Hyphessobrycon langeanii Lima & Moreira 2003, new species

Hyphessobrycon langeanii, new species Figs. 1 - 4

Holotype. MZUSP 75127 (50.4 mm SL): Brazil, Mato Grosso, município de Alto Araguaia, córrego Mosquito, km 476.3 of Ferronorte railroad, 17°25’8”S, 53°13’60”W; C. R. Moreira & F.C. T. Lima, 19 May 2001.

Paratypes. All localities in Brazil, Mato Grosso, município de Alto Araguaia, unless noted otherwise: MZUSP 73313 (166, 8 cs, 15.4-58.5 mmSL); MCZ 162370 (5,29.5-31.8 mmSL); USNM 371922 (5, 26.3-31.8 mm SL);DZSJRP 5467 (5,28.7-34.0 mm SL); ZUEC 6174 (5,26.7- 31.7 mm SL); samedataasholotype. MZUSP 73322 (97, 12.8-34.8 mm SL), córrego do Sapinho, km 474.4 of Ferronorte railroad, 17°25’55”S, 53°14’34”W; C. R. Moreira & F.C. T. Lima, 19May 2001. MZUSP 73256 (259, 8.1-34.3 mm SL); MNRJ 24780 (5, 22.5-30.4 mm SL); córrego Gordura, km 491.4 of Ferronorte railroad, 17°18’20”S, 53°16’22”W; C. R. Moreira & F.C. T. Lima, 15 May 2001. MZUSP 73272 (27,14.1-37.7 mmSL), córrego Boiadeiro, km 487.08 of Ferronorte railroad, 17°20’1”S, 53°14’53”W; C. R. Moreira & F.C. T. Lima, 16 May 2001. MZUSP 73362 (43, 14.6-29.0 mm SL), córrego do Rancho, below Lagoa do Veado; 17°16’12”S, 53°24’52”W; C. R. Moreira & F.C. T. Lima, 22 May 2001. MZUSP 73286 (6, 23.1-32.6mm SL), córrego Jaguatirica, km 496.46 of Ferronorte railroad, 17°16’26”S, 53°17’49”W; C. R. Moreira & F.C. T. Lima, 17 May 2001. MZUSP 73309 (30, 15.5-32.1 mm SL), córrego Bandeira, km 478.35 of Ferronorte railroad, 17°24’5”S, 53°13’32”W; C. R. Moreira & F.C. T. Lima, 18 May 2001. MZUSP 41405 (62, 13.6-29.0 mm SL), córrego do Rancho (headwaters) at swamp close to the road, c. 17°16’S, 53°24’W; L. P.S. Portugal & F. Langeani, 8 March 1989. MNRJ 20351 (2, 21.7-24.0 mm SL), córrego do Rancho, BR-364, 17°12’48”S, 53°20’17”W; F.A.G. Melo, P.A. Buckup and M. R.S. Melo, 13 Feb 2000. MZUSP 41451 (99, 15.8-32.3 mm SL), Goiás, município de Santa Rita do Araguaia, córrego Empantanado, fazenda “Heral” (Herval in a map consulted) (c. 17°32’S, 53°11’W); L. P.S. Portugal & F. Langeani, 7 February 1989.

Diagnosis. Hyphessobrycon langeanii can be distinguished from all congeners by the presence of a single well-defined, round to horizontally oval humeral spot, similar to the one found in species of the Astyanax bimaculatus (Linnaeus) complex (vs. humeral spot absent, double, or variously developed, never round to horizontally oval). It can also be distinguished from its congeners, except H. reticulatus Ellis, by the combination of a reticulate dark pigmentation pattern, a broad, horizontally-elongate caudal-peduncle blotch, a narrow dark stripe extending along the central caudal-fin rays, 5 or 6 horizontal scale rows between the dorsal-fin origin and the lateral line, 4 or 5 horizontal scale rows between the lateral line and the pelvic-fin origin, and 15-20 branched anal-fin rays. Hyphessobrycon langeanii can be distinguished from H. reticulatus by the possession of a conspicuous, dark round to oval humeral spot (vs. relatively faint, vertically-elongate humeral spot), a horizontally-elongate caudal-peduncle blotch (vs. vertically-elongate caudal-peduncle blotch), the midlateral dark stripe relatively wide and faint (vs. midlateral dark stripe extremely narrow and well-defined), and infraorbitals 3 and 4 co-ossified (vs. separated).

Description. Morphometric data of the holotype and paratypes are presented in Table 1. Body compressed, moderately slender, greatest body depth at pelvic-fin origin. Dorsal profile of head convex from upper lip to vertical through middle of orbit; slightly concave from latter point to tip of supraoccipital spine. Predorsal profile of body convex, dorsal-fin base posteroventrally inclined, straight to slightly convex in smaller individuals (less than 50 mm SL), and convex in larger specimens (see Figs. 2-3). Body profile straight to convex from end of base of dorsal fin to adipose fin; slightly concave between latter point to origin of dorsalmost procurrent caudal-fin ray. Ventral profile of head and body convex from lower lip to vertical through pectoral-fin insertion; slightly convex from latter point to pelvic-fin insertion. Ventral profile between pelvic-fin insertion and anal-fin origin straight. Body profile along anal-fin base straight to slightly convex and posterodorsally slanted. Ventral profile of caudal peduncle slightly concave.

Jaws equal, mouth terminal.Maxilla reaching middle of orbit. Premaxillary teeth in two rows (Fig. 4). Outer row with 2(2), 3(16), or 4*(45) uni- to tricuspid teeth. Inner row with 4(8) tetrato hexacuspid teeth. Maxilla with 1(8) tri- to pentacuspid tooth. Dentary with 4(8) large, tetra- to heptacuspid teeth followed by 4(1), 5(5), 6(1), or 7(1) smaller uni- to tricuspid teeth.

Scales cycloid, with few radii. Lateral line incompletely pored, with 6(4),7(6), 8*(13), 9(18), 10(11), 11(3), or12(1)perforated scales. Lateralseriesscalesincludingperforatedscales 30(1), 31(6), 32(17), 33*(16), 34(10), 35(5), or 36(1). Horizontal scale rows between dorsal-fin origin and lateral line 5(7) or 6*(49), not including scale of predorsal series situated just anterior to first dorsal-fin ray. Horizontal scale rows between lateral line and pelvic-fin insertion 4*(53) or 5(3). Predorsal scales 10*(8), 11(33), 12(13), or 13(2). Circumpeduncular scales 12(10), 13*(26), or 14(20).Single row of 5-7 scales covering base of anterior most anal-fin rays.

50.4 mm SL, Brazil, Mato Grosso, município de Alto Araguaia, Dorsal-fin rays typically ii,9, ii, 8 in one specimen. Dorsalfin origin at middle of standard length. Base of last dorsal-fin ray at vertical through anal-fin origin. First dorsal-fin pterygiophore inserting behind neural spine of 10th(2) or 11th(6) vertebra. Adipose fin present, but vestigial in one specimen. Anal-fin rays iii,15(1), 16(2), 17(11), 18*(28), 19(10), or 20(4). First anal-fin pterygiophore inserting behind hemal spine of 16th(5) or 17th(2) vertebra. Pectoral-fin rays i,10(14), 11*(22), 12(19), or 13(1). Tip of pectoral fin reaching vertical through pelvic-fin insertion. Pelvic-fin rays i,6*(3) or i,7(53). Caudal fin forked, lobes rounded, and similar in size. Principal caudal-fin rays 10+9(8). Ten (2), 11(1), 12(1), or 13(3) dorsal procurrent caudal-fin rays, and 9(1), 10(3), 11(2), or 12(1) ventral procurrent caudal-fin rays. First gill arch with 5(1), or 6(7) epibranchial, 7(5), or 8(3) ceratobranchial, 1(8) on cartilage between ceratobranchial and epibranchial, and 1(2), or 2(6) hypobranchial gill-rakers. Four (8) branchiostegal rays, 3(8) on anterior ceratohyal, and 1(8) on posterior ceratohyal. Vertebrae 31(1), 32(3), 33(3), or 34(1). Supraneurals 4(1), or 5(7).

Color in alcohol. Ground color light beige. Guanine present on opercle, infraorbitals, and sides of body. Dark chromatophores densely concentrated on dorsal surface of head, and anterior surface of lower jaw. Small, dark chromatophores present on maxilla, ventral margin of orbit, and first and second infraorbitals; remaining infraorbitals with larger and more scattered dark chromatophores. Ventral portion of head pale, almost devoid of dark chromatophores. Dorsal midline of body with dense concentration of dark chromatophores. Dark chromatophores concentrated mainly on posterior margin of scales of dorsolateral portion of body, resulting in a reticulate pattern. Ventrolateral portion of body with fewer dark chromatophores, present mainly on posterior margin of scales. Humeral spot well-defined, black, and round to horizontally oval. Thin vertical lines extend posterodorsally and anteroventrally from humeral spot. Narrow dark, midlateral stripe running from immediately posterior to humeral spot to caudal-peduncle blotch. Caudal-peduncle blotch large, welldefined, and horizontally-elongate, its depth ranging from half to two-thirds of caudal peduncle depth (compare Figs.1- 3; notice that Fig. 2 is slightly overexposed and consequently caudal peduncle blotch is not so conspicuous). Narrow, dark stripe on three middle caudal-fin rays running from caudalpeduncle blotch to distal margin of fin. Remaining portions of caudal fin with scattered dark chromatophores. Dorsal and anal fins hyaline, with small dark chromatophores scattered on interradial fin membranes; chromatophores more concentrated on distal portion of five anterior dorsal-fin rays, and distal margin of anal fin. Pectoral and pelvic fins almost hyaline, with few dark chromatophores. Adipose fin dusky.

Color in life. Description based on three photographed specimens (MZUSP 73272, 2 ex, 31.8-37.7 mm SL; MZUSP 73313, 1 ex, 58.5 mm SL; Figs.2-3). Ground color beige. Sides of head, and body golden. All fins, except pelvic fin, yellow. Pelvic fin and anterior portion of anal fin orange.

might indicate a tolerance of broader ecological conditions by Hyphessobrycon langeanii than is the case of its congeners in the upper rio Araguaia (see “Ecological notes” of H. eilyos and H. weitzmanorum, below).

Stomach contents of two cleared and stained individuals yielded ants, a beetle, chironomid larvae, unidentified Microcrustacea, diatoms and filamentous algae.

Etymology. The new species is named after our colleague Francisco Langeani, who first collected the new species.