Brycon howesi, Lima, Flávio C. T., 2017

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 : 47-51

Brycon howesi new species

( Figs. 28–29 )

Chalceus opalinus (non Cuvier): Valenciennes, in Cuvier & Valenciennes, 1850: 246 (part; “ Rio Tiquilelonha”).

Brycon insignis: Steindachner, 1877: 587 –591 (part; “ Rio Jequitinhonha”); Godinho et al., 1999: 415, 418, 421 (Rio Jequitinhonha basin; ecology).

Brycon opalinus (non Cuvier): Géry & Mahnert, 1992: 813 –814 (part; Rio Jequitinhonha).

Brycon devillei (non Castelnau): Vieira et al., 2008: 47–48 (part; Rio Jequitinhonha basin; ecology, conservation); Azevedo et al., 2011: 807 –814 (feeding ecology and social behavior, rio Preto, rio Jequitinhonha basin, Minas Gerais).

Brycon sp.: Pugedo et al., 2016: 345 (photo), 346 (table) (barcoding, rio Jequitinhonha).

Diagnosis. Brycon howesi can be diagnosed from all remaining cis-andean Brycon species, with the exception of B. stolzmanni , B. coxeyi , B. coquenani , B. vermelha , B. insignis , B. dulcis , B. ferox , B. vonoi , B. opalinus , and B. nattereri by possessing a color pattern consisting in a humeral blotch and a caudal peduncle blotch, without body stripes or other obvious color markings on caudal and anal-fins (vs. body stripes and caudal/anal fin color markings present; see Fig. 5 ). Brycon howesi can be diagnosed from these species, with the exception of B. insignis , B. vermelha , and B. coquenani , by possessing a fifth infraorbital bone considerably wider than high (vs. fifth infraorbital bone about as wide as high; see Fig. 6 ). Brycon howesi can be diagnosed from B. coquenani by possessing a higher head (65.6–76.2 % of head length, mean 70.6, vs. 59.8–64.9 %, mean 61.4, in B. coquenani ), by possessing pointed tri- to pentacuspidate dentary teeth, with moderately developed lateral cusps (vs. pointed, trito tetracuspidate dentary teeth, with lateral cusps poorly developed), and by mature males displaying hooks only in anal and pelvic-fins (vs. mature males displaying hooks in all rayed fins, including caudal fin). Brycon howesi can be distinguished from B. vermelha by presenting darkened dorsal, caudal, and anal-fins in both living and preserved specimens (vs. dorsal, caudal, and anal-fins reddish in living, clear in preserved B. vermelha specimens), 7–9, modally 8 horizontal scale rows between the dorsal-fin origin and the lateral line (vs. 10–12, modally 10, in B. vermelha ). Brycon howesi can be distinguished from Brycon insignis by possessing 46–50, modally 49 lateral line scales (vs. 51–65, modally 58 in B. insignis ), 7–9, modally 8 horizontal scale rows between the dorsal-fin origin and the lateral line (vs. 9–11, modally 10–11 in B. insignis ), 3–5, modally 4 horizontal scales rows between the lateral line and pelvic (vs. 4–7, modally 5 in B. insignis ) and a relatively rounder snout profile in B. howesi (vs. snout more pointed in B. insignis ).

Description. Morphometric data are presented in Table 7 . Large-sized species, largest alcohol-preserved examined specimen 284.0 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 convex from latter point to basis of supraoccipital process, moderately 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 convex from lower lip to pelvicfin 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 considerably acute anteriorly, mouth terminal. Jaws slightly anisognathous, premaxillary projecting slightly relative to dentary, outer row of premaxillary teeth exposed when mouth is closed in some specimens. Maxillary long, extending posteriorly to middle of pupil. Adipose eyelid well developed. Premaxillary teeth in three rows; teeth of third row largest. Five (1), 6 (1), 7 (3), 8 (10), 9 (9), 10 (8), 11 (4), or 12(1) tricuspidate teeth in outer series. Four (4), 5 (18), 6 (11), or 7 (3) tri- to tetracuspidate teeth in second, inner premaxillary row, plus 1(2), 2 (15), 3 (17), or 4 (2) 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, both pentacuspidate. Maxillary with distal portion considerably expanded and rounded in profile. Seventeen to 33 maxillary teeth, slightly smaller than teeth of first premaxillary row, anterior teeth tricuspidate, posterior teeth unicuspidate. Dentary with 8(1), 10 (3), 11 (5), 12 (8), 13 (3), 15 (2), 16 (1), or 17 (1) teeth in main series. Anterior four dentary teeth assymetrical, considerably larger and bulkier than remaining teeth, tetra- to pentacuspidate, each with central cusp distinctly larger than remaining cusps. Remaining dentary teeth progressivelly smaller, tetra, tri- to unicuspidate. Main dentary present gaps (diastemas) between teeth in small specimens (MZUSP 5139, 6, 31.3– 47.6 mm SL). Inner (lingual) series consisting of a small, single unicuspid symphyseal tooth, situated immediately posterior to symphyseal dentary teeth of main series, plus row of 23–25 small, unicuspidate teeth, originating on lingual crest of dentary replacement trench at level of the fifth to sixth teeth of main series. Inner symphyseal teeth present in all specimens with relatively intact symphyseal dentary area.

Scales cycloid. Lateral line complete, from supracleithrum to caudal-fin base. Forty-four (1), 45 (4), 46 (6), 47 (7), 48 (10), 49 (7), or 50 (2) scales in lateral line series. Laterosensory tube simple in relatively small (<225 mm SL) specimens, deflected upwards in the first 5–6 scales, downwards in the remaining lateral-line scales. Larger specimens (> 225 mm SL) with some scales with 2–3 branches, most lateral scales with a single branch. Tubules short, generally not extending beyond scale anterior third. Horizontal scale rows between dorsal-fin origin and lateral line 7 (2), 8 (31), or 9 (4). Horizontal scale rows between lateral line and pelvic-fin 3 (5), 4 (30), or 5 (2). Circumpeduncular scales 14(3), 15 (16), 16 (15), or 17 (3).

Dorsal-fin rays ii, 9. Dorsal fin origin at, or slightly ahead of, middle of SL. First dorsal-fin pterygiophore inserting behind neural spine of 12th (2) or 13th (1) vertebra. Anal-fin rays iii (not including first, small unbranched ray only visible in the cs specimen), 19(1), 20 (1), 21 (1), 22 (4), 23 (9), 24 (9), 25 (8), or 26 (1). First anal-fin pterygiophore inserting behind haemal spine of 22th (1), 23th (1), or 24th (1) vertebrae. Last unbranched and anterior 3–4 branched anal-fin rays longer, remaining rays progressively shorter towards anal-fin end. Anal fin displaying numerous (c. 20 per fin-ray main branch) middle-sized hooks on last unbranched and posterior main branch of branched rays 17–23, associated with dense, gelatinous tissue in six specimens (MZUSP 55963, 221.8 mm SL; MZUSP 101506, 3, 189.2–219.0 mm SL; MZUSP 101507, 1, 186.1 mm SL; ZUEC 12869, 245.0 mm SL). A single hook per ray segment. Sheath of scales covering basis of anal-fin rays composed of two scale rows, lower scale row formed by 20–25 rectangular scales. Pectoral-fin rays i, 11 (1), 12 (11), 13 (18), 14 (4), or 15 (1). Pelvicfin rays i,7, two specimens i, 8. A few small hooks on posterior branch of branched pelvic-fin rays in five specimens (MZUSP 55963, 221.8 mm SL; MZUSP 101506, 3, 189.2–219.0 mm SL; MZUSP 101507, 1, 186.1 mm SL). Main caudal-fin rays 10/9. Caudal fin forked, lobes slightly pointed.

Four branchiostegal rays, three on anterior ceratohyal and one on posterior ceratohyal. First branchial arch with 11 (2), 12 (1), 13 (1), 14 (5), 15 (1), or 16 (1) lower, 1 at angle, and 10 (3), 11 (4), or 12 (4) upper gill rakers. Vertebrae 42 (1) or 43 (2). Supraneurals 9 (1) or 10 (2).

Coloration in alcohol. Overall color pattern clear in specimens from most localities, but very dark in specimens from the rio Preto (MZUSP 101506, MZUSP 101507, MZUSP 101508). Top of head, snout, supraorbital, sixth infraorbital, and dorsal portion of body brown to dark-brown. Remaining infraorbitals, opercle, dentary, maxillary, lateral and ventral surfaces of body light-brown to brown. Specimens retaining guanine (e.g., MZUSP 55963, ZUEC 12869) with infraorbitals, opercle, and lateral surfaces of body with a silvery hue. Humeral blotch present, little to moderately conspicuous, situated at level of lateral line, extending longitudinally from second to fourth, and vertically to scale row situated immediately above lateral line. Caudal peduncle blotch moderately to highly conspicuous, aproximately rounded in shape, extending along 6–7 last lateral line scales. Pectoral, pelvic, dorsal, and anal-fins clear, with a moderate concentration of dark chromatophores at the interradial membranes in the clear-colored specimens; intensely dark-pigmented in the specimens from rio Preto (MZUSP 101506, MZUSP 101507, MZUSP 101508). Caudal fin with outer caudal fin rays with dark pigmentation on outer rays and basis of middle cudal-fin rays continuous with caudal peduncle blotch, forming a roughly V-shaped blotch. Adipose fin light- to dark-brown. Juveniles (MZUSP 5139, 31.3– 47.6 mm SL) presenting a conspicuous humeral blotch and caudal blotch extending into 3–4 innermost caudal-fin rays.

Color in life. Based on pictures of freshly collected or living specimens from the rio Preto, Rio Preto State Park, taken by P. Azevedo, a specimen collected at the rio Vacaria, a tributary of the rio Jequitinhonha, by F.R. Andrade Neto, and several specimens from the rio Itacambiruçu, collected by T.C. Pessali. Overall color pattern clear-colored to dark-brown; clear-colored specimens with a silvery hue on opercle and infraorbital bones and lateral surfaces of body. Caudal peduncle blotch and dark pigmentantion on outer caudal-fin rays very conspicuous. Adipose-fin cream-colored to orangish. Specimens from the clear to turbid water rio Vacaria and rio Itacambiruçu possess an overall color pattern much more clear when compared with specimens from the black-water rio Preto.

Sexual dimorphism. Five specimens (MZUSP 55963, 221.8 mm SL; MZUSP 101506, 3, 189.2–219.0 mm SL; MZUSP 101507, 1, 186.1 mm SL) were recorded as possessing anal- and pelvic-fin hooks, a single specimen (ZUEC 12869, 245.0 mm SL) presented only anal-fin hooks. One specimen (MZUSP 101507, 1, 186.1 mm SL) proved to be a male after dissection, with relatively well-developed testes. There is an indication in the literature that females may grown larger than males (see “Ecological notes”, below).

Etymology. Named in honour of Gordon J. Howes (1938–2013), in recognition to his important contribution to the knowledge of the taxonomy of the genus Brycon as well as for ichthyology as a whole.

Common names. “ Piabanha ” (Godinho et al., 1998: 415; V. Vono, P. Azevedo, T.C. Pessali, pers. comm.). Valenciennes (in Cuvier & Valenciennes, 1850: 246) mentions the common name “pirabanha” for the species, a name apparently heard by A. de Saint-Hillaire, the collector of the specimen studied by him.

Distribution. Endemic from the rio Jequitinhonha basin, an independent coastal river system at the state of Minas Gerais, Brazil ( Fig. 25 ).

Ecological notes. Feeding and social behavior of the species was quantitavely studied by Azevedo et al. (2011; as B. devillei ) at a dark water tributary of the rio Araçuaí (a tributary of the rio Jequitinhonha). Brycon howesi adopted mainly surface-picking as a foraging tactic, though “digging” and “active-hunting” were also observed ( Azevedo et al., 2011). Surface-picking was more common during the rainy season, whereas “digging” was more frequent during the dry season ( Azevedo et al., 2011). An elaborate cooperative hunting of small characids, and a feeding association of the kind “nuclear-follower behavior” with Leporinus garmani , a bottom feeder, were also documented for the species ( Azevedo et al., 2011). Brycon howesi was reported by Godinho et al. (1998; as B. insignis ) as being mainly insectivore. Largest recorded standard lengths reported for the species by these authors were 254.0 mm SL for males and 342.0 mm SL for females. The species occurs both in clear- (e.g., rio Itacambiruçu) and dark-water (e.g., rio Preto) tributaries of the rio Jequitinhonha basin.

Conservation. The rio Jequitinhonha basin has a long history of anthropogenic disturbances that includes intensive mining, deforestation, and siltation. Probably as a result of these impacts, Brycon howesi was reported by fishermen to be becoming increasingly scarcer in the middle rio Jequitinhonha basin (Godinho et al., 1998). A large hydroelectric dam, the Irapé dam, was build in 2006 a little above the area where most of the records of Brycon howesi come from, in the middle rio Jequitinhonha basin, and the extent of its presumable deleterious effects on the populations of the species are still unknown. Fortunately, an apparently healthy population of the species occurs at the Rio Preto State Park, at the headwaters of the rio Araçuaí, the main tributary of the rio Jequitinhonha ( Azevedo et al., 2011).

Remarks. There are two references to specimens of Brycon howesi in the taxonomic literature, both as misidentifications. The first report for the species was by Valenciennes (in Cuvier & Valenciennes, 1850: 246), which identified it as Chalceus opalinus (now Brycon opalinus ; see under this species). This record was based on a single, stuffed specimen (MNHN A.8612), collected by the botanist Auguste de Saint-Hilaire at the rio “Tiquilelonha” (an evident misspelling of Jequitinhonha), a region surveyed by him between April–July 1817 ( Papavero, 1971). This specimen certainly does not belong to the type-series of Chalceus opalinus , which is composed only of the holotype, MNHN A.8613 (see item “Remarks” of Brycon opalinus , below). Although Géry & Mahnert (1992: 813) considered the specimen MNHN A.8612 to be probably conspecific with the holotype of Chalceus opalinus , our examination of this same specimen leaves no doubt that it in fact represents Brycon howesi .

Steindachner (1877: 591) reported “Rio Jequitinhonha” as being one of the syntypical localities of Brycon insignis , the remaining localities (“Mendez” and “Campos”) being situated at the rio Paraíba do Sul basin. A search in the NMW fish collection revealed a single specimen, NMW 62927 (1, 71.6 mm SL) collected at the “Rio Jequitinhonha”, which undoubtedly represents the material reported by Steindachner (1877). The designation of the specimen NMW 62925 (144.8 mm SL) as the lectotype of Brycon insignis resulted in restricting this name for the species occurring in the rio Paraíba do Sul drainage (see “Remarks” of Brycon insignis ). Thus, the specimen NMW 62927, though a paralectotype of Brycon insignis , is not conspecific with the lectotype and the remaining paralectotypes, representing instead the species which is herein named as Brycon howesi .

In fact, Brycon howesi is more similar to B. insignis than to any other Brycon species. The V-shaped caudal-fin blotch formed by pigmentation concentrated on the outer caudal-fin rays is a feature uniquely shared between these two species. As noticed in the item “Diagnosis”, above, Brycon howesi is clearly distinct from B. insignis by possessing significantly lower scale counts and a distinctly rounder snout profile.

Material examined. Holotype: MZUSP 103075 (230.6 mm SL): Brazil, Minas Gerais, Araçuaí, rio Jequitinhonha, confluence with rio Araçuaí , below village of Itira , 16°45’S, 42°0’W ; J.C. Garavello, A.S. Soares, A.I. Alves & J.C. Soares, 19 Feb 1989.

Paratypes: Brazil, Minas Gerais, rio Jequitinhonha basin: MZUSP 53803 (1, 234.8 mm SL): same data as holotype . MZUSP 53802 (1, 223.1 mm SL): Leme do Prado, rio Araçuaí at Santa Rita village, 17°6’S, 42°39’W; G.B. Santos , A.S. Soares & A.I.S. Alves, 18 Oct 1987. MZUSP 55963 (6, 165.8– 248.6 mm SL) ; ZUEC 6365 (1, 164.9 mm SL): Coronel Murta, rio Jequitinhonha , 16°37’32’’S, 42°16’6’’W; F. Andrade, 6 Aug 2010 . MZUSP 5139 (6, 1 cs, 31.3–47.6 mm SL), Itaobim, rio Jequitinhonha , 16°34’S, 41°29’W; Exc. Departamento de Zoologia, 25 June 1966 . ZUEC 6939 (3, 134.0–242.0 mm SL): Grão Mogol, rio Itacambiruçu , 16°34’52’’S, 42°52’25’’W; T.C. Pessali & T.F. Teixeira, May 2011 . ZUEC 6940 (1, 143.7 mm SL): Grão Mogol, rio Itacambiruçu , 16°35’12’’S, 42°51’15’’W; T.C. Pessali & T.F. Teixeira, May 2011 . ZUEC 7003 (1, 282.0 mm SL); MCP 48399 (1, 268.0 mm SL); ANSP 200242 (1, 232.0 mm SL): Grão Mogol, rio Itacambiruçú , 16°34’52’’S, 42°52’25’’W; T.C. Pessali & A . A. Rodrigues, Feb 2011 . ZUEC 7000 (1, 208.0 mm SL): Grão Mogol, rio Itacambiruçú , 16°35’50’’S, 42°50’22’’W; T.C. Pessali & A . A. Rodrigues, Feb 2011 . ZUEC 12869, 1 , 245.0 mm SL, Grão Mogol, Itacambiruçu, rio Itacambiruçu , above Cachoeira Marias das Neves, 16°34'53''S, 42°52'26''W; T.C. Pessali & A . A. Rodrigues, 25 Dec 2011 . ZUEC 12870, 1 , 213.0 mm SL, Grão Mogol, Itacambiruçu, rio Itacambiruçu , above Cachoeira Marias das Neves, 16°35'58''S, 42°55'37''W; T.C. Pessali & A . A. Rodrigues, 28 Dec 2011 . MZUSP 101506 (4, 167.1–219.0 mm SL): São Gonçalo do Rio Preto, rio Preto (tributary of rio Araçuaí ) , Rio Preto State Park, 18°6’47’’S, 43°20’42’’W; P.G. Azevedo, 8 Oct 2006 . MZUSP 101507 (3, 186.1–243.0 mm SL): same locality and collector , 5 April 2007. MZUSP 103685 (2 skel., 168.0–207.0 mm SL): same locality and collector , July 2009. MZUSP 101508 (3, 244.0–284.0 mm SL): same locality; F. Vieira & G.B. Santos , 10 Jan 2006. MZUEL 3931 (1, 130.0 mm SL): same locality; E.T. Grando , 2 Feb 2004.

Non types. Minas Gerais: LISDEBE uncat. (2, 190.0–243.0 mm SL): Coronel Murta, rio Jequitinhonha , fazenda Jatobá , c. 16°37’S, 42°10’W; V. Vono, April 1989 . ZUEC 6969 (1, 101.7 mm SL): Grão Mogol, rio Itacambiruçú , 16°35’12’’S, 42°51’15’’W; T.C. Pessali & A . A. Rodrigues, Feb 2011. ZUEC 6970 (2, 109.1– 138.4 mm SL): Grão Mogol, rio Itacambiruçú , 16°35’12’’S, 42°51’15’’W ; T.C. Pessali & A . A. Rodrigues, Feb 2011. ZUEC 6974 (3, 101.1– 171.5 mm SL): Grão Mogol, rio Itacambiruçú , 16°34’52’’S, 42°52’25’’W ; T.C. Pessali & A . A. Rodrigues, Feb 2011. ZUEC 6999 (1, 173.3 mm SL): Grão Mogol, rio Itacambiruçú , 16°34’24’’S, 42°49’46’’W ; T.C. Pessali & A . A. Rodrigues, Feb 2011. ZUEC 6367 (1, 94.3 mm SL): Grão Mogol, rio Itacambiruçu , 16°35’56’’S, 42°50’8’’W ; F. Andrade, 22 Nov 2010. Imprecise localities: NMW 62927 (1, 71.6 mm SL): “ Rio Jequitinhonha” (no specific locality); Wertheimer , no date. Paralectotype of Brycon insignis Steindachner . MNHN A.8612 (1, 295.8 mm SL): “ Rio Tiquilelonha . A. Saint- Hilaire, 1822”.

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 25. Map of eastern Brazil, showing known localities of Brycon insignis (red dots), B. vermelha (grey dots), and B. howesi (black dots; dark star indicates type-locality).

FIGURE 28. Brycon howesi, new species, holotype, MZUSP 53803, 234.8 mm SL: Brazil, Minas Gerais, rio Jequitinhonha.

FIGURE 29. Brycon howesi, new species, paratype, MZUSP 101506, 167.1 mm SL: Brazil, Minas Gerais, Rio Preto.

Tables

TABLE 7. Morphometric data of Brycon howesi (A: holotype, MZUSP 103075).

	A	n	Range	Mean
Standard length (SL)	230.6	36	71.6–284.0	-
Percentages of standard length
Depth at dorsal-fin origin	28.6	36	25.7–33.2	29.3
Snout to dorsal-fin origin	52.9	36	46.8–56.0	52.6
Dorsal-fin base length	11.8	36	10.1–13.4	12.1
Posterior terminus of dorsal fin to adipose fin	23.8	36	21.5–25.0	23.3
Posterior terminus of dorsal fin to hypural joint	35.6	36	34.0–39.5	37.0
Snout to pelvic-fin insertion	47.5	36	47.5–53.6	49.9
Snout to anal-fin origin	64.6	36	64.4–71.7	67.7
Anal-fin base length	23.7	36	19.1–26.4	23.8
Caudal peduncle length	15.8	36	11.9–15.8	13.4
Dorsal-fin height	19.2	36	17.9–21.6	20.0
Pectoral-fin length	17.9	36	16.1–20.9	19.3
Pelvic-fin length	14.1	36	14.1–16.8	15.2
Caudal peduncle depth	8.5	36	8.1–9.3	8.7
Head length	26.9	36	25.3–31.7	28.6
Percentages of head length
Head height	70.9	36	65.6–76.9	71.3
Snout length	30.8	36	26.8–32.3	29.9
Upper jaw length	44.0	36	42.7–50.2	45.9
Horizontal eye diameter	21.4	36	19.0–27.3	22.7
Post-orbital length	48.6	36	45.8–53.2	50.3
Least interorbital width	34.5	36	28.6–37.1	33.0