Bunocephalus larai , Ihering 1930

<i>Bunocephalus larai</i> Ihering, 1930 <p>(Fig 1, Table 1)</p> <p> <i>Bunocephalus larai</i> Ihering, 1930: 101, Fig. 4. [type-locality: Rio Piracicaba, junto ao Salto e a 20km abaixo (ilha das flechas) (= Brazil, São Paulo State: Piracicaba Municipality: upper Rio Paraná basin, Rio Piracicaba, a tributary of the Rio Tiete, at Salto, 22º42’59”S 47º39’12”W, and 20 km downstream, at Ilha das Flechas, 22º42’15”S 47º44’29”W)].</p> <p> <i>Dysichthys larai</i>; Mees 1989: 238 [brief redescription; distribution]</p> <p> <b>Syntypes:</b> 3, Instituto Biológico de São Paulo, lost.</p> <p> <b>Nontypes:</b> All from Brazil. DZSJRP 15967, 1, 55.5 mm SL; Goiás State: Indiara Municipality: Rio Paranaíba, Rio Capivari, 17º12’22”S 50º6’20”W; S. Britto <i>et al.</i>, 8 Jun 2012.− LBP 11715, 3, 54.6–59.1 mm SL; Minas Gerais State: Rio Paranaíba Municipality: Rio Paranaíba, in a small tributary, 19º9’5”S 46º15’47”W; C. Oliveira <i>et al.</i>, 18 May 2011.− LIRP 9991, 1, 49.5 mm SL; Goiás State: Campo Alegre de Goiás Municipality: upper Rio Paraná, Rio Paranaíba, Ribeirão Ponte Alta, a tributary of the Rio São Marcos, 17º16’33”S 47º45’09”W; R. Campos da Paz, M. I. Landim, 21 May 2004.− MCP 28376, 2, 47.2–48.6 mm SL; Minas Gerais State: Rio Paranaíba Municipality: Rio Paranaíba, in a small tributary, 19º9’5”S 46º15’46”W; C. Lucena <i>et al.</i>, 26 Jan 2001.− MCP 28377, 2, 51.1–56.1 mm SL, 1 CS, 53.9 mm SL; Minas Gerais State: Rio Paranaíba Municipality: Rio Paranaíba, Ribeirão de Fora, 19º11’57”S 46º21’48”W; C. Lucena <i>et al.</i>, 26 Jan 2001.− MZUEL 114, 1 CS, 53.7 mm SL; Paraná State: Jataiz- inho Municipality: Rio Tibagi, 23º18’36”S 50º59’45”W; M. Rodrigues, 10 Aug 1990.− MZUEL 6800, 1, 53.7 mm SL; Minas Gerais State: Patrocínio Municipality: Rio Paranaíba, Córrego Nhame, 18º59’14”S 46º41’37”W; L. F. Salvador, 27 Feb 2013.– MZUSP 22623, 1, 43.8 mm SL; Mato Grosso do Sul State: Três Lagoas Municipality: Rio Paraná, in front of Jupiá, near the Rio Sucuri mouth, 20º45’S 51º37’W; S. Sair & J. H. Vanzolini, 11 Dec 1960.</p> <p> <b>Diagnosis.</b> <i>Bunocephalus larai</i> can be distinguished from all its congeners, except <i>B. hertzi</i> and <i>B. minerim</i>, by the absence of an epiphyseal bar (<i>vs</i>. present). From <i>B. minerim</i>, it can be diagnosed by the presence of 10 principal caudal-fin rays (<i>vs.</i> 9). <i>Bunocephalus larai</i> can be further distinguished from <i>B. hertzi</i>, the only congener that also occurs in the upper Rio Paraná basin, by the shorter coracoid process size (6.7–9.8% <i>vs</i>. 11.9–16. 2% SL) and the longer maxillary barbel (73.7%–84.6 <i>vs</i>. 54.6–67.4% HL), which extends beyond pectoral-fin origin, distinctly surpassing this point (<i>vs.</i> just reaching the pectoral-fin origin). In addition, <i>B. larai</i> presents skull ornamentation composed by four bony protuberances between the posterior end of the occipital and the origin of the dorsal fin (<i>vs</i>. five).</p> <p> <b>Description.</b> See Fig. 1 for general appearance. Morphometric data for 11 non-types are presented in Table 1. Head dorsoventrally compressed, straight and posterodorsally inclined from tip of snout to posterior tip of occipital. Body widest at cleithrum, greatest depth slightly ahead of dorsal-fin origin. Posterodorsal profile of body straight and posteroventrally inclined from dorsal-fin origin to near base of caudal-fin, becoming slight concave anteriorly to base of caudal-fin. Ventral profile of body convex from tip of snout to near pelvic-fin origin, straight to first analfin ray, and slightly concave from anal-fin origin to base of caudal-fin.</p> <p>Skull ornamentation represented by four dorsomedial bony protuberances (Fig. 2): a protuberance located at posterodorsal end of supraoccipital, formed by posterior dorsal tip of supraoccipital and anterodorsal tip of complex centrum of Weberian apparatus; two smooth protuberances, posterior higher than anterior one, along dorsal edge of complex centrum of Weberian apparatus; and a prominent protuberance at dorsal face of middle nuchal plate, just anterior to first dorsal-fin origin. Frontals in contact anteriorly to cranial fontanel. Epiphyseal bar between paired frontals absent.</p> <p>Eye small, without free orbital margin, located dorsally in anterior half of head. Anterior nostril tubular, located at anterior edge of snout, projecting beyond upper lip; posterior nostril as small opening located anteromedially to eye. All barbels unbranched; maxillary barbel extending beyond pectoral-fin origin, distinctly surpassing this point; two pairs of mental barbels, both shorter than maxillary barbels; anterior mental barbel shortest, its length less than one third length of posterior mental barbel. Mouth subterminal, upper lip more prominent relative to lower lip. Gill openings small, restricted to two ventral valvular slits covered by fleshy skin flaps, located just anterior to pectoralfin spines insertions. Gill membranes united to isthmus. Axial slit pore present, just underneath posterior cleithral process. Small genital papillae just posterior to anus. Unculiferous tubercles densely distributed all over integument; larger tubercles on posterior portion of body longitudinally aligned, forming defined rows on caudal-peduncle, one middorsal, two above lateral-line, one over lateral-line, and one below lateral-line.</p> <p>Dorsal-fin i4*(13); located slightly anterior to mid-standard length. Dorsal-fin spinelet absent; less than half length of last dorsal-fin ray adnate to dorsum by membrane. Adipose-fin absent. Anal-fin ii6(1), iii4(1), iii5*(8), iii6(1), or iv5(2); its origin just posterior to tip of longest ray of abducted pelvic-fin; less than half-length of last anal-fin ray adnate to ventral region of caudal peduncle by membrane. Pectoral-fin I5*(13); its origin just posterior to gill opening, tip reaching pelvic-fin origin; pectoral spine slight curved, bearing recurved serrations all over anterior and posterior margins; serrations increasing in number according to body size, maximum of fourteen serrations over each margin. Pelvic-fin i5*(13); its origin just posterior to vertical through dorsal-fin origin. Principal caudalfin rays i8i; caudal-fin distal profile convex. Caudal-fin unbranched rays shorter than branched rays. Two procurrent caudal-fin rays, first one vestigial. Total vertebrae 33(3), 34*(6), 35(4). Ribs 4*(13). Lateral-line canal complete, not reaching caudal-fin origin; presence of simple ossified tubes, each bearing small hook at posterior region of tube.</p> <p> <b>Color in alcohol.</b> Ground color of dorsal region of body and head dark brown, ventral region light brown. Three black dorsal saddles on the body; first saddle conspicuous, located at and as wide as te dorsal-fin base, extending to ventral region, not surpassing below lateral-line; and two inconspicuous saddles on posterior body region, last one anterior to the caudal-fin origin. Pectoral-fin brown, pelvic and anal fins light yellow with dark blotches, dorsal-fin dark brown with light yellow distal portion, first dorsal-fin ray yellow. Caudal-fin yellow at base and dark brown at posterior portion. All barbels light brown with scattered dark brown blotches.</p> <p> <b>Distribution.</b> <i>Bunocephalus larai</i> is known from the upper Rio Paraná basin, with registered occurrences in the Rio Tiete (Rio Piracicaba), Rio Paranapanema (Rio Tibagi), and Rio Paranaiba (Rio Capivari, Córrego Nhame, and in the headwaters of Rio Paranaiba) basins, and in the Rio Paraná, near the Rio Sucuri mouth (Fig. 3).</p> <p> <b>Remarks.</b> In the description of <i>Bunocephalus larai</i>, Ihering (1930) reported three morphological characteristics that helped us to stablish the morphotype that represents <i>B. larai</i>, since the syntypes are lost (as already reported by Lucinda <i>et al</i>., 2005), and to discriminate it from <i>B. hertzi</i>, described herein: the size of the maxillary barbel, longer in <i>B. larai</i>; the skull ornamentation, composed by four bony protuberances, situated between the posterior end of the occipital and the origin of the dorsal fin, while in <i>B. hertzi</i> it is composed by five prominent bony protuberances; and the coracoid process length, reported as from a third to half length of pectoral-fin basis to <i>B. larai</i>, but extending to near posterior end of pectoral-fin basis in <i>B. hertzi.</i></p>Published as part of <i>Esguícero, André L. H., Castro, Ricardo M. C. & Pereira, Thiago N. A., 2020, Bunocephalus hertzi, a new banjo catfish from the upper Rio Paraná basin, Brazil (Siluriformes: Aspredinidae), with the redescription of Bunocephalus larai Ihering 1930, pp. 105-116 in Zootaxa 4742 (1)</i> on pages 106-109, DOI: 10.11646/zootaxa.4742.1.6, <a href="http://zenodo.org/record/3674515">http://zenodo.org/record/3674515</a&gt

Bunocephalus hertzi, a new banjo catfish from the upper Rio Paraná basin, Brazil (Siluriformes: Aspredinidae), with the redescription of Bunocephalus larai Ihering 1930

Esguícero, André L. H., Castro, Ricardo M. C., Pereira, Thiago N. A. (2020): Bunocephalus hertzi, a new banjo catfish from the upper Rio Paraná basin, Brazil (Siluriformes: Aspredinidae), with the redescription of Bunocephalus larai Ihering 1930. Zootaxa 4742 (1): 105-116, DOI: 10.11646/zootaxa.4742.1.

Fragmentation of a Neotropical migratory fish population by a century-old dam

Loss of connectivity in impounded rivers is among the impacts imposed by dams, and mitigation measures such as fish passages might not accomplish their purpose of reestablishing an efficient bi-directional gene flow in the fish populations affected. As a consequence, fish populations remain fragmented, and a new interpopulational structure may develop, with increased risk of reduced genetic diversity and stochastic extinction. In order to evaluate the effects of the Gavio Peixoto Dam, which was constructed almost a century ago on the Jacar,-Gua double dagger u River in the Upper Parana River basin, Brazil, a comparative morphometric study was undertaken on the populations of the Neotropical migratory characid fish Salminus hilarii living up- and downstream of this dam. Population dynamics, spatial segregation, and habitat use by different age classes were monitored for 2 years. We found that segregation caused by the dam and long periods with no efficient connection by fish passages have led to fragmentation and interpopulational structuring of S. hilarii, as revealed by canonical variable analysis of morphometric features. The fish populations occupying the up- and downstream sections have succeeded in performing short-distance reproductive migrations in the main river and tributaries, have found suitable habitats for completing their life cycle, and have been able to maintain distinct small-sized populations so far