MISCELLANEOUS PUBLICATIONS MUSEUM OF ZOOLOGY, UNIVERSITY OF MICHIGAN NO. 170 Systematics of Oriental Pygmy Squirrels of the Genera Exilisciurus and Nannosciurus (Mammalia: Sciuridae) by Lawrence R. Heaney Museum of Zoology and Division of Biological Sciences University of Michigan Ann Arbor, Michigan 48 109- 1079 Ann Arbor MUSEUM OF ZOOLOGY, UNIVERSITY OF MICHIGAN December 17. 1985 MISCELLANEOUS PUBLICATIONS MUSEUM OF ZOOLOGY, UNIVERSITY OF MICHIGAN NO. 170 The publications of the Museum of Zoology, University of Michigan consist of two series-the Occasional Papers and the Miscellaneous Publications. Both series were founded by Dr. Bryant Walker, Mr. Bradshaw H. Swales, and Dr. W. W. Newcomb. The Occasional Papers, publication of which was begun in 1913, serve as a medium for original studies based principally upon the collections in the Museum. They are issued separately. When a sufficient number of pages has been printed to make a volume, a title page, table of contents, and an index are supplied to libraries and in- dividuals on the mailing list for the series. The Miscellaneous Publications, which include papers on field and museum tech- niques, monographic studies, and other contributions not within the scope of the Occa- sional Papers, are published separately. It is not intended that they be grouped into volumes. Each number has a title page and, when necessary, a table of contents. A complete list of publications on Birds, Fishes, Insects, Mammals, Mollusks, and Reptiles and Amphibians is available. Address inquiries to the Director, Museum of Zool- ogy, Ann Arbor, Michigan 48109-1079. MISCELLANEOUS PUBLICATIONS MUSEUM OF ZOOLOGY, UNIVERSITY OF MICHIGAN NO. 170 Systematics of Oriental Pygmy Squirrels of the Genera Exilisciurus and Nannosciurus (Mammalia: Sciuridae) by Lawrence R. Heaney Museum of Zoology and Divisiori of Biological Sciences University of Michigan Arin Ar-bor, Michigan 48 109- 1079 Ann Arbor MUSEUM OF ZOOLOGY, UNIVEKSITY C)F MICHIGAN December 17, 1985 ABSTRACT Heuney, Lnwrencr R. 1985. systematic.^ of Oriental pygmy ~qui~r-eL7of' the genera Exilisciurus and Narr~losci~~rus(Mammalia: Sciuridae). Misc. Publ. Mu. Zool. Univ. Mzrlligan, 170:l-58,figs. I-16.-Multivariate analysis of cranial morphology does not support the current recognition of four previously described species of pygmy squirrels in the Philippines; all four are here considered to represent a single species, ExzlzJciurw concinnus. There is little geographicfi. variation within the species, and 110 subspecies are recognized. Exilzsczurtu concznnw occurs only on islands separated f'rom Mirrdanao by waters less than 120 m deep, which was rhe level LO which sea level dropped during the late Pleistocene. Analysis of clualitative characters indicates that the genus Exil~.\cinr~is n~o~ropliylctir,and contains thl-ee species, E. concinnw, cxilD, and L;. wlritel~eadi; its sister-group is Nor~r~osc~nru.\~r~~lnno!lJ. Contrary to the set of' I-elationships proposc(l Ily Moor-c (1959). these two gencr-a constitute a rnonophyletic gr-oup. Thc gu~~iSur~da\c~rrr-ci.\ and PI-u.\cirtr-illus are c.losely I-elated, but eviderice intlicares that S~rrr~lc~,sczr~l-ci.\nray he paraphyletic. The subtrihe Hyosciurini should be clisciwtlctl because ir lacks defining characters. All Southeast Asian pygmy sclui~.r.cls;ire member-s of the mibe (:allosciurini. C;onvc~.genc-ein pygrrly squil-I-elsof qualitative ch;irartcrs clue to the allornetric constr-ailits of dwitr-fing is co~isicler-edto Ix likely; SLK 11 COIIV~I-gen~eCOLII~ lead to i~~corrccrco~rclusions ahout pliylogenetic rclationslrips. To identify such con- vcrgc~rccill the tl;ir;~ set, a nicthotl is tlcvclopetl ill wlricl~ I) all ecologically sinlil;il-, s;i~ne-si~ctlr.c~lcr.cnce species is selected, '2) cllar;~crersshared by the I-efcl-elrcci~nd sttld~ species al-e exi~r~iinedi~~rd tlr~se correl;lted with ;irrd likely ro ~-ehultIronr allornetric trentls ar-c r-crllovecl, and 3) rlre atirourlt of variatioti in the rel~~i~i~li~ip.c1iar~acte1.s clue to allomctry is cstilrlatetl. Key wol.tls: Iiotl~r~l~cr,Sr~nrrdu~, SOIILILP~I.\I A.\zu, Pl~rlif)f~rn(,.s,zoogeogr-uf~lr~), cillomrt7y. CONTENTS PAGE ABS7TRACT .................................................................... ii 1N.fKOI)UCfION .............................................................. 1 MIYrI-IODS AND MATEKIALS .................................................. I SYSI'EMATIC ACCOUNTS ..................................................... 2 Esili.sriu~.tu.................................................................. 2 I:'. concinn~r.\................................................................. 7 I:'. oxilr ' ..................................................................... I8 I:'. rul~itrh~a~l~................................................................ 22 Nnt~nosciuru.~................................................................ 24 N . n~e1a~~oli.t................................................................. 25 ANAI.YSES .................................................................... 27 I'rirrcipal cornporletrts ar~alysisof cl-anial variation in 1xrluc~uru.t and Nunno~ciurw.............................................................. 27 Kelatior~shipsof the Soutl~castAsian Pygrny Squirrels .......................... 31 Survey of cranial cllaracrcl.~................................ .,. .............. 32 Analysis ol cranial ch.~rac~ers............................................... 36 SLII-veyof II~II-cr-ani;ll(ha~..~rtcrs ............................................ 39 Analysis of non-crani;il ch;tr;~cter-s .......................................... 43 Mulrivaria~eAllalyses of Qualirarivc C:llal-actcl-s ................................ 45 Principal componcnrs .~nalysih.............................................. 46 W;~gnci-'1'1.c~ a~r;~lysis ..................................................... 48 I)IS(:lJSSION .................................................................. 50 Rclatio~islripsof the pyg111y scl~~irrelsrl~id cirllosciut-ilre 11-ee S~UII.I.CIS ............. 50 Origin ;III~~oogcog~aplric Iristol-y oi the Philippine pygmy bquirrels ............ 51 1)wal.fing. allo~~~et~.y.a~~tlphylogcnctic analysis of squil-I-cls..................... 53 A(.I<NOW12I. .I)<;blENN1'S........................................................ 56 1.l'llrllA~I'UKE (.I.I'EI). ......................................................... 56 AI'l'I1:NI~IX I ................................................................... 58 AIJPENI)IX 11 .................................................................. 58 ILLUSTRATIONS I;IC;UKE PAGE 1 Skull of I:'x~lzsciurustonc-z7tnu.\ sliowi~lgcra~iial ~iieasurenie~its ................ 3 2 Maxillary teeth of Nanno~riui-ucrr~c~lu~~olu ;wcl Ex117.sc~z~ru.sconcinnw ........... 4 4.4 Skull and mandible of' Exilz.sclurzc.\ conci~~nus................................ 10 4U Skull and manclible of Exi1hc1uru.s exili.\ .................................... I I 4C: Skull ;111d mandible of Exllrsczul-us rvl~~l(.l~~.nd~................................ 12 41) Skull and mandible of Nur~7~o.\ctzcru\rr~c,l(~r~olu ............................... 13 5 I'rincipal components a~lalysisot pygmy squirrel cranial measureriients ...... 30 ti I'rincipal components analysis of pygniy a~itltrcc squirrel c~anial r~~e.~srl~.eriiellts......................................................... :I I 7 (;laclogralri of tr-anial cl~;~l-actrl-a.......................................... 38 8 Ililld toot external morphology of' tl-ec ancl pygmy scluirl.els ................ 40 9 13;1cul;1of tree and pyg~iiysclirirrcls ....................................... 42 10 (;l;cdograni of 11o1i-cranialchar.ac.ters ...................................... 45 I I PI-ill~ipalcon~pone~~ts ;rlialysis of qualitative chal.actcl.s, axes I and I1 ........ 46 I2 PI-incipal co~iipo~ie~itsarialysis of' clualitative rha~.acte~.s,axes 111 and 1V ..... 47 I W;I~II~I-'l'rre ;trl;~lysisof q~lalitativccharacters. ............................ 50 14 Phylogcnctic I-elatio~lslripsot pygmy squirrels proposed by Moore (1959) .... 51 15 Pliyloger~eticrelationships of pygmy sqrril-l-clsproposed in this study ........ 52 Iti Map of' thc l'hilippincs showing the cxtr~ltot late I'leistocene islarlds ........ 54 'I'AULk; PA<;E 1 (;r.a~ii;iI~iieasi~rc~~i~c~its of L.t~l~.\r~~cr-ic.~, ,V(IILIIU,\~I~OI~.\, l'~o.~cz~i~-~llus, and ~Sllll~/(l.\c1ulI1.S ........................................................... 5 2 Extcrrlal measurements ant1 \veigl~ts...................................... G 'I 1'1-ir~cipalcorrrpo~~e~lts a~ialysis ot c.~.aliialmcasurc~iicnts ..................... 29 4 PI-intipal c.o~rlpo~le~~tsar~;ilysis of meal1 CI-~III~~I~li~ei~surernerlts ............... 29 5 (;r;wial c-ha~acter-states .................................................. 37 ti (.ha~.actcrstates lor- non-cr-;~r~i;~l( II~I-actcrs ................................ 44 7 I);~tarll;rtrix of el-;ulial arid excel-11;11cli;~r;~ctc~s codetl for Wagnet- '1'1.ee ;t~r;~lysis............................................................... 48 H 1'1-i11c:ipalco~nponents analysis of' qualitative ( Ii.~~..~cter.s..................... 49 'lhe sciurid fauna of the island at-chipelago of Southeast Asia is the most diverse of any in the world, with well over 50 species recognized. Among the most distinctive in this assemblage are the pyglny squirrels of the genera Nan,nos&urus and Exilisci~~ru,~.Adult least pygmy squirrels (Ex- ill,sciur~r,sexilis) from Borneo and adjacent s~nallislands weigh only 15 g, making this