Rhamphichthys pantherinus Castelnau, 1855

Carvalho, Tiago P. & Albert, James S., 2023, A taxonomic review of the Neotropical electric fish Rhamphichthys (Gymnotiformes: Rhamphichthyidae), Neotropical Ichthyology (e 230012) 21 (4), pp. 1-76 : 43-53

Rhamphichthys pantherinus Castelnau, 1855

( Fig. 36–47 ; Tab. 9)

Rhamphichthys pantherinus Castelnau, 1855:86 (original description, type-locality: d’un lac pres du Ucayali). —Günther, 1870:5 (as senior synonym of R. marmoratus ). —Cope, 1878:682 (listed). —Oliveira et al., 1988:604 (chromosome description). —Ferraris, 2003:496 (listed as junior synonym). —Ortega et al., 2011:41 (listed). —Ferraris et al., 2017:28 (listed as senior synonym of R. marmoratus ). —Meza-Vargas et al., 2021:21 (listed).

Rhamphichthys marmoratus Castelnau, 1855:86 (original description, type-locality: l’Araguay (Araguaia River), Brazil. —Günther, 1870:5 (as a junior synonym of R. pantherinus ). —Eigenmann, Ward, 1905:168 (listed). —Santos et al., 1984:19 (Illustrated and briefly described). —Mago-Leccia, 1994:41 (listed). —Santos et al., 2004:105 (illustrated and briefly described). —Ferraris, 2003:496 (listed). — Camargo et al., 2004:139 (listed). —Campos-da-Paz, 2007:123 (listed). —Lucinda et al., 2007:81 (listed). — Anjos et al., 2008:204 (listed). —Montag et al., 2009:246 (listed). —Ferreira et al., 2011:6 (listed). —Ortega et al., 2011:41 (listed). — Carvalho, Albert, 2015:40 (comparative material examined). —Crampton et al., 2016: (outgroup comparison).—Tagliacollo et al., 2016:29, fig.5 (phylogenetic relationships).—Giora, Carvalho, 2018:1060 (accessory electric organ anatomy). —DoNascimiento et al., 2017:66 (listed).

Rhamphichthys atlanticus Triques, 1999:3 (original description, type-locality: Lago Viana, Pindaré–Mearim system, Maranhão, Brazil. —Ferraris 2003:496 (listed). —Campos-da-Paz, 2007:122 (listed). — Carvalho, Albert, 2015:40 (comparative material examined).

Rhamphichthys longior Triques, 1999:4 (original description, type-locality: Paru Lake in the confluence of rios Trombetas and Paru-do-Oeste at Oriximiná, Pará). —Ferraris, 2003:496 (listed). —Campos-da-Paz, 2007:123 (listed). — Carvalho, Albert, 2015:40 (comparative material examined). —Taphorn et al., 2022:40 (listed).

Diagnosis. Rhamphichthys pantherinus differs from its congeners, except R. apurensis and R. rostratus by a color pattern with intercalated dark saddles on the mid dorsum, not paired at the midline, vs. sickle–shaped saddles ( R. drepanium and R. hahni ) or no saddles ( R. lineatus and R. heleios ). It differs from R. rostratus and R. apurensis by the relatively shorter snout 51.4–59.1% of HL, vs. 58.4–62.7 of HL ( Fig. 47 ); and by the number of caudal vertebrae 94–100, vs. 101–115 ( Tab. 5).

Description. Morphometric and meristic given in Tab. 9. Adult body size large compared with other congeners, maximum size 850 mm LEA. Mouth subterminal. Snout relatively short about half of head length. Dorsal profile of snout strongly concave in front of eye, head profile slightly convex posteriorly, some specimens with almost straight profile from snout to end of head. Anterior nares positioned terminally; posterior nares located closer to snout than eyes at about one third of length. Body profile almost straight to slightly concave dorsally. Ventral body profile slightly concave from anal–fin origin to end of anal fin. Greatest body depth slightly posterior to end of body cavity. Body tapering posterior to mid body. Eyes small. Urogenital papilla developed and anteriorly positioned below eyes in specimens larger than 440 mm LEA. Urogenital papilla relatively small in adults. Posterior gas bladder reduced, presenting thin membranous walls. Caudal appendage laterally compressed, its depth about three times its width, relatively short.

Body entirely covered by scales in adults, anterior and dorsal areas naked in juveniles. Scales cycloid elongate in shape posteriorly, length twice as depth. Lateral line complete with ossified tubules. Pectoral fin with 17–21 (mode 20) rays, dorsal rays longer than ventral rays, distal fin margin slightly rounded. Anal fin with 360–444 (median 404) rays. Anal-fin origin at vertical of anterior portion of opercle. Precaudal vertebrae 18– 20 ( Tab. 5). Vertebrae to end of anal fin 94–100 (n = 2). Displaced hemal spines 11–13 (n = 2). Sexual dimorphism unknown.

Coloration in alcohol. Ground color of dorsal and lateral surfaces of head and body pale yellow to dark brown ( Figs. 36–47 ). Head with scattered dark brown blotches of about eye size; snout mostly dark dorsally, its ventral margin less pigmented. Body with dark intercalated saddles reaching ventral to the lateral line. Presence of lateral dark lateral bands, slightly diagonally placed along the long body axis. Bands sometimes contacting the dorsal saddles; bands diffuse over pterygiophores region, extending to the proximal region of the anal fin rays. Anal fin mostly clear or hyaline except for scattered pigments these forming longitudinal stripes; sometimes presenting no pigments or scattered dark spots limited to the posterior end of anal fin. Pectoral fin clear or hyaline with broad dark bars. Caudal appendage with dark vertically elongate blotches.

Geographical distribution. Rhamphichthys pantherinus is the most widespread and common species of the genus, known from the Amazon and several of its tributaries, upper Orinoco, Tocantins, Essequibo, and coastal northern drainages of Brazil from the Turiaçu to Paranaiba drainages ( Fig. 48 ; Tab. 1). In the Orinoco River basin is restricted to its upper portions on the Guiana Shield of Venezuela and in the upper Meta and Guaviare River basins ( Fig. 48 ). This species inhabits a variety of habitats including channels and flood plain lakes of medium to large-sized rivers.

Remarks on synonymy. Rhamphichthys pantherinus is proposed here to have three junior synonyms: R. marmoratus ( Figs. 38–39 ), R. atlanticus ( Figs. 42–43 ), and R. longior

( Figs. 44–45 ). Rhamphichthys pantherinus is the senior synonym as Günther (1870) serves as first reviser treating. Later, starting with Eigenmann, Eigenmann (1891:62), R. marmoratus was treated as valid over R. pantherinus , perhaps due to page precedence. This was perpetuated for a long time in the taxonomic history of Rhamphichthys (see synonym list above). Apparently, this case does not fit the nomen oblitum ICZN’s rule since R. pantherinus was cited as valid in at least two publications (of which we aware) since 1899 (Oliveira, 1988; Ortega et al., 2011). These species have been considered synonyms in the past by several authors (Mago-Leccia, 1994; Triques, 1999; Ferraris, 2003). After examining an extensive quantity of material and types of both species we confirm and agree with these synonymizations. Rhamphichthys atlanticus was diagnosed by Triques (1999:3) by a uniform light brown anal fin without dark marks and a membranous swim bladder overlapped by visceral organs. The first character is highly variable within R. pantherinus throughout its distribution and does not diagnose the R. atlanticus allopatric population as separate from the others. The anal-fin coloration character is shared by R. pantherinus , R. apurensis , and R. rostratus , and does not diagnose R. atlanticus from R. pantherinus . Rhamphichthys longior was also described by Triques (1999:4) based on two measurements: a shallower body depth and a shorter head length. Under an extensive review of material these characters seem to represent the end of a cline in variation observed in very large specimens ( Fig. 49 ; Tab. 9), and do not support a diagnosis for R. longior . In addition, large specimens are frequently stored coiled in jars, impairing accurate measurement of overall body size such as LEA or anal-fin length. A PCA was done using populations of R. pantherinus including types of R. pantherinus , R. marmoratus , R. longior (Trombetas) , and R. atlanticus (Mearim) . No morphological differences were found to support the existence of distinct species within this group. Despite their disjunct distribution, the populations in the Amazon and Northeastern Brazil basins exhibit relatively little morphological differences. A PCA was conducted using 11 morphometric characters to compare geographic groups of R. pantherinus , including types of the putative R. atlanticus and R. longior species. The first three principal components (PC 1, PC 2 and PC 3) explain most of the variance (69.5%; Tab. S7). Scores were plotted for PC 1 vs. PC 2 and PC 1 vs. PC 3 show large morphometric overlap of geographic populations of R. pantherinus . Strong loadings separating some of these groups are the interorbital standard length (SL), anal fin length; preorbital length (PR), distance to posterior nares (PN); branchial opening (BO) and body depth (BD) ( Fig. 50 ; Tab. S8). A Multivariate Analyses of Variance (MANOVA) was done using the PC scores of the first three axes of the PCA. Populations of Rhamphichthys from Trombetas drainage are statistically different from most populations of Rhamphichthys pantherinus except from Negro basin and Mearim system ( Tab. S9; Wilks’ λ: 0.1946; P <0.001; F 15,105.3 = 5.681).

Material examined. Orinoco Guiana Shield: ANSP, 182785, 1, Venezuela, Amazonas, Río Manapiare at mouth of Caño Yutaje 14 km NW of San Juan de Manapiare, 05º26’11”N 66º06’45”W . AUM 41505 , 1 , same collection site of ANSP 182785 . Orinoco Llanos. IavH-P 19414, 2, Colombia, Meta, La Macarena, Lake at left margin of río Guayabero , 02°17’35”N 73°52’32”W . Essequibo: AUM 48696 , 1 , Guyana, Upper Takutu-Upper Essequibo, Aruwa falls on Rupununi river 15 miles upstream of Yupukari, 03º30’06”N 59º20’22”W . AUM 44834 , 1 , Guyana, Upper Takutu-Upper Essequibo, Rupununi river at Yukupari, 03º39’53”N 59º20’36”W . AUM 49772 , 1 , Guyana, Upper Takutu-Upper Essequibo, Aruwa creek Below Aruwa falls , 03º30’N 59º20’W . AUM 49650 , 1 , Guyana, Upper Takutu-Upper Essequibo, Rupununi river at Kwatamang landing, 03º55’03”N 59º06’01”W . AUM 49885 , 2 , Guyana, Upper Takutu-Upper Essequibo, borrow pit 12 km S of Annai, Rupununi River , 03º56’36”N 59º13’40”W . Rio Negro : ANSP 199237 , Brazil, Amazonas, rio Jauaperi 10.3 km upriver of São Francisco, 01º35’08”S 61º28’35”W . ANSP 199238 , 1 , Brazil, Amazonas, rio Negro 3 km upriver from paraná das Onças, 13 km downriver of Novo Caioe, 01º50’S 61º24”W. FMNH 114684 , 1 , Brazil, Amazonas, rio Branco between tributary rio Viruá and mouth in the rio Negro , 01º16’45”S 61º50’33”W . INPA 4429 , 1 (1 specimen measured in Tab. 9, 495 mm LEA), Brazil, Amazonas, Manaus, rio Negro , 03º08” S 60º03”W . MCP 26375 , 5 (4 specimens measured in Tab. 9, 308–355 mm LEA, 1 cs), Brazil, Amazonas, rio Negro 15.0 miles downstream Moura, 01º33’28”S 61º34’15”W . MCP 26304 , 1 , Brazil, Amazonas, rio Jauaperi 9.6 km upstream São Francisco, 01º34’46”S 61º28’38”W . MZUSP 44823 , 1 , Brazil, Amazonas, rio Negro at Anavilhanas, 02º42’S 60º45’W . Amazon Guiana Shield: AUM 35507 , 1 , Upper Takutu-Upper Essequibo, Pirara River tributary of the Ireng River at Pirara, 03º37’17”N 59º40’29”W . MCP 46090 , 1 , Brazil, Roraima, rio Anauá tributary to rio Branco near Rorainópolis , MNRJ 14447 , 1 , Brazil, Roraima, rio Jatapu , 00º45’N 59º17’W . Western Amazon Piedmont : IAvH-P 6062, 1, Colombia, Caquetá, Araracuara, Río Caquetá, 00°35’S 72°26’W . FMNH 103361 , 2 , Ecuador, Napo, tributary to Río Cuyabeno about 3 km upstream Laguna Grande, 00º00’N 76º12’W . FMNH 103362 , 1 , Ecuador, Napo, Río Águas Negras about 2 km S of Marian, 00º02’S 76º18’W . Amazonas lowlands: ANSP 120347 , 2 , Peru, Pucallpa, 08º23’S 74º32’W . ANSP 178359 , 1 , Peru, Loreto, Río Yanayacu downstream from Emerald Forest 25 miles S of Iquitos, 04º14’54”S 73º17’54”W . ANSP 178463 , 1 , Peru, Loreto, Río Nanay at Pampa Chica village about 4.5 km W of Iquitos, 03º45’09”S 73º17’00”W . ANSP 189536 , 2 , Brazil, Amazonas, rio Amazonas 24.1 km upriver of Itacoatiara, 21.3 km downriver of mouth of Madeira 03º16’42”S 58º35’18”W . ANSP 189557 , 1 , Brazil, Pará, rio Trombetas 30.5 km downstream of Porto Trombetas 6.2 km upstream vila Aracua, 01º31’17”S 56º08’47”W . ANSP 199236 , 1 , Brazil, Amazonas, rio Juruá , 10 km downriver of Pauapixuna, 18.6 km upriver of Tamanicoa, 02º37’59”S 65º45’08”W . ANSP 199239 , 1 , Brazil, Pará, rio Trombetas , 7.6 km downstream of Santa Cecilia 17.8 km upstream of Oriximiná, 01º38’04”S 55º58’48”W . ANSP 199241 , 1 , Brazil, Amazonas, rio Japurá, 14 km upriver of rio Solimões , 10 km upriver of Serraria, 02º58’21”S 64º48’56”W . ANSP 199242 , 1 , Brazil, Amazonas, rio Solimões 21.3 km downriver of Tamanicoa, 15.2 km upriver of Palheta, 02º35’21”S 65º30’46”W . FMNH 54704 , 1 , Brazil, Pará, rio Tapajós at Santarém, 02º24’S 54º46’W . FMNH 111592 , 1 , Peru, Loreto, Río Yanayacu about 2.3 km above its mouth in the Río Maranón , 04º40’S 73º50”W. FMNH 114687 , 2 , Brazil, Amazonas, rio Purus upstream from rio Solimões , 04º03’48”S 61º33’50”W . FMNH 114686 , 1 , Brazil, Pará, rio Trombetas between tributaries Cuminá and lago Axipica, 01º32’40”S 56º01’07”W . FMNH 115522, 3 in part (2 specimens measured in Tab. 9, 445–445 mm LEA), Brazil, Pará, rio Trombetas between tributaries lago Bacabal and lago Aracuazinho , 01º31’10”S 56º08’59”W . ICNMCN 5220, 1, Colombia, Amazonas, Leticia, Quebrada Yaguarcaca km 8 on road to Leticia. ICNMCN 16424, 1, Colombia Amazonas, Puerto Nariño, Río Loreto Yacu . INPA 685 , 1 (1 specimen measured in Tab. 9, 415 mm LEA), Brazil, Pará, Santarém, rio Curuá-Una 80 km downstream Curuá-Una Dam. INPA 4815 , 1 (1 specimen measured in Tab. 9, 632 mm LEA), Brazil, Amazonas, Careiro da Várzea, ilha do Careiro at paraná do Rei , 03º09’S 59º36’W . INPA 5077 , 1 (1 specimen measured in Tab. 9, 615 mm LEA), Pará, Oriximina, rio Trombetas at lago do Salgado , 01º28’S 55º58’W . INPA 6497 , 1 (1 specimen measured in Tab. 9, 400 mm LEA), Brazil, Pará, Tucuruí, rio Tocantins at lago Tauá . INPA 9349 , 1 (1 specimen measured in Tab. 9, 375 mm LEA), Brazil, Para, Tucuruí, rio Tocantins at Laguinho . INPA 9363 , 1 (1 specimen measured in Tab. 9, 495 mm LEA), Brazil, Pará, Rio Tocantins at Icangui . INPA 15825 , 2 (1 specimen measured in Tab. 9, 615 mm LEA), Brazil, Amazonas, rio Tefé at Toco Preto . INPA 17684 , 2 , Brazil, Amazonas, Manaus, rio Solimões at Costa do Catalão . INPA 18329 , 1 (1 specimen measured in Tab. 9, 350 mm LEA), Brazil, Amazonas, Alvaraes, rio Japurá at paraná Maiana in reserva Mamirauá . INPA 27614 , 1 (1 specimen measured in Tab. 9, 410 mm LEA), Brazil, Amazonas, rio Purus . INPA 28015 , 2 (2 specimens measured in Tab. 9, 520-525 mm LEA), Brazil, Amazonas, Manaquiri, rio Solimões lago Janauacá , 03º23’S 60º16’W . MCP 24814 , 2 (2 specimens measured in Tab. 9, 310–405 mm LEA), Brazil, Amazonas, rio Madeira . MCP 33380 , 4 , Brazil, Amazonas, canal do lago Mamirauá at the comunidade Boca do Lago Mamirauá , 03º06’37”S 64º47’49”W . MCP 33392 , 1 , Brazil, Amazonas, rio Tefé at ilha do Martelo , 03º46’49”S 64º59’29”W . MCP 33450 , 1 , Brazil, Amazonas, praia Caborini at confluence of rio Solimões and rio Japurá , 03º07’08”S 64º47’18”W . MCP 33454 , 4 (4 specimens measured in Tab. 9, 303–352 mm LEA), Brazil, Amazonas, Alvaraes, rio Japurá at west margin between mouth of lago Mamirauá and mouth of raraná Jaquiri , 03º07’34”S 64º47’18”W . MCP 33458 , 1 , Brazil, Amazonas, Tefé, rio Tefé 1 km downstream mouth of rio Curupira , 03º41’53”S 65º00’57”W . MCP 33459 , 1 , Brazil, Amazonas, Tefé, lago Tefé at comunidade Nogueira, 03º17’58”S 64º46’21”W . MCP 39982 , 1 (1 specimen measured in Tab. 9, 322 mm LEA), Brazil, Acre, Bujari, rio Riozinho do Andirá at highway BR –364 between rio Branco and Sena Madureira , 09º43’21”S 68º07’45”W . MNHN 3993 , holotype of Rhamphichthys pantherinus , Peru, lake near Río Ucayali . MPEG 5373 , 1 , Brazil, Pará, Monte Alegre, Lago Grande de Monte Alegre , 02º14’S 54º09’W . MPEG 5565 , 1 , Brazil, Amazonas, Tefé, rio Solimões at Costa Capivara . MPUJ 6012 , 1 , Colombia, Meta, Casibare, Lake at Río Manacacias , 03°14’50”N 72°58’18”W . MUSM 571 , 1 , Peru, Ucayali, Pucallpa, Río Ucayali at Masisea 08º33’S 74º20’W . MUSM 1645 , 5 , Peru, Ucayali, Río Ucayali, Utiniquia . MUSM 6813 , 2 , Peru, Loreto, Río Huallaga at Yurimaguas, 05º53’S 76º06’W . MUSM 6640 , 2 , Peru, Loreto, Iquitos, market at Iquitos . MUSM 13433 , 3 (2 specimens measured in Tab. 9, 285–296 mm LEA), Peru, Laguna Cachibococha at Coronel Portillo , 08º19’S 74º34’W . MUSM 14239 , 1 (1 specimen measured in Tab. 9, 315 mm LEA), Peru, Loreto, Maynas, Río Aguarico at Puesto de Vigilância Castana , 00º48’14”S 75º14’26”W . MZUSP 9515 , 1 , Brazil, Pará, rio Tapajós at Aveiro . MZUSP 22155 , 1 , Brazil, Amazonas, rio Madeira at Humaitá . MZUSP 23373 , 1 , Brazil, Amazonas, Fonte Boa , igarapé Manduaçu at paraná de Iupiá NW of Fonte Boa, 02º31’S 66º06’W . MZUSP 48507 , holotype of Rhamphichthys longior , Brazil, Pará, Oriximiná, lago Paru on confluence with rio Trombetas and rio Paru do Oeste , 01º31’S 56º01’W . MZUSP 5630 , 3 paratypes of Rhamphichthys longior (3 specimens measured in Tab. 9, 710–760) collected with holotype . MZUSP 44492 , Brazil, Pará, Belo Monte, rio Xingu near rapids at rocky pools, 03º07’S 51º42’W . UFAM uncatalogued, 1, Brazil, Amazonas, rio Juruá upstream Carauari . UMMZ 230841 , 1 , Peru, Loreto, Río Momón near Bora Vilage, 03º40’S 73º16’W . USNM 284578 , 2 , Peru, Loreto, Yarina Cocha side cano, 08º16’S 74º36’W . USNM 284579 , 1 , Peru, Loreto, creek entering Río Manite about 10 km upriver from junction of Río Manite and Amazonas, 03º32’S 72º40’W . USNM 29914 , 1 , Brazil, Amazonas, São José, lago do Castanho at Janauacá. Mamoré-Madre de Dios piedmont : MNHN 1988–1028 , 1 , Bolívia, Puerto Almacén, Río Ibare tributary to Río Mamoré , 14º52’S 64º58’W . Guaporé-Itenez: FMNH 54702 , 3 , Bolivia, San Joaquin, 13º02’S 64º38’W . INPA 9370

(1 specimen measured in Tab. 9, 435 mm LEA), Brazil, Rondônia, rio Guaporé at Surpresa. INPA 9371 , 1 (1 specimen measured in Tab. 9), Brazil, Rondônia, Guarajá- Mirim, rio Mamoré downstream Surpresa, 11º43’S 65º05’W . Xingu: MNRJ 33653 , 2 (2 specimens measured in Tab. 9, 335–353 mm LEA), Brazil, Mato Grosso, Cumaru do Norte, rio Trairão tributary to rio da Ponte 15 km S of Cumaru do Norte, 07º56’S 50º47’W . MNRJ 33659 , 1 (1 specimen measured in Tab. 9, 341 mm LEA), Brazil, Pará, Tucuma, small creek tributary to igarapé Carapana on highway PA-279, 06º44’S 51º09’W . MNRJ 33661 , 1 , Brazil, Pará, São Felix do Xingu, Igarapé Magoarizinho tributary to rio Fresco , 06º42’00”S 51º53’51”W . MZUSP 36016 , 1 , Brazil, Pará, São Felix do Xingu, rio Fresco at aldeia Gorotire , 07º46’S 51º08’W . Tocantins-Araguaia. INPA 9364 , 2 (2 specimen measured in Tab. 9, 375–595 mm LEA), Brazil, Pará, rio Tocantins at Itupiranga , 05º08’S 49º12’W . INPA 9368 , 1 (1 specimen measured in Tab. 9, 370 mm LEA), Brazil, Pará, rio Tocantins at Breu Branco . MCN 18985 , 2 , Brazil, Pará , rio Tocantins between Itupiranga and Nova Ipixuna, 05º07’24”S 49º19’02”W . MNHN 3959 , holotype of Rhamphichthys marmoratus , Brazil, rio Araguaia . MZUSP 22809 , 1 , Brazil, Mato Grosso, rio Araguaia at Santa Terezinha , 10º35’S 50º34’W . MZUSP 44680 , 1 , Brazil, Tocantins, rio Tocantins upstream Itaguatins , 05º46’S 47º31’W . Amazonas estuary and coastal drainages: MNRJ 12177 , 3 (1 specimen measured in Tab. 9, 430 mm LEA), Brazil, Amapá, rio Aporema tributary to rio Araguari at fazenda Modelo do Aporema , 01º08’N 50º50’W . MPEG 2798 , 5 , Brazil, Pará, Cachoeira do Arari, mouth of rio Goiapi . MPEG 2969 , 1 , Brazil, Pará, Cachoeira do Arari, rio Goiapi , Consuelo, fazenda Santa Maria . MPEG 3036 , 1 , Brazil, Pará, Muana, iguarape Maguari Grande tributary to rio Anajás at Fazenda Campo Limpo . MPEG 3009 , 1 , Brazil, Maranhão, rio Turiaçu 1 km upstream posto Indígena Guajá , 03º07’S 46º02’W . MPEG 4504 , 1 , Brazil, Pará, rio Guamá at Ourém , 01º33’S 47º06’W . MPEG 4684 , 2 , Brazil, Pará, Ponta de Pedras, rio Pará , 01º24’S 48º48’W . MPEG 5466 , 1 , Brazil, Pará, Castanhal, rio Apeu at Boa Vista do Apeu , 01º18’S 47º59’W . MPEG 6489 , 1 , Brazil, Pará, Caxiuanã, Estação Cientifica Ferreira Penna , 01º46’S 51º25’W . MPEG 6491 , 2 , Brazil, Pará, Caxiuanã , baia de Caxiuanã, 01º38’S 51º19’W . MPEG 7540 , 2 , Brazil, Pará, Ponta de Pedras, rio Quia-Paraná , at igarapé Baiano , 01º21’12”S 48º57’04”W . MPEG 8234 , 1 , Brazil, Pará, Ipixuna do Pará , 02º53’21”S 47º47’30”W . MPEG 8833 , 1 , Brazil, Pará, Portel, rio Anapu , 01º54’51”S 51º22’36”W . MPEG 9121 , 1 , Brazil, Pará, Paragominas, rio Capim , 03º19’27”S 48º35’53”W . MPEG 11388 , 1 , Brazil, Pará, Melgaço, igarape Curuá tributary to Caxiuanã , 01º43’59”S 51º27’08”W . MPEG 18347 , 2 , Brazil, Pará, Almeirim, mouth of rio Paru , 01º32’S 52º37’W . MPEG 18688 , Brazil, Pará, Santa Cruz do Arari, lago Arari , 00º39’S 49º09’W . MPEG 18690 , 1 , Brazil, Pará, Cachoeira do Arari , lago do Tatu . MPEG 18691 , 2 , Brazil, Pará, Cachoeira do Arari, rio Arari , 01º00’S 48º57’W . MPEG 18695 , 1 , Brazil, Pará, Cachoeira do arari, lago de Santa Cruz at headwaters of rio Goiapi . MPEG 18698 , 2 , Brazil, Pará, Cachoeira do Arari , lago Recreio . MZUSP 22272 , 1 , Brazil, Pará, igarapé Pacui in the highway BR-010 at km 97 . MZUSP 43612 , holotype of Rhamphichthys atlanticus , Brazil, Maranhão, lago do Viana Pindaré-Mearim system, 03º14’S 45º01’W . MZUSP 48508 , paratype of Rhamphichthys atlanticus , collected with the holotype (1 specimen measured in Tab. 9, 650 mm LEA) . MZUSP 44493 , 2 (1 cs), Brazil, Pará, Castanhal, rio Apeu at Boa Vista do Apeu , 01º18’S 47º59’W . MZUSP 44686 , 1 , Brazil, Amapá, rio Araguari at Ferreira Gomes . MZUSP 44689 , 1 , Brazil, Pará, lake at igarapé Muru tributary to rio Tocantins downstream Tucuruí , 03º46’S 49º41’W . MZUSP 104578 , 1 (1 specimen measured in Tab. 9, 550 mm LEA), Maranhão, Caxias, rio Itapecuru , 05º02’44”S 43º24’45”W . MZUSP 104599 , 2 (1 specimen measured in Tab. 9, 590 mm LEA),, Brazil, Maranhão, Governador Eugenio Barros, rio Itapecuru , 05º26’37”S 43º52’03”W . Parnaíba. ANSP 88270 , 1 , Brazil, Piauí, rio Parnaíba at Teresina , 05º05’S 42º49’W . MZUSP 51112 , 1 , Brazil, Piauí, Teresina market .

Figures

FIGURE 36 | Holotype of Rhamphichthys pantherinus, MNHN 3993, 730 mm LEA, lake near Río Ucayali, Peru.

FIGURE 37 | Detail of the head of holotype of Rhamphichthys pantherinus, MNHN 3993, 730 mm LEA, lake near Río Ucayali, Peru.

FIGURE 38 | Holotype of Rhamphichthys marmoratus, MNHN 3959, Rio Araguaia, Brazil.

FIGURE 39 | Detail of the head of holotype of Rhamphichthys marmoratus, MNHN 3959, rio Araguaia, Brazil.

FIGURE 40 | Rhamphichthys pantherinus, ANSP 182785, 410 mm LEA, Río Manapiare at mouth of Caño Yutaje 14 km NW of San Juan de Manapiare, Amazonas, Venezuela.

FIGURE 41 | Detail of head of Rhamphichthys pantherinus, ANSP 182785, Río Manapiare at mouth of Caño Yutaje 14 km NW of San Juan de Manapiare, Amazonas, Venezuela.

FIGURE 42 | Rhamphichthys pantherinus, holotype of Rhamphichthys atlanticus, MZUSP 43612, 690 LEA, lago Viana tributary to Pindare-Mearim System, Maranhão, Brazil.

FIGURE 43 | Detail of the head of Rhamphichthys marmoratus, holotype of Rhamphichthys atlanticus, MZUSP 43612, 690 LEA, lago Viana tributary to Pindare-Mearim system, Maranhão, Brazil.

FIGURE 44 | Rhamphichthys pantherinus, holotype of Rhamphichthys longior, MZUSP 48507, 850 mm LEA, lago Paru at confluence of rio Trombetas and rio Paru-do-Oeste, Pará, Brazil.

FIGURE 45 | Detail of the head of Rhamphichthys pantherinus, holotype of Rhamphichthys longior, MZUSP 48507, 850 mm LEA, lago Paru at confluence of rio Trombetas and rio Paru-do-Oeste, Pará, Brazil.

FIGURE 46 | Fry of Rhamphichthys pantherinus FMNH 103361, 28 mm LEA tributary to Río Cuyabeno about 3 km upstream Laguna Grande, Napo, Ecuador.

FIGURE 47 | Head of juveniles of Rhamphichthys pantherinus, UMMZ 230841, 125 mm LEA (above), and Rhamphichthys rostratus, UMMZ 216489, 110 mm LEA (below), showing the snout size differences early on development.

FIGURE 48 | Distribution of Rhamphichthys pantherinus based on examined museum specimens. Red dot represents the approximate typelocality. Yellow dot is Rhamphichthys atlanticus type-locality; blue dot is Rhamphichthys longior type-locality.

FIGURE 49 | Linear regression of Rhamphichthys pantherinus populations. Blue circles = Amazon Basin (open circle = holotype of R. pantherinus); red circles = Mearim System (open circle = holotype of R. atlanticus); black circles = Trombetas basin (open circle = holotype of R. longior).

FIGURE 50 | Scatter plots of PCA scores.A. PC 1vs. PC 2;B. PC 1vs. PC 3. PCA of Rhamphichthys pantherinus geographic populations: Red = Amazon; blue = Mearim (including R. atlanticus holotype); pink = Negro; golden = Tocantins (type-locality of R. marmoratus); brown = Tombetas (including types of R. longior); yellow = western Amazon (including R. pantherinus holotype) and grey = Xingu.