Hemibrycon helleri Eigenmann, 1927

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 : 741-743

Hemibrycon helleri Eigenmann, 1927

Figs. 5-6

Hemibrycon helleri Eigenmann, 1927: 402 (in key), 406 (pl. 96, fig. 2; original description; type material; type locality: río Comberciato, río Urubamba drainage).

Diagnosis. Hemibrycon helleri is distinguished from all congeners, except H. jelskii , by the size of humeral spot (over 7-8 vs. 3-6 horizontal series of scales). It differs from H. jelskii by the number of branched anal-fin rays (19-23 vs. 25-30, Fig. 2 ),

742 A review of the Cis-Andean species of Hemibrycon and by the number of scales along anal-fin base scale sheath (6-12 vs. 13-28). Hemibrycon helleri is rather similar to H. inambari new species, but can be distinguished by the size of humeral spot (over 7-8 vs. 5-6 horizontal series of scales), number of predorsal scales (16-18 vs. 13-16), and by the total number of vertebrae (41-43 vs. 39-40).

Description. Morphometric data for H. helleri summarized in Table 1. Largest male 78.6 mm SL, largest female 81.6 mm SL. Body compressed and moderately 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 bone 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 analfin 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 nearly at horizontal through 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.

Premaxilla with two tooth rows; outer row with 3-5, tricuspid teeth with central cusp slightly longer; inner row with 4 tetra- to pentacuspids 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 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. 6 ).

Dorsal-fin rays ii,8 (n = 33); first unbranched ray approximately one-half length of second ray. Dorsal-fin origin located posterior 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 or posterior to last anal-fin ray. Analfin rays ii-v,19-23 (mode = 21, n = 37, Fig. 2 ). Anal-fin profile slightly convex in males and nearly straight in females. Analfin 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 twelfth to sixteenth branched rays. One male paratype had bony hooks in all analfin branched rays. Hooks usually located along posteriormost branch and distal 1 /

2

to 2 /

3

of each ray. Pectoral-fin rays i,10-11

V. A. Bertaco & L. R. Malabarba 743

(mode = 10, n = 27). Pectoral-fin tip reaching pelvic-fin origin in males. Males with bony hooks on distal portion of unbranched and all branched rays. Pelvic-fin rays i,6,i (n = 30). 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 fourth to eighth branched rays. Caudal fin forked with 19 principal rays without bony hooks (n = 30); lobes similar in size. Caudal-fin base with a few scales in half-length, followed by one large 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 42-45 (mode = 42, n = 23, Fig. 3). Scale rows between dorsalfin origin and lateral line 7-8 (mode = 8, n = 35); scale rows between lateral line and pelvic-fin origin 5-6 (mode = 6, n = 35). Predorsal scales 15-18, arranged in regular series (mode =16,n = 34). Scales rows around caudal peduncle 16-18 (mode = 16, n = 27). Axillary scale on pelvic-fin origin extends posteriorly covering 2-3 scales. Scale sheath along anal-fin base with 6-12 scales in single series, extending to base of most anterior branched rays.

Precaudal vertebrae 19-21; caudal vertebrae 22-23; total vertebrae 41-43 (n = 12). Supraneurals 6-7 (n = 12). Gill rakers on upper limb of outer gill arch 6-7, and on lower limb 10-11 (n = 11).

Color in alcohol. Type material discolored. Color based on the non-type specimens. 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 fourth to sixth lateral line scales and extending over 7-8 horizontal series of scales, including lateral line. Midlateral dark stripe extending from humeral region to middle caudal-fin rays, broad in the caudal peduncle. Abdominal region almost devoid of black chromatophores. Adipose fin densely black pigmented. Dorsal and caudal fin with black pigmentation diffuse and anal fin with small black chromatophores along its border forming narrow stripe. Pectoral and pelvic fins hyaline ( Fig. 5 ).

Sexual dimorphism. Males of Hemibrycon helleri 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 body depth ( Table 1), and in anal-fin shape, which is slightly convex 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 helleri is known from río Comberciato, and río Urubamba, upper río Ucayali drainage, Cusco, Peru ( Fig. 4 ).

Remarks. Eigenmann (1927: 406) described Hemibrycon helleri and designated the holotype as “13565 Type” [MCZ 31565, the catalog number mistakely cited in the original description] and 17 paratypes (CM 7439, IU 13754) from río Comberciato, Peru. Later, Eigenmann & Allen (1942: 216) listed the type material but did not provided the catalog number for types of H. helleri , but listed 18 type specimens along with their lengths, and type locality. Böhlke (1953) in his catalog of types from Stanford University did not list types of H. helleri . Ibarra & Stewart (1987: 43) listed three paratypes of H. helleri but did not provide the catalog number of FMNH specimens.Eschmeyer (1998: 717) listed two possible lots as holotype, “?MCZ 31565” (1) or MCZ 30980 (1), and the following lots as paratypes: CAS 44354 [ex IU 13754] (5) and FMNH 58439 (3), followed posteriorly by Lima et al. (2003: 129); there are 8 paratypes missing.

According to Eigenmann (1927) the holotype has 100 mm of size [total length - TL]. The specimen from MCZ 31565 measures 78.9 mm SL and 94.9 mm TL and the specimen from MCZ 30980 has 81.1 mm SL and 98.9 mm TL. Although the specimen from MCZ 30980 is larger and more close to the body size of the holotype mentioned by Eigenmann (100 mm TL), the specimen corresponding to the original catalog number referred as the holotype MCZ 31565 (mistyped 13565) has the same number of branched anal-fin rays of the specimen illustrated as the holotype in the figure 2 by Eigenmann (1927, plate 96), 23 vs. 22 branched anal-fin rays on specimen of lot MCZ 30980, and so we consider that the specimen available as MCZ 31565 is actually the holotype. Based on data and fish images taken from the lots MCZ 30980 (1), and MCZ 30981 (7) we can confirm that these specimens are part of the missing type series of H. helleri . The specimen listed as nontype by Eigenmann (1927: 406; CAS 44355, ex IU 17611) from río Crisnejas, Peru is actually a specimen of H. huambonicus .

Material examined. Holotype. MCZ 31565, female (x-ray), 78.9 mm SL, río Comberciato, a small tributary of middle río Urubamba, 30 miles above the Pongo de Mainique , Cusco, Peru , 1,800 ft. elev., ca. 12º28’S 73º07’W, 1910-1915, E. Heller (Yale-National Geographic Expedition) . Paratypes. CAS 44354, 5 , 39.6 -72.0 mm SL , FMNH 58439 , 3 (x-ray), 36.4-78.5 mm SL , MCZ 30980, 1 (x-ray), 81.1 mm SL , MCZ 30981, 8 (x-ray), 46.1-79.2 mm SL, collected with the holotype . Non-type specimens. Peru, Cusco, río Urubamba drainage : ANSP 180775 , 4 (1 c&s), 53.3-81.1 mm SL, quebrada Rosaríomayo, west of Quelluono on road to Kiteni , 12º46’28”S 72º39’06”W, 19 Jul 2004 . ANSP 180777 , 2 , 20.4-72.4 mm SL, río Amaybamba, southeast of Quillabamba on road to Ollantaytambo , 12º59’55”S 72º31’24”W, 17 Jul 2004 . ANSP 180780 , 1 , 23.5 mm SL, Yanayaku Grande, tributary of río Urubamba, southeast of Quillabamba on road to Ollantaytambo , 12º59’49”S 72º32’06”W, 17 Jul 2004 . CAS 70077, 15 , 27.5-81.5 mm SL, río de Santa Ana, creek entering middle río Urubamba at ca. 3000-3400 ft. elev., the farthest point reached by the Eigenmann’s on río Urubamba , ca. 12º52’S 72º43’W, 15 Nov 1918 .

Figures

Fig. 5. Hemibrycon helleri,ANSP 180775, female, 81.1 mm SL, upper río Ucayali basin, Peru.

Fig. 6. Hemibrycon helleri,ANSP 180775, female,66.6 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.