talonid in
M. pinheiroi
.
TABLE 3
Measurements (mm) and Weights (g) of Adult Female Specimens of the Parvidens Group
of
Marmosops
(
Sciophanes
)
a
|
M. parvidens
b
|
M. pinheiroi
c
|
| HBL |
96 (94–97) 2 |
100 (95–108) 15 |
| LT |
136 (133–138) 2 |
141 (125–154) 15 |
| HF |
16 (15–17) 2 |
16 (14–17) 15 |
| Ear |
21 (20–21) 2 |
20 (18–23) 15 |
| CBL |
27.3 (26.7–28.0) 4 |
28.5 (27.9–29.8) 14 |
| NL |
12.9 (12.7–13.4) 4 |
13.9 (13.4–14.6) 9 |
| NB |
3.1 (2.8–3.5) 5 |
3.3 (2.9–3.8) 14 |
| LIB |
5.2 (4.9–5.4) 4 |
5.4 (5.2–5.5) 15 |
| ZB |
14.5 (13.9–14.8) 5 |
15.1 (14.6–15.9) 12 |
| PL |
15.3 (14.9–15.8) 4 |
16.0 (15.5–16.8) 9 |
| PB |
8.3 (8.1–8.7) 5 |
8.8 (8.4–9.3) 14 |
| MTR |
11.1 (11.1–11.2) 5 |
11.6 (11.2–12.1) 15 |
| LM |
5.5 (5.3–5.6) 5 |
5.8 (5.5–6.2) 15 |
| M1–3 |
4.8 (4.7–4.9) 5 |
5.0 (4.8–5.4) 15 |
| WM3 |
1.9 (1.9–2.0) 5 |
2.0 (1.8–2.1) 15 |
| Weight |
22 |
22 (19–25) 11 |
a
Female specimens of
Marmosops pakaraimae
are unknown.
b
The mean, the observed range (in parentheses), and the sample size are provided for each measurement of the following series: AMNH 97333, 267344; FMNH 18545; USNM 548439, 579990.
c
The mean, the observed range (in parentheses), and the sample size are provided for each measurement of the following series: AMNH 130570, 267342 267352; CM 63506; FMNH 95320; USNM 393529–393532, 461459, 461460, 461462, 461464, 461465, 545543.
SPECIMENS EXAMINED (
N
= 8):
Guyana
—
Cuyuni-Mazaruni
,
Mt. Roraima (ROM 115129, 115148, 115254);
Potaro-Siparuni
,
Mt. Ayanganna (ROM 114698), Mt. Wokomung (ROM 115841, 115845).
Venezuela
—
Bolívar
,
85 km
SSE El Dorado (USNM 385046), Churi-tepui (AMNH 176353).