Brycon dulcis
Creators: name: Lima, Flávio C. T.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Characiformes
Bryconidae
Brycon
Brycon dulcis

description: Brycon dulcis Lima & Vieira new species
(Figs. 30–31)
Brycon sp.: Travassos & Freitas, 1948: 628 (Espírito Santo, Lagoa de Juparanã, Brazil: parasites).
Brycon devillei (not Castelnau): Amaral-Campos, 1950: 140 (Rio Doce, Espírito Santo, Brazil); Vieira et al., 2008: 47–48 (part: rio Doce system, Espírito Santo and Minas Gerais, Brazil; ecology, distribution, conservation); Travenzoli et al., 2015: 6, 8–11, 13–14 (Lagoa Carioca, rio Doce, Minas Gerais; cytogenetics, phylogenetics relationships, molecular taxonomy). Brycon cf. devillei: Sunaga & Verani, 1991: 360, 361 (abundance, Lago Dom Helvécio, Lagoa Carioca, rio Doce system, Minas Gerais, Brazil); Godinho & Formagio, 1992: 95, 98 (Lago Dom Helvécio, Rio Doce State Park, Minas Gerais); Godinho et al., 1994: 80, 82 (Lago Dom Helvécio, Lago Ferrugem and Lagoa Carioca, Rio Doce State Park, Minas Gerais); Gomes et al., 2007: 1–2 (Lagoa Carioca, rio rio Doce system, Minas Gerais, Brazil).
Diagnosis. Brycon dulcis 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. howesi, 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 dulcis can be distinguished from B. stolzmanni, B. coxeyi, B. vonoi, B. opalinus, and B. nattereri by possessing a distinctly acute head profile (vs. a roughly rounded to slightly acute head profile). Brycon dulcis can be additionally distinguished from B. stolzmanni and B. coxeyi by the absence of a patch of dark pigmentation on the opercle (vs. dark patch of pigmentation present on opercle). Brycon dulcis can be distinguished from B. insignis, B. howesi, B. coquenani, and B. vermelha by possessing a fifth infraorbital bone about as wide as high (vs. fifth infraorbital bone wider than high; see Fig. 6). Brycon dulcis can be distinguished from B. ferox by presenting an approximately isognathous mouth, with premaxillary and dentary mostly overlapping, leaving only part of outer premaxillary series exposed in ventral view in some specimens (vs. mouth distinctly anisognathous, premaxillary pointed, extending beyond dentary, leaving outer series, and often also the second, series of premaxillary teeth exposed in ventral view). Brycon dulcis can be additionally diagnosed from other Brycon species occurring in the rio Doce basin, B. opalinus, by possessing a higher number of anal-fin rays (22–27, modally 25, vs. 17–23, modally 20). See “Remarks”, for additional notes on the recognition of the species.
Description. Morphometric data are presented in Table 9. Large-sized species, largest examined specimen 372.0 mm SL. Body slender to moderately slender. 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 to straight 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 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 moderately acute anteriorly, considerably acute in specimens <140 mm SL, mouth terminal. Jaws isognathous to slightly anisognathous, premaxillary projecting slightly relative to dentary in some specimens, leaving outer row of premaxillary teeth exposed when mouth is closed. Maxillary long, extending posteriorly to slightly posterior to middle of pupil. Adipose eyelid well developed. Premaxillary teeth in three rows; teeth of third row largest. Six (3), 7 (5), 8 (8), 9 (8), 10 (11), 11 (7), or 12 (3) tricuspidate teeth in outer series. Three (3), 4 (21), 5 (13), or 6 (4) tetra- to pentacuspidate teeth in second, inner premaxillary row, plus 1 (1), 2 (17), 3 (18), 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 hexacuspidate. Maxillary with distal portion distinctly expanded and rounded in profile. Eighteen to 29 maxillary teeth, slightly smaller than teeth of first premaxillary row, anterior teeth tricuspidate, posterior teeth unicuspidate. Dentary with 9 (1), 10 (5), 11 (2), 12 (7), 13 (7), 14 (5), 15 (5), 16 (5), or 17 (2) teeth in main series. Anterior four dentary teeth assymetrical, considerably larger and bulkier than remaining teeth, pentacuspidate, each with central cusp distinctly larger than remaining cusps. Remaining dentary teeth progressivelly smaller, penta-, tetra-, tri- 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 37–44 small, unicuspidate teeth, originating on lingual crest of dentary replacement trench slightly after the symphysis. Inner symphyseal teeth present in all specimens with relatively intact symphyseal dentaries area, except for MZUSP 42627 (2, 127.0– 138.7 mm SL), where symphyseal teeth are missing. Central cusp distinctly larger and pointed, and teeth presenting diastemas in specimens <140 mm SL.
Scales cycloid. Lateral line complete, from supracleithrum to caudal-fin base. Forty-eight (3), 49 (1), 50 (1), 51 (9), 52 (6), 53 (8), 54 (6), 55 (5), 56 (1), 57 (3), 58 (1), 60 (2), or 64 (1) scales in lateral line series. Laterosensory tube simple in small (<180 mm SL) specimens, deflected upwards in the first 5–6 scales, downwards in the remaining lateral-line scales. Larger specimens (> 180 mm SL) with branched tubules, mostly bifurcated in middle-sized specimens but some scales with 3–5 tubules. Horizontal scale rows between dorsal-fin origin and lateral line 8 (3), 9 (27), 10 (14), or 11 (3). Horizontal scale rows between lateral line and pelvic-fin 4 (12), 5 (25), or 6 (10). Circumpeduncular scales 16 (2), 17 (7), 18 (17), 19 (11), 20 (5), 22 (1), or 23 (2).
Dorsal-fin rays ii, 9. Dorsal fin origin slightly ahead of middle of SL. First dorsal-fin pterygiophore inserting behind neural spine of 13th (1), 14th (1), or 15th (1) vertebrae. Anal-fin rays iii (not including first, small unbranched ray only visible in the cs specimen), 22 (4), 23 (7), 24 (11), 25 (19), 26 (4), or 27 (2). First anal-fin pterygiophore inserting behind haemal spine of 23th (1) or 24th (2) 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. 20–30 per fin-ray main branch) middle-sized hooks on last unbranched and posterior main branch of branched rays 13–22, associated with dense, gelatinous tissue in 10 specimens (MZUSP 17070, 265.1– 270.1 mm SL; MZUSP 36663, 225.7– 237.9 mm SL; MZUSP 58911, 267.0 mm SL; MZUSP 106770, 285.0–323.0 mm SL; MCZ 20031, 236.5 mm SL; NMW 62947, 337.0–372.0 mm SL). Some fin rays with hooks also arranged along anterior ray margin. A single hook per ray segment, except when hooks also present on anterior ray margin. Sheath of scales covering basis of anal-fin rays composed of two scale rows, lower scale row formed by 20–22 rectangular scales. Pectoral-fin rays i, 11 (2), 12 (8), 13 (24), 14 (9), or 15 (2). Pelvic-fin rays i,7. Main caudal-fin rays 10/9. Caudal fin forked, lobes pointed.
Four branchiostegal rays, three on anterior ceratohyal and one on posterior ceratohyal. First branchial arch with 10 (1), 11 (2), 12 (2), 13 (5), 14 (6), or 15 (3) lower, 1 at angle, and 9 (1), 10 (1), 11 (9), 12 (5), 13 (3), or 14 (1) upper gill rakers. Vertebrae 44 (3). Supraneurals 9 (1) or 10 (2).
Coloration in alcohol. Overall body coloration clear to dark. Top of head, snout, supraorbital, sixth infraorbital, and dorsal portion of body light to dark-brown. Second, third, and fourth infraorbitals, and opercle light brown, with a silvery hue in specimens retaining guanine (e.g., MZUSP 58911, NMW 62947, ZUEC 6363). Dentary, maxillary, gular area and lower portion of body cream to light brown. Lateral portion of body lightbrown, silvery in specimens retaining a considerable amount of guanine (e.g., MZUSP 58911, NMW 62947, ZUEC 6363). Humeral blotch present, little conspicuous, approximately rounded in shape, situated immediately above lateral line, its anterior margin at level of second to third, extending longitudinally to posterior margin of fourth to fifth lateral line scales, and vertically less than one scale high. Large, moderately conspicuous, oval-shaped caudal peduncle blotch, extending along 8–10 last lateral-line scales. All rayed fins with a considerable amount of dark pigmentation at the interradial membranes, imparting an overall dark coloration to these fins. Caudal-fin with a poorly discernible, roughly V-shaped blotch, formed by dark pigmentantion situated on outer caudal-fin rays. Adipose fin light-grey to light-brown. Specimens collected in lakes surrounded by forest, as those from the lakes of the middle and lower Rio Doce (e.g., MZUSP 36663, MZUSP 58911, MZUSP 17070), with a dark overall coloration, while specimens collected in tributaries of the rio Doce in more turbid water conditions (e.g., ZUEC 6776, ZUEC 6363) with a considerably clearer overall coloration.
Color in life. Description based on a photo of a freshly collected specimen, collected at Rio Doce State Park by P. S. Pompeu, two specimens (ZUEC 6363, and ZUEC 6776) collected by T.C. Pessali from rio Corrente Grande, and specimens collected at a tributary of rio Santo Antônio and at the upper rio Doce, Rio Doce county (photos supplied by J. Dergam). Top of head, snout, and dorsum light-grey to dark. Dentary and maxillary clear. Opercle, infraorbital bones, and lateral portion of body silvery, with some dark pigmentation in the specimen from the Rio Doce State Park. Humeral blotch inconspicuous; caudal peduncle blotch moderately conspicuous. Series of pinkish spots situated along the four horizontal scale rows situated below scale row immediately below lateral line and anterior to insertion of pelvic fins in the specimens from Rio Doce State Park, upper Rio Doce and rio Santo Antônio. Pinkish pigmentation concentrated on the basal portion of the scales. All fins with some amount of dark pigmentation. Caudal fin with outer fin-rays dark, forming a roughly V-shaped blotch.
Sexual dimorphism. As discussed above, anal-fin hooks are present in 10 specimens (MZUSP 17070, 265.1– 270.1 mm SL; MZUSP 36663, 225.7– 237.9 mm SL; MZUSP 58911, 267.0 mm SL; MZUSP 106770, 285.0–323.0 mm SL; MCZ 20031, 236.5 mm SL; NMW 62947, 337.0–372.0 mm SL). Two of them (MZUSP 17070, 270.1 mm SL and MZUSP 36663, 237.9 mm SL) were dissected and are males, with poorly developed testicles. On other hand, a single dissected specimen that does not possess anal-fin hooks (MZUSP 36663, 283.1 mm SL) proved to be a female, with moderately well-developed ovaries.
Etymology. Dulcis, after the Latin word for sweet (“doce” in Portuguese), in allusion to the river system from which the species is apparently endemic.
Common names. “ Piabanha ”.
Distribution. Only known from the middle and lower rio Doce basins, states of Minas Gerais and Espírito Santo, eastern Brazil (Fig. 32). There is a putative historical record for the species for the rio Santa Maria da Vitória, a small coastal drainage situated southward from the rio Doce basin (MZUSP 1748, CAS 11171, CAS 11173). However, there is some uncertainty about the exact locality of these lots (though actually the lots from CAS originated from the lot from MZUSP, and as such refer to a single collection event) since it was recorded in the original MZUSP book catalog as being collected in “ Porto Cachoeiro, rio Doce”. “ Porto Cachoeiro” is the old name of Santa Leopoldina, a small town situated at the banks of the rio Santa Maria da Vitória, rather than the rio Doce. The collector, Ernst Garbe, collected also at the rio Doce during the same field expedition (Pinto, 1945: 17), so the mixing of contradictory information in the label of this lot does not lend much confidence as to the exact provenance of these specimens. Consequerntly, this locality was not mapped.
Ecological notes. Brycon dulcis is recorded as occurring in lake systems associated with the rio Doce, as the Lagoa Juparanã and some other lakes on the lower rio Doce basin and the Lago Dom Helvécio and Lagoa Carioca on the middle rio Doce. Lakes of the middle rio Doce basin, where most the recent records of the species come from, are ancient tributaries of the rio Doce which were dammed either as a consequence of paleoclimatic flutuations or neotectonic activity during the Quaternary (Suguio & Kohler, 1992). It is unclear whether populations of Brycon dulcis occurring in these lakes are in fact isolated from populations in the rio Doce mainstream or not. Stomach contents of two specimens were examined. One specimen (MZUSP 1531, 146.6 mm SL) ingested nine Astyanax sp. (Characidae), one Geophagus brasiliensis (Cichlidae), one Poecilia vivipara (Poeciliidae) and a Lepidoptera larvae. The stomach of the second specimen (MZUSP 36643, 277.8 mm SL) contained unidentified vegetal matter and crushed insects.
Conservation. The rio Doce basin is highly disturbed environmentally, water pollution, siltation and deforestation being the main anthropogenic disturbances in this river basin. Brycon dulcis was apparently extirparted from the lower portion of the basin, in the Espírito Santo state, where it was relatively common until at least the decade of 1960. Recent records of the species come mostly from the natural lakes system at the middle rio Doce in the Rio Doce State Park (Vieira et al., 2008; Gomes et al., 2007; as Brycon devillei). Introduction of two predatory fishes, a species of Cichla and the red-bellied piranha, Pygocentrus nattereri, have however impacted native fish populations in these isolated lakes (Godinho & Formagio, 1992; Godinho et al., 1994). The species still persists at the rio Corrente Grande, a tributary of the rio Doce, in the river stretch between Naque and Periquito, where fishermen report that about three specimens are fished per year (T.C. Pessali, pers. comm.), and was also recently recorded at the upper Rio Doce at Rio Doce county and at the mouth of rio Tanque, a tributary of rio Santo Antônio, near Ferros (J. Dergam, pers. comm., March 2012). The species is considered officially threatened in Brazil (Vieira et al., 2008; as Brycon devillei). The recent catastrophic burst of a tailings dam at the upper rio Doce basin in November 2015, releasing millions of tons of iron waste into the rio Doce, very likely extirpated Brycon dulcis from the rio Doce main channel, though the species might still persist in some tributaries and in the lakes of the middle rio Doce.
Remarks. Brycon dulcis was previously misidentified in the literature as B. devillei (e.g., Amaral-Campos, 1950; Sunaga & Verani, 1991; Godinho et al., 1994; Vieira et al., 2008; Travenzoli et al., 2015; see item “Remarks” of Brycon devillei and B. ferox). As noticed under Brycon devillei, this latter name is actually a species inquirenda, and more similar to B. insignis. Brycon dulcis is very similar morphologically to B. ferox and B. vonoi. Although diagnostic features among these three species are slight and refer only to overall color pattern and head/ snout shape, they are consistent and no gradation among these three morphological types was observed. See additional notes on the item “Remarks” of Brycon vonoi.
Recently, Travenzoli et al. (2015) argued in favor for the usage of the name Brycon devillei for the Brycon species from the rio Doce herein described as Brycon dulcis. They argued that the species also occurs at the rio Mucuri, which has its mouth at the southern portion of Bahia state, and consequently that the name B. devillei could be applied to the species. We have not examined the specimen from the rio Mucuri that Travenzoli et al. (2015) considered to be conspecific with specimens from the rio Doce and consequently cannot confirm their claim. All Brycon specimens from the rio Mucuri examined in the present study were either B. ferox or B. vermelha (see under these species). At any rate, the name Brycon devillei cannot be applied to the Brycon species herein named B. dulcis because its holotype presents a sixth infraorbital bone wider than high (vs. a sixth infraorbital bone as high as wide in B. dulcis). See also the item “Remarks” of Brycon devillei.
Material examined. Holotype: MZUSP 58911 (1, 267.0 mm SL): Brazil, Minas Gerais, Marliéria, Lago Dom Helvécio, Rio Doce State Park, rio Doce system, 19°46’S, 42°36’W; A.L. Godinho & P.S. Pompeu, Sept 1993. Paratypes: Brazil, Minas Gerais, rio Doce basin: MZUSP 28983 (2, 1 cs, 113.8–223.9 mm SL): Marliéria, Lagoa Carioca, Rio Doce State Park, 19°45’S, 42°37’W; J.R.Verani, 27 June–14 July 1983. MZUSP 36663 (5, 211.3– 287.9 mm SL): Marliéria, Lago Dom Helvécio, Rio Doce State Park, 19°46’S, 42°36’W; J.R.Verani, 27 Nov –13 Dec 1985. MZUSP 28968 (1, 111.9 mm SL): Marliéria, Lago Dom Helvécio, Rio Doce State Park, 19°46’S, 42°36’W; J.R.Verani, 25–28 Jun 1983. MZUSP 36643 (3, 1 skel., 147.1–277.8 mm SL): Marliéria, Lagoa Carioca, Rio Doce State Park, 19°45’S, 42°37’W; J.R. Verani, 23–25 Nov 1985. LISDEBE uncat. (7, 245.0–260.0 mm SL): Marliéria, Lago Dom Helvécio, Rio Doce State Park, 19°46’S, 42°36’W; J.G. da Silva, March 1977. ZUEC 6363 (1, 263.0 mm SL): Governador Valadares, rio Corrente Grande (trib. rio Doce), 18°59’38’’S, 42°13’33’’W; T.C. Pessali, May 2010. ZUEC 6776 (1, 156.0 mm SL): Periquito, rio Corrente Grande (marginal lagoon), 18°58’20’’ S, 42°17’13’’ W; T.C. Pessali, July 2011. Espírito Santo, rio Doce basin: MNRJ 11248 (4, 87.7–152.6 mm SL): Linhares, lagoa de Juparanã, road Linhares / São Mateus, 19°16’S, 40°8’W; L. Travassos & H. Travassos, 8 March 1948. MNRJ 11250 (2, 112.8– 126.9 mm SL): Linhares, lagoa de Juparanã, 19°16’S, 40°8’W; L. Travassos & H. Travassos, 29 Feb 1948. MZUSP 17070 (3, 265.1– 283.1 mm SL): Linhares, Lagoa Juparanã, 19°16’S, 40°8’W; H. A.Britski & Izáurio Dias, 3–9 Feb 1965. MZUSP 3308 (1, 183.3 mm SL): Linhares, rio São José, tributary of Lagoa Juparanã, 19°10'S 40°12'W; O. Pinto, Sept 1942.
Non types. Minas Gerais: MCZ 20031 (3, 194.4– 236.5 mm SL): Minas Gerais (?), Rio Doce (no specific locality); C.F. Hartt & E. Copeland, Aug–Sept 1865. MZUSP 42627 (2, 127.0– 138.7 mm SL): Viçosa, c. 20°43’S, 42°54’W; J. Dergam, no date. MZUSP 106770 (2, 285.0–323.0 mm SL); MZUSP 106771 (2, 1 skel., 308.0–326.0 mm SL): Marliéria, Lagoa Carioca, Rio Doce State Park, 19°45’26’’S, 42°37’6’’W; E.N. Fragoso et al., March 2007 – Sept 2009. Espírito Santo: MNRJ 11249 (6, 87.0– 104.9 mm SL): Linhares, Lagoa Juparanã,, 19°16’S, 40°8’W; L. Travassos, H. Travassos & J.T. de Freitas, 8 March 1948. MNRJ 11251 (1, 110.7 mm SL): Linhares, Lagoa de Freitas; L. Travassos & J.T. de Freitas, Oct 1963. MZUSP 1531 (5, 1 cs, 88.7–146.6 mm SL): Linhares, rio Doce, c. 19°24’S, 40°3’W; E. Garbe, 1906. MCZ 60931 (2, 109.9– 167.4 mm SL); MCZ 21102 (2, 148.6– 184.4 mm SL); MCZ 21101 (1, 357.0 mm SL): Rio Doce, between Linhares and Aimorés, 19°37’S, 39°49’W; C.F. Hartt & E. Copeland, 1865. MZUSP 1748 (7, 1 cs, 74.6–138.1 mm SL); CAS 11171 (1, 132.4 mm SL); CAS 11753 (1, 105.1 mm SL): Santa Leopoldina, rio Santa Maria da Vitória, 20°6’S, 40°31’W; E. Garbe, 1906.
Rio Doce, locality not specified: NMW 69928 (3, 132.9–200.0 mm SL); NMW 62940 (4, 191.5–235.0 mm SL); NMW 62947 (2, 337.0–372.0 mm SL); NMW 62940 (4, 191.5–235.0 mm SL); NMW 62947 (2, 337.0–372.0 mm SL); “rio Doce, Steindachner Don., 1912–1913 ”.
description: Published as part of Lima, Flávio C. T., 2017, A revision of the cis-andean species of the genus Brycon Müller & Troschel (Characiformes: Characidae), pp. 1-189 in Zootaxa 4222 (1) on pages 53-58, DOI: 10.5281/zenodo.257769