SPECIES DIVERSITY AND PHYLOGENETIC SYSTEMATICS OF AMERICAN KNIFEFISHES (GYMNOTIFORMES, TELEOSTEI) BY JAMES S. ALBERT MISCELLANEOUS PUBLICATIONS MUSEUM OF ZOOLOGY, UNIVERSITY OF MICHIGAN, NO. 190 Ann Arbor, November 01,2001 ISSN 8076-8405 Species Diversity and Phylogenetic Systematics of American Knifefishes (Gymnotiformes, Teleostei) James S. Albert* Division of Ichthyology Museum of Zoology The University of Michigan Ann Arbor, Michigan 48 109-1079, USA "Florida Museum of Natural History, Department of Ichthyology, University of Florida, Gainesville, Florida 3261 1-7800, U.S.A. MISCELLANEOUS PUBLICATIONS MUSEUM OF ZOOLOGY, UNIVERSITY OF MICHIGAN, NO. 190 Ann Arbor, November 0 1,2001 ABSTRACT Al/~(.r%,,J. S. 2000. Sj~uc.ir:\cliv~rt ily cind pltyloger~elicsyslmrnric:., (fAmc.ric.on knif~/ish~~,s( ($tr~nolz/i,r.tnc~, 'lP1uoski) . Misc. I'ubl. Mu.\. Zool. Ilttin Michiyccrr, 190:l-127, 50,/ig~. Evolutionary relationships among iZlriericaii linifefislics are doc~uner~tedfi-0111 comparative studies of morphological, physiological, and behavioral features. Materials were examined from Inore than 900 lnuselirn lo~scoiltainiiig over 4200 gj~ninotifoi-in specin~ensreferred to 105 described and 32 undcscribed species. Neural tissucs were examined for 31 ~gyninotifor~nspecies, including represei~lativesof 20 genera. These data were cornpiled into a niatrix of' 249 ck~aractcrs,including 45 cl~nractersof the nervous system, for 44 operational taxonomic units. The inolecular sequence data of Alves-Go~ncsc.1 ccl. (1995) were also analyzed, weighting transitions and transversions equally. TI-ee topologies 1.1-om molecular scqtlence and morphological datascts analyzed independently usiilg ~naxi~nl~rnparsi~iiony are very similar, and to the topology resulting iiroin a corn- bined a~ialysis. These data are uscd to provide phylogcilctic diagnoses for 75 cladcs ailti terminal taxa, inclutlii~gthe Gyrnnotilhr~ries,5 L~nrilic:s,and 29 genera. Two new genera and 14 additional supraspecific taxa are introclllccd. (;?rtnnoh.s+1l~~ctropl~onr.s are round to he nioilophyletic, and together Sol-m the sister group to a11 otliei- gy~i~notifo~.~ns.Rhampliiclltllyidac + Hypopornidae and Stcrnopygiclae + Apteronotidac XI-ealso monopliylctic, the latter of which incll~desall species with a toile-type electric organ discharge (EOD). The f'ossil tl<lli,sc,llais dcterrnined to be a member of Sternopygidae. No rvitlcncc was found for the ~nonopliyly01' the non~inalgenera Ircr.crmcc (Triques), f&nntccnnin (Jordan and Evcrmanri), Aplno17oku.s .SPII.YU11~10 (121cPpi-de) or l'orol~;$rl~.s(Ellis). fL1eg(~do17/ognotf~1~s(Mago-1,cccia) a~~dIfiidio (Miles) arc I-c- gardcd as,j~~niorsynonynis oSApt(.r-onol~c.s.ton.\ti ,\tric.to (nwt~sage). An identification key to tl~crecognized genera is provided. The phylogenetic results pcrrnit sevel-al conclusions regardi~igcharacter cvol~rtion.Stc.rn,o11yg.u.s n,slmh/..c most closely resembles tl~caircestral ~yninotiforrriplienotype. Two clades, Apteronotidae ant1 1:'ig~irtnannin + Khnbdo/ic.Iro/).t possess Illumerous tlcrivcd featlu-es, including two specializations of the centl-al nervous system, related to the lrtilizatio~iof' deep ri\ler channels. Gymnotidac, lil~an~pl~icl~tl~yiclac,and I-Iypoyomidac retain the plesiomo~-phicp~~lse-type EOD and larval hypaxial electric organs into matllrity. The tone-type E011 of Sternopygidac and Apteronotitlac is derived, and the larval electric organ of tlresc taxa dcgc~icratesat rncta~norphosis. Elongate snouts have evolvcd iiidepe~identlyin at least I'oui- ~yrnnotiSorn~lineages, invol\ing difl'ere~itsets of bones. The caudal li~iof' aptcl-onotids is derived Srom the caudal appendage of o~llei-Lgy~notifor~~ls, and is not an internletliate state in the loss of a caudal fin. The actrral nrumber of gyxnnotif'orm spccics in tlie wild is lnuch greater than has previously heen recog nized. Tlicrc are currenlly 108 valid species of ~gym~~otif'ormsin thc litcratl~reancl about 34 ~~nclcscribed species recognized ill Irillsetlrn collections. These species are distribl~tedthroughout the hl~rnidNcotropics, li-om the liio Salado in the I'a~npas of Argentina to tllc Rio San Nicoliis of Cl~iapas,Mexico. Spccics diversity is highest in thr A~niwon(89 species) followed by the Ori~~oco(61 species), the G11yanas (35 species), the Parank (26 spccies) , Northwcstcrn South America (14 species), Southeast Brazil and Uru- grlay (1 2 species), Nortl~eastBrazil (9 species), the Pacific slope of South Ailcrica (7 species), Mitldlc Arnc.1-ica (7 species), and the endorhcic liio Sali-Dlrlcc or rial-thwestern Arge~ltiiia(1 species). Tllcrc arc at least seven tra~~s-i\nde:~ngy~nnotif'orm clades. Key \vol.ds: Oiodiv/.rsil,lr,l)iogmogt-/~/)l~~x c.lcrdLlics, c.ln.s.si/ic.rclion,cotripc~mti-or mor/~hology, ~lc,ctric. Ji.sh(,.\, .c,~?~olu- lion, his ioricr~l~c.olo~~, Solil/t ilrtz~ri~~c. CONTENTS I'AGE ADSTIZA(:T ................................................................................................................................................................................ ii INTRODUCTION ............................................................................................................................................................... 1 A BRIEF I-IISTORY OF (;YMNOTIFORM SYSTEMATICS ................... ... ...................................................................... 2 MATEliIALS AND METHODS ............................................................................................................................................... 6 ('1 .... LII nt Ccrs ..................................................................................................................................................................... 9 1). ,LI .. simony Analysis ..................................................................................................................................................... 10 (:HARACTElI DESCIIIPTIONS ........................... ... ......................................................................................................... 11 PI-M. OGENETIC RELATIONSI-111's .................... ... ....................................................................................................... 62 GYR.INOI.II.OI<MI<S(CI.?\I)E A) ................................................................................................................................................ 64 GYR.INO.I.II)I\E(<.IAI)I . H) ...................................................................................................................................................... (34 EI.I..(:~.I~O~,II~,~I.s G11.1. .......................... .. ............................................................................................................................ (56 G~nr.\~o.ir~.sIANN,\I..US (C.~.,\nk (:) .......................................................................................................................................... 66 G1.,1i~\~o711.\(..II<~II'O + G . .IV(.I;I I.L.IIUS ((.I. .\I)I< D) .............................. .. ................................................................................. 66 G~,!IA~O./~~I.\(~17.l,\~lllll(~ll.\ SI'KCIES-t:KOL!I' A1 1\1<1<TAN11 MIL.I.EK.................................................................................................. 66 (;~,\r,\~o.iln c., II~AI~~srec.~b.s-c.~<oul~ AI.IIEIIT AN11 MII.I.ER................... ... ............................................................................ 66 ~;)i)1~\r0716,\Ntllll.l.~\lll.\ SIVI:CI L.. S-(:I<OIII'AI IIEIU /\NI) MII.I.I<II................................................................................................. 66 SII. I<NOI?'(:OII)E~(CI..\l)l' E) ................................................................................................................................................. 66 1<1l~\hll'lll(.11~111~0101::\ ((.I.,\I)E F) ......................................................................................................................................... 67 ~III~\I\.II'III(.III IIYII)AI< (CI.. \L)E G)......................................................................................................................................... 67 R~I,II\IIJ~~I(.I~I.II~M~II.I.I<IIi\~r) TKOS(:IILI ............................................................................................................................... 67 C~.nwoitii.l~~n~~~~(.rr~~i~~~.\+ IIOI(.I~LI.I(CIAI)I' H) ...................................................................................................................... 68 CI.A~~I~II,~~U,III~~II~I~III.SEI.I.IS................................................................................................................................................ 68 Oo~c:r:nri~TIIIQIIICS .................................................................................................................................................................. 68 H\rl'~)~'~)hll~)i\I< (CI.~\I)E 1) .................................................................................................................................................... 68 I-l~.~wi,onrci.sC;II I ......................... ...... ................................................................................................................................ 68 BII,\(.IIYIIYI~~I,OI\.IIN,\L((.I.I\I)EJ . NI:~I.AX~N) ....................... .. ......................................................................................... 68 BI~I~.~~I.III~~~~I~o~\ILI.YMA(.o-LE(.(.I~\ ......................................................................................................................................