Hemibrycon huambonicus ( Steindachner, 1882 )

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 : 743-747

Hemibrycon huambonicus ( Steindachner, 1882) Figs. 8-9

Tetragonopterus huambonicus Steindachner, 1882: 177 (original description, type locality: Huambo [ Peru]).

Hemibrycon huambonicus . -Eigenmann, 1910: 432 (synonym of H. polyodon (Günther)) . -Eigenmann, 1927: 402 (in key), 410-411 (redescription, and valid species).

744 A review of the Cis-Andean species of Hemibrycon

Diagnosis. Hemibrycon huambonicus is distinguished from most of its congeners by the number of lateral line scales (44- 48 vs. 39-43 or 48-58, Fig. 3). From the species sharing similar lateral line counts, it differs from H. beni , and H. dentatus by the number of branched anal-fin rays (22-27 vs. 15-19 and 28- 34, respectively); from H. cairoense by the number of scale rows above lateral line (8-10 vs. 6-7); from H. helleri by the number of scales along anal-fin base scale sheath (17-26 vs. 6- 12) and the number of scale rows above lateral line (8-10 vs. 7- 8), from H. polyodon by the number of caudal peduncle scales (18-20 vs. 16), head length (22.0-26.0 vs. 20.9-22.9% SL), and upper jaw length (45.2-52.6 vs. 43.7-45.6% HL), and from H. raqueliae by the number of predorsal scales (15-19 vs. 10-13) and by the number of cusps of first maxillary tooth (3 vs. 5).

Description. Morphometric data for H. huambonicus summarized in Table 2. Largest male 87.0 mm SL, largest female

109.9 mm SL. Body compressed and elongate; greatest body depth at vertical through middle length of pectoral fins. Dorsal profile of head nearly 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 slightly convex. Ventral body profile convex from pectoral-fin origin to pelvic-fin origin and straight 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 heavy (massive) and relatively small. Mouth terminal, mouth slit nearly at horizontal through below middle of eye. Maxilla long and slightly curved, aligned at angle of approximately 45º to longitudinal body axis, and its posterior tip extending below orbit, reaching nearly to vertical through center of eye.

V. A. Bertaco & L. R. Malabarba 745

Premaxilla with two tooth rows; outer row with 4-6, tricuspid teeth with central cusp slightly longer; inner row with 4 pentacuspid 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 7-13 uni- to tricuspid teeth, with central cusp longer. Three anteriormost dentary teeth larger, with 5 cusps, followed by medium sized tooth with 3-5 cusps, and 7-10 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. 9 ).

Dorsal-finraysii,8 (n= 64); firstunbranchedrayapproximately one-half length of second ray. Dorsal-fin origin located approximately to middle of SL and posterior to vertical through pelvic-fin origin. Males with bony hooks in distal one-third of first branched rays. Profile of distal margin of dorsal fin nearly straight to slightly concave. Adipose-fin located at vertical through insertion of two last anal-fin rays.Anal-fin rays iii-v,22- 27 (mode = 24, n = 64, Fig.2 ).Anal-fin profile slightly concave in males and nearly straight in females.Anal-fin origin approximately at vertical through insertion in the last dorsal fin rays. Anal-fin rays of males bearing one pair of developed bony hooks along posterolateral border of each segment of lepidotrichia, usually along last unbranched ray and first twelve branched rays. Only two males (syntype and non-type male) possess bony hooks in all anal-fin rays. Hooks usually located along posteriormost branch and distal 1 / 2 to 2 / 3 of each ray. Pectoral-fin rays i,10-12 (mode = 11, n = 64). Pectoral-fin tip surpassing pelvic-fin origin in males, and reaching in females. Males with bony hooks on distal portion of unbranched and all branched rays. Pelvic-fin rays i,6,i or i,7 (n = 64). 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 of all branched rays. Caudal fin forked with 19 principal rays (n = 64); lobes in similar size. First third of caudal-fin scaled. Dorsal procurrent rays 11 and ventral procurrent rays 11-12 (n = 4).

Scales cycloid, moderately large. Lateral line complete with 44-48 (mode = 45, n = 64, Fig. 3). Scale rows between dorsal-fin origin and lateral line 8-10 (mode = 9, n = 64); scale rows between lateral line and pelvic-fin origin 6-7 (mode = 7, n = 64). Predorsal scales 15-19, arranged in regular series (mode = 17, n = 62). Scales rows around caudal peduncle 18-20 (n = 64). Axillary scale on pelvic-fin origin extends posteriorly covering 2-3 scales. Scale sheath along anal-fin base with 17-26 scales in single series, extending to base to 18 th to 24 th branched rays.

Precaudal vertebrae 20-21; caudal vertebrae 22-24; total vertebrae 42-43 (x-ray of syntype).Supraneurals 8-9.Gill rakers on upper limb of outer gill arch 7-8,and on lower limb 11-12 (n = 12).

Color in alcohol. General ground body color brown yellowish. Dorsal portion of head and body with concentration of black chromatophores. Dorsolateral portion of head and body with scattered black chromatophores. One vertical black humeral spot, located over fourth to sixth lateral line scales and extending over 5-6 horizontal series of scales, including lateral line. Caudal peduncle and middle caudal-fin rays dark pigmented.Abdominal region almost devoid of black chromatophores. Dorsal, adipose and caudal fin with dark pigmentation diffuse, and pectoral and pelvic fins hyaline ( Fig. 8 ).

746 A review of the Cis-Andean species of Hemibrycon

Sexual dimorphism. Males of Hemibrycon huambonicus are easily recognized by the presence of bony hooks in dorsal, anal, pelvic and pectoral 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 ( Fig. 7 ).

Distribution. Hemibrycon huambonicus is known from río Huambo, río Crisnejas and río Tingo, all tributaries of río Huallaga drainage, and río Marañon drainage, upper río Amazonas basin, Peru ( Fig. 4 ).

Remarks. The original description of H. huambonicus provided by Steindachner (1882) is relatively brief, with the type locality reported only for Huambo ( Peru). In Peru, there are two possible localities for Huambo: (1) río Huambo, San Martin, Peru, ca. 07º04’S 77º10’W, upper río Huallaga drainage, and (2) río Huambo, Huanuco, ca. 09º39’S 74º56’W, río Pachitea and río Ucayali drainage. All lots analyzed and identified as H. huambonicus are from río Huallaga and río Marañon drainages. (= río Higueros) into río Huallaga from the NW at Huanuco, Huanuco, ca. 09º55’S 76º13’W, 16-25 Oct 1918. CAS 70090, 24, 43.0- 85.3 mm SL, CAS 70091, 89, 42.7-94.4 mm SL, Huancachupa creek, a tumultuous small stream from the eastern slope of the central cordillera to río Huallaga a league above Huanuco, ca. 6,000 ft. elev., Huanuco, ca. 09º55’S 76º13’W, 16-25 Oct 1918. CAS 70092, 14, 42.0- 73.1 mm SL, large creek/small river arising from río Huallaga above Cayumba rapids, Chumatagua, ca. 09º27’S 75º58’W, 1 Oct 1918. CAS 70093, 6 of 7, 37.1-84.3 mm SL, Chachara and Ford on lower río Chinchao (into río Huallaga above Cayumba rapids), Pedra Blanca, ca. 09º27’S 75º58’W, 2 Oct 1918. ICNMHN 7317, 73, 32.6-109.9 mm SL, provincia de Leoncio Prado, Parque Nacional Tingo Maria, Huanuco, ca. 09º18’S 75º59’W, May 2003. MUSM 10565, 2 of 3, Huanuco, río Huallaga, río Cayumba, río Marañon drainage, km 495, 09º32’00”S 76º00’00”W, 29 Sep 1996. Río Marañon drainage: CAS 44355, 1, 57.9 mm SL [listed as H. helleri by Eigenmann (1927: 406)], río Crisnejas near its junction with upper río Paipay, at Paipay, Cajamarca, ca. 07º25’S 78º10’W, Geographic variation. The population of H. huambonicus from río Marañon drainage has head length slightly smaller (19.7-25.4 vs. 22.0-26.0% SL), and upper jaw length smaller (39.5-48.9 vs. 45.2-52.6% HL) than the population from río Huallaga drainage. However, no other significant difference was found between these populations for the recognition of a distinct species.

Material examined. Syntype. NMW 57531, male (x-ray), 87.0 mm SL, Huambo, Peru [río Huambo, Huanuco, ca. 09º39’S 74º56’W, río Pachitea and río Ucayali drainage] . Non-type specimens. Peru. Río Huallaga drainage: CAS 70082, 5 , 64.1-95.2 mm SL, río Huallaga at Ambo (or Tambo), ca. 7,500 ft. elev., Huanuco, ca. 10º08’S 76º10’W, 26-29 Oct 1918. CAS 70085, 6 , 59.9-86.1 mm SL, río Huallaga at Huanuco, ca. 6,000 ft. elev., Huanuco, ca. 09º55’S 76º13’W Oct 1918. CAS 70089, 51 , 30.7-81.2 mm SL, río Tingo

V. A. Bertaco & L. R. Malabarba 747

Aug 1923. CAS 70083, 2 , 52.5-53.5 mm SL, on the intercordilleran río Marañon at 3,500 ft. elev., Balsas , Amazonas, ca. 06º50’S 77º58’W , Jul 1923. CAS 70086, 25 , 52.6-82.4 mm SL, Cajamarca, río Paipay into río Crisnejas near its junction with upper río Marañon, ca. 07º20’S 77º45’W , small deeply entrenched stream ca. 4,000 ft. elev., Jul 1923. ROM 52238, 40 of 85, 25.6-94.5 mm SL, ca. 74 km W of road going N to Jean, between Pucara and Guabel , Huancabamba River tributary, río Marañon drainage, 05º56’00”S 79º15’00”W , 8 Jul 1986. ROM 55366, 21 of 47, 24.6-62.1 mm SL, ca. 14 km W of Bagua, Marañon River tributary, 05º41’00”S 78º39’00”W , 1 Jul 1986. ROM 55406, 60 of 603 (3 c&s), 35.1- 105.6 mm SL, 2 km NW from the junction of the road to Chachapoyas and the road to Bagua, Utcubamba River tributary, río Marañon drainage, 06º13’00”S 77º54’00”W , 29 Jun 1986.

Figures

Fig. 8. Hemibrycon huambonicus, ROM 55406, male, 73.3 mm SL, upper río Ucayali basin, Peru.

Fig. 9. Hemibrycon huambonicus, ROM 55406, male, 70.0 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. 7. First gill arch showing gill gland. Lateral view of the left side of (a) Hemibrycon helleri,ANSP 180775, (b) Hemibrycon metae, USNM 228563; (c) Hemibrycon huambonicus, USNM 086794; (d) Hemibrycon jelskii, MCP 35022. Scale bars = 1 mm.

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.