Hemibrycon inambari, Bertaco & Malabarba, 2010

Bertaco, Vinicius A. & Malabarba, Luiz R., 2010, A review of the Cis-Andean species of Hemibrycon Günther (Teleostei: Characiformes: Characidae: Stevardiinae), with description of two new species, Neotropical Ichthyology 8 (4), pp. 737-770 : 747-749

Hemibrycon inambari , new species

Figs. 10-11

Holotype. MUSM 35491 , male, 65.4 mm SL, río Araza , río Inambari basin,upper río Madre de Dios drainage, Sirihua , Camanti, Quispicanchi, Cusco, Peru, 13º24’05”S 70º53’57”W, 17 Oct 2005, M. Hidalgo.

Paratypes. Peru, Cusco, upper río Madre de Dios drainage, río Alto Madre de Dios: ANSP 143290 , 12 (3 c&s), 26.4-39.0 mm SL; ANSP 143293 , 10 , 24.1 -34.0 mm SL; ANSP 143307 , 6 , 25.4-35.2 mm SL, río Pilcopata, wire ferry, 3 km above Pilcopata, 12º53’30”S 71º24’00”W, 16 Jul 1977, R. Horwitz. ANSP 143291 , 1 , 37.2 mm SL, río Hospital, moderate stream, 2 km W of Patria on N/S road, ca. 12º53’S 71º27’W, 12 Jul 1977, R. Horwitz. ANSP 143294 , 5 (x-ray), 28.0-76.0 mm SL; ANSP 143300 , 2 , 38.5-79.3 mm SL; ANSP 143306 , 5 , 34.0- 81.5 mm SL; ANSP 143312 , 10 (x-ray), 28.2-48.2 mm SL; ANSP 143317 , 5 , 28.0-76.0 mm SL, second stream W of end of dirt track off km 143.9 on Huacarpay-Shintuya road, near Patria , Asunción , Cusco, Peru, ca. 12º57’S 71º25’W, 6-7 Jul 1977, R. Horwitz. ANSP 151478 , 1 , 35.0 mm SL; ANSP 151497 , 4 , 28.8-68.7 mm SL, second stream W of end of dirt track off km 143.9 on Huacarpay-Shintuya road, near Patria, Asunción, 12º57’30”S 71º21’30”W, 5-10 Jul 1977, R. Horwitz. ANSP 151526 , 2 , 34.1-37.2 mm SL, río Pilcopata, wire ferry, 3 km above of Pilcopata , ca. 12º56’S 71º24’W, 16-17 Jun 1977, R. Horwitz. Río Inambari drainage: ANSP 180770 , 3 of 4 (1 c&s), 57.1-71.9 mm SL, tributary of río Araza , vicinity of Quince Mil, 13º18’52”S 70º49’13”W, 25 Jul 2004, M. Sabaj et al. MUSM 26299 , 15 of 40, 48.2-87.3 mm SL, MCP 45753, 5 , 63.5 -82.0 mm SL, collected with the holotype. MUSM 26776 , 4 of 8, 43.4-70.9 mm SL, río Araza , San Lorenzo, Camanti, Quispicanchi , Cusco, 13º13’5”S 70º31’39”W, 25 Oct 2005, M. Hidalgo. MUSM 26802 , 15 of 97, 28.3-51.1 mm SL, UFRGS 13201 , 5 , 46.4-50.1 mm SL, quebrada Huaca, Huañuna, Ayapata, Carabaya , Puno, 13º12’16”S 70º22’26”W, 25 Oct 2005, M. Hidalgo .

Diagnosis. Hemibrycon inambari is distinguished from most of its congeners by the number of lateral line scales (41-44 vs. 39-41 or 44-58, Fig. 3). From the species sharing similar lateral line counts, it differs from H. boquiae , H. metae , H. polyodon , and H. taeniurus by the number of scales along anal-fin base scale sheath (6-10 vs. 10-24); from H. jabonero by the number of gill rakers (17-18 vs. 19-21); from H. brevispini by the number of cusps of three anteriormost dentary teeth (5 vs. 3), and by absence of bony hooks in the caudal-fin rays of males (vs. presence); from H. divisorensis and H. surinamensis by the absence of a wide black asymmetrical spot covering base of caudal-fin rays; from H. helleri and H. jelskii by the size of humeral spot (over 7-8 vs. 5-6 horizontal series of scales, and from H. helleri by the number of predorsal scales (13-16 vs. 16-18), and by the total number of vertebrae (41-43 vs. 39-40); from H. mikrostiktos by the size of humeral spot (6-7 vs. 2-3 horizontal series of scales), and by total number of pelvic-fin rays (7 vs. 8); from H. paez , H. quindos , and H. virolinica by the number of cusps of premaxillary inner row teeth (5-7 vs. 3- 4); from H. rafaelense and H. raqueliae by the number of predorsal scales (13-16 vs. 10-12 and 10-13); from H. raqueliae by the number of cusps of first maxillary tooth (3 vs. 5).

Description. Morphometric data for Hemibrycon inambari summarized in Table 2. Largest male 69.5 mm SL, largest female 87.3 mm SL. Body compressed and elongate; greatest body depth at vertical through middle length of pectoral fins. Dorsal profile of head straight to slightly convex. Dorsal body profile convex from occipital bony to base of last dorsal-fin ray; straight from this point to adipose-fin origin. Ventral profile of head nearly straight to slightly convex. Ventral body profile convex from pectoral-fin origin to pelvic-fin origin, and straight to slightly convex to anal-fin origin. Body profile along anal-fin base posterodorsally slanted. Caudal peduncle elongate, nearly straight to slightly concave along dorsal and ventral margins.

Snout rounded from margin of upper lip to vertical through anterior nostrils.Head small. Mouth terminal, mouth slit below at horizontalthroughmiddleofeye.Maxillalongandslightlycurved, aligned at angle of approximately 45º to longitudinal body axis.

Premaxilla with two tooth rows; outer row with 3-5, tricuspid teeth with central cusp slightly longer; inner row with 4 penta- to heptacuspids teeth, gradually decreasing in length from first to third teeth and last tooth smallest; central cusp twice or three times longer and broader than other cusps. Maxilla almost fully toothed with 8-14 uni- to tricuspid teeth, with central cusp longer. Three anteriormost dentary teeth larger, with 5 cusps, followed by medium sized tooth with 3 cusps, and 7-9 teeth with 1-3 cusps or conical; central cusp in all teeth two to three times longer and broader than other cusps. Cusp tips slightly curved posteriorly and lingually ( Fig. 11 ).

Dorsal-fin rays ii,8 (n = 80); first unbranched ray approximately one-half length of second ray. Dorsal-fin origin located approximately to middle of SL and posterior to vertical through pelvic-fin origin. Profile of distal margin of dorsal fin nearly straight to slightly concave. Males with bony hooks in distal one-third of first branched rays. Adipose-fin located at vertical through insertion of last anal-fin rays. Anal-fin rays iiiv,22-26 (mode = 24, n = 79, Fig. 2 ). Anal-fin profile slightly convex to nearly straight both sexes. Anal-fin origin approximately at vertical through insertion in the last dorsal fin rays. Anal-fin rays of males bearing one pair of small bony hooks along posterolateral border of each segment of lepidotrichia, along last unbranched ray and almost all branched rays. Hooks usually located along posteriormost branch and 748 A review of the Cis-Andean species of Hemibrycon distal 1 / 2 to 2 / 3 of each ray. Pectoral-fin rays i,10-12 (mode = 11, n = 80). Pectoral-fin tip not reaching pelvic-fin origin in both sexes. Males with bony hooks developed on distal portion of unbranched and all branched rays.Pelvic-fin rays i,6,i or i,7 (n = 79). Pelvic-fin origin located 4-5 predorsal scales anterior to vertical through dorsal-fin origin. Pelvic fin of males usually bearing one small bony hook per segment of lepidotrichia along ventromedial border in all branched rays. Caudal fin forked with 19 principal rays without bony hooks (n = 79); lobes similar in size. Caudal-fin base with a few scales in the half of lobes, following by one large and round scale in each lobe. Dorsal procurrent rays 8-10 and ventral procurrent rays 9-10 (n = 12).

Scales cycloid, moderately large. Lateral line complete with 41-44 (mode = 41, n = 71, Fig. 3). Scale rows between dorsal-fin origin and lateral line 7-8 (mode = 7, n = 78); scale rows between lateral line and pelvic-fin origin 5-6 (mode = 6, n = 78). Predorsal scales 13-16, arranged in regular series (mode = 16, n = 75). Scales rows around caudal peduncle 14 (mode = 14, n = 70). Axillary scale on pelvic-fin origin extends posteriorly covering 2-3 scales. Scale sheath along anal-fin base with 6-10 scales in single series, extending to base of most anterior branched rays.

Precaudal vertebrae 18-19; caudal vertebrae 21-22; total vertebrae 39-40 (n = 17). Supraneurals 6-7 (n = 16). Gill rakers on upper limb of outer gill arch 6-7, and on lower limb 10-11 (n = 11).

Color in alcohol. General ground body color yellowish. Dorsal portion of head and body with dense concentration of black chromatophores. Dorsolateral portion of head and body with scattered black chromatophores. Midlateral body silvery. One large and vertical black humeral spot, located over third to sixth lateral line scales and extending over 5-6 horizontal series of scales, including lateral line. Midlateral dark stripe extending from humeral region to middle caudalfin rays, broad in the caudal peduncle. Abdominal region almost devoid of black chromatophores. Adipose fin densely dark brown pigmented. Dorsal and caudal fin with dark borwn pigmentation diffuse and anal fin with small black chromatophores along its border forming narrow stripe. Pectoral and pelvic fins hyaline ( Fig. 10 ).

Sexual dimorphism. Males of Hemibrycon inambari are easily recognized by the presence of bony hooks on the dorsal-, pectoral-, anal- and pelvic-fin rays. Males and females also slightly differ in pectoral- and pelvic-fin lengths and body depth ( Table 2), and in anal-fin shape, slightly concave in males and nearly straight in females. Mature males with gill gland on first gill arch, covering the first branchial filaments.

Distribution. Hemibrycon inambari is known from río Alto Madre de Dios and río Inambari drainages, upper río Madre de Dios drainage, Peru ( Fig. 4 ).

Etymology. The specific name, inambari , is in reference to the type locality, río Inambari. A noun in apposition.

V. A. Bertaco & L. R. Malabarba 749

Figures

Fig. 10. Hemibrycon inambari, MUSM 35491, holotype, male, 65.4 mm SL, upper río Madre de Dios basin, Peru.

Fig.11. Hemibryconinambari,ANSP 143290, paratype,female, 39.2 mm SL. Scanning electron micrograph of right side upper and lower jaws. Scale bar = 1 mm.

Fig. 2. Tukey box plots of number of branched anal-fin rays in Hemibrycon species. Mean represented by thick vertical bar, and 25th and 75th percetiles as lateral borders of box plots. Number in parentheses = N.

Fig. 4. Map of central and northern South America showing geographic distribution of Hemibrycon beni (1, solid hexagon), H. divisorensis (2, open triangle), H. helleri (3, ellipse), H. huambonicus (4, solid triangles), H. jelskii (5, solid dots), H. inambari (6, rectangles), H. metae (7, solid squares), H. mikrostiktos (8, open square), H. polyodon (9, inverted triangle), H. surinamensis (10, solid diamonds), H. taeniurus (11,Trinidad Island), H.tridens (12, open circle).Some symbols represent more than one lot or locality of specimens. 1-12 = type locality of each species.