Revision of Banded Knifefishes of the Gymnotus carapo and G. tigre clades (Gymnotidae Gymnotiformes) from the Southern Neotropics Craig, Jack M. Malabarba, Luiz R. Crampton, William G. R. Albert, James S. Zootaxa 2018 2018-02-13 4379 1 47 73 3HVMK 94173 Valenciennes, 1847 Valenciennes 1847 [151,712,1906,1933] Actinopterygii Gymnotidae Gymnotus GBIF Animalia Gymnotiformes 20 67 Chordata species inaequilabiatus     Materialexamined:  Argentina: MACN 5979, 250mm, Rosario, Río La Plata(~ 32°56’S, 060°38’W);  MLP 3353, 250mm, Misiones, Río Paraná(~ 26°49’S, 055°00’W); MNHN 4615 (neotype), 920 mm( 600 mmaccording to the original description, 850 mmaccording to the label), Argentina, Buenos Aires, Rio de La Plata (~30°40’S, 058°30’W according to MNHN database or ~34°37’S, 058°23’W).   Brazil, Mato Grosso:LBP 12616, ~ 650 mm, Corumbá, Rio Paraguaidrainage, Rio Cuiabá(~ 18°09’S, 057°33’W).   Brazil,  Mato Grossodo Sul: MCP 15818, 535mm, Rio Paraguainear Cáceres;  USNM 1643, 791mm, Rio Paraguaidrainage (~ 17°53’S, 057°29’W).   Brazil, Rio Grande do Sul: MCP 6059(3), 173–355 mm, Iraí, Rio Uruguaidrainage, Sanga das Águas Frias,  100 mfrom Rio Uruguai( 27°12’00”S, 053°16’60”W);  MCP 6956, 602mm, Rio Uruguaiat Santana Velha, near Uruguaiana(~ 29°45’S, 057°50’W);  MCP19552 (3), 145–336 mm, Rosário do Sul, pool next to Olariain the floodplain along Rio Santa Maria, Northside of BR290 (30°14’16”, 054°53’33”W);  MCP 31177, 560mm, Roque Gonzales, Rio Uruguaidrainage, Rio Ijuínear small hydroelectric power station ( PCH) Pirapó(~ 28°30’S, 055°10’W);  MCP 39375, 550mm, same locality as MCP31177; UFRGS 14457, 498 mm, (~27°11’S, 053°06’W).   Brazil, Santa Catarina: MCP 19044, 440mm, Itá, Rio Uruguai, Rio do Engano, road between Itá and Seara(27°08’60”S, 52°13’00”W);  MCP 20683, 410mm, Itapiranga, Rio Uruguai, near Fortaleza( 27°11’42”S, 053°38’34”W).   Brazil, São Paulo: MZUSP 22246(3), 130–282 mm, Represa do Boa, Corumbataí, Rio Paranádrainage, Rio Tietê(~ 21°46’S, 048°58’W);  MZUSP 22862, 238mm, Corumbataí, Rio Paranádrainage, Rio Tietê, Lagoa Ponte Seca(~ 21°46’S, 048°58’W);  MZUSP 46001, 998mm, Rio Paranádrainage, Porto Primavera(~ 22°31’S, 053°10’W).   Diagnosis.  Gymnotus inaequilabiatusdiffers from all sympatric members of the  Gymnotus tigreclade (  G. paraguensis) on the following characters: 1, more precaudal vertebrae ( 45 inall specimens vs. 32–35, median 34); 2, fewer ventral lateral-line rami (VLR 23–38, median 32 vs. 49–55, median 50).  Gymnotus inaequilabiatusfurther differs from sympatric  Gymnotusspecies on the following characters: 1, total length (max. 998 mmvs. max. 419 mmin  G. c. australisand max. 305 mmin  G. cuiathe next two largest species); 2, a color pattern characterized by 21–29, mode 22 obliquely-oriented, chocolate-colored bands in juveniles (< 400 mm), replaced in adults by large, irregular spots and blotches.   Description:Morphometric and meristic data in Table 1. Sexually monomorphic, including in breeding condition. Total length to  1 m.Morphological maturity at roughly 130 mm. Scales rounded to slightly ovoid on anterior two thirds of body, ovoid on posterior one third. Gape large in mature specimens, to or beyond posterior nares. Mouth superior with lower jaw longer than upper, rictus decurved. Chin especially fleshy and protuberant with fleshy pad of electrosensitive organs overlying tip of snout and oral jaws. Anterior narial pore partially to entirely included within gape in narial fold. Anterior nares large, subequal to eye diameter. Circumorbital series ovoid. Ethmoid region broad between anterior nares, with rounded anterior margin. Eye position lateral, lower margin of eye dorsal or horizontal to rictus. Premaxilla with 11 teeth disposed in single row along outer margin, arrow-head shaped anteriorly, conical posteriorly. Straight median margin of premaxilla. Maxilla-palatine articulation near anterior tip of endopterygoid. Maxilla vertical, rod-shaped, narrow distally with a straight ventral margin, length equal to roughly width of 4–6 dentary teeth. Dentary with one row of 12–15 teeth, none arrow-head shaped anteriorly. Posterodorsal and posteroventral dentary processes abut at midlength. Dentary posteroventral process shorter than posterodorsal, narrow distally. Dentary ventral margin lamella narrow, depth less than posterior process. Opercle dorsal margin straight to slightly convex. Dorsal opercular process lamellar or rugose, crest absent or small, posterior margin entirely smooth, without spines or processes. Preopercle with anteroventral notch, posterodorsal laterosensory ramus with two superficial pores, margin of medial shelf entire, median shelf large, more than one-half width of symplectic. Metapterygoid superior and inferior portions approximately equal in size, ascending process robust, long, base shorter than length, curved, tip simple. Interopercle dorsal margin ascending process broad. Subopercle dorsal margin concave. Retroarticular with an arched lamella posteriorly forming a small canal, posterior margin square. Anguloarticular process short, extending beyond ventral margin of dentary. Mandible long, extended, length greater than twice depth. Trigeminal nerve canals divided within the hyomandibula. Posterior lateral line fenestra not contacting posterodorsal margin of hyomandibula. Cranial fontanels closed in juveniles and adults. Frontal shape broad, width at fourth infraorbital greater than that of parietal, anterior margin of straight, continuous with margins of adjacent roofing bones, postorbital process broad, more than two times width of supraorbital canal. Lateral ethmoid absent. Parietal rectangular, length less than width. Parasphenoid anteroventral portion robust, extending ventral to lateral margin of parasphenoid, posterior processes narrow. Prootic foraminae separate for cranial nerves Vp and V2–3+VII. Adductor mandibula muscle undivided at insertion, intermuscular bones absent. All basibranchials unossified. Gill rakers not contacting gill bar. Pectoral with 13–21 (mode 19) rays, medial radial large. Mesocoracoid elongate, length more than four times width. Cleithrum broad, ventral margin curved, anterior limb long, more than 1.8 times ascending limb, deeply incised on its anteroventral margin, without large facet for insertion of muscle from supracleithrum. Postcleithrum thin, discoid or sickle shaped. Body cavity of long, with 45 precaudal vertebrae. Rib five robust along its entire extent, less than three times width of rib six. Hemal spines present. Displaced hemal spines absent. Length anal-fin pterygiophores equal to or longer than hemal spines. Anal fin with 214–390 (median 370) rays. Lateral line ventral rami 23–38 (median 32). Caudal appendage short, less one-half length of pectoral fin. Single hypaxial electric organ along entire ventral margin of body. Four rows of electroplates near caudal insertion of anal fin.  Color in Alcohol:Bands, spots and blotches irregular in shape, width and color, on specimens and among individuals. Ground color tan to yellow. In juveniles ( 250–400 mm), obliquely-oriented, chocolate-colored bands with wavy, irregular margins on lateral surface from nape and to tip of caudal appendage, occurring singly or as band-pairs, increasingly divided and irregular with size (21–29 mode 22). In adults, bands replaced by spots and blotches. Head never banded, spotted, or blotched, dark grey dorsally grading to lighter grey ventrally. Numerous chromophores speckled over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown, interradial membranes hyaline. Anal-fin membrane with irregular broken horizontal stripes on posterior 20%. 1806563206 [151,1296,2008,2033] MACN Rosario Argentina -32.933334 Rio La Plata 1207 -60.633335 Material 20 67 MACN 5979, 250 1 1806563198 MLP Argentina 21 68 -26.816668 Rio Parana 1240 -55.0 20 67 MLP 3353, 250 1 Misiones 1806563201 Corumba Brazil -18.15 Rio Cuiaba 1276 -57.55 Rio Paraguai 21 68 1 Mato Grosso 1806563196 MCP Caceres Brazil Rio Paraguai 21 68 535 1 Mato Grosso do Sul 1806563204 [569,1350,294,319] USNM Paraguay -17.883333 Rio Paraguai 1277 -57.483334 21 68 USNM 1643, 791 1 1806563200 MCP Irai & Sanga das Aguas Frias Brazil 100 -27.2 Rio Uruguai Rio Uruguai 21 68 MCP 6059 1 Rio Grande do Sul 1806563213 MCP Santana Velha & Uruguaiana Uruguay -29.75 Uruguai 1225 -57.833332 21 68 MCP 6956, 602 1 1806563199 MCP Olaria & North Uruguay Rio Santa Maria -54.8925 21 68 1 Rosario do Sul 1806563205 MCP, PCH Roque Gonzales Uruguay -28.5 Pirapo 1232 -55.166668 Rio Ijui 21 68 560 1 1806563208 MCP Roque Gonzales Uruguay -28.5 Pirapo 1232 -55.166668 Rio Ijui 21 68 550 1 1806563212 MCP Ita Brazil Rio do Engano -52.216667 Rio Uruguai 21 68 440 1 Santa Catarina 1806563211 [318,1349,580,605] MCP Itapiranga & Fortaleza Uruguay -27.195 Uruguai 20 -53.64278 21 68 410 1 1806563203 MZUSP Corumbatai Brazil Represa do Boa -21.766666 Rio Tiete 1262 -48.966667 Rio Parana 21 68 MZUSP 22246 1 Sao Paulo 1806563210 MZUSP Corumbatai & Lagoa Ponte Seca Brazil -21.766666 Rio Tiete 1262 -48.966667 21 68 MZUSP 22862, 238 1 Parana 1806563202 [422,1408,687,712] MZUSP Porto Primavera Brazil -22.516666 Parana 1259 -53.166668 21 68 MZUSP 46001, 998 1 Parana