Molecular Phylogeny of Western Atlantic Representatives of the Genus Hexapanopeus (Decapoda: Brachyura: Panopeidae) BRENT P. THOMA 1 , CHRISTOPH D. SCHUBART 2 & DARRYL L. FELDER 1 1 University of Louisiana at Lafayette, Department of Biology and Laboratory for Crustacean Research, PO Box 42451, Lafayette, Louisiana 70504-2451, U.S.A. 2 Universittit Regensburg, Biologie 1,93040 Regensburg, Germany ABSTRACT Species of the brachyuran crab genus Hexapanopeus Rathbun, 1898, are common benthic inhabitants in coastal and nearshore waters of the Americas. Despite the frequency with which they are encountered, they are taxonomically problematic and commonly misidentified by non-experts. Little previous work has been undertaken to explain relationships among the 13 nominal species of Hexapanopeus or their relationship to other phenotypically similar genera of the family Panopeidae. In the present study we examine partial sequences for 16S and 12S mitochondrial rDNA for 71 individuals representing 46 species of Panopeidae and related families of the Brachyura. Phylogenies inferred from both of these datasets are largely congruent and show, with one exception, the included genera and species of the Panopeidae to represent a monophyletic grouping. Within this group, Hexapanopeus is polyphyletic, being distributed among several separate major clades and clearly warranting taxonomic subdivision. INTRODUCTION As part of ongoing studies of the superfamily Xanthoidea sensu Martin & Davis (2001), we have undertaken a reexamination of phylogenetic relationships among genera assigned to the family Panopeidae Ortmann, 1893, on molecular and morphological bases. Early in the course of our morphological studies, we saw reason to conclude that the genus Hexapanopeus Rathbun, 1898, as currently defined, was polyphyletic. Differences in the characters of the carapace, chelipeds, and male first pleopod (gonopod) served to obscure what, if any, relationship existed among the species in the genus. The present study serves as the first step towards restricting species composition of the genus Hexapanopeus s.s. (sensu stricto) and defining its phylogenetic relationships. Presently, the genus Hexapanopeus consists of 13 species distributed on both coasts of the Americas; six species are known from the western Atlantic ranging from Massachusetts to Uruguay, while seven more range in the eastern Pacific from Mexico to Ecuador (Table 1). Representatives of Hexapanopeus are commonly encountered in environmental studies and inhabit a variety of nearshore environments ranging from sand-shell bottoms to rubble and surface fouling accumulations, where they often reside amongst sponges and ascidians (Rathbun 1930; Felder 1973; Williams 1984; Sankarankutty & Manning 1997). Even so, available illustrations and morphological descriptions are of limited detail and quality for many species, and little can be deduced from present literature to clarify their phylogenetic relationships. Herein, we provide evidence for polyphyly in the genus Hexapanopeus on the basis of two mitochondrial genes (16S rDNA and 12S rDNA). We also examine relationships among species 552 Th oma el 01. Table I. Known species presentl y assigned to I-Iexapanopells with authority and known di striblllion. Those preceded by an asterisk (*) arc incl uded in the present phylogenetic analyses, along with one putative new s jX:cies o f the genus from the western Gulf of Mex ico, yet to be described . Taxon Name Distribution * HexapallopellS allg llsl;jrolls (Benedict & Rathbun , 189 1) Hexapallopeus beebe; Garth , 1961 * Hexapallopells car;bbaells (Stimpson, 187 I) Hexapallop eus cartagoellsis Garth, 1939 HexapmlOpeus costaricensis Garth , 1940 * Hexapanopeus lohipes C A. Milne-Edwards, 1880) * Hexapallopells lIIal1l1;II8; Sankaranku lLy & Western Atl ant ic; from MassachuselLs to Brazil Eastern Pacifi c; Ni caragua Weste rn Atl ant ic; southeast Florida to Brazil Eastern Pac ifi c; Galapagos Islands, Ecuador Eastern Pac ifi c; Costa Ri ca Western Atl antic; Gulf of Mex ico Western Atl antic; Rio Grande do Norte, Brazil Ferrci ra, 2000 Hexapallopells Iliearagllellsis (Rathbun , 1904) HexapallopeLls oretllI; Rathbun , 1930 * Hexapal/opells pallleflsis Rathbun , 1930 Hexapallopells qLlinqlledenraIlIs Rathbun , 190 1 Hexapallop ells rtlbicllndus Rathbun , 1933 HexapmlOpelis sinaloensis Rathbun , 1930 Eastern Pac ific; Nicaragua EaslCrn Pac ifi c; Mex ico Western At lantic; South Carolina to Uruguay Western Atl antic; Puen o Ri co Eastern Pac ific; G ulf of California Eastern Pac ifi c; Mex ico currently ass igned to H exapmlOpeus and relati onsh ips o f th is genus to other genera and speci es encompassed wi th in the family Panopcidae. Thi s serves to furth er clarify the species compos iti on of Hexapanopeus s.s., and to confirm its phy logenetic prox imit y to other taxa constitutin g a putative panopeid lin eage. 2 MATERIALS AND METHODS 2. 1 Taxon sampling Seventy-one indi viduals representing 46 spec ies. 30 genera , and 10 families were subjected to molecu lar analyses. Of the 142 sequences used in thi s study. 132 were ge nera ted for this project, whi le the remaining 10 were obtained from GenB ank (Table 2). Si nce the ide ntity of the sister group to the fa mil y Panopeidae remains de batab le (see Martin & Davis 200 1, Karasawa & Schweitzer 2006, and Ng e t al. 2008 for di scuss ion), we incl uded 22 taxa that represent the fam ilies Xanthidae MacLcay, 1838, Pscudorhombilidae Alcock , 1900, Pilumnidae Samouell e, 1819, Chasmocarc inidae Serene, 1964, Euryplac id ae Stimpson, 187 1, Goneplacidae MacLeay, 1838, Carpiliid ac Onmann, 1893, Eriphiid ac M ac Lcay, 1838, and Ponunid ae Rafi nesquc, 18 15. Speci me ns used in thi s study were collec ted during researc h crui ses and fie ld expeditions and ei lher directl y preserved in 80% ethyl alcohol (EtOH ) or first frozen in either seawater or glycerol at - 80°C before later being tran sferred to 80% EtOH . Additi onal material s were obtained on loan from the Nationa l Museum of Natura l Hi story-Smithsoni an Instituti on (USNM). When possible, identifi cations of specimens were confirmed by two or more of the investi gators to limit the chance of mi sidentifi cat ions. Table 2. Crab species used for phyl ogeny reconstruction, showing catalog number. collection locality. and GenBank accession numbers for partial sequences of 16S and 12S. respectively (ULLZ = University of Lou isiana at Lafayette Zoological Collection, Lafayette, Loui siana: USN M = United States Nati onal Museum of Natural History. Smithsonian Institution, Washington D.C.). Taxon Carpiliidae Ortmann, 1893 Carpi/ius macula/us (Linnaeus. 1758) Chasmocarcinidae Serene. 196-' Cilasmocarcinus ch(lcei Felder & Rabalais, t986 CJwsmocarcinus m;ssissippiensis Rathbun, t931 Eriphiidae MacLeay, 1838 Eriphia verru cosa (ForskAI, 1775) Euryp lacidae Stimpson. 187 1 Frevillea borbom A. Milne-Edwards. 1880 Sorop/ax roberts; Guinot, 1984 Goneplacidae MacLeay, 1838 Bath)p/ax ryphllis A. Milne-Edwards. 1880 Panopeidac Ortmann, 1893 Aca nrholobllfu.f bermudensis (Benedict & Rathbun . 189 1) Acanth%bll fus bermudensi s (Benedict & Rathbun, 189 1) Acamholobulus bermudellsis (Benedict & Rathbun, 1891) AcO/u}wlobufus schmilti (Rathbun . (930) Aca ntholobllills schmitti (Rat hbun , 1930) Cyrlop/ax nr. spillidem(lla (Bened ict, 1892) Dyspallopeus sayi (Smith, 1869) EllcralOpsis crassimanlls (Dana. 185 1) £urypanop eus abbreviallls (Stimpson, 1860) Ellrypallopells depresslls (Smith, 1869) Ellrypanopells depresslls (Smith, 1869) Eurypanopeus dissimilis (Benedict & Rathbun, 1891) Eurypanop eus dissimilis (Benedict & Rathbun, 1891) Ellryponop el4s p/onissinUis (Stimpson. 1860) G/)plOplax smithii A, Milne-Edwards, 1880 G/Wtopla:c smith;; A. Milnc-Edwards. 1880 G/)p/Opla:c smithii A. Milne-Edwards, 1880 G/ypfopla:c smi fh ii A. Milne-Edwards, 1880 Glypropla.t smithii A. Milne-Edwards, 1880 Catalog. No. Collection Locality GenBank 16S l lS AF50 1732 AFSO l705 ULLZ S018 ULLZ 7346 Northem Gulf of Mexico: 2006 SOUlhwestern Gulf of Mexico; 2005 EU86340 1 EU863406 EU863335 EU863340 ULLZ ｾＲ ＷＵ＠ ｅ｡ｾ EU863398 EU863332 ULLZ 8369 ULLZ 7857 Southeastern Gulf of Mexico: 2004 Northern Gulf of Mexico: 2006 EU863399 EU863400 EU863333 EU863334 ULLZ 8032 Northwestern Gulf of Mexico: 2006 EU863397 EU86333 I ULLZ 5843 ULLZ6558 ULLZ6924 ULLZ6613 ULLZ 8367 ULLZ 8423 ULLZ 7227 ULLZ6427 ULLZ 3753 ULLZ3976 ULLZ6077 ULLZ 5878 ULLZ 8424 ULLZ 4140 ULLZ 6793 ULLZ 7686 ULLZ 8 142 ULLZ 8335 ULLZ 9020 Gulf of Mexico; Mexico: Campcche, 2002 Westem Atlantic: Aorida , Ft. Pierce, 2005 Western Atlantic: Florida . Ft. Pierce, 2006 Western Atlantic: Brazil: Sao Paulo, 1999 Western Atlantic: Bral.il: Sao Paulo. 1999 WeStern Atlantic: Florida, Ft. Pierce, 200 I Western Atlantic: Florida, Ft. Pierce, 2006 Western Atlantic; Florida, Ft. Pierce, 2006 Western Atlantic: Aorida, Ft. Pierce, 1998 Northern Gulf of Mexico; Mississippi , 1998 Eastern Gulf of Mexico; Tampa Bay, 2005 Westcrn Atlantic: Florida, Ft. Pierce. 1997 Western Atlantic: Florida. Ft, Pierce. 1997 Eastem Pacifi c: Mexico: Baja California, 1999 Southwestern Gulf of Mexico: 2005 Northern Gulf of Mexico; 2006 Northern Gulf of Mexico: 2006 Northern Gulf of Mexico: 2006 Western Atlantic ; Florida, Ft. Pierce, 2003 EU863355 EU863354 EU863372 EU863364 EU863357 EU863369 EU863395 EU!!63392 EU863388 EU86339 I EU863390 EU863396 EU863387 EU863386 EU8633..2 EU863379 EU863350 EU86337 I EU863384 EU863289 EU863288 EU863306 EU863298 EU86329 1 EU863303 EU863329 EU!!63326 EU863322 EU863325 EU863324 EU863330 EU86332 I EU863320 EU863276 EU8633 13 EU863284 EU863305 EU8633 18 ｴ ｣ｭ＠ Atlantic: Spai n: Cadiz, 1998 ." '"ｾ＠ ｾ＠ ｾ＠ " '"' :I: n " ｾ＠ "0 ｾ＠ 0 0 "0 ｾ＠ c ｾ＠ V> V> W V> V> "- Tablc 2. conti nued. Cata log . Taxon Hexapanopel/s Gllgllsrifrons (Benedict & Rat hbun, 189 1) Hexapanopells ongllsrifrolls (Benedict & Rat hbun. Hexapanopeus onglfstifrons (Benedict & Rat hbun. H e.mpallopeus al/gusti/rolls ( Benedict & Rathbun. Hexapanopeus Glzgustifrolls (Benedict & Rathbun. H e:capol/(Jpells .ar ib/mell! (Stim pson. 187 1) 189 1) 189 1) 189 1) 189 1) H exopollopeus coribbae ll s (Stimpson. 187 1) H exopo nopells coribboe lls (Stimpson. 1871 ) H exopa llopells l obipes (A. Mi lne- Edwards, 1880) H exapanopeus lobipes (A. Milne-Edwards, 1880) H exapanopells l obipes (A. Milne-Edward.'!, 1880) H exapa nopells ma llni llgi Sankarankuuy & Ferreira, 2000 H exapanopeus nov. sp. H e.mpmlOpells pal/lensis Rathbun. 1930 H exapmlOpel/s pal/ leI/sis Rathbun. 1930 H exapmlOpelis pmllensis Rathbun, 1930 H exapanopell.f pal/leI/sis Rathbu n, 1930 H e:capanopeus pOl/lensis Rathbun, 1930 H e:wpanopeus paulensis Rathbu n, 1930 H exapanopeus pOl/lensis Rathbun, 1930 Neopanope packardii Kingsley, 1879 PonopellS afr ican lls A, Mil ne·Edwards, 1867 POl/opells omericon lls Sau-"surc, 1857 POl/opells herbstii H. Milne Edwards. 1834 Ponopells loclistris Dcsbonne, 1867 Panopells occidentalis Saussure. 1857 Pallopeus occidelllalis SaUl,sure. t 857 ｾｯ ｮ Ｎ＠ 187 1 Pallop/ax dep ressa ｓｴｩｭｰ Rhi rhropal1opells harrisii (Gould, 184 1) Pilumnidae Sa mouelle. 18 19 Lobopi/umnus agassizi i (Stimpson. 187 t) P ilwrmus jlo ridalllis Stimpson. 187 t No. Collection Locality 16S 12S ULLZ69-'3 UL LZ 7 174 ULLZ 7757 ULLZ 8368 We:-.lem Atlantic; Florida. Ft. Pierce. 2006 Western Atlantic; t-l orida. FI. Pierce. 2003 Western Atlantic: R orida. Ft. Pierce, 2006 ｅ｡ｾ ｬ ｣ ｭ＠ Gul f o f M exico; A onda. 2()()..l Western Atlant ic: Florida, FI. Pierce. 2003 ' Western Atl ant ic: Florida. Ft. Pierce. 2006 EU863343 EU863368 EU86335 I EU863277 EU863302 EU863285 EU8633 1-' EU8633 19 ULLZ 90 19 ULLZ 6859 ULLZ 6859 ULLZ 7743 ULLZ 473 1 ULLZ 3995 Western Atl antic: Florida. Ft. Pierce. 2006 ｗ ･ｾ ｴ ･ ｭ＠ Atlant ic: Florida. Ft. Pierce, 2006 Non hcrn Gulf of Mexico: Louisiana. 2001 Southeastern Gulf of Mexico: 2004 Northern Gulf of Mexico: 2006 Western Atlantic: Brazil: Rio Grande do Norte, 1996 Northern Gulf of Mexico: Texa..., 1998 Northern Gulf of Mex ico: Texa'i, 1998 We.q ern Atlantic: Brazil: Sao Paulo, 1996 Northern Gulf of Mex ico: Texas, 2006 Northern Gulf of Mex ico: Texa. . , 2006 Northern Gu lf of Mex ico: Texas, 2006 Nonhern Gulf of Mex ico: Texas, 2006 Northem Gulf of Mex ico: Panama City. 2007 United States: Florida, FI. Pierce, 1998 Eastern Atlantic: Spain : Cadiz, 1999 Western Atlantic: Florida, Ft. Pierce, 1996 Western Atlantic: South Carolina. 1997 Western Atlantic: Florida. FI. Pierce. 1997 Nonhem Gul f of Mexico: Panama City. 2007 Nonhcm Gul f of Mexico: Panama City. 2007 Nonhern Gulf of Mexico: 2006 Northern Gulf of Mexico: Texas. 1998 ULLZ 7121 ULLZ 7343 Southwestern Gulf of Mexico: 2005 Southern Gulf of Mexico: 2005 ULLZ 6909 ULLZ 7828 USNM 260923 ULLZ 86-16 ULLZ 389 1 ULLZ6608 ULLZ6862 ULLZ6870 ULLZ6875 ULLZ6882 ULLZ8645 ULLZ 3772 ULLZ .-273 ULLZs.-56 ULLZ 8-'57 ULLZ38 18 ULLZ 8640 ULLZ 8M3 ULLZ 8056 EU863380 EU863385 EU86338 I EU8633-' 8 EU863353 EU863356 EU8633 t5 EU863282 EU863287 EU863365 EU863352 EU863290 EU863299 EU863286 EU863383 EU8633 17 EU86336I EU863295 EU86329. EU863360 EU863373 EU863358 EU863307 EU863292 EU86337.EU863376 EU863308 EU863375 EU863309 EU863377 EU8633'-9 EU863370 EU8633-'5 EU863362 EU863363 EU863393 EU8633 10 EU8633 I I EU863283 EU8633O" EU863279 EU863296 EU863297 EU863394 EU 863347 EU863346 EU863327 EU863328 EU86328 I EU863280 EU863402 EUK63403 EU863336 EU863337 :::l ｾ＠ S - " ｾ＠ ｾ＠ Table 2. continued. Catalog. Taxon Portunidae Rafinesque. 18 15 ｏｾ Ｇ ｡ｊｪｰ･ｳ＠ pllnctatlls (De Haan. 1833) Pseudorhombilidae Alcock. 1900 Trapeziop!ax Iridentma ( A . Milne-Edwards. 1880) Xanthidae MacLeay. 1838 Atergatis reticula/lis (De Haan. 1835) Batodaells urillator (A. Mi lne-Edwards. 1881) Eucratodes agassizii A. Milne-Edwards. 1880 Garthiope barbadensis (Rathbun . 192 1) Garthiope barbadens;s (Rat hbun . 192 1) Liomera cillctimtllla (White, 1847) Macromedaeus distingu elldlls (De Haan. 1835) Micropanope sculplipes Stimpson. 187 1 Micropallope sculplipes ｓｴｩｭｰ Ｎ ｾｯ ｮ Ｎ＠ [87 1 Speocarcillus lobatlls Guinot. 1969 Speocarcillus mOllotliberclllatlls Felder & Rabalais. 1986 Xamhias callaliclllalllS Rathbun . 1906 No. Collection Locality GenBank ULLZ 8054 GenBank UI..LZ 8 13 1 UllZ 8400 Ul..lZ 8 170 ULLZ 8 183 GenBank GenBank ULLZ6603 UI..LZ 8025 UI..LZ 7820 ULLZ 7562 Ul..LZ438 1 Northern Gulf of Mellico: 2006 Southern Gulf of Mellico; 2005 Northern Gulf of Mellico; louisiana. ]996 Northern Gulf of Mellico: 2006 Northern Gulf of Mell ico: 2006 Southeastern Gul f of Mellico; 2004 Northern Gulf of Mellico: 2006 Northern Gulf of Mexico: 2006 Southwestern Gulf of Mexico: 2005 Indian Ocean : South Africa: Sodwana Bay. 200 ] 16S 118 DQ062733 DQ060652 EU863344 EU863278 DQ062726 EU863405 EU863389 EU863367 EU863366 AF50 1736 DQ06273 I EU863404 EU863378 EU863-'07 EU863359 EU863382 DQ060646 EU863339 EU863323 EU863301 EU863300 AF501708 DQ060654 EU863338 EU8633 12 EU86334 I EU863293 EU8633 16 j ｾ＠ .Q, :I: ｾ＠ x ] ｾ＠ ｾ＠ c ｾ＠ u. u. u. 556 Thoma el al. Table 3. Primers used in thi s study. Gene Primer Sequence 5' -+3' Ref. 16S 16S 16S 16S 12S 12S 16Sar 16S br 16L2 1472 12sf 12slr CGC CTG 1TT ATC AAA AAC AT CCG GTC TGA ACT CAG ATC ACG T TG C CTG 1TT ATC AAA AAC AT AGA TAG AAA CCA ACC TGG GAA ACC AGG ATT AGA TAC CC AGC GAC GGG CGA TAT GTA C (I) ( I) (2) (3) (4) (4) References: ( I) Palumbi ct al. 1991. (2) Schubart ct 31. 2002. (3) Crandall & Filzpatrick 1996. (4) Buhay Cl al. 2007. 2.2 DNA extractioll, pe R. and sequencing Genomic DNA was extrac ted from muscle tissue of the pcrcopods of a (Olal of 66 specimens of the fami ly Panope idac and related taxa of the Xanthoidea sensu Marti n & Davis (200 1) utili zing one of the foll owi ng extraction protocols: Genomi c DNA Extrac tio n Kit for Arthropod Samples (Carlagcn Molecular System s, Cal. No. 208 10-050), Qiagen DNeasy" Bl ood and Tissue Kit (Qi agcn. Cal. No. 69504) , or isopropanol precipitation following Robles ct al. (2007). Two mitochondrial markers were sel ec ti ve ly amplified usi ng po lymerase cha in rcacti on (PC R). A fragm ent of the 165 large subunit rONA approximately 550 basepairs (bp) in le ngth was amplifi ed using the primers 1472 or 165br in combi nati on with 16L2 and 16Sar and a fragment of the 12S sma ll subun it rONA approximatel y 3 10 bp in leng th was amp lified using the primers 12s f and 12s 1r (sec Table 3 for complete primcr informatio n). PCR reactions were performed in 25-1-'1 volumes contai ning: 0.5 .uM forward and reverse primcr, 200 /.LM cach dNTP, 2.5 1-'1 lOx PCR buffer, 3 mM MgCI" I M betai ne, I unit NEB Standard Taq polymerase (New England Bioiabs, Cal. No. M0273S), and 30--50 ng of genom ic DNA. Rcac tions were carried o ut using the follow ing cycli ng parameters: initi al denaturation at 94° C for 2 min ; 40 cyc les at 94° C for 25 sec, 40° C (l6S) o r 52° C ( 12S) for I min , 72°C for I min ; fin al ex tension at 72°C for 5 min . PCR products were purified using EPOC H GenCa tch PCR C lea n-up Kit (EPOC H BioLabs, Cal. No. 13-60250) and seq uenced in both directions using ASI BigDye@ Term inator v3 . 1 Cycle Sequencing Kit (A ppli ed Biosystcms, Foster City, CA , USA). Cycle sequencing product s were purified us ing Scphadex G-SO columns (S igma-Aldrich Chemicals, Cal. No. S6022). Seq uencing products were run o n an ABI PRJSM @ 3 100 Genetic Analyzer (Applied Biosyslems, FOSLer City, CA, USA). 2.3 Phylogenetic allalyses Seq uences were assembled using Seq ue ncher 4.7 (Gc neCodes, Ann Arhar, MI, USA). Once assembled, seq uences were aligned using MUSCLE ( MUltiple Sequence Compari son by Log-Expectation), a com puter program found to be ma rc accuratc and faster than other ali gnmcnt algorithms (Edgar 2004). Alig nmen ts were furth er refined using GBlocks vO.9 l b (Castrcsana 2000) to om it poorly aligned or ambiguous posi tions. Default parameters were used for GBloc ks except: I) minimum length of a block = 4, 2) all owcd gap positi ons = half. We conducted a partition heteroge ne ity test or incongruence leng th difference test (ILD) ( Bull et al. 1993), as impl emcnted in PAUP* v4blO (Swo fford 2003), to determ ine if the two gene region s could be co mbined . The model of evolu ti o n that best fit each of the dataset s was determined by like lihood tests as impl emented in Mode ltest version 3.6 (Posada & C randa ll 1998) under the Akaike In format ion Phylogeny of Hexapanopeus 557 Criterion (AlC). The max imum likelihood (ML) analyses were conducted using PhyML Online (G uindon et aL 2005) using the model parameters selected with free parameters estimated by PhyML. Confidence in the resulting topology was assessed using non-parametric bootstrap esti mates (Felse nstein 1985) with 500 replicates. The Bayes ian (BAY) analyses were conducted in MrB ayes (Huelsenbeck & Ronquist 2(01 ) with computations performed on the computer cluster of the Cy berJnfrastructure for Phylogeneti c RESearch project (CIPRES) at the San Diego Supercomputer Center, using parameters selected by Modeltesl. A Markov Chain Monte Carlo (MCMC) algorithm with 4 chains and a temperature of 0.2 ran for 4,000,000 generations, sampling I tree every 1,000 generati ons. Preliminary analyses and observati on of the log. likelihood (L) va lues all owed us to detennine burn-ins and stationary di stri butions for the data. Once the values reached a plateau, a 50% majority rule consensus tree was obtained from the remaining trees. Clade support was assessed with posterior probabililies (pP). 3 RESULTS The ini tial sequence ali gnment of the l6S dataset. includ ing gaps and primer regions, was 606 bp in length , while th at of the 12S dataset was 384 bp in length . GB locks was used to further refi ne the alignment , removing ambiguously aligned reg ions resulting in fin al alignments of 52 1 bp (86%) and 284 bp (74%) for 16S and 12S, respectively. Despite recent studi es combining multipl e loc i into a single alignment (Ah yong & 0 ' Meally 2004, Porter et 2(05), we chose in this in stance not to combine the datascts. The partition heterogeneity test or incongruence length difference test, as implemented in PAUP*, indi cated that the combin ati on of the two gene regions was significantl y rejec ted (P = 0.0240). Furthermore, preliminary analys is of the combined dataset resulted in lower support for some of the tip branches than was the case in the single gene trees. This is due to different branching pattern s ( 16S vs. 12S) at this level of the tree, whi ch will be di scussed later in this paper. This information would be lost in a combined tree. Appli cation of the likelihood lests as implemented in Modellest revealed that the selected model of DNA substitution by AI C for the 16S dataset was HKY+i+G (Hasegawa et al. 1985) with an assumed proportion of invari able sites of 0.3957 and a gamm a di stri buti on shape parameter of 0.4975. The seleeled model for Ihe I2S dalasel was GTR+I+G (Rodriguez CI al. 1990) wilh an assumed proporti on of invari able sites of 0. 3228 .and a gamma di stributi on shape parameter of 0.6 19 1. Phylogenetic relati onships among 7 1 individuals representing 46 species of the Xanthoidea sellsu Martin & Davis (200 1) were detenn ined us ing Bayesian and ML approaches for both the 16S and 12S datasets. For the Bayesian analyses, the fi rst 1,000 trees were discarded as burn- in and the consensus tree was estim ated using the remaining 3,000 trees (= 3 milli on generations). Topol og ies resulting from the Bayesian analyses o f both the 16S and 12S datasets were largely congruent (Figs. I and 2). A num ber of monoph yletic clades are supported by both datasets, as fo ll ow: I) Acamholobullls bermudellsis, Acantholobulus schmitti, and Hexapallopeus caribbaells with pP ( 16S/ 12S) of 99n7 ,2) Hexapanopeus allgLlsrijrolls and Hexapallopeus pau/ellsis with pP of 100199, 3) Eu rypallopells depresslIs, Ell rypanopells dissimi/is, Dyspallopeus sayi, Neopanope packardii, and Rhithropanopeus harrisii with pP of 97/99, 4) Ew y panopeus abbreviaw s and £ 11rypallopeus planissimus with pP of 99/87. In general, Bayes ian IX>steri or probabilities have been shown 10 be higher th an the corresponding bootstrap values. but, in many cases, posterior probabilities tend to overrate confidence in a topology whil e bootstrap values based on neighbor j oining, max imum parsimony, or ML methods tend to slightl y underestim ate support (Huelse nbeck et al. 2001 , Huelsenbeck et al. 2002, Suzuki et al. 2002). With thi s in mind , it is not surprising to find that ML bootstrap supports for the same four cl ades are lower than the pP. The bootstrap values of the above cl ades are as foll ows: I) < 50/ < 50,2)7215 1, 3) < 50/< 50, and 4) < 50/< 50. al. 558 Thoma et al. 88/1 Hexapanopeus paulensis - ULLZ 6870 Hexapanopeus p8ulensis · ULll 6875 97"00 Hexapanopeus paulensis - ULLZ 6882 Hexapanopeus pau/ensis - UlLZ 3891 Hexapanopeus p8u/ensis - UlLZ 6862 Hexapanopeus paulensis· ULLZ 8645 Hexapanopeus pau/ensis - UlLZ 6608 1 100 Hexapanopeus angustifrons - ULlZ 8368 '-,,,,,.,\. Hexapanopeus angustiflOns - ULLZ 7174 Hexapanopeus angustifrons - UlLZ 9019 91188 Hexapanopeus angustifrons - ULtz 7757 Hexapanopeus angustifrons - ULll 6943 '-_-:- Hexapanopeus nov. sp. - ULLZ '8646 Cyt10iY8x nr. spinidentata - UlLZ 8423 Panopeus americanus - UlLZ 8456 Hexapanopeus lobipes - ULLZ 7828 . J""'-- - - -"IO=, OI oo " - Hexapanopeus Iobipes - ULLZ 4731 Hexapanopeus /obipes - UlLZ 6909 ＯＹ ［ｾ ］ｾ ｅｕｲｹｰ｡ｮｯ･ｵｳ＠ panissimus - ULLl 4140 Eurypanopeus abbreviatus - ULLZ 3753 631100 Neopanope packardii - ULLZ 3772 ./ Dyspanopeus sayi - UlLZ 7227 Eurypanopeus dissimilis - UlLZ 8424 1" Eurypanopeus dissimilis • ULLZ 5878 ｲＢＧｾ ＮｊＸ ｌ ｊＭ［Ｚ］ ｒｨｩｴｲｯｰ｡ｮ･ｵｳ＠ harrisii - ULLZ 3995 5 Eurypanopeus depressus - ULLZ 6077 Eurypanopeus depressus - UlLZ 3976 Panopeus oa:identalis - UlLZ 8640 Panopeus ocddentalis - UlLZ 8643 .22!''-- Panopeus lacustris - UlLZ 3818 Panopeus africanus - ULLZ 4273 .J86 '"'-- - Panopeus herbst;; - UlLZ 8457 ·os r _ _ _ _''''OOI,,'' 'O'O'l Garthiope barbadensis - ULLZ 8170 ./1 Garthiope barbadensis - UlLZ 8183 r--::-:-.,--.,-- Euaatopsis aassimanus - UlLZ 6427 G/yptoplax smith. - ULLZ 7686 ｾ ｌ ｟ Ｌｯ Ｎｬ＠ ｇＯｹｾｯｰｬ｡ｸ＠ smith; - ULLZ 9020 G/yfJopJax smith" - ULLZ 8335 Glyptoplax smithii· ULLZ 6793 . Glyptoplax smith;i - ULLZ 8142 100/100 Acantholobulus sdlmitti - ULLZ 6613 Acanth%bu/us schmitti - UlLZ 8367 Acantholobulus bermudensis - ULLZ 6558 _ _2!IOOI"" ,OO"l Acantholobulus bermudensis· ULLZ 6924 ./99 r Acanth%bulus bermudensis - UlLZ 5843 Hexapanopeus manning; - ULlZ 8649 ' -_ _ _ＱｾＰｉＢ｟Ｇｬ＠ Hexapanopeus caribbaeus - ULLZ 6859 Hexapanopeus caribbaeus - ULLZ 6859 Hexapanopeus caribbaeus - ULLZ 7743 Speocardnus Iobatus • ULLZ 7820 ｾ '-!1lr-l ｾｳｰ･ｯ｣｡ｲ､ｮｵ＠ monotuberrulatus · ULLl 7562 Trapezioplax tridentala - ULLZ 8054 Euaatodes agassizii - ULLZ 8400 Miaopanope sculJXipes - ULLZ 6603 ' -;;,0=, 01 oIMicropanope srulJXipes - ULLZ 8025 Panopax depressa - ULLZ 8056 Batodaeus urinator - ULLZ 8131 Xanthias canalirulatus · ULLZ 4381 ./99 Atergatis releulatus - GenBank Liomera cindimana - GenBank Maaomedaeus dislinguendus - GenBank Eriphia velTUOOsa - UlLZ 4275 91/1 1001100 Lobopifumnus agassizjj· ULLZ 7121 Plumnus fIoridanus - UlLZ 7343 ""00 Carpiius macula/us - GenBank ./99 Ovafipes pundatus - GenBank 58/100 Balhypax typh/us· UlLZ 8032 C. mississippiensis - ULLZ 7346 100/100 ;6. C. chacei - UlLZ 8018 ＹﾧｪＧｩｏ＼ｬ ｃ］ ｾｆＬＮ ｾ･ ｾ｡｢ｲｬ＠ - ULLZ 8369 0.05 Soloplax roberts; - ULLZ 7857 ｲ ｟ Ｌｩｊ ｲｾ ,... .'58L__ !<'igurc 1. Phylogeneti c relati onships among panopeid crab species and selected representatives of the superfamily Xanthoidca sel/su Martin & Davi s (200 I). inferred by Bayes ian analysis from 521 basepairs of the 16S rDNA gene. Confidence intervals are from 500 bootslrap maximum li keli hood analysis fo ll owed by Bayesian posterior probabilities. Genus shown as "c." =Chasmocarcil1l1s. Values below 50 are indicated by "-". Phylogeny of Hcxapanopeus 559 Hexapanopeus paulensis - UlLZ 6870 Hexapanopeus paulensis - UlLZ 6875 Hexapanopeus paulensis - UlLZ 6882 Hexapanopeus paulensis - ULLZ 6862 Hexapanopeus paulensis - UlLZ 3891 Hexapanopeus paulensis - ULLZ 8645 Hexapanopeus paulensis - ULLZ 6608 ---" ",, ,'O"1 O ,Hexapanopeus angustifrons - ULLZ 8368 L Hexapanopeus angustifrons - ULLZ 7174 Hexapanopeus angustifrons - ULLZ 9019 Hexapanopeus angustifrons - ULLZ 7757 Hexapanopeus angustifrons - UL12 6943 Hexapanopeus nov. sp. - ULLZ8646 ｾ＠ G/Y!ioplax smithii - ULLZ 7686 G/Y!ioplax smithii · ULLZ 9020 ....ｭＱ ｾ ｇｬｹＡｩｯｰ｡ｸ＠ smithii · ULLZ 8335 Glvptoplax smithii · ULLZ 6793 Giy!ioplax smithii - UL12 8142 I ｾ ｃ］ Ｂｅﾣｵｲｹｰ｡ｮｯ･ｳ＠ abbrevia/us· ULll 3753 :ji 7 Eurypanopeus panissimus - UL12 4140 -195 Hexapanopeus Iobipes· UL12 4731 , __-,'001 ",,'0,0 Hexapanopeus lobipes . ULLZ 6909 Hexapanopeus lobipes · ULLZ 7828 Panopeus herbstii · ULLZ 8457 Panopeus africanus - UlLZ 4273 Panopeus lacvstris· ULLZ 3818 L - I - - Panopeus ocddentalis - UlLZ 8640 Panopeus ocddentalis • ULLZ 8643 Eurypanopeus depressus - UlLZ 6077 Eurypanopeus depressus - UlLZ 3976 Eurypanopeus dissimilis - UlLZ 8424 100'100 Eurypanopeus dissimilis - UlLZ 5878 Oyspanopeus sayi· UlLZ 7227 Neopanope packardii . UlLZ 3772 Ｍ Ｌ ｾ ［ｃ］Ｍ ＺＧｒｨｩｦｲｯｰ｡ｮ･ｵｳ＠ harrisi; - ULLZ 3995 Panopeus americanus - ULLZ 8456 Hexapanopeus caribbaeus · ULLZ 6859 Hexapanopeus caribbaeus - UlLZ 6859 '001' Hexapanopeus manningi. ULLZ 8649 Hexapanopeus caribbaeus - ULl2 7743 Acantholobu/us schmitti· ULLZ 6613 Acanth%bu/us schmitti - ULLZ 8367 Acanth%bu/us bermudensis . ULLZ 5843 Acanth%bu/us bermudensis - ULLZ 6924 Acantholobulus bermudensis . ULLZ 6558 Cyrtoplax nr spinidentata . ULLZ 8423 Eucratopsis crasstmanus . ULLZ 6427 Speocarrinus monotubercu/atus · UlLZ 7562 Trapezioplax tridentata - UlLZ 8054 Speocardnus Iobatus - Ul LZ 7820 '" ./. '''5 ｾＬ ｾ + ｟ＭＺＬ " ｴＺ］Ｍ l ___...:...___________....l!"!!!2 IＭＢ Ｇｃ］ ｃｾｨ Ｎ｡ｳｭｯ｣ｲｩｮｵ＠ mississippiensis· UlLZ 7346 Chasmocarcinus chace; - ULLZ 8018 ｾ［ｯ＠ Panoplax depressa • ULLZ 8056 Eucratodes agassizii· UlLZ 8400 L_ _Tciiw;LMicropanope sculpt/pes - ULLZ 6603 100"1 Micropanope sculptipes· ULLZ 8025 , - - - -Batodaeus urinator - ULLZ 8131 ,. 0.05 ｾ Ｇ｛］Ｌ ］ｾ ｾ［Ｚｌ ﾷ＠ ｭ･ｾＬＮｯｮ､［｡＠ - GenBank Atergatis reticulatus - GeoBank Xanth ias canaliculatus - UlLZ 4381 ｐｩＯｵｭｮｳ＠ f/oridanus· UlLZ 7343 L____Ｌｾ ｏｉ ｾ Ｌ ｾ ］ Lobopilumnus agassizii· ULLZ 7121 L - - - - - - Macromedaeus distinguendus · GeoBank 1(01 Garthiope barbaclensis - ULLZ 8170 Garthiope barbadensis · ULLZ 8183 Eriphia verrucosa - UlLZ 4275 Carpi/ius mawla/us - GeoBank Bathypax typllius - ULLZ 8032 Ovalipes punda/us· GenBank Sotopax robertsi - ULLZ 7857 Frevillea barbata - ULLZ 8369 Figure 2. Phylogenetic relation ships among panopeid crab species and selected representalivcs of the superfam il y Xanthoidea sensu Martin & Davi s (2001), inferred by Bayesian analysis from 284 bascpairs of the l2S rDNA gene. Confidence intervals are from 500 bootslrap maxi mum likelihood analysis followed by Bayesian posterior probabililies. Values below 50 are indicated by ;'-". 560 4 Thoma et al. DISCUSS ION Here we report two molecul ar phylogenies o f the genus Hexapallopeus and related genera of the fa mil y Panopcidae. These ph ylogeni es, which are based on parti al sequences of the 165 and 12S rO NA, contain fi ve of the 13 nom inal spec ies in Hexapanopeus and a sin gle undescri bed spec ies that appears to be assignable to the genus. In add ition, we have included representatives of 18 species of the family Panope id ae in order to better address both the monoph yly of HexapGlwpells and the relat ionships of spec ies curre ntly ass igned to Hexapallopells to other panope id taxa. Alth ough onl y five spec ies of Hexapollopells arc included in the dataset, these five species represent five of the six nom inal species known from the western At lantic. It is clear from our analyses th at the genus HexapGllOpellS is markedl y polyphyletic and that furth er study of all its putative members is warranted, by both morpholog ica l and molecu lar methods. 4.1 Hexapanopeus angust ifrons and Hexapa nopcus paule nsis The phy logenies presented here le nd support to a narrowed defini tion of Hexapallopells that includes on ly the type-spec ies of the ge nu s Hexapallopells allgllst'ijrolls (Benedict & Rath bun , 189 1) and Hexapollopells palllensis Rathbun . 1930, pe nding results o f morphologica l and molec ul ar analyses for the remai ning eight prese nt co ngeners. It is interesting to note th at in all ana lyses thcse taxa form a monophy leti c clade and that within both species there is further ev idence for genetic structure. II is unclear if the genctic divergence seen in these clades is the result of crypti c speciation or popu lation diffcrentiation, but the current analyses suggest some combi nation of the two mighl occur in each complex. 4.2 Hexapa nopeus nov. sp. In the ana lyses of the 165 dataset, the sistcr group to the H. mlgllstijrollslH. paule' lsis clade is an undescribed species from intertida l waters of south Texas in the western Gu lf of Mex ico. This undescri bed spec ies resem bles H. paulellsis in general morphology, but it has a very dist incti ve gonopod, which most resembles that of Aeon tllO/obu/lIs schmilli (Rathbun , 1930). In contrast 10 the results of the 165 dataset, the 125 dataset lends support to a cl ade th at is composed of th e undescri bed spec ies and Glyptoplax smithii A. Milne-Edwards. 1880, as the sister group 10 the H. angllsti/ronslH. paulensis clade. Un fortunately, suitable materia l of GJypropJax pugnax Smith, 1870, lhe type spec ies of the genus. has not to date been ava il able for molecu lar analysis; therefore. it rcmains unclear whether this undescribed spec ies is Illost appropr iately treated as a me mber of the genus Hexapallopeus, the genus GlyplOpJa:r, or a new monospecific genus. 4.3 Hexapanopeus lobipcs The species Hexapallope//s lobipes (A. Milne-Edwards, 1880) has had a very un settled taxonomic hi story. After bei ng described as a spec ies of Neopallope A. Miln e-Edwards, 1880, it was later tra nsferred to the ge nus Lop/Jopallopells Rathbun , 1898, by Rathbun in 1898. In his 1948 revision of the gc nus LophopalJopeus. Menzies pointcd out that H. /obipes does not fit the diagnosis of the genus Lophopallopells. Upon transferrin g the species 10 the genus Hexapallopeus, he noted Ihat " it seems to fit Ihe d iagnos is of that genus beller th an tha t of any oth er America n ge nus." On ly isolated records o f Hexapanopeus lobipes have been reported since Menzies' 1948 work (Wickstcn 2005, Fclder et al. in press), and thcre has been no reassessment o f its placement with in the gen us Hexapallopells. The gOllopod of H. lobipes is di stincti ve and has little rese mbl ance 10 those in othcr members of the genus Hexopanopeus. Furthermore, unlike the carapaces of H. allgllstijrons and H. pal/leI/sis, which have five distinct anterolateral teet h, the 1st and 2nd antero-iateral teeth of PhylogellY of Hexapanopeus 56 1 H. lobipes are generally fused, giving the appearance of four anterolateral teeth . On the basis of these and other morpholog ical fea tures, it is unclear whether H. Jobipes is justifi ably assignab le to the genus H exapan opeus. Whalever the case to be made on the basis of morphology alone, we cannot concur with Ng el al. (2008) in reass igning thi s species to Lophopanopells . OUf analyses s upport removal of H. lohipes from the genus Hexapanopeus and appear to justify establishment o f a new mOllospccific genus for H. lobipes. In both topologies, H. Jobipes fall s outside the clade formed by H. angustifrons and H. pallle'lsis. In the phy logeny inferred from the 165 dataset, H. lobipes is the s ister group 10 Panopells americanus Saussure, 1857, with ML boot· strap and pP values of <50/90, respectively. The phylogeny inferred from the 12S datase t presents H. lobipes as a sister group to Pal10pells s.s. H. Milne Edwards, 1834, with ML bootstrap and pP va lues of < 5015 1, respective ly. Despite low support va lues, both topologies lend support to the re· moval of H. lobipes from the genus Hexapanopeus and the erection of a new genus for the species, as is currentl y in progress. 4.4 Hexapanopeus manningi HexapmlOpellS malllling; Sankarankutty and Ferreira, 2000, was descri bed on the basis of materi al from Rio Grande do Norte, Brazil. This spec ies was distingu ished from Hexapanopells caribbaells (Stimpson, 187 1) by characters of the frontal margin, the 3rd anterolatcral tooth of the carapace, and the apica l process of thc gonopocl; however, upon the basis of sy nopti c comparisons of the mal e paratypc (USNM 260923) to malerial of H. caribbaells from eastern Florida, it appears that there is considerable morphological overl ap between these two taxa, raising the question as to whether H. l1uUln;ngi migh t be a junior synonym of H. caribbaeus. The topology inferred from the l6S dataset places H. mamlillgi in very close proximity to H. caribbaeus; di stance between these taxa is very short and comparable to th at wit hin other accepted single·species clades in our tree. The clade contai ning both H. manningi and H. caribbaells has high support values, with ML bootstrap and pP values o f 100/ 100, respectively. The stron gest support for a synonymy of the two taxa comes from the topology inferred from the 12S datase t, with H. mmmingi positioned with in the clade of H. caribbaeus. Our molecular phylogeni es support sy nonymy of H. mallllillgi wi th H. caribbaeus, and we herew ith recommend that taxonomic revision, regardless of the eventual generic assig nment to be accorded (see below). 4.5 Hexapanopeus caribbaeus Hexapanopeus caribbaeus was ori ginall y descri bed as a representative of the genus Micropanope; however, upon erection of the genus Hexapallopeus, Rathbun ( 1898) transferred this spec ies to the genus Hexapanopeus appare ntl y on the basis of carapace shape. It wasn' t unt il th e 1997 work by Sankarankuuy and Manning that di stinct differences between the gonopod of H. caribbaells and that of the type·species H. angllstijrolls were noted . In the prese nt ana lys is, this spec ies is clearly separated from Hexapallapeus 5.5., and shown to be more closel y allied to the ge nus Acam/w lobulus. 4.6 Genlls Acantholobulus Fe lder and Martin (2003) erected the genus AcarllllOlobllllls to accommodate a num ber of species from th e ge nera Panopells and Hexapanopeus, whic h included: I) the type·spccies Acalltholobl/ IllS bermuderzs;s (Benedict & Rathbun , 1898), formerly Panopel/s bermlldensis; 2) Acanth%bu/us mirajlorensis (Abele & Kim , 1989), fa nnerl y Pallopeus mirajlorellSis; 3) Acantholobulus pacifiC/lS (Edmondson, 1931), formerly Panopells pacijiclls; and 4) Acantho /abu/lls schmitt; (Rathbun , 1930), fonnerl y Hexapanopeus schmilli. Despite similarities between H. caribbaeus and A. schmitti in both carapace and gonopod morphology, the possible relat ionsh ip between H. caribbaeus and newly assigned members of the ge nus Acantholobuills was not addressed. The phylogenies inferred 562 Thoma e( at. from both our datasets strongly support incl usio n of H. caribbaells within the genus Acantha/obulus. While the phylogeny inferred from th e 16S dataset shows H. caribbaells nested with Acarl (h%bu/lls , the topology in ferred by analys is of the 12S datasets supports a sister gro up relat ionshi p betwee n H. caribbaells and both A. bermudellsis and A. schmif(i. Altho ug h both of these relat ionships are supported by pP > 75, the 165 dataset shows considerabl y hi gher pP (99177 for 1651125, respccli vely). As add iti o nal spec ies of Acantho/abulus become avai lable ,for incl usion in o ur analysis, the re lati o nship between Acantho/abullls and its closest re latives should be more definiti ve ly resolved. Even so, it is by prese nt find ings establi shed thai H. caribbaells is well separated from Hexapallopeus S.S., and we app ly the new combinatio n Acantholobu/lls caribbae/ls (Stimpson, 187 1). 4.7 Panope us ameri can us In a study of mud crabs fro m the northwestern Atlantic, Schubart et al. (2000) clearly showed polyphyl y in the genus Panopells, with both Acan(/IO/ablilus bermlldellsis (as Pallapells bermudellsis , see di scussion above) and POl/opells american liS fa llin g we ll oUl side Pal/opells s.s. (Schubart et al. 2000, Fig. I). In the presem study, we find additio nal support for these findin gs with the topologies inferred fro m both datasets positi oning P. american lls outside Panopeus s.s.; however, the topologies differ in where P. ameriCQllllS is placed re lat ive to spec ies of other genera. In the topo logy inferred from the 16S dataset, P. americallus is a sister group to H. lobipes, while in the topo logy inferred from the 12S dataset, P. americallllS is Ihe sister group to the clade cont aining E. depresslIs , E. dissimilis, N. packardii, D. sayi, and R. harrisii. However, thi s arrangeme nt is poorly supported wi th ML bootstrap and pP va lues less than 50. Desp ite the differences in the topologies inferred from th ese two dat asets, both provide evidence for the removal of P. arnericO/IIIs from Pallopeus. Pe nding a thoroug h ana lysis of ad ult and larval morphology, data presented here support the establishme nt of a new genus for P. americantls. 4.8 Genus Eurypanopeus Schubart et a1. (2000, Fi g. \) also provided ev idence for polyphyly among spec ies presently assigned to the genus Eurypanopeus A. Milne-Edwards, 1880, with species of ElirypanopeLls fa lli ng into three separate clades. In the present stud y, topol og ies inferred from both datasets support the polyphyle tic nature of Eurypallopells, wi th represent atives found in three c lades for 165 (Fig. I) and two clades for 12S (Fig. 2). It is unclear what effect the additi on of sequence data from other spec ies of EUl)lPat/Opeus would have o n the ana lyses; however, on the basis of evidence presented here and by Sc hubart et al. (2000), comprehensive study and taxonomic rev ision of the genus are needed . 4.9 Panoplax depressa Des pite a gOllopod that shares little in comm on with that of the typi cal panopeid, Panop/ax depressa Stimpson, 187 1, has lo ng been considered a me mber of the subfamil y Eucratopsin ae within the famil y Panopeidae (Martin & Abele 1986, Mc Laug hlin et al. 2005, Ng et al. 2008). The analyses presented here prov ide no support for the inclusion of Panoplax within the fam il y Panopeidae. In topologies inferred from both datasets, Panoplax depressa is well separaled from remaining representatives of the family Panopeid ae. III the phyloge ny inferred from the 165 dalasel, Panoplax depressa is found nested within a poorly supported clade cont ainin g representati ves of the fami lies Xanthidae and Pseudorh ombilid ae (MLlpP <50/99). In the phylogeny inferred from the 125 dataset, Panoplax depressa is al so ex cluded from the remainin g representat ives of the family Panopeidae, nested within a poorly supported c lade conl aining representatives of the family Xanthidae (MUpP <50/90). Despite the low support values for the clades curre ntly containing Pafloplax depressa, there is littl e evide nce to support the inclusion of Panoplax wi thin the fami ly Panopeidae. Phylogen), of Hexapan opcus 4. 10 563 Garthiope barbadensis The genus Garrhiope Guinot, 1990, was described to accommod ate three small species formerl y attributed to the genus Micropanope. Upon its erection, similarities between Garthiope and the family Trapeziidae were noted; however, in their recent review Ng et al. (2008) co nsidered the genus to be a part of the famil y Xanthidae. In the present analyses the compl ex relationship of Garth iope to the remaining taxa of the Xanthoidea sensu Martin & Davi s (2001 ) is shown in the conflict between the 16S dataset and 12S dataset in regards to the placement of Garthiope. In the phyloge ny inferred from the 16S dataset, Garthiope barbade'lsis (Rathbun , 192 1) is found within the famil y Panopeidae, where it is located within a cl ade containing representatives of the subfamily Eucratopsin ae. However, thi s cl ade has support va lues with ML and pP values of <50/98. To furth er confound our understanding, in the an alyses of the 12S dataset, Garthiope barbadellsis fall s well outside the family Pan opeidae in a clade containing representatives of the Eriphi oidea, Carpilioidea, Goneplacoidea, and Portunoidea. As thi s arrangement also has poor support values «50), the rel ationship . of Garthiope to these groups remains unclear. The type-species of the ge nus Garthiope spillipes (A Miln e-Edwards, 1880) was not ineluded in these analyses; as a result , it is un clear what effect its inclusion may have on the analyses. Further study of the group is needed to clarify how thi s genus is related [0 other representatives of the Xanthoidea sensu Martin & Davis (2001 ). 4. 11 Olltgroup taxa Composition of the superfamily Xanthoidea sensu Martin & Davi s (2001) is a subject of ongoing debale (Guinol 1978; Jamieson 1993; Coelho & Coelho Filho 1993; Schuba" el al. 2000; Welzer et aL 2003; Karasawa & Schweitzer 2006; Ng et a!. 2008). In all of our analy ses, the family Xanthidae is clearl y show n to be polyphyleti c, Analysis of the 16S dataset reveals a single clade containing representati ves of Panopeidae, Pseudorhombilidae, and three subfamilies of Xa nrhidae; however, thi s cl ade is poorly supported with ML bootstrap values and pP of <50/99 (Fig. I). Furthermore, a second clade contains a single representative of the famil y Xanthidae as well as reprc4 sentativcs of Eriphioidea, Pilumnoidea, Carpilioidea, Gonepl acoidea, and Portunoidea. This cl ade is well supported with ML bootstrap values and pP of 97/ 100. Within thi s cl ade we al so find representatives of three famili es of Gonepl acoidea, with two spec ies of Chasmocarcifllls representing Chasmocarcinidae, Frevillea barbara and SOlOplax roberts; representing Eurypl ac idae, and Bathyplnx typhlus representing Goneplacid ae. While Chasmocarcinidae and Eurypl ac idae form a poorly supported monophyleti c clade, Gonepl acidae is found in another cl ade with representati ves of Portunoidea and Carpilioidea. Although neither of th ese cl ades is well supported (MUpP <50/58 & <50/98 ), they provide ev idence for a pol yphyleti c Gonepl acoidea. While the topology inferred from the 12S dataset (Fig. 2) still presents evidence for a polyphyletic Xanthidae and Goneplacoidea, the evidence differs fro m th at inferred by the 16S dataset (Fig. I). However, support va lues for the oulgroup topology inferred by the 12S dataset are very low, making any conclusions drawn from thi s topol ogy questi onable: Regardless of differences between these two topologies, it is apparent th at both Goncpl acoidea and Xanthidae are polyphyletic and in need of rev ision. AC KNOWLEDG EMENTS We th ank H. Bracken, M. Bruglcr, J. Felder, S. France, E. Palac ios-Theil, E. Pante, V. Paul , R. Robles, J. Thoma, and A. Windsor for assisting in obtaining specimens or with various aspects of data coJlecti on, analysis, and manuscript preparat ion. We 'are grateful to J. Martin and G. Davi s for providing loans of material s from the Natural Hi story Museum of Los Ange les County, R. Lemaitre for access to specimens at the National Museum of Natural Hi story-S mithsonian In stitution, and F. Mantelatto for loan s of spec imens from Braz il. This study was supported in part by U.S. Nati onal 564 Th oma et al. Science Foundation grants NSF!BS&I DEB -03 15995 and NSF! AToL EF-053 1603 to D. Fe lder, as well as severa l small travel grants from th e Smithso ni an Marine Stat io n, Ft. Pi erce, Fl orida. Addi lional support to B. Th oma was provided under a Lo ui siana Board of Regent s doctoral fellowship . This is Uni versi ty of Loui siana Labora tory fo r Crustacea n Research contributi o n no. 128 and Smith sonian Marine Stati on contribution no. 737. REFERENCES Ahyong, S.T. & O ' Mea ll y, 0.2004. 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