Characidium samurai Zanata &amp; Camelier 2014, new species
Creators: name: Zanata, Angela M.
name: Camelier, Priscila
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Characiformes
Crenuchidae
Characidium
Characidium samurai

description: <i>Characidium samurai</i>, new species <b>Fig. 1</b> <b>Holotype.</b> MZUSP 108188, 46.6 mm SL, Brazil, Bahia, Piraí do Norte, rio do Peixe, tributary of rio das Almas, 13°46’35”S 39°23’40”W, 177 m a.s.l., 13 Aug 2012, O. T. Oyakawa, A. M. Zanata, P. Camelier &amp; T. F. Teixeira. <b>Paratypes.</b> All from Brazil, Bahia, rio das Almas basin: MZUSP 112385, 9, 1 mol, 25.4-42.7 mm SL, UFBA 7259, 7, 20.8-42.6 mm SL, collected with holotype. MNRJ 40727, 4, 31.6-39.2 mm SL, UFBA 5971, 9, 2 c&amp;s, 29.3-40.9 mm SL, Piraí do Norte, rio do Peixe, a tributary of rio das Almas, 13°46’35”S 39°23’40”W, 177 m a.s.l., 8 Oct 2009, A. M. Zanata, P. Camelier, R. Burger &amp; A. B. A. Góes. MZUSP 111239, 5, 1 c&amp;s, 1 mol, 28.1-42.6 mm SL, Nilo Peçanha, rio das Almas, about 10 km of Nilo Peçanha, 13°36’27.8”S 39°08’38.8”W, 17 m a.s.l., 12 Aug 2012, J. L. Birindelli, F. C. Dagosta &amp; M. V. Loeb. UFBA 5726, 3, 26.4-31.3 mm SL, Piraí do Norte, small stream under bridge between Piraí do Norte and Gandú, 13°43’59”S 39°24’20”W, 157 m a.s.l., 8 Oct 2009, A. M. Zanata, P. Camelier, R. Burger &amp; A. B. A. Góes. Rio Vermelho basin: UFBA 7258, 5, 27.9 -34.0 mm SL, Taperoá, rio Sarapuí, at Pousada Paraíso das Ilhas, 13°30’05.2”S 39°05’50.4”W, 24 m a.s.l., 12 Aug 2012, J. L. Birindelli, F. C. Dagosta &amp; M. V. Loeb. <b>Diagnosis.</b> <i>Characidium samurai</i> can be distinguished from its congeners, except <i>C</i>. <i>lanei</i> Travassos, by the presence of a dark lateral band along the head and body that is particularly broad (1.5 or 2 scales wide) from the rear of head to the end of the caudal peduncle and by the absence of dark bars or blotches on the ventral half of the body. The new species differs from <i>C. lanei</i> by having the lateral band with straight borders overall (<i>vs.</i> lateral band with somewhat irregular borders due to blotches slightly extending dorsally or ventrally), absence of dark pigmentation around the insertion of the dorsal-fin rays (<i>vs.</i> presence), anal fin ii,7-8 (<i>vs.</i> ii,6), and 4 horizontal scale rows above the lateral line and 4 below (<i>vs.</i> 5/3). <i>Characidium samurai</i> further differs from congeners that occur in Brazilian rivers by having a complete lateral line (<i>vs.</i> incomplete in <i>C. bahiense</i>, <i>C. interruptum</i> Pellegrin, <i>C</i>. <i>laterale</i> (Boulenger), <i>C. mirim</i> Netto-Ferreira, Birindelli &amp; Buckup, <i>C</i>. <i>nupelia</i> Graça, Pavanelli &amp; Buckup, <i>C</i>. <i>rachovii</i> Regan, <i>C. stigmosum</i> Melo &amp; Buckup, and <i>C. xavante</i> Graça, Pavanelli &amp; Buckup), isthmus completely covered by scales (<i>vs.</i> isthmus naked or partially covered by scales in <i>C. alipioi</i> Travassos, <i>C. boavistae</i> Steindachner, <i>C. crandellii</i> Steindachner, <i>C. declivirostre</i> Steindachner, <i>C. fasciatum</i>, <i>C. gomesi</i> Travassos, <i>C. grajahuensis</i> Travassos, <i>C</i>. <i>japuhybense</i> Travassos, <i>C. lauroi</i> Travassos, <i>C. macrolepidotum</i> (Peters), <i>C. oiticicai</i> Travassos, <i>C. schubarti</i> Travassos, <i>C. timbuiense</i>, and <i>C. vidali</i> Travassos), 14 scales around the caudal peduncle (<i>vs.</i> 10 or 12 in <i>C. bahiense</i>, <i>C. brevirostre</i> Pellegrin, <i>C</i>. <i>gomesi</i>, <i>C</i>. <i>heirmostigmata</i> Graça &amp; Pavanelli, <i>C</i>. <i>lagosantense</i>, <i>C. macrolepidotum</i>, <i>C. mirim</i>, <i>C</i>. <i>nupelia</i>, <i>C</i>. <i>occidentale</i> Buckup &amp; Reis, <i>C</i>. <i>orientale</i> Buckup &amp; Reis, <i>C. papachibe</i> Peixoto &amp; Wosiacki, <i>C</i>. <i>rachovii</i>, <i>C</i>. <i>serrano</i> Buckup &amp; Reis, <i>C</i>. <i>tenue</i> (Cope), <i>C</i>. <i>xanthopterum</i> Silveira, Langeani, da Graça, Pavanelli &amp; Buckup, <i>C. xavante</i>, and <i>C. zebra</i> Eigenmann), and presence of adipose fin (<i>vs.</i> absent in <i>C. mirim</i>, <i>C. nupelia</i>, <i>C. stigmosum</i>, <i>C. xavante</i> and absent or reduced in <i>C</i>. <i>vestigipinne</i> Buckup &amp; Hahn). <i>Characidium samurai</i> can be further distinguished from congeners by the absence of dark bars or spots on the fins, except for a faded dorsal-fin bar (<i>vs.</i> presence of conspicuous dark bars or spots at least on one fin in <i>C</i>. <i>alipioi</i>, <i>C. brevirostre</i>, <i>C. declivirostre</i>, <i>C. gomesi</i>, <i>C</i>. <i>grajahuensis</i>, <i>C. hasemani</i> Steindachner, <i>C</i>. <i>japuhybense</i>, <i>C</i>. <i>lauroi</i>, <i>C</i>. <i>macrolepidotum</i>, <i>C</i>. <i>occidentale</i>, <i>C. oiticicai</i>, <i>C</i>. <i>orientale</i>, <i>C. papachibe</i>, <i>C</i>. <i>pterostictum</i> Gomes, <i>C</i>. <i>rachovii¸ C. serrano</i>, <i>C. schubarti</i>, <i>C. steindachneri</i> Cope, <i>C. timbuiense</i>, <i>C. vestigipinne</i>, <i>C. vidali</i>, and <i>C. zebra</i>), and analfin rays ii,7-8 (<i>vs.</i> ii, 6 in <i>C. brevirostre</i> and <i>C. roesseli</i> Géry). Concerning congeners known to occur in northeastern Brazilian rivers, <i>C. samurai</i> further differs from <i>C. bahiense</i> by having the aperture of the pseudotympanum enclosed between ribs of the fifth and sixth vertebrae (<i>vs.</i> aperture surpassing the ribs of the fifth vertebra anteriorly and/or sixth vertebra posteriorly), presence of the parietal branch of the supraorbital canal (<i>vs.</i> absence), two series of teeth on the dentary (<i>vs.</i> one), and 7-11 premaxillary teeth (<i>vs.</i> 5-8); from <i>C</i>. <i>bimaculatum</i> by having 7-8 branched anal-fin rays (<i>vs.</i> 5-6), usually a higher number of lateral-line scales (34-37 <i>vs.</i> 32-34), one faded dark bar on the proximal half of the dorsalfin rays (<i>vs.</i> a conspicuous black bar at the proximal portion of the rays and a second faded bar on the distal portion), and absence of a blotch on the caudal peduncle, or blotch merged to the longitudinal bar (<i>vs.</i> a conspicuous elongated caudal blotch); from <i>C</i>. <i>fasciatum</i> and <i>C</i>. <i>lagosantense</i> by having ii,7-8 anal-fin rays (<i>vs.</i> iii,5-6). <b>Description.</b> Morphometric data of the holotype and paratypes presented in Table 1. Body elongate and moderately compressed. Greatest body depth at vertical through dorsalfin origin. Dorsal profile convex from upper lip to vertical through nares, slightly convex from this point to end of occipital process, slightly convex or straight from this point to origin of dorsal-fin base, convex along dorsal-fin base, almost straight between end of dorsal-fin base and adipose fin, slightly concave from this point to origin of anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head straight, except for the convex portion close to dentary symphysis, slightly convex from isthmus to pelvic-fin origin, straight from latter point to anal-fin origin, slightly concave from this point to origin of anteriormost ventral procurrent caudal-fin ray. Snout triangular in lateral view. Mouth subterminal, aligned or slightly lower than ventral edge of the orbit. Distal tip of maxilla barely reaching the vertical through anterior margin of orbit. Orbit approximately round, larger than snout length. Cheek thin, its depth approximately one third to one quarter of orbit diameter. Nares separated; anterior naris with raised margins; posterior naris considerably closer to orbit than to anterior naris and without skin flaps. Supraorbital elongated in dorsal view, medial margin slightly convex, abutting the frontal, and lateral margin straight; anterior and posterior tip similarly pointed. Parietal fontanel limited anteriorly by frontals. Parietal branch of supraorbital canal present, slightly surpassing frontal-parietal border or extending to one third of parietal. Orbithosfenoid slightly rectangular in lateral view, connected anteriorly to rhinosphenoid. Pterosphenoid foramen for ophthalmic nerve relatively small, formed by tunnel crossing pterosphenoid diagonally, bordered by bony crest that prevents direct lateral view of brain cavity through foramen. Dentary teeth in two rows; outer series with 10(5), 11*(5), 12(4), or 13(1) teeth; anterior two to four teeth from symphysis usually tricuspid, posterior conical; teeth decreasing in size from symphysis; inner series with several minute conical teeth inserted on edge of replacement tooth trench. Premaxilla with single series of 7*(4), 8(21), 9(11), or 10(1) conical teeth, decreasing in size from symphysis. Maxillary edentulous. Ectopterygoid with a single series of 7(1) or 10(2) conical teeth. Mesopterygoid teeth absent. Scales cycloid; <i>circulii</i> absent on posterior field of scales located immediately below 10 th scale of lateral line, 6 to 12 <i>radii</i> present. Lateral line complete, perforated scales 34(6), 35(28), 36*(5), or 37(2); horizontal scale rows above lateral line 4*(40); horizontal scale rows below lateral line 4*(40). Scales along middorsal line between supraoccipital and origin of dorsal fin 9(2), 10(16), 11*(7) or 12(2) in single row or irregularly arranged (8). Scale rows around caudal peduncle 14*(38). Isthmus completely scaled. Pseudotympanum present, represented by muscular hiatus at vertical through anterior portion of swimbladder and situated between ribs of the fifth and sixth vertebrae (see ‘Remarks’ for details). Dorsal-fin rays ii,9(1), ii,9,i(2), iii,9(3) or ii,10*(33); distal margin of dorsal fin rounded.Adipose fin present. Pectoral-fin rays highly variable, ii,9,i(2), iii,5,iii(4), iii,6,ii(1), iii,7,ii(3), iii,8,i*(19), iii,8ii,(1), or iii,9,i(2); first and second branched pectoral-fin rays longest; posterior tip of pectoral fin not reaching pelvic-fin insertion. Pelvic-fin rays i,7,i*(40); second to fourth branched pelvic-fin rays longest; posterior tip of pelvic fin not reaching anal-fin origin. Anal-fin rays ii,7*(39) or ii,8(1); posterior margin of anal fin varying from rounded to straight; fin elements (<i>i.e.</i>, adnate rays) on last pterygiophore 2*(16). Caudal-fin rays i,8,8,i*(2), i,9,8,i*(35), or i,9,9,i(1). Dorsal procurrent caudal-fin rays 8(3); ventral procurrent caudal-fin rays 7(1) or 8(2). Total number of vertebrae 34(1) or 35(2); precaudal vertebrae 18(1) or 19(2); caudal vertebrae 15(2) or 17(1). Supraneural bones 5(1) or 6(2), anterior to neural spine of fifth centrum. Epural bones 2(3). Uroneural bones 1(3). Branchiostegal rays 4(3); 2 or 3 connected to anterior ceratohyal, 1 connected to the cartilage between anterior and posterior ceratohyals, none or 1 connected to posterior ceratohyal. <b>Color in alcohol.</b> Ground color of head and body pale yellow, with dorsum darker (Fig. 1a). Small melanophores concentrated over dorsal and anterior portion of head; superior half of maxilla, upper and lower lip distinctly darker. Dark band extending from snout to posterior margin of opercle. Ventral half of head clear, with sparse small melanophores, except by the dark lower lip. Scales of dorsal half of body with melanophores concentrated on posterior margin of scales, resulting in somewhat reticulated aspect. Dorsal half of body with 8 to 10 inconspicuous dark vertical bars, broader dorsally (usually 3 scales wide), merged ventrally with dark longitudinal band. Most specimens with vertical bars inconspicuous and merged to one another resulting in dark and somewhat homogeneous dorsal half of body. Broad dark band (1.5 or 2 scales wide) with straight borders extending from rear of opercle to end of caudal peduncle. Dark humeral blotch on rear of opercle merged to longitudinal band and somewhat inconspicuous; in some specimens visible as a rounded or somewhat triangular and vertically elongated blotch. Ventral half of body yellowish, without dark bars or spots. Some specimens with concentrations of dark chromatophores on posterior border of scales situated on the row immediately below dark longitudinal stripe but not forming stripes or blotches. Ventral area located between pelvic and anal fin origins with dark narrow stripe, usually conspicuous on specimens of 30 mm SL or smaller and faded on larger specimens. Fins with melanophores sparsely distributed on border of rays, more concentrated on distal half. Dorsal fin with faded dark band below midlength of rays. Small dark round spot near base of middle caudal-fin rays. Adipose fin somewhat dark, with sparse melanophores. <b>Color in life</b>. Ground color of dorsal half of body grayish and ventral half whitish (Fig. 1b). Dark lateral band extending from snout tip to end of caudal peduncle; band usually poorly visible immediately after the fish capture but clearly conspicuous if the specimen is allowed to stay a few minutes alive in a container such as a plastic bag. Approximately ten inconspicuous dark vertical bars over dorsal half of body; bars larger dorsally and not extending beyond ventral border of dark longitudinal band. Ventral half of body without dark bars or spots. Yellow chromatophores sparsely distributed over opercle, infraorbitals, ventral half of iris, and area posterior to opercle. Fins yellowish. <b>Etymology.</b> The name <i>samurai</i> is given to honor the Japanese warrior caste that provided the administrative and fighting aristocracy from the 11 th to the 19 th centuries. The samurais are known by their expertise in several kinds of martial arts.Currently, expertise in martial art is attested by the term “black belt”, a condition inherent to that warrior caste. The name samurai was used herein in allusion to the conspicuous midlateral black band present in the new species. A noun in apposition. <b>Sexual dimorphism.</b> No hooks on fins or other sexually dimorphic features were observed externally on the specimens that were examined. <b>Distribution.</b> <i>Characidium samurai</i> is known from the rio das Almas and rio Vermelho basins, two small coastal river systems at the central coastal area of Bahia State, eastern Brazil (Fig. 2a). Extensive ichthyological collecting efforts in the main coastal rivers across Bahia in the last eight years have failed to yield samples of <i>C. samurai</i> from another river drainages, making it possible that the species is endemic to rio das Almas (Figs. 2 b-c) and rio Vermelho basins (Fig. 2d). <b>Habitat and ecological notes.</b> <i>Characidium samurai</i> was collected in clear water streams with water running over rocks, pebbles, sand and/or muddy bottoms, at altitudes ranging from 17 to 177 m a.s.l. in habitats characterized mainly by moderate water current. The riparian vegetation mainly comprises remnants of the Atlantic Forest, cocoa trees or cattle pasture. The rio do Peixe (a tributary of rio das Almas basin), the type locality and where most specimens were collected, is approximately 2 m wide, 1-2 m deep, and has a medium to fast water current, muddy substrate and grassy river borders (Fig. 2b). <i>Characidium samurai</i> was collected syntopically with <i>Characidium</i> aff. <i>timbuiense</i>, <i>Awaous tajasica</i> (Lichtenstein), <i>Astyanax</i> aff. <i>bimaculatus</i> (Linnaeus), <i>Astyanax</i> sp., <i>Dormitator maculatus</i> (Bloch), <i>Geophagus</i> sp., <i>Gymnotus carapo</i> Linnaeus, <i>Hoplias malabaricus</i> (Bloch), <i>Leporinus bahiensis</i> Steindachner, <i>L. melanopleurodes</i> Birindelli, Britski &amp; Garavello, <i>Hypostomus</i> sp., <i>Parotocinclus</i> sp., <i>Poecilia reticulata</i> Peters, <i>Sycidium punctatum</i> (Perugia), and <i>Synbranchus marmoratus</i> Bloch. The analysis of stomach contents of the three c&amp;s specimens revealed the presence of vascular plant fragments, Trichoptera (Hydroptilidae) larvae, adults of terrestrial insects (Hymenoptera: Formicidae and Orthoptera), and fragments of unidentified arthropods. <b>Remarks.</b> The new species described herein apparently does not fit in any group of <i>Characidium</i> that has been previously proposed in the literature (<i>e.g.</i>, Buckup &amp; Reis, 1997; Buckup &amp; Hahn, 2000; Graça &amp; Pavanelli, 2008) and does not share any synapomorphy that was hypothesized by Buckup (1993a) to any particular subgroup of Clade C. Although <i>C. samurai</i> externally resembles <i>C. lanei</i>, a member of clade C4 of Buckup (1993a), particularly by sharing a broad dark longitudinal band, the new species has the parietal branch of the supraorbital canal, the absence of which is a diagnostic feature of clade C4. <i>Characidium samurai</i> also does not share the two synapomorphies of the species included in the C4 clade that were previously proposed by Buckup &amp; Reis (1997) and Buckup &amp; Hahn (2000): an increased number of vertical bars on the sides of the body and an absence of the inner row of dentary teeth. Various populations of <i>Characidium</i> that have been sampled in rivers draining Bahia State are usually left unidentified or are tentatively identified as species described to nearby drainages, accompanied by the terms “ <i>affinis</i> ” or “ <i>confer</i> ”(<i>Characidium</i> sp., <i>C</i>. cf. <i>bahiense</i>, <i>C.</i> cf. <i>bimaculatum</i>, and <i>C.</i> aff. <i>timbuiense</i>, <i>e.g.</i>, Santos &amp; Caramaschi, 2007, 2011; Sarmento-Soares <i>et al.</i>, 2008, 2009; Cetra <i>et al.</i>, 2010; Burger <i>et al.</i>, 2011). These tentative identifications are actually indicative of the current poor taxonomical knowledge about the <i>Characidium</i> species in that region, which very likely, harbors several undescribed species of the genus. Thus, the only <i>Characidium</i> species that can be considered to be reliably documented for the coastal river drainages of Bahia State is <i>C. bahiense</i>, described from Arembepe, at the northern coastal area of the state. Furthermore, examination of museum specimens that were previously identified as <i>C. bimaculatum</i> from Bahia State led to doubts about the occurrence of that species in those rivers (see ‘Comparative material’). Considerable further taxonomical work is necessary to unveil the diversity of the genus <i>Characidium</i> occurring at the rivers from northeastern Brazil. Géry (1977: 127) called attention to the absence of a humeral spot in <i>C. bahiense</i>, being replaced by a humeral hiatus. The presence of a hiatus within the muscles in the region over the anterior chamber of the swimbladder (the pseudotympanum) is well known in diverse groups of Characiformes (<i>e.g.</i>, Cheirodontinae: see Malabarba, 1998; Characinae: see Mattox &amp; Toledo-Piza, 2012). Although some authors questioned the homology of the pseudotympanum in different lineages of Characiformes (Böhlke, 1953; Malabarba, 1998), recent studies revealed that the structure occurs in many species of the remaining orders of the Otophysi (Moreira <i>et al</i>. 2007) and is possibly plesiomorphic within the Characiformes (Mattox &amp; Toledo- Piza, 2012). Details of the pseudotympanum form and position have been used to diagnose species (Menezes, 2006) and define evolutionary lineages among South American characiforms (Malabarba, 1998). Particularly in <i>Characidium</i>, in addition to <i>C. bahiense</i>, the presence of the pseudotympanum was reported in the description of some species and in phylogenies that included a few species of the genus (<i>e.g.</i>, Graça <i>et al.</i>, 2008; Silveira <i>et al.</i> 2008; Mirande, 2010; Peixoto &amp; Wosiacki, 2013). The pseudotympanum of three species of <i>Characidium</i> that occur in the northeastern Brazilian drainages (<i>C. bahiense</i>, <i>C. bimaculatum</i>, and <i>C. samurai</i>
description: Published as part of <i>Zanata, Angela M. &amp; Camelier, Priscila, 2014, A new species of Characidium (Characiformes: Crenuchidae) from small coastal drainages in northeastern Brazil, with remarks on the pseudotympanum of some species of the genus, pp. 333-342 in Neotropical Ichthyology 12 (2)</i> on pages 334-340, DOI: 10.1590/1982-0224-20130168, http://zenodo.org/record/4551213
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