Hemigrammus machadoi, Ota & Lima & Pavanelli, 2014

Ota, Rafaela P., Lima, Flávio C. T. & Pavanelli, Carla S., 2014, A new species of Hemigrammus Gill, 1858 (Characiformes: Characidae) from the rio Madeira and rio Paraguai basins, with a redescription of H. lunatus, Neotropical Ichthyology 12 (2), pp. 265-279 : 266-270

Hemigrammus machadoi , new species Figs. 1-3

Hemigrammus lunatus Durbin in Eigenmann, 1918: 165 [part; “rio Boa Ventura”].

Hemigrammus sp. “falso lunatus” Lima et al., 2013: 272-273 [ Brazil, rio Madeira basin: photo, short description, diagnosis, habitat preferences, distribution in the rio Madeira basin].

Holotype. INPA 39889 , 30.4 mm SL, Brazil, Mato Grosso State, Pontes e Lacerda, igarapé Barreiro , tributary of rio Guaporé , rio Madeira basin, road to Vila Bela da Santíssima Trindade , 15°11’34”S 59°25’26”W, 13 Dec 2011, W. M. Ohara.

Paratypes. All from Brazil. Rondônia State, rio Madeira basin : ANSP 194408 , 2 , 28.2 -29.0 mm SL, Cerejeiras , igarapé Azul, about 10 km on road RO-399, 13º19’09”S 61º03’16”W, 2 Sep 2011, W. M. Ohara & G. Torrente Vilara ; INPA 24098 , 1 , 26.2 mm SL, Guajará- Mirim , middle rio Cautário, 12º05’06”S 64º37’58”W, 12 Jul 2003, G. Torrente Vilara ; INPA 39892 , 1 , 35.2 mm SL, Guajará-Mirim , rio Pacaás Novos, 10º56’15”S 65º14’11”W, 17 Jan 2012, W. M. Ohara ; MCP 47946, 1 , 28.0 mm SL, Jaci-Paraná , stream tributary of rio Madeira, road BR-364, 09º28’41’’S 64º46’23’’W, 19 Jul 2004, F. Langeani, F. C. T. Lima, E. H. L. Pereira & R. E. Reis ; UFRO-I 11226 , 2 , 22.3 -25.0 mm SL, Cerejeiras , igarapé do Trevo, tributary of rio Guaporé, 13º11’38”S 60º56’59”W, 2 Sep 2011, W. M. Ohara & G. Torrente Vilara ; UFRO-I 11317 , 3 , 20.4-22.9 mm SL, Cerejeiras , igarapé tributary of rio Guaporé, road RO-399, 13º20’02”S 60º54’16”W, 2 Sep 2011, W. M. Ohara & G. Torrente Vilara ; UFRO-I 11571 , 2 , 24.7-28.5 mm SL, Cerejeiras , igarapé Azul, about 10 km on road RO-399, 13º19’09”S 61º03’16”W, 2 Sep 2011, W. M. Ohara & G. Torrente Vilara ; UFRO-I 11712 , 6 , 26.9- 32.2 mm SL, Corumbiara , igarapé at Estrada dos Bois, tributary of rio Corumbiara, 12º59’54”S 61º08’52”W, 1 Sep 2011, W. M. Ohara ; UFRO-I 14036 , 2 , 25.6-25.7 mm SL, Guajará-Mirim , rio Pacaás Novos, 10º56’15”S 65º14’11”W, 17 Jan 2012, W. M. Ohara ; ZUEC 7637 , 1 , 32.6 mm SL, Ariquemes , stream tributary of rio Jamari, 09º38’33”S 63º02’05”W, 30Apr 2013, D.T. B. Nielsen. Mato Grosso State, rio Madeira basin : MCP 46218, 2 , 22.7-26.9 mm SL, Nova Lacerda , stream tributary of rio Guaporé, road BR-174, 14°46’15’’S 59°20’22’’W, 12 Jul 2004, V.A. Bertaco, F. C. T. Lima, J. F. Pezzi da Silva & P. Lehmann ; MZUSP 37611 , 20 , 24.6-35.8 mm SL ; ZUEC 7770 , 5 , 26.7-34.9 mm SL, Nova Lacerda , stream on road Cuiabá- Porto Velho , 72 km from Pontes e Lacerda, ca. 14°46’S 59°20’W, 23 Sep-10 Oct 1984, MZ/ Polonoroeste ; MCP 45042, 5 , 23.6-33.1 mm SL, Pontes e Lacerda, córrego Barreiro, road BR-174, 15°07’04’’S 59°18’46’’W, 12 Jul 2004, R. E. Reis, P. A. Buckup, F. Langeani & A. R. Cardoso ; MCP 15730, 4 , 22.6-29.2 mm SL, Pontes e Lacerda, rio Guaporé and floodplains, ca. 15º12’S 59º21’W, 13 Aug 1991, R. E. Reis, L. R. Malabarba, N.A. Menezes & M. J. Weitzman ; MZUSP 95365 , 54 , 19.1-31.1 mm SL, 4 c&s, 24.9-27.2 mm SL, Vila Bela da Santíssima Trindade , rio Guaporé, 15º00’28”S 59º57’22”W, 13 Oct 2006, F. A. Machado, F. C. T. Lima, C. M. C. Leite & N. E. Silva ; UFRO-I 12513 , 3 , 23.9-33.1 mm SL, Vila Bela da Santíssima Trindade , stream tributary of rio Guaporé, 15°08’24”S 59°59’21”W, 13 Dec 2011, W. M. Ohara ; UFRO-I 12619 , 8 , 26.7-29.3 mm SL, 1 c&s, 28.4 mm SL ; NUP 15053, 2 , 27.1-28.4 mm SL; same data as holotype. Rio Paraguai basin : MCP 15718, 6 , 24.8-26.6 mm SL ; MZUSP 44390 , 17.7-26.8 mm SL, Cáceres , rio Paraguai and surroundings, ca. 16º09’S 57º37’W, 11 Aug 1991, R. E. Reis, L. R. Malabarba, N. A. Menezes & M. J. Weitzman ; MCP 15727, 18 , 25.1-34.9 mm SL, stream crossing the road Cuiabá / Cáceres , 13 km east from Cáceres, tributary of rio Paraguai, 16º09’S 57º37’W, 14 Aug 1991, R. E. Reis, L. R. Malabarba, N. A. Menezes & M. J. Weitzman ; MCP 44566, 30 , 21.9-32.4 mm SL, Cuiabá , stream at road MT-060, 15º44’41’’S 56º20’08’’W, 10 Jul 2004, J. F. Pezzi da Silva, F. Langeani, E. H. L. Pereira & P. Lehmann .

Non-types. All from Brazil. Rondônia State, rio Madeira basin: INPA 21835 , 18 , 23.4 -30.0 mm SL ; INPA 21854 , 25 , 24.6-28.3 mm SL, Costa Marques, middle rio Cautário, tributary of rio Guaporé , 12°11’06”S 63°33’12”W ; UFRO-I 7321 , 1 , 23.4 mm SL, São Francisco do Guaporé, igarapé tributary of rio Guaporé , 12º38’09”S 63º07’43”W ; UFRO-I 8408 , 1 , 23.9 mm SL, Corumbiara, rio Guaporé, upstream mouth of rio Corumbiara , 13º19’02”S 62º01’37”W . Mato Grosso State, rio Madeira basin : MCP 44873, 6 , 22.1-28.9 mm SL, Nova Lacerda, rio Galera (tributary of rio Guaporé ), balneário Galera , 14º28’59’’S 59º35’07’’W ; MZUSP 37648 , 2 , 18.6-24.9 mm SL, Vila Bela da Santíssima Trindade, rio Guaporé , ferryboat pier, 15º00’35”S 59º57’26”W ; MCP 45070, 106 , 19.2-32.6 mm SL, Vila Bela da Santíssima Trindade, stream at km 10 at the road between Pontes e Lacerda and Vila Bela da Santíssima Trindade , 15°12’02’’S 59°24’30’’W . Rio Paraguai basin: MZUSP 96658 , 4 , 23.4-24.6 mm SL, Barão de Melgaço, flooded areas 1 km from Mimoso , ca. 16º17’S 55º48’W ; MZUSP 96714 , 1 , 20.5 mm SL, Barão de Melgaço, rio Mutum , between Mimoso and Joselândia, 16º19’30’’S 55º49’59’’W .

Diagnosis. Hemigrammus machadoi differs from most congeners by possessing a wide dark horizontal stripe across the eye (vs. eye stripe absent or, when present, vertical, except H. barrigonae Eigenmann & Henn , H. lunatus , and H. ulreyi (Boulenger)) and by the possession of a well defined narrow dark stripe at the basis of the anal fin (vs. dark stripe at the basis of anal fin absent, except H. barrigonae , H. boesemani Géry , H. geisleri Zarske & Géry , H. lunatus , H. mimus Böhlke , and H. ulreyi ). Hemigrammus machadoi can be easily distinguished from H. boesemani , H. geisleri , and H. mimus by possessing a distinct dark humeral blotch (vs. humeral blotch absent) and by lacking a blotch on caudal peduncle or any distinct patch of pigmentation on caudal fin (vs. dark blotch on caudal peduncle present in H. boesemani and H. geisleri , a dark marking present at the basis of each caudal-fin lobe basis in H. mimus ). Hemigrammus machadoi can be distinguished from H. barrigonae and H. ulreyi by lacking a narrow, welldefined longitudinal midlateral dark stripe (vs. present) and by lacking a discrete blotch on caudal peduncle (vs. present in H. barrigonae ) and a dark pigmentation patch on the basis of anteriormost dorsal-fin rays (vs. present in H. ulreyi ). The new species can be diagnosed from Hemigrammus lunatus , the sympatric and morphologically most similar congener, by having a conspicuous vertically elongated dark humeral blotch, extending horizontally from second through sixth lateral-line scales, and vertically from third row above lateral line to first row below it (vs. a small roundish humeral blotch, extending horizontally from fourth through sixth lateral-line scales, and vertically from fourth through fifth scale rows above lateral line), and by having 4-5 gill-rakers on upper branch and 9-10 on lower (vs. 6-7, and 11-12, respectively). Additionally, the higher number of cusps on inner premaxillary, dentary, and maxillary largest tooth (5-7 cusps, mode 7, in premaxillary and dentary, vs. 5; 3-5 cusps, mode 5, in maxillary vs. 1-3), and total vertebrae (34-35 vs. 32-33) helps to distinguish the new species from H. lunatus .

Description. Morphometric data summarized in Table 1 . Body compressed, moderately high; greatest body depth located anteriorly to dorsal-fin origin. Dorsal profile of head convex from tip of snout to anterior naris, straight to slightly concave from latter point to tip of supraoccipital spine. Dorsal profile of trunk moderately convex from tip of supraoccipital spine to dorsal-fin origin; inclined from latter point to adipose-fin origin and slightly concave along caudal peduncle. Ventral profile of body convex from tip of lower jaw to anal-fin origin; inclined along anal-fin base. Ventral profile of caudal peduncle slightly concave.

Jaws equal, isognathous; mouth terminal. Maxillary slightly curved; posterior terminus surpassing vertical through anterior margin of eye. Premaxillary teeth in two rows, outer row composed by 2(4), 3(52), or 4*(15) tri- to pentacuspid teeth, central cusp longer; inner row with 5*(72) penta- to heptacuspid teeth, central cusp longer. Maxilla with 2(26), 3*(37), or 4(5) tri to pentacuspid teeth along anteroventral margin, anteriormost tooth broader. Dentary with 9-15 teeth, anteriomost four teeth distinctly larger than remaining teeth, with 5-7 cusps, central cusp longer, then abruptly decreasing in size, 1-2 tri to pentacuspid teeth, and remaining 4-9 tri- or unicuspid, small teeth ( Fig. 2 ).

Scales cycloid, with circuli marked anteriorly, but absent distally; with two to six radii (“ Hemigrammus type ” of Cockerell, 1914). Lateral line incomplete, slightly curved ventrally, with 6(1), 7(2), 8(1), 9(9), 10*(14), 11(19), 12(9), 13(8), 14(5), or 15(1) pored scales; longitudinal series including perforated scales 30(1), 31(3), 32(5), 33(17), 34*(19), 35(19), or 36(4); 5(1) or 6*(66) scales rows between dorsal-fin origin and lateral line; 3(1) or 4*(66) scales rows between lateral line and pelvic-fin insertion. Predorsal scales 9*(19), 10(42), or 11(8). Anal sheath along anal-fin base composed by 5(3) or 6*(8) scales in a single row, covering base of first unbranched to fifth branched anal-fin rays. Circumpeduncular scales 11(4), 12(13), 13*(20), or 14(35). Caudal-fin scales covering about basal third of upper and lower caudal-fin lobes, mainly arranged on upper and lower caudal lobes margins, gradually decreasing in size.

Dorsal-fin rays ii,9*(72), first unbranched ray approximately one-third of second unbranched ray; small ossification anterior to first unbranched ray present in all five c&s specimens examined. Distal margin of dorsal fin straight. Dorsal-fin origin at midbody or slightly behind this point; base of posterior most dorsal-fin ray slightly behind vertical through anal-fin origin. First dorsal-fin pterygiophore insertion posterior to neural spine of tenth vertebra.Adipose fin small. Pectoral-fin rays i,10*(46), 11(20), or 12(5). Pelvic-fin rays i,7*(72); its origin ahead of vertical through dorsal-fin origin; tip of longest ray surpassing anal-fin origin.Anal-fin rays iv, 22(2), 23(18), 24*(28), 25(19), or 26(5); anal fin falcate, last unbranched ray to fourth branched ray longest, with remaining rays decreasing gradually in size towards anal-fin end; last anal-fin pterygiophore insertion behind hemal spine of fifteenth caudal vertebrae (5). Caudal fin bifurcated; lobes slightly pointed, almost equal in size, inferior lobe slightly longer than superior. Principal caudal-fin rays i,17,i*(67); dorsal procurrent caudal-fin rays 11(5); ventral procurrent caudal-fin rays 8(3) or 9(2). Precaudal vertebrae 13(4) or 14(1); caudal vertebrae 21(5); total vertebrae 34(4) or 35(1). Supraneurals 4(3) or 5(2). Branchiostegal rays 4(5). Upper branch of gill-rakers 4(4) or 5(67), lower branch 9(43) or 10(28).

Color in alcohol. Overall ground coloration of body light tan. Anterior portion of lower jaw, snout and dorsal portion of head with dense concentration of small dark chromatophores, imparting an overall darker color. Gular area and infraorbitals clearer; third infraorbital and opercle silver in specimens retaining guanine pigmentation.

Opercle upper half and fourth and fifth infraorbital with scattered, relatively large dark chromatophores. Eye with broad dark longitudinal midlateral stripe (not discernible in specimens retained for long period in formalin). Longitudinal dark stripe along midline of body present, faint and very narrow, originating at end of second humeral spot, becoming wider and more conspicuous at vertical of insertion of dorsal fin. Scales from dorsal region of body posteriorly bordered with dark chromatophores, forming subtle reticulate pattern. Dark humeral blotch conspicuous, its contour slightly blurred, vertically elongated, extending horizontally from second through sixth lateral-line scales, and vertically from third row above lateral line to first row below it. Dark chromatophores below midlateral line arranged along margins of hypaxial muscles bundles from area above anal fin to caudal peduncle.Dorsal fin mostly hyaline, with few dark chromatophores concentrated along unbranched rays and third or fourth branched rays and its interradial membranes. Adipose, pectoral and pelvic fins almost hyaline, with few dark chromatophores scattered mainly along their distal margins.Anal fin hyaline, with few dark chromatophores usually concentrated on unbranched rays and its interradial membranes, forming dark narrow margin. Anal fin with narrow, very conspicuous dark stripe along anal-fin base. Caudal fin hyaline, main outer rays with dark chromatophores along its margins. Dark caudal spot absent ( Fig. 1 ).

Color in life. Based on the picture of two specimens collected during the Transcontinental Catfish Expedition, at the type locality, the Igarapé Barreiro, taken by the second author, that unfortunately could not be located during a recent search in MCP (field number TCE2004071101B). Opercle, infraorbital bones, and sides of body below midline light yellow to light orange, with a silvery hue. Tip of dentary, snout and top of head dark gray. Dorsum and posterior portion of body (area immediately behind vertical passing through anal-fin origin) translucent, with a light brown hue. Dorsal, pelvic, anterior portion of anal, caudal and adipose fins, and caudal peduncle light orange. Dark midlateral stripe faint, broad, plumbeous, extending into caudal peduncle.

Sexual dimorphism. Anal- and pelvic-fin hooks were observed in males of Hemigrammus machadoi collected during December and January (UFRO-I 12513 and 14036, respectively). The pelvic fin bears tiny hooks (usually one pair of hooks per ray segment), anterodorsally arranged almost all over the entire length of the unbranched ray and first two branched fin rays. The anal fin bears 7-11 tiny hooks, anterodorsally arranged along the last unbranched ray and first three branched fin rays, one pair per ray segment.

mm SL, possessing large yellowish oocytes and two mature males, 24.9-25.9 mm SL, with lobulated, whitish testicles.

Etymology. The specific name honors Francisco de Arruda Machado, ichthyologist from the Universidade Federal de Mato Grosso, Brazil, for his tireless dedication in surveying the fishes of his native State, as well as for his struggle for their conservation and the conservation of the rivers from the Mato Grosso State. A genitive noun.

Figures

Fig. 1. Hemigrammus machadoi, INPA 39889, holotype, 30.4 mm SL, Brazil, Mato Grosso State, Pontes e Lacerda, igarapé Barreiro, tributary of rio Guaporé, rio Madeira basin.

Fig. 2. Scanning electronic micrography of Hemigrammus machadoi, new species, MZUSP 95365, paratype, 27.2 mm SL, left internal lateral view of premaxilla, maxilla and dentary. Scale bar = 1 mm.

Fig. 3. Map of northern South America showing distribution of Hemigrammus machadoi. The white circle represents the type locality, black circles represent the paratypes localities, and the gray circles represent the non-types localities.