Brycon orthotaenia Günther, 1864

Lima, Flávio C. T., 2017, A revision of the cis-andean species of the genus Brycon Müller & Troschel (Characiformes: Characidae), Zootaxa 4222 (1), pp. 1-189 : 82-90

Brycon orthotaenia Günther, 1864

( Figs. 49–51 )

Chalceus carpophagus (not Valenciennes): Castelnau, 1855: 68, pl. 34, fig. 3 (description; “ Rio de Sabara de la province de Minas Geraës”).

Brycon orthotaenia Günther, 1864: 335 (type locality: “River Cipo”); Howes, 1982: 38 –41 (redescription of holotype; literature compilation); Géry & Mahnert, 1992: 817 (possible synonym between B. orthotaenia and B. lundii ); Rizzo & Godinho, 2003: 119, 122 (egg surface structure); Pompeu & Godinho, 2003a: 170, 171 (occurrence, lagoons at middle rio São Francisco basin, Minas Gerais); Pompeu & Godinho 2003b: 185, 187–188 (diet, lagoons at middle rio São Francisco basin, Minas Gerais); Sato et al., 2003: 231, 237, 240, 242–246, 248–252 (fecundity, egg and larvae characteristics; rio São Francisco, Minas Gerais); Sato, Fenerich-Verani & Godinho, 2003: 277 –278, 284–287 (reproduction in captivity); Bazzoli, 2003: 292, 300 (reproduction; rio São Francisco, Minas Gerais); Godinho et al., 2003: 352 –353, 355 (fisheries; rio São Francisco, Pirapora, Minas Gerais); Godinho & Pompeu, 2003: 366 –367 (occurrence in small tributaries, rio Paracatu basin, Minas Gerais); Alves & Pompeu, 2003: 183 (Rio das Velhas basin, Minas Gerais); Alves & Pompeu, 2005: 593 –594 (idem); Pompeu & Godinho, 2006: 430 (lagoons at middle rio São Francisco basin, Minas Gerais); Gonçalves et al., 2006: 513 –522 (reproduction, gametogenesis; Rio São Francisco, Pirapora); Silva et al., 2006: 835, 837, 838 (Juramento reservoir, rio São Francisco basin, Minas Gerais); Sanches et al., 2012: 177–185 (Rio São Francisco, Três Marias, Minas Gerais: population structure analysed through microsatellite loci) [not Günther, 1880: 13].

Brycon lundii Lütken (ex Reinhardt) 1874: 135–136 (Type locality: “flumine Rio d. Velhas”). Lütken, 1875: 223–226, fig. (Brazil, Minas Gerais, Rio das Velhas; redescription); Steindachner, 1917: 38 –40 (Barra, rio São Francisco, Bahia); Amaral Campos, 1950: 141 (rio São Francisco); Howes, 1982: 33 (literature compilation; discussion); Britski et al., 1988: 49, 98, fig. 43 (common name, short description; Três Marias reservoir, Minas Gerais); Menin & Minura, 1993: 340, 344, 349, 351, 354, 357, 360–361, figs. 5, 10, 12, 20–21 (Três Marias reservoir; digestive tract anatomy); Sato & Godinho, 1999: 410 (Rio São Francisco basin); Margarido & Galetti Jr., 1999: 357 –358 (caryotype); Sato & Godinho, 2003: 205, 208, 210, 216, 222, 224, 225 (Rio São Francisco basin; biology, importance to fisheries). [not Magalhães, 1931: 160 –162, fig. 86; Schubart, 1943: 111; 1962: 27; Godoy, 1975: 288 –307, figs. 45–50].

Brycon hilarii (not Valenciennes): Braga, 1982: 175–180 (common name; Cabrobó and Jatinã, rio São Francisco, Pernambuco).

Brycon carpophagus (not Valenciennes): Howes, 1982: 17 (Castelnau’s specimen; as a possible specimen of B. orthotaenia ); Géry & Mahnert, 1992: 816 –817 (idem).

Diagnosis. Brycon orthotaenia can be distinguished from all remaining cis-andean Brycon species, except for B. orbignyanus , B. hilarii , B. whitei , and B. polylepis , by possessing a caudal peduncle blotch extending as a stripe to the distal portion of caudal-fin rays (caudal peduncle blotch, when present, limited to the caudal peducle or extending only into centralmost caudal-fin rays; Fig. 5 ). It can be distinguished from Brycon hilarii and B. whitei primarily by possessing lower scale counts (49–58, modally 52 lateral line scales, vs. 67–82, modally 74 in B. hilarii and 66–76, modally 70 in B. whitei ; 9–12, modally 10 scales between lateral line and dorsal-fin basis, vs. 12–17, modally 15 in B. hilarii and 12–13, modally 13, in B. whitei ; 18–21, modally 19 circumpeduncular scales, vs. 20–28, modally 26, in B. hilarii , and 19–24, modally 21, in B. whitei ). Brycon orthotaenia can be further distinguished from B. whitei by lacking a midlateral dark stripe (vs. midlateral dark stripe present). Brycon orthotaenia can be distinguished from B. orbignyanus by possessing a aproximately rounded, obtuse head profile (versus pointed in the latter species; compare Fig. 6 F and H), by possessing a relatively broad and short dentigerous premaxilary surface (vs. a narrow and elongated dentigerous surface of the premaxillary), by possessing a lower number of teeth in the second, inner premaxilary row (not counting the teeth of the second row situated between the first and third rows) (3–5, modally 5, versus 5–9, modally 6, in B. orbignyanus ), and by possessing the anteriormost four dentary teeth considerably larger than the remaining teeth (vs. dentary teeth decreasing gradualy in size in B. orbignyanus ).

Description. Morphometric data are presented in Table 14 . Middle-sized species, largest examined specimen 392.8 mm SL. Body moderately slender to moderately high. Largest body height slightly ahead of dorsal-fin origin. Dorsal body profile slightly convex from upper lip margin to vertical through anterior naris, slightly concave from latter point to basis of supraoccipital process, moderately to pronoucedly convex from latter point to dorsal-fin origin, straight along dorsal-fin basis, and straight to slightly convex from dorsal-fin basis to adipose-fin origin. Dorsal profile of caudal peduncle slightly concave. Ventral profile slightly to moderately convex from lower lip to pelvic-fin insertion, straight to slightly convex from this point to anal-fin origin and approximately straight along anal-fin base. Ventral profile of caudal peduncle slightly concave.

Head profile obtuse, mouth terminal. Jaws isognathous to slightly anisognathous, premaxillary projecting slightly relative to dentary, leaving outer row of premaxillary teeth and in some specimens a portion of second series exposed when mouth is closed. Maxillary moderately long, extending posteriorly to anterior margin to anterior third of pupil. Adipose eyelid well developed. Premaxillary teeth in three rows; teeth of third row largest. Eight (6), 9 (23), 10 (15), 11 (11), 12 (5), or 13 (1) tricuspidate, relatively small teeth in outer series. Three (2), 4 (26), 5 (31), or 6(1) tri- to pentacuspidate teeth in second, inner premaxillary row, plus 2 (20), 3 (49), or 4 (5) tricuspidate teeth between the first and third rows. Two teeth in third premaxillary row, medial teeth largest, symphyseal teeth smaller, slightly tilted towards each other, penta- to hexacuspidate. Maxillary margins approximately parallel, straight in profile. Ten to 22 maxillary teeth, slightly smaller than teeth of first premaxillary row, anterior teeth tricuspidate, posterior teeth unicuspidate. Dentary with 6 (2), 7 (4), 8 (21), 9 (19), 10 (6), 11 (3), or 12 (1) teeth in main series. Anterior four dentary teeth assymetrical, considerably larger and bulkier than remaining teeth, penta- to hexacuspidate, each with central cusp distinctly larger than remaining cusps. Remaining dentary teeth progressivelly smaller, penta- to unicuspidate. Inner (lingual) series consisting of a small, single unicuspid symphyseal tooth, situated immediately posterior to symphyseal dentary teeth of main series, plus row of 10–17 small, unicuspidate teeth, originating on lingual crest of dentary replacement trench at the level of sixth to seventh main series dentary teeth.

Scales cycloid. Lateral line complete, from supracleithrum to caudal-fin base. Forty-nine (3), 50 (2), 51 (7), 52 (11), 53 (13), 54 (8), 55 (8), 56 (9), 57 (5), or 58 (1) scales in lateral line series. Laterosensory tube simple in specimens smaller than 100 mm SL, ramified in specimens larger than 100 mm SL. Tubules ramification increasing in complexity along ontogeny, specimens between 100–150 mm SL with tubules with two or three branches, four to seven branches in specimens between 150–250 mm SL, and with more than 10 branches and developing a dendritic pattern of ramification, with tubules overlapping each other in larger (> 300 mm SL) specimens. Horizontal scale rows between dorsal-fin origin and lateral line 9 (1), 10 (33), 11 (30), or 12 (2). Horizontal scale rows between lateral line and pelvic-fin 5 (28), 6 (37), or 7 (1). Circumpeduncular scales 18 (10), 19 (44), 20 (9), or 21 (1).

Dorsal-fin rays ii, 9. Dorsal fin origin slightly ahead middle of SL. First dorsal-fin pterygiophore inserting behind neural spine of 13th (1), 14 th (1), or 15th (1) vertebra. Anal-fin rays iii (not including first, small unbranched ray only visible in the cs specimen), 22 (1), 23 (1), 24 (8), 25 (16), 26 (21), 27 (16), 28 (4), or 29 (1). First anal-fin pterygiophore inserting behind haemal spine of 25th (1) or 26th (1) vertebra. Anal-fin rays decreasing only slightly in size towards anal-fin end. Anal fin displaying several (c. 8–15 per fin-ray main branch) small hooks on last unbranched and posterior main branch of branched rays 1–12, associated with dense, gelatinous tissue in 8 specimens (MZUSP 39278, 6, 220.2– 247.7 mm SL; MZUSP 17018, 1, 206.8 mm SL; MZUSP 2007, 1, 193.1 mm SL). A single hook per ray segment. Sheath of scales covering basis of anal-fin rays composed of four scale rows, lower scale row formed by 25–28 rectangular scales. Pectoral-fin rays i, 11 (2), 12 (25), 13 (40), or 14 (2). Pelvicfin rays i, 7. Main caudal-fin rays 10/9. Caudal fin slightly forked, distal margin slightly concave. Central caudalfin rays with a small, pointed middle projection extending beyond primary margin of fin. Laterosensory tube extending over interradial membrane between upper and lower caudal-fin lobes to the distal portion of fin at the middle caudal-fin projection. Laterosensory tube on caudal fin with dorsally and ventrally oriented side branches across its length.

Four branchiostegal rays, three on anterior ceratohyal and one on posterior ceratohyal. First branchial arch with 14 (2), 15 (1), 16 (12), 17 (14), 18 (6), or 19 (1) lower, 1 at angle, and 15 (1), 16 (6), 17 (14), 18 (12), or 19 (4) upper gill rakers. Vertebrae 46 (4). Supraneurals 10 (4).

Coloration in alcohol. Top of head, snout, supraorbital, and sixth infraorbital gray to light-brown. Dorsal portion of body light-brown to dark-brown, with silvery hue in specimens retaining guanine. Second, third, fourth, and fifth infraorbitals, and opercle silvery. Dentary, maxillary, gular area and lower portion of body clear in relatively recently collected specimens, light brown in specimens stored for some years in alcohol. Lateral portion of body silvery in relatively recently collected specimens, light brown, with a silvery hue, in specimens that were stored for a long period in formalin/alcohol. Humeral blotch present, conspicuous, approximately rounded in shape, situated immediately above lateral line, its anterior margin at level of second, extending longitudinally to posterior margin of fourth to fifth, lateral line scales, and vertically one and half scales high. Dark, wavy longitudinal stripes formed by dark pigment concentrated on upper and lower scale margins extending along trunk. Stripes more discernible dorsally. Caudal peduncle with broad median stripe, originating 4–6 scales from hypural joint and continuing posteriorly over 4 central principal caudal-fin rays to caudal-fin distal margin. Remaining caudal-fin rays, and remaining fins, clear.

Color in life. Description based on the examination of several living specimens collected at the middle rio São Francisco at São Romão, one of which preserved (MZUSP 94993), and on a picture of one unpreserved specimen, fished at the Três Marias dam. Lateral body surfaces, infraorbital and opercular bones silvery. Dorsum and adiposefin light grey, with a greenish tinge. Anal, pelvic, and pectoral-fins pinkish. Caudal fin pinkish to deep red, basis of caudal fin yellowish.

Sexual dimorphism. Eight examined specimens (MZUSP 39278, 6, 220.2– 247.7 mm SL; MZUSP 17018, 1, 206.8 mm SL; MZUSP 2007, 1, 193.1 mm SL) presenting numerous small hooks present on first unbranched and posterior branch of branched anal-fin rays. Two of these specimens were dissected and proved to be males. Female specimens identified through dissection or through presence of ripe eggs at the urogenital opening (MZUSP 39728, 2, 190.3– 245.8 mm SL) lack fin hooks.

Common names. “Matrinchã” ( Günther, 1864: 335, como “matrinxim”; Lütken, 1875: 223; 2001: 138); “ piabanha ” ( Castelnau, 1855: 68, as “piabana”). Quoting Reinhardt, in Lütken, 2001: 138, footnote 1, “this species is incorrectly called “ Piabanha ”, a name which actually belongs to another fish species that does not occur at the Rio das Velhas” (our translation). Although “ piabanha ” is a common name widely employed for several Brycon species, the common name currently in use by fishermen for B. orthotaenia in the rio São Francisco basin is generally “matrinchã”.

Distribution. Endemic from the rio São Francisco basin, eastern Brazil ( Fig. 52 ). There is a purported record for the species from the rio Poti, a tributary of the rio Paranaíba basin in northeastern Brazil (MCZ 21268). These two specimens were collected by Orestes St. John, a member of the Thayer Expedition, in December 1865. There are no other records for the species for the rio Parnaíba and in fact, so far no Brycon species has been reported from this river basin (see the item Biogeography, below). Since Orestes St. John also collected at the rio São Francisco basin ( Higuchi, 1996), we consider that this specimens were probably mislabelled and that they were actually collected at the rio São Francisco basin.

Remarks. Günther (1864: 335) described Brycon orthotaenia based on a single specimen, collected at the “River Cipo” in Brazil. The description is quite short, with no figures appended. Lütken (1874: 135–136) described Brycon lundii from the rio das Velhas. In this description (attributed to Reinhardt), he notices that B. lundii might be actually a synonym of B. orthotaenia , both nominal species differing only in lateral-line scale counts (slightly higher in B. lundii ) and in the absence of the inner dentary pair of symphyseal teeth in the holotype of B. orthotaenia . A little later, Lütken (1875: 225; 2001: 114) discussed in more detail the possible synonym between both nominal species, noticing that the distinct scale counts were probably a result of different count methods employed by him and Günther, and that the inner dentary teeth might have been simply lost in the holotype of Brycon orthotaenia . However, these remarks were overlooked by subsequent authors working with specimens from the rio São Francisco basin, which generally prefered to use Lütken’s name ( Steindachner, 1917; Amaral Campos, 1950; Britski et al., 1984). Brycon orthotaenia was relegated as a synonym of B. orbignyanus by Berg (1895: 124), based on the erroneous assumption that the type locality of B. orthotaenia was at the La Plata basin. This synonym was reproduced in latter compilations on the genus (e.g., Fowler, 1950). Howes (1982: 33, 38–40) reexamined the holotype of Brycon orthotaenia , plus additional material of both B. orthotaenia and B. orbignyanus , and argued that B. orthotaenia was not a synonym of B. orbignyanus , but instead a valid species and very probably a senior synonym of B. lundii , a point of view also supported by Géry & Mahnert (1992: 817). Howes (1982: 39) incorrectly remarked that the “River Cipo” is a tributary of the rio Itapicurú (an independent coastal river system in northern Bahia state, northeastern Brazil). However, the rio Cipó is actually a well-known tributary of the rio das Velhas (a tributary of the rio São Francisco) at Minas Gerais state, a region in fact visited by the collector of the holotype of Brycon orthotaenia, Cumberland (Lütken, 1875: 134, 225; 2001: 29, 114), and, oddly, the very same river basin from where the type-material of B. lundii was collected.

Although neither the holotype of Brycon orthotaenia (BMNH 1861.5.16.71) nor the syntypes of Brycon lundii (ZMUC 227, ZMUC 228-229, ZMUC 232; though Lütken, 1875: 225; 2001: 112, mentioned that he had a single specimen of this species) were directly examined in the present study, there is no doubt that, as earlier advanced by Lima (2003: 177–178) that both nominal species are synonymous. The examination of a photograph of the holotype of Brycon orthotaenia , the good description of B. lundii provided by Lütken (1875, 2001), and a wealthy of specimens from the entire rio São Francisco examined in the present study allow us to conclude that the differences between Günther’s and Lütken’s description are in fact ascribable to different lateral-line scale count methods and loss of the inner symphyseal dentary teeth in the holotype of B. orthotaenia .

Valenciennes (1850: 252–253) described Chalceus carpophaga based on three syntypes, one of which said to be collected at “l’Amazone” by Castelnau. Castelnau (1855: 68), when referring to this specimen, mentioned that it was actually collected at the “rio de Sabara de la province de Minas Geraës”. The “rio de Sabara” is the rio das Velhas, thus this specimen was actually collected at the same river basin where the type specimens of Brycon orthotaenia and B. lundii were collected. Lütken (1875: 225–226; 2001: 114–115) considered Castelnau’s (1855) Chalceus carpophagus as probably distinct from Brycon orthotaenia and B. lundii . Howes (1982: 17) considered that Castelnau’s syntype of Chalceus carpophagus was not conspecific with the remaining two syntypes but instead was probably a specimen of B. orthotaenia . Géry & Mahnert (1992: 816) selected as lectotype of Chalceus carpophagus the syntype from the Essequibo River, and consequently the syntype collected by Castelnau at the rio das Velhas (MNHN A.8615) became a paralectotype. Géry & Mahnert (1992: 816–817) compared the data of this specimen with the data of the type material of both Brycon orthotaenia and B. lundii and agreed with Howes (1982) in considering it as probably a specimen of B. orthotaenia . The examination of this paralectotype allowed us to confirm that it is in fact a specimen of Brycon orthotaenia .

Ecological notes. At the rio São Francisco basin, Brycon orthotaenia is sometimes found syntopically with the its congener B. nattereri , but contrary to this species it favors larger, low-gradient rivers. It is also commonly found in floodplain lakes ( Pompeu & Godinho, 2003a; Pompeu & Godinho, 2006). As other Brycon species, B. orthotaenia is recorded to be an omnivore, with a tendency towards herbivory. Lütken (1875: 224; 2001: 114) reported that Reinhardt found vegetal matter and seeds in two stomach contents. Pompeu & Godinho (2003b) examined 30 stomachs of Brycon orthotaenia specimens collected in marginal lagoons of the rio São Francisco and found it to be composed mainly of macrophytes and filamentous algae, with smaller amounts of aquatic insects, seeds and fruits. As most of its congeners, Brycon orthotaenia is a highly-fecund, total-spawner migratory fish (Sato et al., 2003), with a mean total fecundity of 400.000 eggs (Sato, Fenerich-Verani & Godinho, 2003). The breeding season is recorded in the rio São Francisco at Pirapora to be between October and January, with smallest recorded sizes of first maturity reported as being 32.0 cm TL for males and 40.5 cm TL for females (Gonçalves et al., 2003). Females are reported to grow larger than males and a maximum weigth of 7 kg is recorded for the species (Sato & Godinho, 2003). An analysis of microsatellites loci in populations of B. orthotaenia from below Três Marias dam by Sanches et al. (2012) indicated the presence of two distinct populations, which might indicate distinct sites of communal reproduction (“piracema”) for migratory schools of each population within a relatively small stretch of the rio São Francisco basin.

Conservation. Brycon orthotaenia is an important target of subsistence and small-scale commercial fisheries in the rio São Francisco basin (Sato & Godinho, 2003). It was the third more captured species, and the fifth most important fish species in biomass in the fisheries of the rapids of Pirapora during 1999 ( Godinho et al., 2003). Though reported to be declining in the last decades (e.g., Sato & Godinho, 2003), it is still a common and widespread species in the undammed portion of the rio São Francisco river, i.e., between the Três Marias and Sobradinho reservoirs.

Material examined. Type material. BMNH 1861.6 .16.71, 330 mm SL: “ River Cipo ” [= Rio Cipó, trib. Rio das Velhas, Minas Gerais, Brazil, c. 18°41’S, 43°59’W] ; Cumberland , no date (photographs only). Holotype of Brycon orthotaenia Günther. MNHN A.8615 (1, 314.1 mm SL): " Rio de Sabara de la province de Minas Geraës " (= Brazil, Minas Gerais, rio das Velhas at Sabará, 19°53'S, 43°48'W) ; F. Castelnau. Paralectotype of Chalceus carpophagus Valenciennes (designated by Géry & Mahnert, 1992: 816).

Non types. Brazil, rio São Francisco basin. Minas Gerais: MZUSP 18950 (5, 173.8–248.0 mm SL): Três Marias reservoir, rio São Francisco , c. 18°22’S, 45°17’W; CODEVASF, 1978 . MZUSP 95402 (35, 3 sc, 90.5–230.8 mm SL): Três Marias, CODEVASF fish hatchery; O.T. Oyakawa et al., 4 Oct 2007. MZUSP 95166 (2, 153.0– 153.8 mm SL): Três Marias, rio São Francisco, immediately downstream Três Marias reservoir, c. 18°10’S, 45°14’W; Y. Sato, 23 March 2007 . MCP 14119 (5, 175.8– 219.4 mm SL): Três Marias, rio São Francisco , between Três Marias and Pirapora; Y. Sato, Nov 1987 . MZUSP 1619 (1, 102.2 mm CP): Pirapora, rio São Francisco , 17°21’S, 44°57’W; E. Garbe, 1903 . MNRJ 47676 (1, 392.8 mm SL): Pirapora, rio São Francisco , 17°21’S, 44°57’W; G.S. Myers, P. Miranda-Ribeiro & A.L. Carvalho, Oct 1942 . MZUSP 73836 (1, 275.0 mm SL): Lassance , rio das Velhas at the ferry, 17°54’45’’S, 44°34’20’’W; C.B.M. Alves & P.S. Pompeu, 17 Jun 1999 . MCZ 21268 (1, 167.2 mm SL): Rio das Velhas (precise locality unknown); O. St. John , 1865 . MZUSP 89514 (1 skel., 181.6 mm SL): Pirapora, rio São Francisco , between Buritizeiro and Pirapora; A. Akama et al., 28 Aug 2004 . MZUSP 39728 (19, 181.2– 319.3 mm SL): rio São Francisco and tributaries, immediately below Pirapora , c. 17°4’S, 44°57’W; Y. Sato et al., Nov 1987 – Aug 1988. MZUSP 39693 (1, 230.7 mm SL), rio São Francisco, Pontal do Abaeté , c. 17°4’S, 44°57’W; Y. Sato et al., 22 Jul 1988 . MZUSP 94993 (1, 141.2 mm SL): São Romão, rio São Francisco, near Ribanceira village , 16°28’26’’S, 45°6’16’’W; F.C. T . Lima & M. Ribeiro, 23–25 Jun 2007. MNRJ 18130 (1, 323.0 mm SL): Palmital, rio Preto, trib. rio Paracatu , below Cachoeira de Queimados , Fazenda Mata , 16°12’35’’S, 47°13’54’’W; C . A. Figueiredo & D.F. Moraes Jr., 8 Jan 1998 . MZUSP 17018 (1, 206.8 mm SL): Buritis, ribeirão Confins (trib. rio Urucuia ), 15°38’S, 46°22’W; P.E. Vanzolini, Oct 1964 . ANSP 171719 (1, 162.9 mm SL): Rio Empoeirado (lagoon) on road bewtween Pedra de Maria and Januária, 15°33’56’’S, 44°24’6’’W; S . A. Schaefer et al., 13 Jul 1993 . MNRJ 15834 (2, 188.2– 189.7 mm SL): Itacarambi, rio São Francisco , c. 15°6’S, 44°5’W; D.F. Moraes Jr. & J.C. Oliveira, 17 Aug 1990 . MZUSP 42074 (1, 120.7 mm SL); MNRJ 15866 (1, 122.2 mm SL): Manga, lagoon at Mocambinho, rio São Francisco , c. 15°4’S, 44°1’W; J.C. Oliveira & O.T. Oyakawa, 17–22 Jul 1990 . MNRJ 16065 (1, 139.9 mm SL): Manga, lagoa do Sossego, Mocambinho , c. 15°4’S, 44°1’W; D.F. Moraes Jr. & J.C. Oliveira, 23 Aug 1990 . MNRJ 14226 (4, 104.0– 116.6 mm SL): Manga, rio Mocambinho, at mouth at the rio São Francisco , c. 15°4’S, 44°1’W; D.F. Moraes Jr. & J.C. Oliveira, 17 Aug 1990 . MNRJ 16345 (2, 100.6– 105.1 mm SL): Manga, riacho Mocambinho, trib. rio São Francisco , Mocambinho , c. 15°4’S, 44°1’W; J.C. Oliveira et al., 6 Apr 1990 . MNRJ 16352 (1, 111.7 mm SL): Manga, lagoa de Mocambinho, rio São Francisco right margin, c. 15°4’S, 44°1’W; J.C. Oliveira, 6 March 1990 . MNRJ 15856 (1, 138.5 mm SL), Manga, rio São Francisco at ilha do Caju , below Mocambinho , c. 15°2’S, 44°0’W; D.F. Moraes Jr. & J.C. Oliveira, 21 Aug 1990 . MNRJ 15870 (1, 156.1 mm SL): Manga, lagoa do Cajueiro ( rio São Francisco , right margin), below Mocambinho , c. 15°2’S, 44°0’W; D.F. Moraes Jr. & L.C. Alvarenga, Sept 1990 . MNRJ 16191 (1, 160.6 mm SL): Manga, lagoa do Caju, rio São Francisco right margin, 4 km below Mocambinho , c. 15°2’S, 44°0’W; D.F. Moraes & J.C. Oliveira, 23 Aug 1990 . LISDEBE uncat. (1, 210.0 mm SL): Manga, rio Verde, trib. rio São Francisco , 5 km from Gado Bravo , c. 14°44’S, 43°49’W; G.B. Santos, 7 April 1986 . MNRJ 16193 (2, 127.7– 134.1 mm SL): rio Verde Grande, 5 km from its mouth at the rio São Francisco , Minas Gerais / Bahia border, c. 14°36’S, 43°52’W; D.F. Moraes & J.C. Oliveira, 23 Aug 1990 .

Bahia: ZUEC 9189 (1, 168.0 mm SL): Carinhanha, rio Carinhanha (marginal lagoon), 14° 20’46’’S, 43°47’26’’W; G.N. Salvador & E. Estevam, 6 Oct 2014 . MCP 16676 (1, 157.1 mm SL): Bom Jesus da Lapa, riacho Santana, 31 km S from Bom Jesus da Lapa , road to Malhada , 13°31’13’’S, 43°21’28’’W ; R.E. Reis et al., 18 Jul 1993. UFPB 2956 (3 of 8, 1 cs, 89.0– 108.4 mm SL): riacho Pedra Branca, trib. rio Corrente, 31 km E from Santa Maria da Vitória , c. 13°18’S, 43°51’W ; G. G. Filho & R.S. Rosa, 6 April 1994. MZUSP 94656 (1, 151.5 mm SL): Santa Maria da Vitória, rio Corrente at Santa Maria da Vitória , 13°24’S, 44°11’W ; O.T. Oyakawa et al., 6 May 2007. MZUSP 28796 (1, 154.1 mm SL): rio das Fêmeas, near Barreiras , c. 12°28’S, 45°13’W ; M. A. Cestarolli & J. Camargo, 2–6 May 1985. MZUSP 28771 (1, 140.8 mm SL): rio Desidério, São Desidério , 12°21’S, 44°58’W ; M. A. Cestarolli & J. Camargo, 2–6 May 1985 . MZUSP 70220 (4, 1 skel., 252.8–320.0 mm SL): Bahia, Barra , fish market, c. 11°6' S, 43°9’ W; O.T. Oyakawa et al., 10 April 2001 . MZUSP 98750 (1, 92.2 mm SL): Barra, rio Grande, praia Cabeça de Touro , 11°6’8’’S, 43°9’26’’W; O.T. Oyakawa et al., 10 Apr 2001 . NMW 62941 (2, 248.0– 249.0 mm SL): rio São Francisco, Barra , 11°5’S, 43°8’W ; F. Steindachner et al. (Austrian Expedition), March 1903. UMMZ 216373 (1, 106.7 mm SL): Barra, rio São Francisco , 11°5’S, 43°8’W ; J.R. Bailey, 8 Apr 1942. MZUSP 18558 (1, 192.4 mm SL): Marcos, Remanso, Sobradinho reservoir, c. 9°38’S, 42°4’W ; S. F. Santos, 20 Jul 1975. MZUSP 18666 (2, 303.3– 324.8 mm SL): rio São Francisco, downstream Sobradinho reservoir, c. 9°26’S, 40°47’W ; J. Dias, 27 Sept 1976. MZUSP 2007 (13, 1 cs, 132.3–225.0 mm SL); CAS 11822 (1, 243.0 mm SL): rio São Francisco , between Juazeiro and Barra; E. Garbe, 1908 . FMNH 56814 (2, 182.0–212.0 mm SL): Juazeiro, rio São Francisco , 9°24’S, 40°30’W; J.D. Haseman, 28 Nov 1907 . UMMZ 216349 (1, 85.3 mm SL): Juazeiro , small oxbow ponds on E (downstream edge of town), c. 9°24’S, 40°30’W; J.R. Bailey & J.M. de Oliveira, 18 Apr 1942.

Pernambuco: UMMZ 147396 (2, 142.1– 148.7 mm SL): Santa Maria da Boa Vista, “ Lake Aripos ”, c. 8°48’S, 39°49’W ; R.S. Menezes, c. 1945. MZUSP 3797 (3, 83.5–135.1 mm SL): rio São Francisco (precise locality unknow); A. P. Marques, 1941.

Locality uncertain (see Distribution): Piauí: MCZ 21268 (2, 152.3– 167.2 mm SL): “ rio Puty , Therezina ” ( rio Poti , tributary of rio Parnaíba at Teresina , 5°5’S, 42°49’W); O. St. John , Dec 1865.

Figures

FIGURE 5. Diagrammatic representation of the patterns of dark colour markings found among cis-andean Brycon species, represented by selected species. A. Brycon stolzmanni. B. Brycon coxeyi. C. Brycon insignis. D. Brycon nattereri. E. Brycon hilarii. F. Brycon whitei. G. Brycon amazonicus. H. Brycon gouldingi. I. Brycon melanopterus. J-L. Brycon falcatus.

FIGURE 6. Diagrammatic representation of the head profile, maxillary and infraorbitals showing the distinct morphologies found among cis-andean Brycon species, represented by selected species. A. Brycon amazonicus, MZUSP 3815, 152.3 mm SL. B. Brycon insignis, MCZ 21112, 232.2 mm SL. C. Brycon dulcis, MZUSP 1531, 146.6 mm SL. D. Brycon falcatus, MZUSP 3845, 195.1 mm SL. E. Brycon opalinus, MCZ 21123, 210.5 mm SL. F. Brycon orbignyanus, MZUSP 3900, 108.9 mm HL. G. Brycon ferox, MCZ 60934, 310.3 mm SL. H. Brycon orthotaenia, MZUSP 2007, 188.7 mm SL. I. Brycon polylepis, MZUSP 70413, 203.9 mm SL. J. Brycon stolzmanni, UMMZ 185306, 120.0 mm SL.

FIGURE 49. Brycon orthotaenia, BMNH 1861.6. 16, 71, 330 mm SL: Brazil, Minas Gerais, “ River Cipo ”. © The Natural History Museum, London

FIGURE 50. Brycon orthotaenia, MZUSP 39728, 319.3 mm SL: Brazil, Minas Gerais, rio São Francisco.

FIGURE 51. Brycon orthotaenia, MNRJ 15856, 138.5 mm SL: Brazil, Minas Gerais, rio São Francisco.

FIGURE 52. Map of eastern Brazil, showing known localities of Brycon orthotaenia (red dots).

Tables

TABLE 14. Morphometric data of Brycon orthotaenia (A: paralectotype of Chalceus carpophagus, MNHN A. 8615). Mean and range does not include paralectotype of Chalceus carpophagus (which is a stuffed specimen).

	A	n	Range	Mean
Standard length (SL)	314.1	66	83.5–324.8	-
Percentages of standard length
Depth at dorsal-fin origin	30.2	57	29.9–37.2	33.3
Snout to dorsal-fin origin	49.1	66	43.3–53.9	49.9
Dorsal-fin base length	11.0	66	9.3–12.6	11.3
Posterior terminus of dorsal fin to adipose fin	26.6	66	22.5–29.7	26.0
Posterior terminus of dorsal fin to hypural joint	41.6	66	35.5–43.9	39.0
Snout to pelvic-fin insertion	46.0	58	42.3–48.5	45.4
Snout to anal-fin origin	67.7	66	61.3–70.2	65.9
Anal-fin base length	25.1	66	23.0–28.4	25.5
Caudal peduncle length	15.0	66	11.9–17.8	15.7
Dorsal-fin height	-	64	12.5–22.9	19.9
Pectoral-fin length	-	65	14.5–21.7	18.9
Pelvic-fin length	14.3	62	15.3–21.7	16.9
Caudal peduncle depth	10.3	66	9.0–15.3	10.7
Head length	21.8	66	20.3–28.6	23.4
Percentages of head length
Head height	1.03	66	82.2–97.6	88.5
Snout length	31.6	66	26.4–34.1	30.2
Upper jaw length	45.8	66	40.4–52.2	46.1
Horizontal eye diameter	23.1	66	22.2–37.4	27.5
Post-orbital length	49.6	66	41.4–50.3	46.4
Least interorbital width	46.1	66	35.4–46.3	41.7