Morphological and Geographic Definitions of the Sulawesian Shrew RatsEchiothrix leucura and E. centrosa(Muridae, Murinae), and Description of a New Species of Sucking Louse (Phthiraptera: Anoplura)

2014·106.7 MB·English

by  Guy G. Musser

Scientific Publications of the American Museum of Natural History M
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American Museum Novitates SS MORPHOLOGICAL AND GEOGRAPHIC
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Bulletin of the American Museum of Natural History &
D DEFINITIONS OF THE SULAWESIAN SHREW
Anthropological Papers of the American Museum of Natural History U
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Publications Committee EN RATS ECHIOTHRIX LEUCURA AND E. CENTROSA
Robert S. Voss, Chair : ECH (MURIDAE, MURINAE), AND DESCRIPTION
IO
Board of Editors T
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R OF A NEW SPECIES OF SUCKING LOUSE
Jin Meng, Paleontology IX
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Lorenzo Prendini, Invertebrate Zoology E
U (PHTHIRAPTERA: ANOPLURA)
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Robert S. Voss, Vertebrate Zoology U
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Peter M. Whiteley, Anthropology A
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D GUY G. MUSSER AND LANCE A. DURDEN
Managing Editor E
. C
Mary Knight E
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A
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On the cover: Reproduction of Adolf Bernhard Meyer’s
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plate of ‘‘Craurothrix leucura’’ (= Echiothrix leucura) from B
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his 1899 article, “Säugethiere vom Celébes- und Philippinen- LE
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Archipel.” Moderately large with a lean body, long head, bris- 3
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tly dark gray upperparts, white underparts, mostly white tail
that is longer than head and body, delicate front legs and
small feet but robust hind legs with large and elongate hind
feet, and very large ears, species of Echiothrix are terrestrial,
nocturnal, adapted to primarily an earthworm diet, and occur
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only on the Indonesian island of Sulawesi. 014 BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY
MORPHOLOGICAL AND GEOGRAPHIC
DEFINITIONS OF THE SULAWESIAN SHREW RATS
ECHIOTHRIX LEUCURA AND E. CENTROSA
(MURIDAE, MURINAE), AND DESCRIPTION OF A
NEW SPECIES OF SUCKING LOUSE
(PHTHIRAPTERA: ANOPLURA)
GUY G. MUSSER
Division of Vertebrate Zoology (Mammalogy),
American Museum of Natural History
LANCE A. DURDEN
Department of Biology
Georgia Southern University, Statesboro
BULLETINOFTHEAMERICANMUSEUMOFNATURALHISTORY
Number391, 87pp., 19figures,18tables
IssuedJuly 25,2014
CopyrightEAmericanMuseumofNaturalHistory2014 ISSN0003-0090
CONTENTS
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The Shrew Rats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The Sucking Louse (Polyplax) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Gazetteer and Specimens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Echiothrix Gray, 1867. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Echiothrix leucura Gray, 1867 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Echiothrix centrosa Miller and Hollister, 1921. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Natural History Particulars of Echiothrix centrosa. . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Some Morphological Adaptations for Vermivory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Ectoparasites of Echiothrix centrosa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
The New Sucking Louse Polyplax beaucournui, new species . . . . . . . . . . . . . . . . . . . 70
Other Ectoparasites of Echiothrix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Order Siphonaptera (fleas), Family Pygiopsyllidae . . . . . . . . . . . . . . . . . . . . . . . . 77
Subclass Acari, Order Ixodida, Family Ixodidae (hard ticks). . . . . . . . . . . . . . . . . 77
Subclass Acari, Order Mesostigmata, Family Laelapidae. . . . . . . . . . . . . . . . . . . . 78
Subclass Acari, Order Sarcoptiformes, Family Atopomelidae (fur mites) . . . . . . . . 78
Subclass Acari, Order Trombidiformes, Family Trombiculidae (chiggers). . . . . . . . 78
CODA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Phylogenetic Affinity of Echiothrix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Sucking Lice (Anoplura) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
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ABSTRACT
Amongthe15knowngeneraofmurinerodentsendemictotheislandofSulawesi,istheshrew
ratgenusEchiothrix.Physicallylarge(lengthofheadandbody5182–235mm;weight5215–
310g)withabicoloredtailtypicallylongerthanheadandbody(100%–135%ofheadandbody
length), elongate hind feet (48–55 mm), large ears (31–35 mm), long and thin muzzle, spinous
fur,andtinymolarsrelativetosizeofskull(lengthofmolarrow512%–13%ofoccipitonasal
length),Echiothrixwasnamedanddescribedin1867andthroughtheyearshasbeentreatedas
monotypic or containing up to three species. Results from analyses of morphometric traits
derivedprimarilyfromcranialanddentalmeasurementsdocumentthepresenceoftwospecies.
Echiothrix leucura (Gray, 1867) is restricted to the northern peninsular mainland east of the
Gorontaloregion(00u319N,123u039E).Thisdistributionisconcordantwiththatoffourother
muridsendemictothenortheasterntipofthenorthernpeninsula:Bunomysfratrorum,Taeromys
taerae, Rattus xanthurus, and R. marmosurus. Echiothrix centrosa Miller and Hollister, 1921
(EchiothixbreviculaMillerandHollister,1921,isasynonym),isdocumentedbyspecimensfrom
thenorthernpeninsulawestoftheGorontaloregionandinthecentralportionoftheisland;19
other murine species are also known only from the core of Sulawesi. Whether the range of E.
centrosa extends to the eastern, southeastern, and southwestern peninsulas is at present
unknown. Echiothrix leucura has a more elongate skull compared with E. centrosa (greater
lengths of skull, rostrum, diastema, and bony palate), a wider interorbital region, larger
braincase, narrower bony palate and mesopterygoid fossa, shorter incisive foramina, and
appreciably larger molars; the two species also differ in frequencies of particular molar cusps
and cusplets. Both species of Echiothrix are nocturnal, terrestrial, and occupy habitats in
tropical lowland evergreen rain forest. Natural history observations made in the field for
Echiothrix centrosa show it to be primarily vermivorous; other natural history observations
derived from fieldwork incentral Sulawesiareprovided. Oneaspectofthatnatural historyis
theectoparasiticloadbornebyE.centrosa.Thisshrewratishosttoatleastfourspeciesofticks
(Haemaphysaliskadarsani,Haemaphysalishystricis,Haemaphysalissp. and Amblyommasp.),a
tiny fur mite (Listrophoroides echiothrix),mesostigmatidmitesbelongingtothegenusLaelaps,
currentlyundeterminedchiggers,aflea(Farhangiaquattuordecimdentata),andanewspeciesof
suckinglousedescribedhereinasPolyplaxbeaucournui.Thislousehastibiotarsalclawsadapted
forgraspingslendersofthairsinthepelageandnotthewidehostspines;femalelicealsoattach
their eggs only to these slender hairs. The closest relative of Echiothrix is probably
Paucidentomys vermidax, another Sulawesian endemic shrew rat that is also vermivorous but
lacks molars and has been collected only in montane forests. The present report documents
morphologicalanddistributionallimitsofspeciesinEchiothrix,placesoneofthosespeciesinan
ecological and parasitological landscape, and generally contributes to knowledge covering
endemic muridspecies diversityandidentifyinguniquezoogeographical areasonSulawesi.
INTRODUCTION feeblydocumentedandrequireseriousinqui-
ry.Toalterthatlackofinformationforsuch
Echiothrix and and the two species of this an interesting and unique product of murine
genus defined here, along with four other evolution on Sulawesi is our purpose here.
genera and five species of described shrew Our investigation into the nature of
rats—Melasmsothrix naso, Tateomys rhino- Echiothrix concentrates on describing results
gradoidesandT.macrocercus(Musser,1982), from two primary research endeavors. One
Sommeromys macrorhinos (Musser and Dur- looks to define limits of the species in
den, 2002), and Paucidentomys vermidax Echiothrix employing examples of the genus
(Esselstyn et al., 2012)—and two additional housed in collections of museums in North
undescribed genera are among the 15 known America, Europe, and Asia. It is from these
genera and more than 50 species of murids voucher specimens that we have gathered
endemictotheislandofSulawesi(Musser,in data concerning color and texture of the fur;
press). Of these shrew rats, the diversity of qualitative aspects of physical build and
species in Echiothrix, their range over the cranial conformation; external, cranial, and
island, and their associated ecologies are dental measurements; morphology of the
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incisors and molars; and geographic and both the shrew rat and its ectoparasites;
elevational distributions on Sulawesi. Sup- (2) gazetteer of collection localities and
plemental information comes from field record of specimens examined from each
journals and publications. We also include locality; (3) introduction to the genus, which
ecological observationsforoneofthespecies includesthenomenclaturalhistoryofthetwo
(E.centrosa)madebyMusserduringthetime othergenericnamesthatinthepasthavebeen
heworkedincentralSulawesi.Resultsreflect attachedtoEchiothrix, indication of thetype
an alpha-level systematic contribution that species, an emended generic diagnosis, and a
frames species limits based upon our inter- notice of the species contained in the genus;
pretation of present morphological and (4) an account of E. leucura, the type species
geographicdata,ahypothesisreadilytestable ofthegenus;(5)theaccountofE.centrosa;(6)
by using a combination of qualitative ana- natural history observations pertaining to E.
tomical, morphometric, and molecular ap- centrosa; (7) brief discussion of particular
proaches drawn from additional material anatomical systems showing adaptation to a
collected in unsurveyed regions of Sulawesi. vermivorous diet; (8) description of the new
The other goal provides results from speciesoflouseandrecordsofotherectopar-
surveyingskinsforectoparasitesofEchiothrix asites infesting Echiothrix (based on E.
with a focus on sucking lice (Insecta, Ano- centrosa); (9) a closing section (Coda) in
plura). Many groups of sucking lice are host which we briefly comment on the phyloge-
specific and phyletically track their hosts netic affinity of Echiothrix, and include an
(Kim, 1985, 1988; Light and Hafner, 2007; overview of anopluran sucking lice recorded
Smithetal.,2008):‘‘Amonginsects,nogroup from endemic Sulawesian murines.
ismorespecializedforparasitismthanarelice Responsibilities for the contents are divid-
(Phthiraptera) because they are probably the
ed:Mussercontributedthebasicanatomical,
only insect parasites to spend their entire life
morphometric, and distributional data and
cycle, from egg to adult, on one host’’
analyses used in the taxonomic revision of
(Grimaldi and Engel, 2005: 278). While we
Echiothrix, along with the ecological obser-
found lice on skins of only one of the two
vations and significance of particular ana-
species of Echiothrix (E. centrosa), the dis-
tomical systems as pertains to vermivory.
covery allowed us to name and describe the
Description of the new sucking louse, the
new species, Polyplax beaucournui. New
records of other groups of ectoparasites, and
research will have to determine whether the
overview of Sulawesian sucking lice springs
new louse infests only E. centrosa or it also
from Durden’s research. We integrated our
parasitizes E. leucura or any other species of
individual efforts, carefully reviewed each
Echiothrix that might be identified in future
other’s contribution,and share responsibility
surveys of small mammals on Sulawesi.
for the finished product.
Because of the intimate bond between para-
site and the parasitized, morphological and
eventuallymolecularcomparisonsamongthe MATERIALS AND METHODS
Polyplax residing on different species of THE SHREW RATS
Echiothrix might add another set of data
potentiallyusefulfordiscerningspecieslimits INSTITUTIONS AND SPECIMENS: The defi-
ofthehosts.Inthemeantime,thenewrecord nitions of species documented here are
broadens the inventory of sucking louse determined from examination of specimens
species (in Polyplax and Hoplopleura) found stored in the following institutions: the
on endemic Sulawesian rodents in general American Museum of Natural History,
(Musseretal.,2010)andmurinesinparticular New York (AMNH); Natural History Mu-
(Durden, 1986a, 1986b, 1987, 1990; Durden seum (formerly British Museum of Natural
andMusser,1991,1992;MusserandDurden, History), London (BMNH); Field Museum
2002). of Natural History, Chicago (FMNH); Mu-
Our exposition of Echiothrix is presented seum Zoologicum Bogoriense, Cibinong,
in the following parts: (1) materials and Java (MZB; now the Indonesian National
methods covering the sections relevant to Museum of Natural History, also known as
2014 MUSSERAND DURDEN: ECHIOTHRIX LEUCURAAND E.CENTROSA 5
the Research Center in Biology–Lembaga length of tail, and measured length of the
Ilmu Pengetahuan Indonesia); Naturhistor- distal white tail segment on the dry study
isches Museum Basel, Switzerland (NMB); skin; value for ear length, when available,
Nationaal Museum of Natural History Nat- was sometimes ignored because it was
uralis (formerly the Rijksmuseum van Nat- unclear how preparators measured that
uurlijke Historie), Leiden (RMNH); Nation- dimension. Values for length of hind foot
al Museum of Natural History, Smithsonian were usually ignored and instead Musser
Institution, Washington, D.C. (USNM). measured those distances on the dry skins.
Specimens referenced by catalog number in He also did not use total length from either
gazetteers,tables,text,andfigurelegendsare group in any analyses, but subtracted length
preceded by one of these acronyms. Some of tail from it to obtain a value for length of
specimens are also cited by Archbold Sula- head and body, which is a more useful
wesi Expedition field numbers (ASE). metric.
Many of the generic and specific traits In the laboratory, several measurements
describedherearethoseassociatedwithadry were made on specimens from both groups.
skin (usually stuffed as a museum study The number of scale rings per centimeter on
specimen) and an associated skull—one type the tail was counted about one-third the
of standard museum preparations. Color distancefromitsbase.Tomeasurelengthsof
descriptions of fur, ears, feet, and tail of E. overfur and guard hairs on the dorsum,
leucura are derived from those museum Musser placed a ruler at a right angle to the
specimens—Musser’s field work did nottake skin surface on the back near the rump and
him to the geographic regions where that recorded the approximate mark where ends
species resides. Color descriptions of E. of the bunched hairs rested; the technique is
centrosa come primarily from his field unsophisticatedandtheresultsimprecise,but
journals (stored in Mammalogy Archives, provides a descriptive estimate of lengths for
AMNH) where he recorded coloration and those pelage constituents.
other details of freshly caught rats. His Using handheld dial calipers, Musser
collectionalsoincludesfluid-preservedwhole measured the following cranial and dental
specimens or skinned carcasses that were dimensions to the nearest 0.1 mm; shorter
initially fixed in 10% formalin, soaked for dimensions (BBP, LIF, BIF, BMF, LB, and
several days in water, and finally stored in dimensions of toothrows and individual
70% ethanol. From this material comes molars) were measured under a dissecting
descriptions of stomach morphology and microscope. Dimensional limits are illustrat-
topography of palmar and plantar regions. ed in figure 1; abbreviations are used in the
MEASUREMENTS: Values for external di- tables.
mensions are from two groups of specimens.
One consists of samples Musser collected in ONL occipitonasal length (5 greatest
centralSulawesi.Foreachofthesespecimens lengthof skull;distancefrom tip
he measured total length; length of tail (LT); ofthenasals toposterior margin
length of the dorsal distal white tail segment of the occiput)
(taken from the distal border of the basal ZB zygomaticbreadth(greatestbread-
brown portion to tip of the tail along the thacrossthezygomaticarches)
dorsalsurface);lengthofhindfoot,including IB interorbital breadth (least dis-
claw(LHF);andlengthofear,fromnotchto tance, as viewed dorsally, across
crown (LE). He took these measurements the frontal bones between the
soon after the rat was caught, and also orbital fossae
obtained a value for body weight (WT, in LR length of rostrum (from tip of
grams). the nasal bones to the posterior
The second group contains specimens margin of the zygomatic notch)
in museums caught and prepared by other BR breadth of rostrum (greatest
collectors.Theyrecordedtotallength,lengths breadth across the rostrum, in-
oftailandhindfoot,sometimeslengthofear, cluding the bony nasolacrimal
but not weight. Musser used their value for capsules)
6 BULLETIN OFTHEAMERICAN MUSEUM OFNATURALHISTORY NO.391
Fig.1. AnadultBunomyschrysocomusillustrating limitsof cranial and dentaldimensions measured.
Additionaldefinitions are providedin thetext.
2014 MUSSERAND DURDEN: ECHIOTHRIX LEUCURAAND E.CENTROSA 7
BBC breadth of braincase (measured of first lower molar, excluding
from just above the squamosal the root, to posterior enamel
root of each zygomatic arch) face of third lower molar)
HBC height of braincase (from top clm1–3 crown length ofmandibularmo-
of the braincase to the ventral lar row (from anterior enamel
surface of the basisphenoid) face of first lower molar to
BZP breadth of zygomatic plate (dis- posterior enamel face of third
tance between the anterior and lower molar)
posterior edges of the zygomatic BM1 breadth of first upper molar
plate) (taken across widest part of
LD length of diastema (distance molar)
from posterior alveolar margins bm1 breadth of first lower molar
of upper incisors to anterior (taken across widest part of
alveolar margins of first upper molar)
molars)
PPL postpalatallength(distancefrom In the multivariate analyses used to
the posterior margin of the generate principal-components and discrimi-
palatal bridge to posterior edge nant-function graphs, values for alveolar
of the basioccipital—ventral lip length of the maxillary molar row (ALM1–
of the foramen magnum) 3) instead of crown length of the molar row
LBP length of bony palate (distance (CLM1–3) were used. The molars are very
from posterior edge of incisive small,particularly thethird molar,and some
foramina to posterior margin of were lost when skulls were cleaned. By using
the bony palate) alveolar length, a complete set of variables
BBPM1 breadth of bony palate at first for the analyses could be employed, even
molar (least distance between when teeth were missing, and the largest
lingual alveolar margins of first possible sample sizes assembled.
molars) AGE AND SEX: Specimens could consis-
LIF length of incisive foramina (dis- tentlybeplacedintooneofthefollowingage
tance from anterior to posterior groups:oldadult(bodysizeusuallyamongthe
margin of one of the foramina) largest in a sample; clothed in adult pelage;
BIF breadth across incisive foramina occlusal surfaces of molars worn nearly to
(greatest distance across both topsofrootssocusppatternsareobliterated,
foramina) the crowns worn into shallow basins with
BMF breadth of mesopterygoid fossa either intact or eroded margins); adult (body
(distance from one edge of me- sizeamongthelargestinasample;coveredin
sopterygoid fossa to the other) adult pelage; molars worn; occlusal surfaces
LB length of ectotympanic (audito- retain outlines of major cusps, but their
ry) bulla (greatest length of the enamelmarginsarewornlowsothatdentine
bullar capsule, excluding the is broadly exposed forming shallow basins;
bony eustachian tube) labialcuspletsobliterated);youngadult(body
ALM1–3 alveolar length of maxillary mo- sizeusuallysmallerthanolderadults;covered
lar row (from anterior alveolar in fresh adult fur; molars slightly worn;
rim of first upper molar to enamel borders of cusps much higher than
posterior alveolar rim of third the enclosed dentine, which has a restricted
upper molar) exposure; laminae, cusps, and labial cusplets
alm1–3 alveolar length of mandibular are discrete; juvenile (body size among small-
molar row (from anterior alveo- est in a sample; covered in juvenile pelage,
lar rim of first lower molar to which is easily recognizable compared to the
posterior alveolar rim of third adult coat; upper and lower third molars
lower molar) uneruptedorif erupted usually unworn).
CLM1–3 crown length of maxillary molar These roughly defined age groups are
row (from anterior enamel face unequally represented among samples: old
8 BULLETIN OFTHEAMERICAN MUSEUM OFNATURALHISTORY NO.391
TABLE 1
DifferencesinMeansofCranialandDentalVariablesbetweenSexesinSamplesofEchiothrixcentrosa
andE.leucura
Mean61SDarelisted;probabilityvalues(P)arederivedfromt-tests.Samples(consistingofyoung-to-old
adults)fromdifferentlocalitieshadtobecombinedtoobtainasufficientlylargenumberofspecimensfor
testingthesignificanceofsexual differences.
E.centrosa E.leucura
PinedapaandKualaNavusua Rurukan,Tondano,GunungMasarang,Temboanb
Variable UN58 -N511 P UN510 -N56 P
ONL 51.861.32 51.861.27 0.984 55.161.18 54.762.17 0.682
ZB 23.560.86 23.060.67 0.168 23.661.06 23.561.38 0.949
IB 6.560.18 6.760.23 0.108 7.360.30 7.460.17 0.309
LR 20.460.82 20.360.75 0.805 22.461.00 22.361.35 0.907
BR 7.560.29 7.560.34 0.646 7.460.53 7.360.35 0.846
BBC 18.760.25 18.760.36 0.949 19.360.45 19.660.21 0.078
HBC 14.060.25 14.260.31 0.119 14.660.53 15.160.41 0.076
BZP 3.460.21 3.460.24 0.720 3.560.16 3.560.35 0.899
LD 18.360.68 18.360.81 0.922 19.161.00 18.761.08 0.522
PPL 18.360.31 18.160.50 0.330 18.460.90 18.361.13 0.867
LBP 9.860.25 9.960.51 0.468 12.260.62 11.960.81 0.424
BBPM1 4.960.24 5.060.25 0.616 4.760.62 4.660.39 0.866
BMF 2.660.11 2.660.10 0.856 2.360.19 2.360.19 0.893
LIF 9.760.62 9.560.38 0.463 9.460.63 9.260.71 0.563
BIF 3.260.16 3.260.24 0.430 3.360.28 3.260.42 0.714
LB 6.160.15 6.160.15 0.562 6.160.17 6.160.21 0.542
ALM1–3 6.560.12 6.360.26 0.097 7.360.42 7.360.38 0.873
BM1 2.060.05 2.060.07 0.967 2.360.11 2.460.10 0.510
aLocalities3and4forE.centrosaingazetteerandonthemapinfigure2;bothplacesarefromlowlandsinthesame
generalregion.
bLocalities2–4and6forE.leucuragazetteerandonthemapinfigure2.
adults and juveniles are scarce, adults and ble 1).Withineach ofthespecies,differences
young adults are most common. Old adults, betweenmeanswerenotsignificantacrossall
adults,andyoungadultswerecombinedinto variables—sex is a trivial contribution to
samples from which cranial and dental intrasample nongeographic variation of cra-
measurement values were obtained for mul- nial and dental variables.
tivariate analyses and univariate descriptive Results of principal-components analysis
statistics. Recognition of relative age classes of each species (not illustrated here) did not
was important for identifying relative age reveal a different pattern in variation among
of holotypes and gauging the position of the cranial and dental variables due to sex.
particular specimens showing incongruous Thedistributionofspecimenscoresprojected
distributions in principal-components and onto first and second components for each
canonical-variate ordinations. speciesproducedasinglecloudofthoroughly
Males and females were not separated in intermixed points for males and females—
anyof thestatistical analyses. Examined side polygons enclosing maximum dispersion of
by side, size differences in adult skulls of scores representing each sex, and ellipses
males and females within a single species outlining 95% confidence limits for cluster
collected from the same area appeared centroids broadly overlapped.
negligible. This observation was reinforced Weak sexual dimorphism in cranial and
by results from determining significance of dental variables generally characterizes non-
differences between means for cranial and geographic sexual variation among muroid
dentalvariablesofeachsex(t-test)insamples rodents. For examples of sigmodontines, see
of Echiothrix centrosa and E. leucura (ta- Carleton and Musser (1989, 1995 [Microryz-
2014 MUSSERAND DURDEN: ECHIOTHRIX LEUCURAAND E.CENTROSA 9
TABLE 2 Archboldomys]). A striking exception is the
PopulationSamplesEmployedinUnivariateand sigmodontineOryzomyscouesi(Carletonand
MultivariateAnalysesofCranialandDental
Arroyo-Cabrales, 2009).
VariablesforSpeciesofEchiothrix
Localities,alongwithelevationsandgeographic STATISTICAL ANALYSES: Standard univar-
coordinates,arereferencedinthegazetteersand iate descriptive statistics (mean, standard
markedonthedistributionmap.Bracketsenclose deviation, and observed range) were calculat-
totalnumberofspecimensforeachspecies. ed for population samples (identified in
Specimensmeasuredareidentifiedinfootnote.
table 2) as well as for each species and are
listedintablesthroughoutthetext.Principal-
Speciesandpopulationsamplea N
component and discriminant-function analy-
Echiothrixleucura [16] ses were computed using original cranial and
NORTHEAST dental measurements transformed to natural
Northeast(Rurukan,Tondano,Gunung logarithms. Principal components were ex-
Masarang,Temboan)
tracted from a variance-covariance matrix,
Echiothrixcentrosa [30] andcanonicalvariateswereextractedfromthe
NORTHCENTRAL discriminant-functionanalyses;loadings(cor-
Molinggapoto 3 relations)ofthevariablesaregivenasPearson
Bumbulan 1
product-moment correlation coefficients be-
CORE tween the extracted principal components or
KualaNavusu–Pinedapa 19 canonical variates and the log-transformed
Sadaunta–Besoa(SungaiSadaunta,Kulawi, inputvariables.Probabilitylevelsdenotingthe
Winatu,Gimpu,Besoa) 7
significance of the correlations in both kinds
aE. leucura—Rurukan: AMNH 101243, 101245– ofanalysesareunadjusted.Analysesarebased
101248; BMNH 97.1.2.46. Tondano: RMNH 21066– on 16 cranial and two dental measurements
21069.GunungMasarang:BMNH97.1.2.45.Temboan: from intact skulls of adults (young to old).
RMNH21065;USNM217802,217804,217806–217808, The statistical packages in SYSTAT 11 for
217906. Windows,Version11(2005),wereusedforall
E. centrosa—Molinggapoto: USNM 200266, 200268, analytical procedures.
200269. Bumbulan: AMNH 153013. Kuala Navusu:
ANATOMY: Terminology follows Brown
AMNH 225678–225681, 225683–225685. Pinedapa:
(1971) and Brown and Yalden (1973) for
FMNH 43409; RMNH 21064; USNM 219715, 219740,
particular external features of the head and
219741, 219743, 219744 (holotype of Echiothrix brevi-
cula),219746–219749,219751.SungaiSadaunta:AMNH limbs; Bugge (1970) for cephalic arteries;
225043,225044,226815.Kulawi:BMNH40.385.Winatu: Wahlert (1985) for cranial foranima; Carle-
USNM218706(holotypeofEchiothrixcentrosa).Gimpu: ton (1980), Musser and Newcomb (1983),
USNM219742.Besoa:USNM219750. Carleton and Musser (1984), Musser and
Heaney (1992), and Voss (1988) for cranial
morphology; and Rinker (1954), Turnbull
omys and Oligoryzomys], Carleton et al. (1970),andSatohandIwaku(2006,2008)for
(1999 [Sigmodon]; 2009 [Oecomys]), Voss cranial musculature. Names of cusps and
(1991 [Zygodontomys]), and Emmons and cuspletsofmaxillary(upper)andmandibular
Patton (2012 [Juscelinomys]); for murine (lower)molarsareindicatedinfigure 9where
examples, see Carleton and Robbins (1985 sources of the terminology are explained in
[Hybomys]), Carleton and Martinez (1991 the legend.
[Dasymys]), Carleton and Van der Straeten STOMACH CONTENTS: Musser recorded in
(1997 [Lemniscomys], Maryanto (2003 [Rat- his field journal the contents found in
tus argentiventer]), Carleton and Byrne (2006 stomachs of some freshly caught rats. Some
[Otomys]), Carleton and Stanley, 2005, 2012 samples were preserved in ethanol, which he
[Hylomyscus and Praomys]), Helgen and examined later in the laboratory under a
Helgen (2009 [Pseudohydromys]), Musser dissecting microscope. He supplemented this
(unpublished data [Bunomys, Margaretamys, material by extracting stomachs from fluid-
Rattusfacetus,andCoccymys]),Heaneyetal. preserved animals. Stomachs were removed
(2006 [Apomys, Batomys, and Limnomys]), byseveringtheposteriorendoftheesophagus
and Balete et al. (2012 [Soricomys and and the anterior section of the duodenum.