A new species of Margaretamys (Rodentia: Muridae: Murinae: Rattini) from Pegunungan Mekongga,...

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A new species of Margaretamys(Rodentia: Muridae: Murinae:Rattini) from Pegunungan Mekongga,southeastern Sulawesi, IndonesiaA. Mortelliti a , R. Castiglia a , G. Amori b , I. Maryanto c & G. G.Musser da Department of Biology and Biotechnology “Charles Darwin”,Sapienza University of Rome, Viale dell'Università 32, 00185,Rome, Italyb CNR-Institute for Ecosystem Studies – c/o Department of Biologyand Biotechnology “Charles Darwin”, Sapienza University of Rome,Viale dell'Università 32, 00185, Rome, Italyc Museum Zoologicum Bogoriense-LIPI, Jl. Raya Jakarta-Bogor KM.46, Cibinong, Bogor, Indonesiad Division of Vertebrate Zoology (Mammalogy), American Museumof Natural History, Central Park West at 79th Street, New York, NY,USA

Version of record first published: 20 Jul 2012

To cite this article: A. Mortelliti, R. Castiglia, G. Amori, I. Maryanto & G. G. Musser (2012): Anew species of Margaretamys (Rodentia: Muridae: Murinae: Rattini) from Pegunungan Mekongga,southeastern Sulawesi, Indonesia, Tropical Zoology, 25:2, 74-107

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A new species ofMargaretamys (Rodentia: Muridae: Murinae: Rattini)from Pegunungan Mekongga, southeastern Sulawesi, Indonesia

A. Mortellitia*, R. Castigliaa, G. Amorib, I. Maryantoc and G. G. Musserd

aDepartment of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome,Viale dell’Universita 32, 00185 Rome, Italy; bCNR-Institute for Ecosystem Studies – c/o Departmentof Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, Vialedell’Universita 32, 00185 Rome, Italy; cMuseum Zoologicum Bogoriense-LIPI, Jl. Raya Jakarta-Bogor KM. 46, Cibinong, Bogor, Indonesia; dDivision of Vertebrate Zoology (Mammalogy),American Museum of Natural History, Central Park West at 79th Street, New York, NY, USA

(Received 12 December 2011; final version received 17 May 2012)

Margaretamys christinae n. sp. is described from an adult male collected in tropicallower montane rain forest in Pegunungan Mekongga, the most extensive mountainousregion on the southeastern peninsula of Sulawesi. Physical characteristics of thespecimen (body size, fur coloration and texture, and dimensions of appendages) alongwith cranial and dental qualitative and quantitative aspects are contrasted with similartraits in samples of M. beccarii (Musser, 1981), M. elegans (Musser, 1981), and M.parvus (Musser, 1981), the three other described species in the genus. The new speciesjoins M. elegans and M. parvus as representatives of montane endemics, the former inPegunungan Mekongga, the latter two in the west-central mountain block of Sulawesi’score; M. beccarii occupies habitats in tropical lowland evergreen rain forest and isknown by voucher material from the northeastern tip of the northern peninsula andcentral Sulawesi. Aside from its capture site 1.5 m above ground at 1537 m in lowermontane forest, its age and sex, no other ecological information exists for theMekongga species, but its possible if not probable ecology is inferred from ecologicalinformation associated with the three other species. The four species are also thesubjects of short discussions covering sympatry, zoogeography, phylogenetic alliances,and conservation.

Keywords: Margaretamys christinae; Sulawesi; Indonesia; mountain rain forest;arboreal

Introduction

At least 53 species of murine rodents have been recorded as endemic to Sulawesi (Musser

2012). One of these was discovered in 2011 and is represented by a specimen obtained

during an inventory of the small mammals occurring in Pegunungan Mekongga on the

southeastern peninsula of Sulawesi. Small body size, soft brownish tawny upperparts,

grayish buff underparts, a long tufted bicolored tail, and capture in an understory tree in

tropical lower montane rain forest identify the animal as a species of the Sulawesian

endemic, Margaretamys, a clade that in the most recent classification of extant Murinae at

the tribal level is a member of Rattini, which includes many Indomalayan and Philippine

endemics (Aplin and Helgen 2010).

ISSN 0394-6975 print/ISSN 1970-9528 online

q Istituto per lo Studio degli Ecosistemi of the Consiglio Nazionale delle Ricerche, Firenze 2012

http://dx.doi.org/10.1080/03946975.2012.696439

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*Corresponding author. Email: [email protected]

Tropical Zoology

Vol. 25, No. 2, June 2012, 74–107

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http://dx.doi.org/10.1080/03946975.2012.696439

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Three species of Margaretamys have been described (Figure 1; Musser 1981; Musser

and Carleton 2005). Margaretamys parvus and M. elegans are represented by specimens

collected only in tropical lower and upper montane rain forest formations in the west-

central mountain block in the western portion of Sulawesi’s core (see the map in Figure 2).

The two are members of a suite of montane species that are endemic to the west-central

mountain block (Musser et al. 2010, p. 109). In contrast, M. beccarii has been collected

only from tropical lowland evergreen rain forest habitats and is documented by voucher

specimens from the northeastern segment of the northern peninsula (east of the Gorontalo

region) and the core of the island.

Until now, no examples of Margaretamys have been collected from the southeast

peninsula of Sulawesi. Formerly, our knowledge of the small mammal fauna in that region

mostly derived from the expeditionary efforts of Heinrich, who in 1932 collected birds and

mammals in the lowlands and adjacent Pegunungan Mekongga. In addition to samples of

species of rats and squirrels that also occur elsewhere on Sulawesi (the murines Paruromys

dominator (Thomas, 1921), Taeromys celebensis (Gray, 1867), Maxomys hellwaldii

(Jentink, 1878), Max. musschenbroekii (Jentink, 1878), Bunomys chrysocomus

(Hoffmann, 1887), B. andrewsi (Allen, 1911), B. penitus (Miller & Hollister, 1921),

and Rattus hoffmanni (Matschie, 1911); the squirrels Prosciurillus alstoni (Anderson,

1879, Pros. murinus (Muller & Schlegel, 1844), and Rubrisciurus rubriventer (Muller &

Schlegel, 1844)), Heinrich obtained samples of several species that proved to be

endemic to montane forests covering the Mekongga highlands: the murines Taeromys

Figure 1. The three described species of Margaretamys: M. elegans (left) and M. parvus (upperright), endemic to montane rain forest in the west-central mountain block of Sulawesi, andM. beccarii (lower right), an occupant of tropical lowland evergreen rain forest on the northeasternpeninsula and central Sulawesi. Source: Musser (1981).

A New Species of Margaretamys 75

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arcuatus (Tate & Archbold, 1935), Taeromys microbullatus (Tate & Archbold, 1935),

Maxomys sp., and Rattus salocco (Tate & Archbold, 1935), and the squirrel Prosciurillus

abstrusus (Tate and Archbold 1935; Musser et al. 2010; Musser 2012). To this small suite

of endemic montane species we now add the single example of Margaretamys captured

during January 2011, in an understory tree on the southern slope of Gunung Moserosero at

1537 m. The pelage coloration and texture resembles that of M. elegans and M. parvus

Figure 2. Mainland Sulawesi, offshore islands, and nearby archipelagos. Two highlighted areasare relevant to this paper, the west-central mountain block (also see the geography section inMaterials and methods section) and Pegunungan Mekongga. Boundaries denoting otherbiogeographical regions of interest are indicated by dashed lines: SM-D ¼ lowland reaches of theSungai Onggak Mongondaw and Sungai Onggak Dumoga; SB-DL ¼ lowlands of the Sungai Boneand Danau Limboto; TD ¼ Tempe Depression.

76 A. Mortelliti et al.

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which come from the west-central mountain block, but its cranial morphology and

occlusal molar patterns recall the characteristics of the highland M. elegans and lowland

M. beccarii. On the basis of these contrasts, along with the distinctive geographic origin of

the specimen, we hypothesize that it is a sample of a fourth species of Margaretamys, one

that is endemic to the montane forests of Pegunungan Mekongga; naming and describing

this Mekongga endemic is the subject of this paper.

Materials and methods

Study area

The field study was carried out in Pegunungan Mekongga on the southeastern peninsula of

Sulawesi (Sulawesi Tenggara), Indonesia (Figures 2 and 3). The area is characterized by

tropical lowland evergreen rain forest and tropical montane rain forest (with the highest

mountain peaks being Gunung Mosembo and Gunung Moserosero) and is not enclosed in

any protected area. During this survey, we verified that because large portions of the study

area were logged during the period 1993–1997 vast portions of the mountain range are

now covered by secondary forest (Mortelliti, personal observation) or, following clearing,

have been converted to cacao plantations by the local people.

Trapping was performed in five primary and secondary forest sites at altitudes ranging

from 50 to 1900 m. Rodents were live-trapped using a mix of Sherman traps (LFA) and

locally available wire traps (size: 30 £ 15 £ 20 cm3). Traps were baited with diced

coconut fried in coconut oil, peanut butter, and small fruits gathered on the forest ground.

Traps were laid in transects with two traps per trapping point, with one trap placed on the

forest floor and the other trap placed above the ground on tree branches. A total of 2100

Figure 3. Pegunungan Mekongga. Pale gray shading shows land below 1400 m asl, dark grayabove 1400 m asl. Asterisk pinpoints the site of capture of Margaretamys christinae.


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trap nights were carried out during the field sampling. Animals were euthanized using

chloroform, weighed using a Pesolaq spring balance (precision: 0.05 g), and external

measurements (total length and lengths of tail, hind foot, and ear; total length minus tail

length yielded length of head and body; see Table 1) were obtained with a metal caliper

and a plastic meter. Position of captures was measured using a Garminq 60 CSX Global

Positioning Unit. Sea level is the base for all altitudes indicated in this paper.

Specimens

We compared the holotype of the new species with the samples of M. beccarii, M. elegans,

and M. parvus that are documented by Musser (1981). Specimens representing M. elegans

and M. parvus were collected by Musser on Gunung Nokilalaki in the northern portion of

the west-central mountain block (see the location maps in Musser et al. 2010, pp. 16–17).

Examples of both have been trapped elsewhere in the mountain block, namely in the

Mamasa region (Musser’s unpublished records; KC Rowe, personal communication) but

we did not include this material in our comparative analyses. Samples of the lowland

M. beccarii have been obtained by several collectors but the largest series were obtained

by Musser (Kuala Navusu, Sungai Tolewonu, and Sungai Sadaunta) and H.C. Raven

(Gimpu) in central Sulawesi (see the maps in Figures 3, 4, and 17 in Musser et al. 2010)

and form the core of our comparative material. We also include a specimen caught in 2010

in lowland forest on Gunung Balease. The specimens are stored in the American Museum

of Natural History, New York (AMNH); the Indonesian National Museum of Natural

History, Cibinong, Java (MZB); the Museum of Vertebrate Zoology, Berkeley; and the

National Museum of Natural History, Smithsonian Institution, Washington DC. A list of

specimens including museum catalog is provided in Appendix 1.

Measurements

Total length and lengths of tail, hind foot (excluding claws) ear, and weight of the

Mekongga Margaretamys were measured in the field; the value for length of tail was

subtracted from total length to yield length of head and body, which is the estimate we use

– along with mass – to estimate overall physical body size.

The Mekongga skull was measured with a digital calliper and values were recorded to

an accuracy of about 0.01 mm. Comparable cranial and dental measurements for the

samples of Margaretamys employed here were obtained by Musser (1981) using dial

calipers graduated to tenths of millimeters.

We measured 16 cranial and 2 dental dimensions; their limits are graphically illustrated

in Figure 4. Abbreviations that are used in the tables are: ONL, occipitonasal length; ZB,

zygomatic breadth; IB, interorbital breadth; LR, length of rostrum; BR, breadth of rostrum;

BBC, breadth of braincase; HBC, height of braincase; BZP, breadth of zygomatic plate; LD,

length of diastema; PPL, postpalatal length; LBP, length of bony palate; BBP, breadth of

bony palate at M1; BMF, breadth of mesopterygoid fossa; LIF, length of incisive foramina;

BIF, breadth of incisive foramina; LB, length of auditory bulla; CLM1-3, crown length of

maxillary molar row; and BM1, breadth of first upper molar.

Dentition

The maxillary and mandibular molar rows diagrammed in Figure 5 are labeled with the

terminology we use to describe various cusps and cusplets.


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Tab

le1.

Cra

nia

lan

dden

tal

mea

sure

men

ts(m

illi

met

ers)

der

ived

from

the

spec

imen

of

Ma

rga

reta

mys

chri

stin

ae

and

the

sam

ple

so

fM

.p

arv

us,

M.

bec

cari

i,an

dM

.el

ega

ns.

Mea

n^

1S

Dan

do

bse

rved

ran

ge

(in

par

enth

eses

)ar

eli

sted

.T

he

thre

ela

rge

sam

ple

sco

nsi

sto

fco

mb

ined

adu

ltm

ales

and

fem

ales

;M

.ch

rist

ina

eis

anad

ult

mal

e.

Var

iab

le

M.

chri

stin

ae

Peg

un

un

gan

Mek

on

gg

aN¼

1

M.

eleg

an

sG

un

un

gN

ok

ilal

aki,

wes

t-ce

ntr

alm

ou

nta

inb

lock

N¼

24

M.

bec

cari

iC

entr

alS

ula

wes

iN¼

19

M.

pa

rvu

sG

un

un

gN

ok

ilal

aki,

wes

t-ce

ntr

alm

ou

nta

inb

lock

N¼

13

ON

L3

1.6

24

1.6

^1

.00

(38

.9–

42

.9)

33

.5^

0.9

3(3

1.5

–3

5.5

)2

8.6

^0

.6(2

7.7

–2

9.7

)Z

B1

6.0

51

9.6

^0

.52

(18

.7–

20

.6)

16

.4^

0.5

7(1

5.5

–1

7.5

)1

3.5

^0

.3(1

3.1

–1

4.1

)IB

4.9

65

.6^

0.1

7(5

.2–

6.0

)5

.4^

0.2

4(5

.1–

6.0

)4

.6^

0.2

(4.3

–4

.8)

LR

10

.54

13

.7^

0.4

8(9

.2–

11

.0)

10

.2^

0.4

5(9

.2–

11

.0)

9.2

^0

.3(8

.5–

9.5

)B

R5

.55

7.1

^0

.33

(6.4

–7

.6)

6.1

^0

.32

(5.4

–6

.6)

4.8

^0

.2(4

.3–

5.2

)B

BC

15

.18

16

.5^

0.3

5(1

5.8

–1

7.1

)1

4.7

^0

.37

(14

.1–

15

.5)

13

.2^

0.3

(12

.8–

13

.7)

HB

C1

0.0

61

1.8

^0

.29

(11

.3–

12

.5)

10

.2^

0.3

3(9

.6–

10

.6)

8.8

^0

.3(8

.2–

9.2

)B

ZP

2.3

13

.4^

0.2

6(2

.8–

3.9

)2

.6^

0.1

7(2

.3–

2.8

)1

.7^

0.1

(1.6

–2

.1)

LD

8.0

31

1.4

^0

.43

(10

.3–

11

.9)

8.6

^0

.42

(7.9

–9

.6)

7.4

^0

.3(6

.8–

7.8

)P

PL

11

.74

15

.8^

0.6

6(1

4.1

–1

6.8

)1

2.3

^0

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(11

.4–

13

.0)

9.8

^0

.2(9

.3–

10

.2)

LB

P5

.08

5.9

^0

.25

(5.6

–6

.5)

5.5

^0

.32

(5.1

–6

.4)

4.7

^0

.2(4

.4–

5.0

)B

BP

3.0

63

.8^

0.1

4(3

.5–

4.1

)3

.4^

02

6(3

.0–

3.9

)3

.1^

0.1

(2.9

–3

.4)

BM

F2

.49

3.7

^0

.22

(3.0

–4

.1)

2.5

^0

.22

(2.0

–2

.9)

2.5

^0

.2(2

.2–

2.8

)L

IF5

.02

8.0

^0

.35

(7.3

–8

.9)

5.8

^0

.24

(5.4

–6

.4)

5.1

^0

.2(4

.6–

5.4

)B

IF2

.23

.0^

0.1

6(2

.7–

3.3

)2

.5^

0.1

7(2

.3–

2.9

)2

.2^

0.2

(2.0

–2

.5)

LB

4.6

55

.3^

0.1

8(4

.8–

5.6

)4

.7^

0.2

3(4

.3–

5.2

)4

.2^

0.2

(3.8

–4

.5)

CL

M1

–3

4.9

36

.4^

0.2

2(5

.9–

6.8

)5

.0^

0.1

5(4

.7–

5.3

)4

.6^

0.1

(4.4

–4

.9)

BM

11

.52

1.9

^0

.08

(1.8

–2

.1)

1.5

^0

.06

(1.4

–1

.6)

1.3

^0

.1(1

.2–

1.5

)


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Morphometric analyses

Descriptive (summary) univariate descriptive statistics listed in the tables consist of mean,

standard deviation, and observed range.

Plottings of cluster analyses provided visual patterns that reflect similarity or contrast

in the combination of cranial and dental variables used to compare the Mekongga

specimen with samples of the three documented species of Margaretamys. Principal

component analyses were computed using the combination of 16 cranial and 2 dental

variables and were extracted from a variance–covariance matrix; loadings of the variables

Figure 4. Cranial diagram of Bunomys chrysocomus illustrating limits of the cranial and dentalmeasurements we employed.


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Figure 5. Occlusal views of maxillary (on the right in each pair) and mandibular (on the left)molar rows. Upper left: Diagrams of molar rows from Lenothrix canus on which dental structuresare labeled. Cusps of maxillary molars are referred to in the text with the prefix “t”. Abbreviations:a-cen, anterocentral cusp, a-lab, anterolabial cusp; a-ling, anterolingual cusp; alc, anterior labialcusplet; ed, entoconid; hd, hypoconid; md, metaconid; pc, posterior cingulum; pd, protoconid; plc,posterior labial cusplet. Upper right: Margaretamys beccarii (AMNH 224061). Lower left: M.parvus (AMNH 226068). Lower right: M. elegans (AMNH 225143). Adapted from Musser (1981).A posterior cingulum does not occur on the third upper molar of M. parvus and M. christinae butforms the posterior border of the third molar in M. beccarii and M. elegans. The posterior cingulumhas broadly fused with cusp t9 on each first and second upper molar of M. parvus, but a comparablestructure remains unattached to cusp t9 on the second molar of M. christinae – the relation ofthe posterior cingulum to cusp t9 resembles the configuration illustrated for M. beccarii andM. elegans.


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are given as Pearson product-moment correlation coefficients of the extracted principal

components. Probability levels denoting the significance of the correlations are

unadjusted. The illustrated ordinations bounded by first and second principal components

are extracted, which contain most of the information relevant to our inquiry. Similar

patterns of scores were present in scatter plots employing first and third components,

which are not illustrated.

Geography

Sulawesi consists of a central region from which four arms or peninsulae radiate (see

Figure 2): the northern peninsula, which ends in a northeastern jog; the eastern peninsula;

the southeastern peninsula; and the southwestern peninsula. We use these informal labels

when describing distributions of the various species over the island, and refer to the central

portion as Sulawesi’s core.

In the text and in some tables we refer to the west-central region or west-central

mountain block that forms the western portion of Sulawesi’s core. It is that region of

foothills, peaks, and interior valleys situated above 100 m and lying roughly west of

Danau Poso and extending from the Palu area in the north to Pegunungan Latimojong in

the south (outlined in Figure 2). Two of the species of Margaretamys are endemic to this

mountain block and they are part of a suite of small mammals that have been collected

only in the west-central mountain block (Musser et al. 2010). The other endemic

mountain region relevant to the topic of this paper is Pegunungan Mekongga, extending

along the southwestern coast of the southeastern peninsula (Figure 2). In this paper, we

use the Indonesian terms danau (lake), sungai (stream or small river), kuala (stream

discharging directly into the sea), gunung (mountain), and pegunungan (mountain

range).

Forests

The tropical rain forests embracing the habitats of Sulawesi’s species of Margaretamys

will be described broadly by applying three of the forest formations categorized by

Whitmore (1984): tropical lowland evergreen rain forest, tropical lower montane rain

forest, and tropical upper montane rain forest. Whitmore’s descriptions of these forest

landscapes are enlightening and, as he notes, an extension and elaboration of Richards’

(1952) classical The Tropical Rain Forest (for the second edition, refer to Richards 1996).

Description of the new species and comparison

A large sample is always preferable to a small sample when it is to represent a newly

discovered species of mammal – in this case, a murid rodent in the genus Margaretamys –

that requires a scientific name, diagnosis, description, and comparison with related

species. However, we have at hand only one individual, an adult male represented by

photographic images of the whole animal and a cataloged skull. The mixture of physical

size, fur coloration and texture, tail patterning, conformation of the skull, and particular

details of cusp patterns forming molar occlusal surfaces exhibited by the adult male is

unlike any of the specimens forming samples in museum collections of the three described

species of Margaretamys – M. beccarii, M. elegans, and M. parvus. We confidently

propose the hypothesis that the specimen is a sample of a fourth species in the genus with

the ancillary hypothesis that it will prove to be another member of the suite of rodents


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endemic to montane habitats in Pegunungan Mekongga, an assembly currently comprising

the squirrel Pros. abstrusus, and the murids T. arcuatus, T. microbullatus, R. salocco, as

well as an undescribed species of Maxomys.

Margaretamys christinae n. sp.

Holotype

An adult male (testes scrotal) was collected on 10 January 2011 by Alessio Mortelliti

(original field number MK 14). The holotype consists of the complete cranium and mandible

(Figure 6) and preserved tissue samples (muscles). Unfortunately, the skin was inadvertently

destroyed when the specimen was processed in the laboratory. Photographic images of the

dead animal showing physical conformation of the rat; its long, hirsute, and bicolored tail;

fur coloration and texture; and topography of plantar pads are provided in Figure 7. The

holotype (MZB 35283) is deposited in the Museum Zoologicum Bogoriense-LIPI,

Cibinong, Java. External measurements and weight of the specimen that were obtained in

the field are provided in Table 2, cranial and dental measurements are listed in Table 1.

Type locality

South slopes of Osu (Gunung) Moserosero (S3838011.000 E121811039.600, WGS84), 1537 m,

Pegunungan Mekongga, Provinsi Sulawesi Tenggara, Indonesia (Figure 3). The area of

capture was a few hundred meters from a trail used by local hunters and a former track that is

now covered by tall secondary re-growth. The area is characterized by interspersed patches

of primary and secondary forest at the beginning of tropical lower montane rain forest.

Etymology

The patronym honors Christina Thwaites who shared with Mortelliti the adventure of

living in Sulawesi Tenggara and was crucial to implementing and managing the field

expedition.

Diagnosis

Margaretamys christinae is characterized by the following combination of traits: (1)

comparable in body size to M. parvus (using lengths of head and body, tail, and hind foot

as indices) but heavier (greater body mass); (2) long, soft, and dense fur, upperparts of

head and body dark brownish tawny, underparts grayish buff; (3) no apparent facial mask;

(4) a bicolored tail, the proximal portion brownish gray, the distal portion white, the hairs

increase in length along the tail so the distal third is penicillate and the tip ends in a tuft; (5)

robust skull that in conformation and magnitude of most cranial dimensions and in size of

molars (indicated by length of maxillary molar row and breadth of first molar) is

comparable to the skull and dentition of M. beccarii rather than the smaller M. parvus or

the larger M. elegans; (6) mesopterygoid fossa spatulate in outline, wider in anterior half

and bounded by the concave margin of the bony palate; (7) cusp patterns forming occlusal

surfaces of first and second maxillary molars similar to those in M. beccarii (arcuate

laminae, free posterior cingulum on first molar but melded with cusp t9 on second molar),

but without a posterior cusp-like projection on cusp t6; (8) third maxillary molar small

relative to others in each toothrow, without cusp t3 and posterior cingulum; (9)


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Figure 6. The cranium and mandible of Margaretamys christinae (MZB 35283, holotype).


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anterocentral cusp part of anteroconid of first mandibular molar; and (10) anterolabial cusp

present on third lower molar.

Description and comparison

Comparisons between M. christinae and all three of the described species in the genus are

necessary because the Mekongga endemic expresses a combination of characters that

separately recall certain features seen in each of the other three species. Small body size is

typical of M. christinae and M. parvus; long and soft fur is common to M. christinae,

M. parvus, and M. elegans; a bicolored tail is found in the Mekongga species

Figure 7. Adult male Margaretamys christinae from Pegunungan Mekongga (Alessio Mortelliticode no. MK 14). The standard lengths of head and body, tail, hind foot, and ear, along with weight,are listed in Table 2. The cranium and mandibles of this individual constitute the holotype.


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Tab

le2

.S

um

mar

ies

of

len

gth

so

fh

ead

and

bo

dy

(LH

B),

tail

(LT

),h

ind

foo

t(L

HF

),ea

r(L

E)

inm

illi

met

ers,

alo

ng

wit

hw

eig

ht

ing

ram

s(W

T);

do

cum

ente

dg

eog

rap

hic

dis

trib

uti

on

and

alti

tud

inal

ran

ge

inm

eter

s;an

dfo

rest

form

atio

nd

eriv

edfr

om

the

adu

ltM

arg

are

tam

ysch

rist

ina

ean

dsa

mp

les

of

M.

eleg

an

s,M

.b

ecca

rii,

and

M.

pa

rvu

s(a

llad

ult

s).

Mea

n^

1S

Dan

do

bse

rved

ran

ge

(in

par

enth

eses

)ar

eli

sted

;m

ean

val

ues

wer

eu

sed

toco

mp

ute

LT

/LH

B.

Su

bje

ct

M.

chri

stin

ae

Peg

un

un

gan

Mek

on

gg

aN¼

1

M.

eleg

an

sW

est-

cen

tral

mo

un

tain

blo

ckN¼

29

M.

bec

cari

iC

entr

alS

ula

wes

iN¼

17

M.

pa

rvu

sW

est-

cen

tral

mo

un

tain

blo

ckN¼

17

Sex

Mal

eM

ales

and

fem

ales

Mal

esan

dfe

mal

esM

ales

and

fem

ales

LH

B1

11

18

6.3

^6

.97

(16

5–

19

7)

13

3.1

^8

.16

(11

7–

14

7)

10

2.6

^4

.18

(96

–1

14

)L

T1

75

26

0.2

^1

6.2

7(2

20

–2

86

)1

78

.7^

14

.12

(15

0–

21

2)

16

5.5

^8

.23

(15

4–

18

4)

LT

/LH

B(%

)1

58

14

01

34

16

1L

HF

20

37

.4^

1.1

5(3

5–

39

)2

8.3

^1

.31

(26

–3

1)

24

.5^

0.8

0(2

3–

26

)L

E2

4.5

a2

4.3

^.9

0(2

3–

27

)2

0.2

^0

.81

(19

–2

1)

19

.9^

0.7

0(1

9–

21

)W

t4

91

19

.2^

18

.03

(85

–1

50

)6

3.9

^1

1.4

3(5

0–

85

)3

1.6

^5

.46

(23

–4

0)

Geo

gra

ph

icd

istr

ibu

tio

nP

egu

nu

ng

anM

eko

ng

ga

Wes

t-ce

ntr

alm

ou

nta

inb

lock

No

rth

east

pen

insu

laan

dS

ula

wes

i’s

core

Wes

t-ce

ntr

alm

ou

nta

inb

lock

Alt

itu

din

alra

ng

e1

53

71

50

0–

22

72

40

–1

00

01

80

0–

22

72

Tro

pic

alfo

rest

form

atio

nL

ow

erm

on

tan

eL

ow

eran

du

pp

erm

on

tan

eL

ow

lan

dev

erg

reen

Lo

wer

and

up

per

mo

nta

ne

aM

ort

elli

tim

easu

red

the

rig

ht

hin

dfo

ot

of

M.C

hri

stin

ae

and

om

itte

dth

ecl

aws;

Mu

sser

mea

sure

dal

lth

esp

ecim

ens

of

M.P

arv

us,

M.B

ecca

rii,

and

M.el

egan

san

dh

isv

alues

incl

ud

eth

ecl

aws.


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and M. elegans; and most aspects of the skull and molars of M. christinae are more like

M. beccarii than either M. parvus or M. elegans.

Our comparisons are provided with the understanding that a single adult male cannot

measure the range of individual and sexual variation in physical and morphometric traits

within the population of M. christinae. Some traits will be found to be predictably variable

in a larger sample – body size, length of tail relative to length of head and body, length of

white tail segment relative to total tail length, cranial and dental dimensions, and minor

variations in cusp patterns – as seen in the relatively larger samples of the other three

species of Margaretamys (Tables 1 and 2). While integrity of results from the contrasts

outlined below can be tested with additional representatives of M. christinae, we are

confident such data will not alter our contention that the Mekongga voucher represents a

unique and deeply divergent gene pool – a separate species geographically and genetically

isolated in the mountains of the southeastern peninsula.

External traits

Because the skin is no longer available, our description of fur color and texture and other

external features is based on photographic images of M. christinae taken in the field (some

are exhibited in Figure 7) and journal notes made at the time. The dark brownish tawny fur

covering upperparts of the head and body is long, soft, and dense; the head lacks a facial

mask and the muzzle is grayish white. The chin and throat are covered with grayish-white

fur, but the remainder of the ventral coat, from chest to inguinal region, is grayish buff.

Facial vibrissae are long and the large ears are brown and appear naked but are actually

covered with short inconspicuous hairs. The tail is appreciably longer than the length of

head and body (LT/LHB ¼ 158%), its proximal two-thirds is grayish brown on all

surfaces, the distal third is white. Three hairs emerge from each tail scale and these hairs

increase in length along the tail, so the distal half is penicillate and the tail ends in a distinct

tuft. Dorsal metacarpal and metatarsal surfaces of the front and hind feet are brown, the

digits are white, and the claws and palmar and plantar surfaces unpigmented. Shape of the

feet and number and topography of the pads adorning the palmar and plantar surfaces

closely resemble these features in M. beccarii and M. parvus, as illustrated in Figure 8.

Margaretamys christinae does not appear to be the Mekongga equivalent of M. elegans

from the west-central mountain block. That species also has a bicolored tail but it is

appreciably larger in body size than M. christinae (Table 2) and is characterized by brown

or brownish gray upperparts, grayish white underparts, and a more elongate hind foot

(Figures 1 and 8).

In its physical size, along with fur coloration and texture, M. christinae at first glance

appears to be the Mekongga counterpart of M. parvus, another endemic of the west-central

mountain block. Both have soft, dense, and long fur and are not so different in body size,

and dimensions of tail, appendages, and ears. For example, values for lengths of head and

body, tail, hind foot, and ear obtained from M. christinae fall within the range of variation

recorded for the sample of M. parvus (Table 2). However, M. christinae is heavier (49 g;

23–40 g is the range for M. parvus), has dark brownish tawny upperparts as opposed to the

bright reddish brown coat so characteristic of M. parvus, lacks the facial mask seen in all

M. parvus, and expresses a bicolored tail, which is unknown in M. parvus, at least as

represented by the sample from Gunung Nokilalaki (Musser 1981).

Margaretamys beccarii, the other small-bodied member of the genus, is physically

larger than M. christinae as reflected by its longer head and body, tail, and hind feet; length

of ear, however, is comparable in the two species, indicating that M. beccarii has relatively


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smaller ears compared with the proportion in M. christinae, and the two species are similar

in mass (Table 2). Also, in contrast to the Mekongga species, M. beccarii has dense and

semi-spinous fur that is grayish brown on the head and body and ranges from cream

through yellow to ochraceous buff over the venter; the long pencillate tail is brown in most

specimens but there is variation in the patterning of brown and white: of the 20 specimens

examined by Musser (1981, p. 278), 5 have monocolored brown tails, in 14 the tails are

Figure 8. Upper row: from left to right, palmar views of left front feet of Margaretamys elegans,M. beccarii, and M. parvus. Lower row: from left to right, plantar views of left hind feet of M.parvus, M. beccarii, and M. elegans. Source: Musser (1981).


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brown on the dorsal surface but pale along the ventral surface, and one specimen has a

brown tail in which the distal one-third is white.

The scatter plots of specimen scores projected on the first and second principal

components extracted from principal-components analysis in Figure 9 summarize the

quantitative affinities of the specimen of M. christinae as measured by external variables.

In both ordinations, the dispersal of scores along the first axis, which indicates size

contrasts, unsurprisingly forms three discrete aggregations: points for the largest-bodied of

the species, M. elegans, lay to the right; scores representing the smallest-bodied M. parvus

fall to the left; and the cluster representing M. beccarii is about in the center of each

ordination. Covariation among all variables is responsible for the spread of scores along

the first component as indicated by the high and positive loadings (Table 3).

In the principal component analysis including lengths of head and body, tail, hind foot,

and ear, M. christinae clusters with the sample of M. parvus (Figure 9), which reflects the

close similarity between the two species in these dimensions (Table 2). Weight of the

holotype exceeds that of any M. parvus specimen (Table 2).

Figure 9. Specimen scores representing samples of Margaretamys parvus (filled circle; N ¼ 17), M.beccarii (empty circle; N ¼ 17), M. elegans (filled triangle; N ¼ 29), and the specimen of M.christinae (filled square) projected on first and second principal components extracted from principal-components analysis. This was derived from a covariance matrix of log-transformed values for lengthsof head and body, tail, hind foot, and ear. See Table 3 for correlations of variables and percent variance.

Table 3. Results of principal-components analysis contrasting the specimen of Margaretamyschristinae with samples of M. parvus (N ¼ 17), M. beccarii (N ¼ 17), and Margaretamys elegans(N ¼ 29). Correlations (loadings) of log-transformed measurements for lengths of head and body(LHB), tail (LT), hind foot (LHF), ear (LE), with derived principal components are based on 63specimens. Results are illustrated in the scatter plot in Figure 9.

Length dimensions only (upper scatter plot)

Variable PC1 PC2

LHB 0.99*** 0.15LT 0.98*** 20.20LHF 0.99*** 0.03LE 0.93*** 20.13Eigenvalue 0.155 0.004% Variance explained 96.4 2.2

***p # 0.001; **p # 0.01; *p # 0.05.


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Brownish tawny upperparts, grayish buff underparts, no conspicuous facial mask,

bicolored tail, external dimensions fitting with M. parvus rather than M. beccarii but mass

comparable with M. beccarii, and body size appreciably less than M. elegans combine to

identify M. christinae as highly distinctive compared with the three other species of

Margaretamys.

Cranial traits and molar size

The skull of M. christinae is robust, stocky in aspect, with a short and rectangular rostrum (as

seen in both dorsal and lateral views; Figure 6) supporting spacious nasolacrimal capsules

that bulge beyond the rostral walls. Tips of the nasals are gently rounded, overhang the

external nares, and their posterior margins project slightly beyond ends of the rostral

processes of the premaxillae at the premaxillary-frontal suture. Each zygomatic plate is

narrow and erect (not sloping), its maxillary root originates anterior to the first molar

(posterior margin of the zygomatic plate is situated anterior to the first molar), its anterior

margin is straight and has a slight spine so there is a shallow notch between the anterior spine

and side of the skull (as seen from dorsal perspective). Zygomatic arches converge slightly

anteriorly relative to the axis of the skull; the maxillary and squamosal roots of each arch are

united by a moderately long jugal. The squamosal root of each zygomatic arch originates

high on the outer braincase wall and its posterior margin extends along the braincase to the

occiput as a low but conspicuous ridge. Dorsolateral margins of the wide interorbital and

postorbital regions are defined by conspicuous ridges that sweep back along dorsolateral

margins of the postorbital region and onto the braincase to form prominent temporal ridges;

those above the postorbit form moderately wide shelves. Each side of the braincase from the

temporal beading to squamosal roots of the zygomatic arches is vertical and composed of

squamosal and a narrow ventral projection of the parietal. The squamosal above each

auditory capsule and just anterior to the lamboidal ridge is complete (not penetrated by a

subsquamosal foramen). The inner walls of the braincase are smooth, without squamosal-

alisphenoid grooves. The occipital region is moderately deep and roofed by the interparietal

and dorsal part of each exoccipital; the boundary between squamosal and exoccipital is

marked by prominent lamboidal ridges, and the posterior wall of the occipital is gently

convex (in lateral view) and overhangs the occipital condyles.

Moderately long and wide, the incisive foramina terminate anterior to the faces of the

first molars. Except for a pair of fairly deep grooves, the bony palate is smooth, its

posterior margin is anterior to backs of the third molars. A pair of posterior palatine

foramina penetrates the palate at the maxillopalatine suture opposite each second molar.

The maxillary molar rows are parallel. The mesopterygoid fossa is broad and each

dorsolateral wall is perforated by a long and narrow slit that expose the medial borders of

the presphenoid and basisphenoid. The pterygoid plates adjacent to the mesopterygoid

fossa are moderately excavated and intact (not pierced by a large sphenopterygoid

vacuity). The posterolateral and posterior edges of each plate converge behind the foramen

ovale to form a wide and smoothly rounded ridge, which defines the anterolateral border of

the spacious medial lacerate foramen that separates each pterygoid plate from the

ectotympanic bullar capsule. Just medial to this pterygoid ridge is a deep groove for the

infraorbital branch of the stapedial artery. The point where the artery leaves the groove and

passes to the dorsal surface of the pterygoid plate defines the posterior opening of the

alisphenoid canal.

Each ectotympanic (¼ auditory) bulla is relatively small and bears a short bony

eustachian tube. The medial sagittal plane of each bullar capsule is oriented


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ventromedially so the capsules appear to rest on the basicranium and project toward the

midline rather than more nearly vertical. A large stapedial foramen lies between the bullar

capsule and periotic, and a conspicuous wedge of the periotic (seen in ventral view) is

exposed at the posteromedial margin of the auditory capsule and along its anterodorsal

margin (seen in lateral view). Dorsoposterior portion of the bullar capsule and part of the

periotic contact the squamosal, but anteriorly the capsule and periotic are separated from

the squamosal by a postglenoid foramen that is confluent with the wide, ventral middle

lacerate foramen. The mastoid portion of the periotic is slightly inflated, its outer wall

complete.

Within the orbit the ethmoid foramen is small and the optic foramen is moderately

large. The junction of the orbitosphenoid, alisphenoid, and frontal bones forms a solid

section of the braincase wall, unbroken by a sphenofrontal foramen. Sphenopalatine and

dorsal palatine foramina are separate, a pattern similar to that found in species of Rattus

(Musser, 1982, p. 22). In the alisphenoid region posterior to the orbit (seen in lateral view),

a bony alisphenoid strut is not present, resulting in coalescence of foramen ovale

accessorius and masticatory-buccinator foramina. Exposed to view is the anterior opening

of the alisphenoid canal, the open canal itself, and the foramen ovale.

The holotype of M. christinae and all specimens of the other three species of

Margaretamys possess a carotid arterial plan that is derived for muroid rodents in general

but primitive for members of subfamily Murinae (character-state 2 of Carleton, 1980,

pattern 2 described by Voss 1988; conformation diagrammed for Oligoryzomys by

Carleton and Musser 1989; and described from dissection by Bugge 1970). It is reflected in

the skulls by the presence of certain cranial foramina and osseous landmarks: no

sphenofrontal foramen penetrates the bony junction of orbitosphenoid, alisphenoid, and

frontal bones; no squamosal-alisphenoid groove scores the inner surface of each wall of

the braincase; and no shallow trough extends diagonally over the dorsal (inner) surface of

each pterygoid plate; there is a large stapedial foramen in the petromastoid fissure, and a

deep groove extending from the middle lacerate foramen to the foramen ovale on the

ventral posterolateral surface of each pterygoid plate. This disposition of foramina and

grooves indicates that the stapedial artery branches from the common carotid, enters the

periotic region through a large stapedial foramen, and as the infraorbital artery exits the

pteriotic through the middle lacerate foramen, then courses in a short groove on the outside

of the pterygoid plate to disappear into the braincase through the alisphenoid canal from

which it emerges to course through the anterior alar fissure into the orbit. The supraorbital

branch of the stapedial is absent. The circulatory plan is common among murines (Musser

and Newcomb 1983; Musser and Heaney 1992).

This array of cranial features seen in M. christinae generally describes the skulls

representing the three other species of Margaretamys with the exceptions that are

discussed below, beginning with comparison between the new species and the largest-

bodied species in the genus.

In parallel with the contrasts in body size between M. christinae and M. elegans are

different in skull size and other cranial traits. The skull of the Mekongga endemic is

appreciably smaller than any adult M. elegans of comparable age. Values for all the cranial

measurements are less and outside the range of variation recorded for measurements

obtained from the sample of M. elegans (Table 1).

Compared with M. christinae, the skull of M. parvus is smaller, gracile in aspect,

appearing delicate (Figures 6, 10 and 11). From a dorsal view, the rostrum is tapered from

the anterior edges of the zygomatic archs to tips of the nasals, and also moderately tapered

from a lateral view. Profile of the braincase and interorbit (from dorsal view) is vase


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shaped because dorsolateral margins of the interorbit are smooth and margins of the

postorbital region support weak and inconspicuous beading – the interorbital region is

hourglass or amphoral in dorsal outline. The braincase is round in dorsal aspect and

smooth, the temporal ridges so reduced they are barely evident. Outline of the

mesopterygoid fossa is rectangular, and the posterior border of the bony palate is straight,

not concave.

Figure 10. Cranial views of Margaretamys elegans (left: AMNH 223693), M. beccarii (middle;AMNH 224064), and M. parvus (right; AMNH 225063). Source: Musser (1981).


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By contrast, occipitonasal length, zygomatic and interorbital breadths, length and

breadth of the rostrum, size of the braincase, breadth of the zygomatic plate, lengths of the

diastema and postpalatal region, and length of bulla for M. christinae exceed their

Figure 11. Lateral views of crania and dentaries of same specimens in Figure 9. Margaretamyselegans (top), M. beccarii (middle), and M. parvus (bottom). Source: Musser (1981).


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counterparts in M. parvus (Table 1). Especially notable is the longer and wider skull of

M. christinae (as indexed by occipitonasal length and zygomatic breadth) with its heavier

rostrum and larger braincase, all configurations that give the skull its more robust aspect

when compared with the gracile form typical of M. parvus. The Mekongga species is

characterized by a stocky skull with a rectangular rostrum (viewed from both dorsal and

lateral aspect), somewhat squarish rather than round braincase, dorsolateral edges of the

interorbital and postorbital regions defined by strong ridging that continues back as

temporal crests along dorsolateral margins of the braincase, and a mesopterygoid fossa

that is spatulate in outline (wider in its anterior half and bounded by the concave margin of

the bony palate).

While the small physical body size and thick, soft fur of M. christinae recalls

M. parvus, conformation of the skull closely resembles that of M. beccarii (Figures 6, 8

and 9). The description for the skull of M. christinae elaborated above could equally apply

to that of M. beccarii. Especially notable are the robust conformation of the skull shared by

both species, the rectangular rostrum (as seen in both dorsal and lateral views), the

prominent dorsolateral ridging along the interorbital and postorbital regions and strong

temporal ridges, moderately long incisive foramina that typically end just before faces of

the first molars, a short and wide bony palate terminating anterior to backs of the third

molars, and a mesopterygoid fossa that is spatulate in outline.

The cranial resemblance between M. christinae and M. beccarii extends to skull size.

Values of all but two cranial measurements recorded for M. christinae fall within or lay at

the lower end of the range of values for comparable measurements derived from the

sample of M. beccarii (Table 1). The shorter and narrower incisive foramina of

M. christinae are the exception as indicated by their smaller values that are outside of the

ranges for these variables in the sample of M. beccarii.

The univariate mensural differences and visual cranial and dental dimensional

dissimilarities among M. christinae, M. elegans, M. beccarii, and M. parvus are

summarized by results from multivariate analyses portrayed in Figure 12, which contains a

scatter plot showing the distribution of specimen scores for samples of the four species

projected on first and second principal components extracted from principal-components

analysis. Three discrete constellations of points aligned along the first axis represent the

small-bodied M. parvus in the left half of the ordination, the larger-bodied M. elegans in

the right half, and middle-sized M. beccarii near the center. Covariation among variables

point to size as the primary force separating the scores into the three clusters along the first

component, as indicated by the positive and high correlations on that axis for all the

variables (r ¼ 0.80–0.100; Table 4). The score identifying the specimen of M. christinae

clusters with the cloud of scores representing M. beccarii, a position reflecting similarities

in magnitude of cranial and dental dimensions recorded by measurements (Table 1).

Significant covariation among two variables on the second component reflects

differences in proportions (Table 4). Both M. christinae and M. beccarii have a relatively

wider interorbital region and mesopterygoid fossa (r ¼ 0.45 and 20.44, respectively) as

compared with the proportional configuration in M. parvus and M. elegans.

Differences among the mandibles of each species generally parallel the size

distinctions shown by the skulls (Figures 6, 10 and 11). Dentaries of M. christinae closely

resemble those of M. beccarii in size and overall conformation and are smaller than the

larger dentaries of M. elegans. In all three, the coronoid process is moderately large, the

concave rim between condyloid and angular process is moderately deep, and the bottom of

the angular process is shelf-like. The incisor capsule terminates just behind the base of the

coronoid process and does not extend into the condyoid process. The dentaries of


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M. parvus are similar in conformation but smaller, appearing gracile compared to the

robust elements of M. christinae, M. beccarii, and M. elegans.

In summary, size of the skull and molars (as indexed by the cranial and dental

dimensions measured) of M. christinae, combined with its overall configuration, conforms

most closely to skulls in the sample of M. beccarii.

Figure 12. Specimen scores representing samples of Margaretamys parvus (filled circle; N ¼ 13),M. beccarii (empty circle; N ¼ 19), M. elegans (filled triangle; N ¼ 24), and the specimen of M.christinae (filled square) projected on first and second principal components extracted fromprincipal-components analysis of 16 cranial and 2 dental log-transformed variables. See Table 4 forcorrelations of variables and percent variance.

Table 4. Results of principal-components analysis contrasting the specimen of Margaretamyschristinae with samples of M. parvus (N ¼ 13), M. beccarii (N ¼ 19), and M. elegans (N ¼ 24).Correlations (loadings) of 16 cranial and 2 dental log-transformed variables with derived principalcomponents are based on 57 specimens; see Figure 12.

Variable PC1 PC2

ONL 0.100*** 0.01ZB 0.99*** 0.10IB 0.80*** 0.45***LR 0.98*** 20.14BR 0.95*** 0.24BBC 0.97*** 0.09HBC 0.97*** 0.10BZP 0.96*** 0.23LD 0.98*** 20.07PPL 0.99*** 0.06LBP 0.87*** 0.24BBP 0.86*** 20.06BMF 0.88*** 20.44**LIF 0.97*** 20.14BIF 0.91*** 20.05LB 0.91*** 20.01CLM1–3 0.95*** 20.20BM1 0.95*** 20.06Eigenvalue 0.406 0.018% Variance explained 90.6 4.1

***p # 0.001; **p # 0.01.


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Incisor and molar occlusal patterns

Other than size, incisor conformation in M. christinae is not so different than that typical

of M. elegans, M. beccarii, and M. parvus. In all four species, the upper incisors are

typically orthodont in position relative to the rostrum (emerge from the rostrum at about

908); the enamel layers are smooth (without sulci) with the enamel of the uppers

pigmented orange, those of the lowers cream.

Like some of the cranial dimensions, length of the maxillary molar row and breadth of

the first molar in M. christinae lie at the upper end of the range of values for these variables

in the sample of M. parvus and within the range of values for the sample of M. beccarii and

are much less than comparable measurements in the sample of M. elegans (Table 1).

The bunodont molars are firmly rooted in the skull of M. christinae and we did not

attempt to pull them from their alveoli to definitively determine number of roots anchoring

each tooth. However, judging from the proximal portions of the roots that are visible, the

patterns for all the molars are like those recorded for the three other species of

Margaretamys (Musser, 1981). Typically, the first maxillary molar is anchored by three

large roots (anterior, posterior, and lingual) only, or three large roots and a small labial

rootlet; three roots anchor each second and third molars. The first mandibular molar has

only two large roots (anterior and posterior) in some specimens and two roots with a small

labial rootlet in others; in all specimens, each second and third mandibular molar is held in

the bone by two roots.

Occlusal cusp patterns and relative size of the third maxillary molar in M. christinae

exhibit a distinctive combination because some features recall those seen in the three other

species (Figures 5 and 13). Sizes of the first and second molars relative to one another and

the degree of overlap of the first on the anterior portion of the second closely resemble

comparable proportions in M. beccarii and M. elegans.

Cusp patterns of the first and second molar in M. christinae resemble those exhibited

by M. beccarii. In both species, the anterior and second laminae on the first molar are

arcuate (in occlusal view); the third lamina on each tooth is also arcuate in outline and

formed by a large cusp t8 and smaller cusp t9. The posterior rim of the first molar is formed

by a wide posterior cingulum that extends labially from its origin on cusp t8 to form a wide

and laminar chewing surface; the labial tip of the posterior cingulum is unattached to cusp

t9, as seen in M. christinae and the image of M. beccarii (Figures 5 and 13) except in a few

very old individuals where extreme wear has obliterated cusp margins. A cusp t3 is

typically present as a small cusp or inconspicuous enamel bulge on the anterolabial

cingular margin of the second molar (Table 5) and shape of the anterior lamina and

narrower posterior row of cusps (from occlusal perspective) resemble those on the first

molar. But the labial margin of the bowed and thick posterior cingulum is fused with cusp

t9, so the posterior half of the molar is an enamel and dentine oval formed by the arcuate

cusp t8 and t9 and the curved posterior cingulum.

The primary difference in cusp pattern on first and second molars between

M. christinae and M. beccarii lies in the configuration of cusp t6. That cusp in M. beccarii

possesses a posteriorly directed large cusp-like extension, clearly seen in the molars

portrayed in Figure 5. A comparable element is not present in M. christinae and in this

aspect its cusp t6 is more similar to that seen in M. elegans in which cusp t6 is unadorned

with a posterior cusp-like projection (compare cusp t6 of the three species in Figures 5

and 13).

In its relative size and cuspidation, the third maxillary molar of M. christinae is unlike

those typical of either M. beccarii or M. elegans and is more like the proportion and cusp


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pattern seen in M. parvus. In both species, the entire tooth is conspicuously smaller relative

to sizes of the first and second molars. The molar consists of a large cusp t1 forming the

anterolingual margin (cusp t3 is absent from the anterolabial margin, which is typical of all

the species; Table 5), a lamina made of broadly coalesced cusps t4, t5, and t6 that usually

takes the shape of a deformed arc, and a small lamina that may be comprised of cusp t8 and

t9 that forms the posterior third of the tooth; a posterior cingulum appears to be absent.

In contrast, both M. beccarii and M. elegans have a larger third molar relative to the others

in the row and a prominent posterior cingulum forms the posterior border of the tooth

(Figure 5).

Aside from the relative size and cusp pattern of the third molar in M. parvus, its second

molar generally resembles that of the other species, including M. christinae, but its first

molar is quite different. In the occlusal plane, the first and second laminae are chevron-

shaped rather than broadly curved, and the posterior cingulum is broadly fused to cusp t9

in all specimens. This configuration of cusp rows is not seen in M. beccarii, M. elegans, or

M. christinae.

The patterns of laminae, cusps, and cusplets forming the occlusal surfaces of the

mandibular molars are similar in M. christinae and the other three species (Figures 5 and

13). The anteroconid (the anterior lamina on the first molar) of M. christinae shows the

remnant of an anterocentral cusp, which is indicated by a slight anterior projection and a

small enamel island in the middle of the anteroconid. An enamel island in the anteroconoid

Figure 13. Occlusal views of the maxillary and mandibular molar rows of Margaretamyschristinae (MZB 35283, holotype).


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or other evidence of an anterocentral cusp is typical in most M. beccarii and in some

examples of M. elegans but not in M. parvus.

Like most of the other species, M. christinae has prominent anterior and posterior

labial cusplets on the first molar, and an anterolabial cusp along with a large posterior

labial cusplet on the second molar (Table 5). The third molar of M. christinae bears a

prominent anterolabial cusp but a comparable element is not present in the samples of

M. beccarii and M. parvus and is absent from most specimens in the sample of M. elegans.

Ecology

Meager ecological data is attached to the specimen of M. christinae. It is an adult male

(testes scrotal) trapped on 10 January 2011 on the southern slopes of Mount Moserosero at

1537 m in lower montane rain forest, and was caught in a Sherman trap placed on a tree

1.5 m above the ground level. We assume the species is nocturnal because the rat entered

the trap during the night. It obviously is able to move about in the understory but we cannot

say that the species is primarily arboreal, scansorial, terrestrial, or is typically active at all

levels in the forest – on the ground, in the understory, and in the forest canopy. But the

Mekongga animal is a species of Margaretamys and we can make some preliminary

inference about its ecology by examining ecological information gathered from the three

Table 5. Presence (þ) or absence (2) of cusp and cusplets in samples of the four species ofMargaretamys: t3 on second maxillary molar (M2) and cusp t3 and posterior cingulum on third (M3)maxillary molar; anterolabial cusps, anterior labial cusplets, and posterior labial cusplets onmandibular molars (m1–m3). Number of individuals with or without the structure is expressed as apercentage of entire sample of a species; actual number of specimens with or without the cusp orcusplet is in parentheses.

Cusp and cusplet M. christinae M. beccarii M. elegans M. parvus

Cusp t3 on M2þ 100 (1) 85 (17) 94 (32) 93 (14)2 – 15 (3) 6(2) 7 (1)

Cusp t3 on M3þ – – 35 (12) –2 100 (1) 100 (20) 65 (22) 100 (15)

Posterior cingulum on m3þ – 100 (20) 100 (34) –2 100 (1) – – 100 (15)

Anterior labial cusplet on m1þ 100 (1) 50 (9) 100 (34) 36 (5)2 – 50 (9) – 64 (9)

Posterior labial cusplet on m1þ 100 (1) 100 (19) 100 (34) 86 (12)2 – – – 14 (2)

Anterolabial cusp on m2þ 100 (1) 100 (19) 100 (34) 93 (13)2 – – – 7 (1)

Posterior labial cusplet on m2þ 100 (1) 100 (19) 97 (32) 79 (11)2 – – 3 (2) 21 (3)

Anterolabial cusp on m3þ 100 (1) – 26 (7) –2 – 100 (19) 74 (17) 100 (14)


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other species of Margaretamys, which comes from Musser’s unpublished observations

and field journals (archived in Mammalogy at AMNH).

Musser trapped M. parvus on Gunung Nokilalaki, M. elegans on that mountain and

adjacent Gunung Kanino, and M. beccarii along the Sungai Sadaunta, Kuala Navusu, and

Sungai Tolewonu in the lowlands of central Sulawesi. Traps were placed on the ground, on

decaying tree trunks and limbs bridging streams and ravines, and above ground at different

levels in the understory forest and lower parts of the upper canopy. Examples of both

M. parvus and M. elegans were caught on the ground and at various levels above ground in

the understory, which includes the activity categories of terrestrial, scansorial, and

arboreal. All the rats were trapped in primary forest largely undisturbed except for

openings resulting from treefalls and landslips. A few examples of the kinds of habitats

where traps were placed are described in Table 6.

Nineteen M. parvus were caught, and eight of these were trapped on the ground in

runways along decaying trunks and limbs lying on the forest floor and at the bases of trees.

Eleven were caught in traps set in the understory through a vertical distribution from 1.5 to

5 m, where traps were placed in the crotches of canopy trees, on slender woody vines, and

on branches of understory trees.

The large-bodied M. elegans was more frequently encountered. From the total of 39

trapped, 25 were taken on the ground in moss-covered runways alongside decaying trunks

and limbs lying on the forest floor, in hollows among tree roots, in runways beneath moss-

covered roots and branches on the ground, and on open ground at the bases of trees.

Fourteen individuals were caught at levels from 1 to 8 m above ground in the understory

where traps were set on tree trunks, in canopies of understory trees, and on large woody

vines looping through the understory and draped from tall emergent trees.

Margaretamys beccarii is the only one of the three species that can be regarded as

typically arboreal in habits. Musser trapped 22 individuals; two were taken on trees

growing nearly horizontal, one over a stream, the other across a deep ravine. The rest are

from 1 to 6 m above ground level in understory forest where nearly all were caught in traps

set on woody vines dangling from tree crowns. No rat was caught in any trap placed on the

ground.

All three species are nocturnal. Examples of each were trapped only during the night.

Individuals representing each of the species housed in small cages remained concealed in

globular leaf nests during the day but were active at night.

One or two young in litters is typical for M. parvus, M. elegans, and M. beccarii. This

assessment is based on number of embryos or fresh placental scars found in uterine horns.

Fruit and invertebrates, particularly insects, constitute the diet of all three species, as

determined by offering foods to captive rats (Table 7). With the exception of a few kinds

of fruit that dropped to the ground from canopy trees, the fruits consumed were from

palms, understory trees, and woody vines.

We suspect that M. christinae will share many of the ecological characteristics briefly

described here with the other three species of Margaretamys. The hypothesis that its

activity niche encompasses the forest floor and space above ground in understory forest,

that litter size does not exceed two young, and that fruit and insects are the primary dietary

components can be tested by results from further survey of the murine species inhabiting

montane forest in Pegunung Mekongga with an emphasis on M. christinae.


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Tab

le6

.S

elec

ted

exam

ple

so

fh

abit

ats

atsi

tes

wh

ere

spec

imen

so

fM

arg

are

tam

ysp

arv

us

(Gu

nu

ng

No

kil

alak

i),

M.

eleg

an

s(G

un

un

gK

anin

oan

dG

un

un

gN

ok

ilal

aki)

,an

dM

.b

ecca

rii

(Su

ng

aiS

adau

nta

,K

ual

aN

avu

su,

and

Su

ng

aiT

ole

wo

nu

)w

ere

trap

ped

by

Mu

sser

.

Sp

ecie

sP

lace

and

alti

tud

eD

escr

ipti

on

M.

pa

rvu

sA

MN

H2

25

06

4G

rou

nd

(22

58

m)

Bas

eo

fa

larg

eca

no

py

tree

gro

win

gfr

om

sid

eo

fa

slo

pe.

Tre

eem

erg

esfr

om

am

ou

nd

1.5

mh

igh

and

1.5

mw

ide

of

tan

gle

dro

ots

on

its

up

slo

pe

sid

e.T

he

roo

tsar

ecl

ose

lyin

terw

ov

enan

dco

ver

edw

ith

pea

tyea

rth

and

thic

kan

dw

etm

oss

,o

nw

hic

har

eg

row

ing

fern

s,sm

all

shru

bs,

and

oth

erp

lan

ts.

Th

em

ou

nd

ish

on

eyco

mb

edw

ith

pas

sag

esan

dm

any

of

thes

ele

adb

enea

thth

eb

ase

of

the

tree

on

the

do

wn

slo

pe

sid

eo

nto

asm

all

flat

terr

ace

emb

race

db

yth

ela

rge

exp

ose

d,

wal

l-li

ke

mai

nro

ots

and

par

tial

lyro

ofe

db

yth

etr

eetr

un

k.

Ash

rew

rat,

Mel

.n

aso

,w

asta

ken

insa

me

spo

t.A

MN

H2

25

05

4G

rou

nd

(22

72

m)

Ind

amp

run

way

(13

cmw

ide

and

hig

h)

ben

eath

dec

ayin

gan

dd

ense

lym

oss

-co

ver

edla

rge

tree

tru

nk

lyin

go

ng

rou

nd

.A

shre

w,

Cro

cid

ura

rho

dit

isM

ille

ran

dH

oll

iste

r,1

92

1,

was

cau

gh

tin

sam

ep

lace

.A

MN

H2

25

06

8U

nd

erst

ory

(18

30

m)

Inb

ran

ches

of

un

der

sto

ry4

mfr

om

gro

un

d.

Tw

otr

aps

wer

eti

edto

a3

-mp

ole

that

was

pla

ced

inth

ecr

ow

ns

of

the

smal

ltr

ees

form

ing

the

un

der

sto

ryb

ecau

seth

eli

mb

san

dsm

alle

rb

ran

ches

wer

en

ot

stro

ng

eno

ug

hto

sup

po

rttr

aps.

Nu

mer

ou

sin

terc

on

nec

ted

lim

bs

and

bra

nch

esfo

rma

den

seu

nd

erst

ory

.A

fru

itin

gE

laeo

carp

us

sp.

L.

isn

earb

y,

can

op

yfo

rmed

mo

stly

by

oak

s(L

ith

oca

rpu

ssp

.B

lum

e,1

82

5).

AM

.el

ega

ns

was

tak

enin

sam

esp

ot.

AM

NH

22

50

70

Un

der

sto

ry(1

83

0m

)O

nsl

end

erw

oo

dy

vin

e(1

0m

min

dia

met

er)

gro

win

gfr

om

gro

un

do

nn

arro

wri

dg

eto

3m

,th

enlo

op

ing

ou

tta

utl

yo

ver

nea

rly

ver

tica

lsl

op

ean

das

cen

din

gto

12

min

cro

wn

so

fth

esh

ort

tree

sfo

rmin

gu

nd

erst

ory

can

op

yo

ver

rid

ge-

top

.T

wo

trap

sw

ere

pla

ced

bac

kto

bac

ko

nv

ine

3m

fro

mg

rou

nd

,ra

tw

asca

ug

ht

intr

apfa

cin

gca

no

py

,n

ot

the

trap

faci

ng

gro

un

d.

AM

NH

22

50

56

Un

der

sto

ry(2

25

8m

)1

.5m

fro

mg

rou

nd

inh

oll

ow

of

larg

eca

no

py

tree

on

nar

row

,co

ld,

and

win

dy

rid

ge.

Tre

esp

lits

into

two

mai

nli

mb

san

do

ne

of

thes

eis

cov

ered

wit

ha

thic

kw

oo

dy

vin

eth

atfo

rms

aro

of

abo

ve

the

lim

bs

bel

ow

wh

ich

isa

lon

gh

oll

ow

spac

e.T

her

ear

eal

soh

oll

ow

sin

mai

ntr

un

kw

her

eli

mb

sd

iver

ge.

En

tire

tree

isco

ver

edw

ith

thic

kan

dw

etm

oss

and

on

lyn

arro

wru

nw

ays

inth

eh

oll

ow

pla

ces

are

free

of

mo

ssan

dso

mew

hat

dri

erth

ano

uts

ide.

M.

eleg

an

sA

MN

H2

25

14

6G

rou

nd

(22

72

m)

Inh

oll

ow

bas

eo

fst

and

ing

,d

ecay

ing

bas

eo

fan

oak

(Lit

ho

carp

us)

on

sum

mit

rid

ge.

Tru

nk

bas

eis

2m

ind

iam

eter

and

3m

of

bo

lere

mai

ns

erec

t.R

est

of

tru

nk

lay

nea

rby

and

do

wn

slo

pe

inv

ario

us

size

dse

ctio

ns.

Th

eb

ase

ism

ost

lyh

oll

ow

and

ther

ear

ela

rge

and

lon

gsp

aces

and

pas

sag

eway

sb

enea

thth

ero

ttin

gro

ots

asw

ell.

Th

era

tsR

.m

arm

osu

rus,

P.

do

min

ato

r,an

dth

esq

uir

rel

Hyo

sciu

rus

hei

nri

chi

Arc

hb

old

and

Tat

e,1

93

5w

ere

tak

enin

sam

esp

ot.

Th

era

tsE

.ca

nu

s,B

.p

enit

us,

and

Ra

ttu

sh

off

ma

nn

iw

ere

cau

gh

tb

enea

tho

ne

of

the

dec

ayin

gro

ots

abo

ut

1.5

maw

ay,

and

the

shre

wra

tsM

el.

na

soan

dT

at.

rhin

og

rad

oid

esw

ere

trap

ped

ina

run

way

ben

eath

ase

ctio

no

fth

etr

un

kly

ing

nea

rby

.A

MN

H2

25

14

5G

rou

nd

(22

72

m)

Am

on

gro

ots

of

larg

eD

acr

yca

rpu

sci

nct

us

Pil

ger

,1

93

8g

row

ing

on

stee

psi

de

of

slo

pe.

Tre

eis

gro

win

gaw

ayfr

om

slo

pe,

its

bac

ksi

de

isco

ver

edw

ith

ath

ick

wo

od

yv

ine.

Ex

po

sed

roo

tsco

ver

dee

pcr

evac

esin

the

hil

lsid

e.C

aug

ht

the

rats

Bu

no

mys

pen

itu

san

dP

.d

om

ina

tor

insa

me

spo

t.


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AM

NH

22

51

37

Un

der

sto

ry(1

83

0m

)S

ixm

fro

mto

po

fri

dg

ein

cro

wn

so

fu

nd

erst

ory

tree

sth

atfo

rma

10

-mu

nd

erst

ory

can

op

yo

ver

that

sect

ion

of

rid

ge.

Tra

ps

wer

ese

to

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Sympatry

Margaretamys christinae shares its montane habitat with other species of mammals.

Among murine rodents, which are the focus of this paper, B. penitus, B. chrysocomus,

P. dominator, and Maxomys sp. were captured in the same area as the specimen of

M. christinae (Mortelliti, personal observation; Table 8). When Heinrich worked in the

montane forests in the Mekongga highlands, he obtained samples of T. arcuatus,

T. microbullatus, and R. salocco; these species could be found to occur together with

M. christinae. In the same montane forests is an endemic species of squirrel, Pros.

abstrusus (Musser et al. 2010), which Mortelliti also encountered.

The species of Margaretamys that might inhabit tropical lowland evergreen rain forest

on the lower flanks of the Mekongga range and adjacent lowlands has yet to be discovered.

Table 7. Examples of foods eaten by Margaretamys parvus, M. elegans, and M. beccarii.(Determined by recording the foods accepted by live rats.)1

Species FruitInsects and otherarthropods

Otherinvertebrates Vertebrates

M. parvus The palm, Areca vestiariaGiseke; Pandanus sp.;understory trees (Elaeocarpussp., Eurya acuminata, Ficussp.), and fruit from woodyvine (Vaccinium sp.)

Moths, orthopterans(cicadids, katydids,crickets)

– –

M. elegans The palm, A. vestiaria;Pandanus sp.; understorytrees (Elaeocarpus sp.,E. acuminata), and fruit fromwoody vine (Vaccinium sp.)

Moths, orthopterans(cicadids, crickets)

– –

M. beccarii Several species of Figures(the understory Ficus vrie-seana, F. Aurita Blume,F. Latimarginata Corner, andF. geocarpa; emergentstrangler Ficus); the palms,A. vestiaria, Licuala sp., andPigafetta filaris Giseke; softpulp of wild bananas (Musasp.); ginger (Etlingera sp.);fruit from a variety of shrubsand understory trees (Ardisiakorthalsiana Scheff., Elaeo-carpus speciosus Brongn. andBris, Spondias pinnata Kurz,Antidesma stipulare Blume),from canopy trees (L. gluti-nosus Blume, Sapium leuco-gynum C. Wright ex Griseb.,Cubilia cubili (Blanco) Adeb,and from woody vines (Gne-tum cuspidatum Blume)

Moths, orthopterans(katydids), preyingmantises, adult andlarval beetles

Small snails Small lizards

1 The listed inventory, especially of fruit, is certainly incomplete. For example, only a few understory trees werein fruit in the montane forest during the periods Musser worked in those habitats, and surveying contents ofstomachs, which he has yet to do, may reveal a greater variety of insects in the diets. Not listed are the foodsprovided but which the rats rejected.


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Margaretamys beccarii should occur in this lowland region and if it does it would share

the habitats with the rats T. celebensis, R. hoffmanni, B. chrysocomus, B. andrewsi, Max.

hellwaldii, Max. musschenbroekii, and P. dominator (specimens in AMNH identified by

Musser), and the squirrels Rub. rubriventer, Pros. alstoni, and Pros. murinus (Musser et al.,

2010), all represented in the material collected by Heinrich.

Despite trapping at these lower altitudes in the Mekongga highlands, Mortelliti did not

encounter M. beccarii (Mortelliti, unpublished data). However, this species is not easily

trapped. For example, during 1973–1976, Musser worked in the northern part of central

Sulawesi, he trapped in tropical lowland evergreen rain forest habitats (between 30 and

1150 m) in different places and during different periods for a total of 15 months and captured

only 22 specimens of M. beccarii. This number contrasts with the relative numbers of

specimens representing totals for the more common species obtained in the same habitats

during the same time interval: 36 T. celebensis, 118 Max. hellwaldii, 34 Max.

musschenbroekii, 162 R. hoffmanni, 153 R. facetus (Miller and Hollister, 1921), 105

P. dominator, and 318 B. chrysocomus (Musser 2012); many specimens of R. facetus were

also caught above ground in the understory. Musser found M. beccarii to be spottily

distributed in the forest, concentrated in pockets here and there and seemingly absent from

extensive areas trapped.

In lowland forests of central Sulawesi where Musser worked, M. beccarii occurs in the

same areas as 16 other murine species (Table 8). Twelve species are sympatric with

M. parvus and M. elegans in the montane forests of Gunung Kanino and Gunung

Nokilalaki in the northern part of the west-central mountain block.

Table 8. Species of murid rodents trapped in the same area with Margaretamys christinae inPegunungan Mekongga (Mortelliti, unpublished data), and with M. parvus, M. elegans, and M.beccarii in the west-central region (Musser, unpublished data).

Tropicalrain forestformation

M. christinaePegununganMekongga1

M. parvus and M. elegansGunung Kanino, GunungNokilalaki

M. beccariiSungai Sadaunta

Montane B. chrysoco-mus,B. Penitus;Maxomys sp.;P. dominator

T. hamatus, Taeromys sp.;Haeromys sp.; Tat. macrocer-cus, Tat. rhinogradoides; Mel.naso; E. canus;B. penitus; Max. musschen-broekii; R. hoffmanni,R. facetus; P. dominator

–

Lowlandevergreen

– T. callitrichus, T. celebensis;Max. dollmani, M. hellwaldii,M. musschenbroekii, M. sp.;Crunomys celebensis; E. cen-trosa; Haeromys minahassae;L. meyeri; B. chrysocomus,B. andrewsi, B. sp.;R. hoffmanni, R. facetus;P. dominator

1 While working in Pegunungan Mekongga in 1932, Heinrich obtained samples of T. arcuatus and T.microbullatus (the Mekongga counterparts of T. sp. and T. callitrichus, respectively) and R. salocco (a closerelative of R. facetus), all from montane forest habitats. We suspect these species may also be found to occur inthe same forest as M. christinae.


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Zoogeographic notes

Subsequent to its Miocene origin as an archipelago east of Borneo, the land outline of

Sulawesi by the Pliocene was similar to its configuration today (Wilson and Moss 1999;

Hall 2001). During the Pleistocene, fluctuations in sea level joined by tectonic uplift and

subsidence along with volcanism returned the island to an archipelago and later reunited

the islands into the present day landmass (Fooden 1969). Particular regions of the island

supporting endemic groups of mammals – particularly murines, which is the focus of this

paper – reflect these past geologic perturbations. The northeastern end of the northern

peninsula east of the lowlands of the Sungai Bone and Danau Limboto in the Gorontalo

region (Figure 2) is one of these endemic units and five species of murines occur there and

nowhere else: Echiothrix leucura (Gray, 1867), Taeromys taerae (Sody, 1932), Bunomys

fratrorum Thomas, 1896, Rattus marmosurus Thomas, 1921, and R. xanthurus (Gray,

1867) (Musser 2012).

A population of Margaretamys is represented by a few specimens from the

northeastern peninsula, but it is not an endemic and has all the physical and morphometric

attributes of M. beccarii from central Sulawesi (Musser 1981, unpublished data). Although

unsampled or inadequately sampled geographic areas lay between the northeastern end of

the northern peninsula and central Sulawesi, it is possible that M. beccarii will turn out to

be one of those species with a wide distribution through the lowlands of Sulawesi possibly

similar to other murines such as B. chrysocomus, R. hoffmanni, T. celebensis, and

P. dominator (Musser and Holden 1991; Musser 2012).

Whether M. beccarii is or was present in lowland forest on the southwestern peninsula

south of the Tempe Depression (Figure 2) is unknown. Much of the lowlands in the

southwestern peninsula are deforested and converted to agriculture, but low forest cover

still exists in limestone regions (Mortelliti unpublished data; Whitten et al. 1987), which

are difficult to traverse and have never been surveyed for small mammals; possibly

M. beccarii still lives in those places. Other murines now present in central Sulawesi also

occur or once did south of the Tempe Depression. Lenomys meyeri, B. andrewsi,

P. dominator, Max. musschenbroekii, Max. hellwaldii, and R. hoffmanni are represented

by modern samples (Musser 2012); subfossils document T. celebensis, T. punicans (Miller

and Hollister, 1921), and B. chrysocomus (Musser, 1984).

Distributions of the other three species of Margaretamys are not concordant with the

distributional pattern of M. beccarii.

Margaretamys elegans and M. parvus are presently known to occur only in montane

forests in the west-central mountain block (Figure 2), a landscape originally springing from

Pliocene orogeny connected to the late Miocene-early Pliocene collision of the Banggai-

Sula Australian microcontinental fragment with eastern Sulawesi (Calvert and Hall 2007;

Hall 2001) and another region of murine endemism. Here the two species of Margaretamys

are part of an endemic suite that includes Max. dollmani (Ellerman, 1921), Max. sp., B. sp.,

Sommeromys macrorhinos Musser & Durden, 2002, Eropeplus canus Miller & Hollister,

1921, Melasmothrix naso Miller & Hollister, 1921, Tateomys rhinogradoides Musser,

1969, Tat. macrocercus Musser, 1982, Haeromys sp. Thomas, 1911, T. hamatus (Miller &

Hollister, 1921), and an undescribed species of large-bodied shrew rat (Musser et al. 2010;

Musser 2012).

The fourth species, M. christinae is likely endemic to montane habitats in Pegunungan

Mekongga. The murines T. arcuatus, T. microbullatus, and R. salocco also share this

distinction.


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What montane species of Margaretamys, if any, will be found to occupy the mountainous

backbone of the eastern peninsula is presently unknown, but if the genus is found there it

will likely be represented by endemic species. Our insight into the endemic murines in that

region comes from Gunung Tambusisi (Figure 2) at the western end of the peninsula where

samples of B. prolatus Musser, 1991 and Max. wattsi Musser, 1991 were collected in

montane habitats (Musser 1991). From the few inventories focusing on small mammals in

lowland forests on the eastern peninsula, it is clear that the murines there – such as Max.

hellwaldii, B. andrewsi, R. facetus, P. dominator, and R. hoffmanni – also occur elsewhere

on the island. Margaretamys beccarii has not been collected from those lowlands but it

probably occurs there. The highlands, except for Gunung Tambusisi, remain an enigma.

Phylogenetic alliance

To which species of described Margaretamys is M. christinae most closely allied? We

cannot answer this question here. In the exposition of its characteristics above, we noted

that fur color and texture resemble M. elegans and M. parvus, that its white tail tip is a

feature shared by M. elegans, that magnitude of external dimensions are similar to

M. parvus but body mass approximates M. beccarii, that configuration of the skull and its

various dimensions match M. beccarii, that occlusal surfaces of first and second maxillary

molars closely resemble those patterns in M. elegans, and that its relatively small molar

without a posterior cingulum recalls the proportion and cusp pattern in M. parvus.

Reconstructing the phylogenetic pattern of relationships among the species using DNA

sequences would be desirable. Tissue samples from which DNA can be extracted were

obtained from the holotype of M. christinae and samples from M. elegans and M. beccarii

are available (K Rowe, K Aplin, personal communication) – results of these molecular

comparisons will be most illuminating.

Conservation

Margaretamys christinae was caught at 1537 m in lower montane rain forest, which

represents montane formations in general that are an important ecoregion (AA00124,

WWF 2001) threatened by deforestation. It is highly likely that M. christinae is endemic to

these high forests on Pegunung Mekongga. As previously mentioned, our in situ

observations have shown that large portions of lowland and montane forests on the

southeastern peninsula have been logged during the 1990s and none of the presumed

distributional range of the species is enclosed in a protected area. Ongoing modeling work

(Mortelliti, unpublished data) shows that rain forest formations above 1500 m in south-east

Sulawesi are relatively scarce and scattered between several peaks separated by deep

valleys. It is therefore possible that the species may occur with relatively disconnected

subpopulations in a total area of less than 1000 square km. Further ecological research in

the area is mandatory, but based on our preliminary observations we propose to classify

the species as EN B1a, b (iii) according to the IUCN criteria.

Acknowledgements

The study was funded by the Mohamed bin Zayed Species Conservation fund (Project Number:0925478) and was carried out under RISTEK permit 0275/SIP/FRP/XII/2010. Thanks to Mr Dey andhis family for genuine and much appreciated hospitality at Walasiho village. Thanks to the Citakapeople for taking Mortelliti to Poya-Poya, and to Mr. Dey, Moharram, and friends for takingMortelliti to the slopes of Tange salocco.


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Figures 1, 5, 8, 10 and 11 were adapted from Figures 23 and 26–32 that were originally published inMusser (1981; see references for full citation) and are used here through the courtesy of theAmerican Museum of Natural History.

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Appendix 1: All localities are from Provinsi Sulawesi Tengah (Central Sulawesi),Indonesia

Margaretamys beccarii (28 specimens)

1. Malakosa region, Kuala Navusu, 008580S/1208270E, 42–122 m: AMNH 225667–225670.2. Tolai area, Sungai Tolewonu, 018040S/1208270E, 288–333 m: AMNH 226409, 226410.3. Valley of Sungai Miu, Sungai Sadaunta (also spelled “Sidaonta” or “Sidaunta”; tributary

on right side of Sungai Miu), 018230S/1198580E, 600–1000 m: AMNH 224058–224068,2243187, 224634, 224635, 226818, 224636.

4. Gimpu, 018360S/1208020E, 424 m: USNM 219682–219686.5. Gunung Balease, 2.4995333338S, 120.48738338E, 900 m: MVZ 225726.

Margaretamys elegans (39 specimens)

1. Gunung Nokilalaki, 018130S/1208080E, 1616–2272 m): AMNH 225131–225146, 225677–223683–223692, 223693 (holotype of Margaretamys elegans), 223694–223697, 223699,225147.

Margaretamys parvus (19 specimens)

1. Gunung Nokilalaki, 018130S/1208080E, 1818–2272 m: AMNH 225053–225062, 225063(holotype of Margaretamys parvus), 225064–225071.


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A new species of Margaretamys (Rodentia: Muridae: Murinae: Rattini) from Pegunungan Mekongga,...

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