Hyphessobrycon diastatos, Dagosta & Marinho & Camelier, 2014

Dagosta, Fernando C. P., Marinho, Manoela M. F. & Camelier, Priscila, 2014, A new species of Hyphessobrycon Durbin (Characiformes: Characidae) from the middle rio São Francisco and upper and middle rio Tocantins basins, Brazil, with comments on its biogeographic history, Neotropical Ichthyology 12 (2), pp. 365-375 : 366-370

Hyphessobrycon diastatos , new species

Figs. 1-3

Hasemania sp. - Lima & Caires, 2011: 235, 239, 243, and 248 (listed). Hemigrammus sp. 2 “Sapão” - Lima & Caires, 2011: 235, 241, 243, and 248 (listed).

Holotype. MZUSP 114030 , 24.4 mm SL, Brazil, Bahia, São Desidério, rio Galheirão (or rio da Estiva) at BR-020 road, affluent of rio Grande , rio São Francisco basin, 12°58’42.7"S 45°59’28.7"W, 802 m above sea level, 4 Dec 2012, J. Birindelli, F. Dagosta, M. V. Loeb & C. Santos.

Paratypes. All from Brazil . INPA 39960 , 5 , 18.8-20.9 mm SL ; MCP 48060, 5 , 18.7-22.2 mm SL, and MZUSP 114029 , 41 , 14.4-25.2 mm SL, same data as holotype . MZUSP 114026 , 35 , 10.3-22.3 mm SL, 2 c&s, 19.2-29.9 mm SL, Bahia, Barreiras, rio das Balsas, bridge at BA-458 road, Luís Eduardo Magalhães to Cotia , affluent of rio Grande , rio São Francisco basin, 11°59’34.5"S 45°34’49.2"W, 3 Dec 2012 , J. L. O. Birindelli, F. Dagosta, M. V. Loeb & C. Santos . MZUSP 40894 , 62 , 15.7-25.5 mm SL, Goiás, São Domingos, Riacho Curral de Pedra along GO-362 road, 3 km from São Domingos , affluent of rio São Domingos , rio Tocantins basin, 13°23’59"S 46°18’59"W, 14 Jan 1989 , J. C. Oliveira & W. J. M. Costa. MZUSP 58586 , 62 , 19.2-27.9 mm SL, Goiás, São Domingos, stream affluent of rio São Domingos, at road to São Domingos , about 5 km of bifurcation on BR-020 road, rio Tocantins basin, 13°19’23"S 46°07’15"W, 10 Jul 1998 , O. T. Oyakawa, A. Akama & V. Garutti . MZUSP 98494 , 16 , 22.6-26.1 mm SL, Tocantins, Mateiros, rio Novo, near mouth of córrego Lajeiro , rio Tocantins basin, 10°46’23"S 46°43’08"W, 1 Feb 2008 , F. C. T. Lima , R. A. Caires & C. Nogueira . MZUSP 98507 , 1 , 23.4 mm SL, Tocantins, Mateiros, rio Preto, North limit of Estação Ecológica Serra Geral do Tocantins, near Região das Dunas, rio Tocantins basin, 10°38’40"S 46°41’02"W, 1 Feb 2008 , F. C. T. Lima , R. A. Caires & C. Nogueira . MZUSP 98531 , 38 , 11.8-17.6 mm SL, Bahia, Formosa do Rio Preto, Vereda do rio Sapão , rio São Francisco basin, 10°44’41"S 46°11’45"W, 3 Feb 2008 , F. C. T. Lima , R. A. Caires & C. Nogueira . MZUSP 109772 , 1 , 23.6 mm SL, Bahia, São Desidério, rio Galheirão (or rio da Estiva) at BR-020 road, affluent of rio Grande , rio São Francisco basin, 12°58’S 45°59’W, 17 Feb 2011 , A. Akama & J. L. O. Birindelli. MZUSP 114027 , 10 , 19.2-21.2 mm SL, Bahia, Luís Eduardo Magalhães, rio do Borá, affluent of rio das Ondas, affluent of rio Grande at BR-020, 12°17’58.9"S 45°50’55.4"W, 4 Dec 2012 , J. Birindelli, F. Dagosta, M. V. Loeb & C. Santos . MZUSP 114031 , 11 , 18.9-26.7 mm SL, Goiás, São Domingos, rio São Domingos at road GO-463 to São Domingos , rio Tocantins basin, 13°19’23"S 46°07’15.2"W, 5 Dec 2012 , J. L. O. Birindelli, F. Dagosta, M. V. Loeb & C. Santos . MZUSP 114028 , 4 , 19.2-21.4 mm SL, Bahia, São Desidério, rio Pau de Óleo, affluent of rio das Fêmeas, affluent of rio Grande at BR-020 road, rio São Francisco basin, 12°41’24.3"S 45°55’48.9"W, 4 Dec 2012 , J. L. O. Birindelli, F. Dagosta, M. V. Loeb & C. Santos .

Diagnosis. Hyphessobrycon diastatos differs from all congeners, except H. amandae Géry & Uj , H. axelrodi (Travassos) , H. brumado Zanata & Camelier , H. compressus (Meek) , H. diancistrus Weitzman , H. eilyos Lima & Moreira, H. georgettae Géry , H. heteresthes (Ulrey) , H. gracilior Géry , H. milleri Durbin , H. minimus Durbin , H. negodagua Lima & Gerhard, H. otrynus Benine & Lopes , H. parvellus Ellis , H. piabinhas Fowler , H. procerus Mahnert & Géry , H. saizi Géry , H. scutulatus Lucena , H. taurocephalus Ellis , and H. tukunai Géry by the absence of any concentration of chromatophores at the humeral region (vs. presence of a dark humeral spot or/ and a longitudinal dark stripe extending over the humeral region). The new species can be diagnosed from H. otrynus , H. piabinhas , and H. procerus by having 15-18 branched anal-fin rays (vs. 19 or more); from H. amandae , H. axelrodi , H. compressus , H. georgettae , H. heteresthes , and H. milleri by the absence of a dark blotch in the dorsal fin (vs. presence); from H. eilyos and H. scutulatus by having 1-3 maxillary teeth (vs. 5 or more); from H. diancistrus by having hyaline caudalfin lobes (vs. caudal lobes with a black spot); from H. gracilior by the presence of 4-5 longitudinal scale rows below the lateral line (vs. 3); from H. minimus by having the largest dentary teeth with 3-5 cusps (vs. 7); from H. saizi by having 14 horizontal scale rows around caudal peduncle (vs. 12) and 10- 12 predorsal scales (vs. 9); from H. taurocephalus by having adipose fin (rarely absent, 1 of 294 specimens) and 15-18 branched anal-fin rays (vs. adipose fin absent and 12-15); and from H. tukunai by having 2-5 teeth in the outer premaxillary teeth row (vs. 1, rarely 2), besides the maxillary teeth with 1-3 cusps (vs. 5 or more). It can be distinguished from H. brumado , H. negodagua , and H. parvellus by the round and relatively well-defined dark caudal-peduncle spot in males (vs. caudalpeduncle blotch with inconspicuous border in males, frequently only represented by dense pigmentation on this region) and also by the absence of white pigmentation on distal portions of first rays of dorsal, anal, and caudal fins in life (vs. presence). The new species is further distinguished from H. negodagua and H. parvellus by having dark pigmentation of caudal-peduncle spot extending to base of few middle caudal-fin rays or reaching their tip, never on caudal lobes in males (vs. caudal-peduncle pigmentation spread from middle caudal-fin rays to inner portions of caudalfin lobes in males). Hyphessobrycon diastatos is further distinguished from H. brumado and H. parvellus by having pectoral, pelvic, and anal fins hyaline to slightly yellowish in life (vs. distinct orange- to reddish) and presence of sexually dimorphic elongation of dorsal and anal fins in males (vs. absence). It can be further diagnosed from H. brumado by the overall silvery body color in life (vs. orange- to reddish) and from H. negodagua by the absence of dense concentration of dark chromatophores over dorsum and posterior portion of body (vs. presence) and by the presence of adipose fin (rarely absent, 1 of 294 specimens) (vs. usually absent; 4 of 158 with adipose fin; see discussion for further details).

Description. Morphometric data in Table 1 . Body compressed, moderately elongate. Greatest body depth slightly anterior to dorsal-fin origin. Dorsal profile of head convex from upper lip to vertical through anterior nostril; slightly convex from that point to tip of supraoccipital spine. Dorsal profile of body slightly convex along predorsal region, straight and posteroventrally inclined along dorsal-fin base, slightly convex from terminus of dorsal-fin base to adipose-fin origin, and concave to origin of anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head and body convex from tip of lower lip to pelvic-fin origin, straight to slightly concave between latter point to origin of anal-fin origin, straight to slightly convex and posterodorsally inclined along anal-fin base, and concave to origin of anteriormost ventral procurrent caudal-fin ray.

Jaws equal, mouth terminal. Premaxillary teeth in two rows. Outer row with 2(3), 3(19), 4(7), or 5*(1) conical or tricuspid teeth. Inner row with 5*(29) or 6(1) tri- to pentacuspid teeth. Posterior tip of maxilla at vertical through posterior half of second infraorbital. Maxilla with 1(18), 2*(11), or 3(1) conical or tricuspid teeth. Dentary with 3*(30) larger teeth, medial tooth tri- to pentacuspid, lateral teeth tricuspid, followed by one smaller conical or tricuspid, and a series of 6(2) diminute conical teeth. Central median cusp in all teeth longer than lateral cusps. Branchiostegal rays 4(2). First gill arch with 1(1) or 2(1) gill rakers on hypobranchial, 7(1) or 8(1) rakers on ceratobranchial, 1(2) rakers on intermediate cartilage, and 4(1) or 5(1) rakers on epibranchial.

Scales cycloid, with 3-5 radii on posterior border, and conspicuous circulii anteriorly. Lateral line incomplete, with 5(1), 6(10), 7*(12), or 8(7) perforated scales, and 31(9), 32*(17), 33(2), or 34(2) scales on longitudinal series. Longitudinal scale rows between dorsal-fin origin and lateral line 5*(24) or 6(6). Longitudinal scale rows between lateral line and pelvic-fin origin 4*(22) or 5(8). Scales along middorsal line between tip of supraoccipital process and dorsal-fin origin 10(5), 11*(19), or 12(6). Horizontal scale rows around caudal peduncle 14*(30). Base of anteriormost anal-fin rays covered by a series of 4 or 5 scales. Caudal fin not scaled.

Supraneurals 4(1) or 5(1). Dorsal-fin rays ii*(27) or iii(3), 8(3) or 9*(27). First dorsal-fin pterygiophore inserted posterior to neural spine of 10 th vertebra (2). Base of last dorsal-fin ray at vertical through base of first branched anal-fin ray. Pectoralfin rays i*(30), 9(8), 10(20), or 11*(2). Pelvic-fin rays i,6*(30). Adipose fin of variable size, present in 294 specimens, absent in one individual (MZUSP 40894; Fig. 4 ). Anal-fin falcate, with iii(16) or iv*(14), 15(6), 16*(15), 17(8), or 18(1) branched rays. First anal-fin pterygiophore inserted posterior to haemal spine of 16 th (2) vertebra. Principal caudal-fin rays i,9/8,i*(30); caudal fin forked, lobes somewhat pointed, of similar size. Dorsal procurrent caudal-fin rays 9(2); ventral procurrent caudal-fin rays 5(1) or 7(1). Total vertebrae 31(1) or 32(1): precaudal vertebrae 14(1) or 15(1) and caudal vertebrae 17(2). Color in alcohol. Overall ground coloration pale ( Fig. 1 ). Infraorbital, opercular, and gular areas retaining some guanine. Dorsal portion of head and body dark. Dark chromatophores concentrated at upper and lower jaws and upper portion of opercle. Upper and lower lips with a dark line. Some specimens with dark chromatophores scattered at infraorbital series. Humeral spot absent.A thin longitudinal line formed by embedded dark pigmentation along horizontal septum, approximately from vertical through pelvic-fin origin to caudal peduncle. No evident longitudinal stripe, some specimens from rio Tocantins basin with more intense concentration of chromatophores along the midlateral body line. Body pigmented by small dark chromatophores, more intense at its dorsolateral portion, fading ventrally. Some specimens with slight reticulated pattern on first two horizontal scale rows, formed by concentration of chromatophores on the posterior portion of scales. Abdominal region devoid of chromatophores. Distal portion of dorsal and anal fins with dark pigmentation on interadial membranes, more intense in males than in females ( Figs. 1 b- c, respectively). A well-defined black round spot extending from posterior half of caudal peduncle to base of middle caudal-fin rays ( Figs. 1c ; 6a, c ), or reaching their tips ( Figs. 1a, b ; 6b ). All fins with dark chromatophores along edge of lepidotrichia.

Color in life. Coloration in life similar to described above for preserved specimens, except for overall body coloration silver to yellowish. Infraorbitals, preopercle, and opercle silvery. Dorsal portion of iris yellow to orange. Pectoral, pelvic, and anal fins slightly yellowish to almost hyaline. Some specimens with distal portion of first anal-fin rays distinctly darker, especially males ( Fig. 3a ). Dorsal and adipose fins orange- to slightly yellowish. Conspicuous black blotch over caudal peduncle and median caudal-fin rays. Caudal fin orange- to slightly yellowish ( Figs. 3a, b ).

Sexual dimorphism. Mature males with dorsal (30.2-39.7%, mean = 33.1% of SL) and anal fins (22.5-34.6%, mean = 26.4% of SL) longer than in females (24.7-31.3%, mean = 28.0%, 19.0-

23.0%, mean = 20.8% of SL, respectively) ( Fig. 4 ). Bony hooks on fins were not found in any specimen analyzed. Based on the five photographed live specimens, two males and three females, it is possible that Hyphessobrycon diastatos presents sexual dimorphic coloration in life. Males have dorsal and caudal fins orange, and distal portion of first dorsal- and analfin rays dark ( Fig. 3a ). Females have slightly yellowish to almost hyaline fins ( Fig 3b ).

Geographic distribution. Hyphessobrycon diastatos is known from tributaries of the rio Grande (rio São Francisco basin) draining east to the Serra Geral de Goiás, from the rio São Domingos (upper rio Tocantins basin) and rio do Sono basins (middle rio Tocantins basin) ( Fig. 5 ) .

Etymology. The specific name diastatos comes from the Greek, meaning divided, in reference to its geographic distribution in both the rio São Francisco and the rio Tocantins basins.

Habitat and ecological notes. Hyphessobrycon diastatos was collected in clear water streams running over submerged vegetation and sandy bottom, at altitudes ranging from 430

to 935m above sea level, with relatively swift water current. The riparian vegetation is mainly composed of grass, herbs, and shrubs. Analysis of stomach contents of four specimens revealed the presence of allochthonous and autochthonous items, composed of fragments of plants, organic debris, insect larvae (Diptera and Trichoptera : Hydroptilidae ), fragments of adults of terrestrial insects ( Hymenoptera : Formicidae, Orthoptera , and unidentified orders) and of other unidentified arthropods. One specimen (MZUSP 114029) has a parasitc Isopoda attached to the inside its urogenital cavity.

Figures

Fig. 1. Hyphessobrycon diastatos, all from Brazil, Bahia, São Desidério, rio Galheirão (or rio da Estiva), affluent of rio Grande, rio São Francisco basin, (a) holotype, MZUSP 114030, 24.4 mm SL, male, (b) paratype, MZUSP 114029, 25.2 mm SL, male, and (c) paratype, MZUSP 114029, 20.8 mm SL, female.

Fig. 2. Hyphessobrycon diastatos, paratype, MZUSP 114026, 19.2 mm SL; medial view of left side, upper and lower jaws. Part of Meckel’s cartilage damaged was reconstituted using graphic software. Coronomeckelian is missing.

Fig. 3. Live coloration of Hyphessobrycon diastatos. (a) paratype, MZUSP 114029, 25.2 mm SL, male, Brazil, Bahia, São Desidério, rio Grande drainage, rio São Francisco basin, and (b) paratype, MZUSP114031, 26.7 mm SL, female, first anal-fin rays broken, Brazil, Goiás, São Domingos, rio São Domingos, rio Tocantins basin.

Fig. 4. Fin lengths as function of standard length by sex in males (black square, n = 20) and females (white circle, n = 14) of Hyphessobrycon diastatos, (a) dorsal fin, and (b) anal fin.

Fig. 6. Adipose fin variation in Hyphessobrycon diastatos, paratypes, all from MZUSP 114029, (a) 20.1 mm SL, (b) 19.4 mm SL, and (c) 18.1 mm SL. Arrows indicate the position of the adipose fin.

Fig. 5. Distribution of Hyphessobrycon diastatos in the middle rio São Francisco basin and upper and middle rio Tocantins basin, Brazil. Yellow dot represents the holotype and red dots the paratypes. Each dot may represent more than one collection event.