Odontostilbe splendida, Bührnheim & Malabarba, 2007

Bührnheim, Cristina M. & Malabarba, Luiz R., 2007, Redescription of Odontostilbe pulchra (Gill, 1858) (Teleostei: Characidae: Cheirodontinae), and description of two new species from the río Orinoco basin, Neotropical Ichthyology 5 (1), pp. 1-20 : 11-15

Odontostilbe splendida , new species Fig. 12

Holotype. ANSP 181040 , 1 male (32.7 mm SL), Colombia, Meta, río Negrito at bridge at La Balsa, Meta drainage, J. E. Böhlke et al., 27 March 1975.

Paratypes. ANSP 181041 , 30 m, (8x of 30), (8 males 29.4-36.4 mm SL, 1 male 34.7 mm SL c&s, 20 females 31.3-41.6 mm SL, 1 female 32.1mm SL c&s), same data as holotype . MCP 38862, 27 (13 males 28.9-33.6 mm SL, 1 male 29.5 mm SL c&s, 13 unsexed 28.5-34.4 mm SL), same data as holotype , formerly ANSP 139572 . MCNG 54519 , 13 (7 males 29.2-33.2 mm SL, 6 unsexed 30.1-34.4 mm SL), same data as holotype . MBUCV 32890 , 13 (7 males 29.3-32.9 mm SL, 6 unsexed 25.8-32.3 mm SL), same data as holotype . ICNMHN 14168 , 13 (7 males 29.0- 33.0 mm SL, 6 unsexed 31.0- 32.8 mm SL), same data as holotype . INPA 25173 , 13 (7 males 29.5-32.2 mm SL, 6 unsexed 29.7-34.2), same data as holotype .

Non types. Río Meta basin, COLOMBIA , META: MHNG 2512.93 , 3 (unsexed 22.9-27.0 mm SL), río Humadea , near El Merey basin of río Meta. ANSP 139484 , 7 (2 males 32.8-33.9 mm SL, 5 unsexed 29.7-33.6 mm SL), confluence of río Guayariba and río Metica. Río Apure basin, VENEZUELA , GUARICO: ANSP 181137 , 50 (1 male 31.1 mm SL, 49 unsexed 19.2-37.5 mm SL), tributary of río Guarico, 3 km S of Calabozo on federal highway no. 2, formerly ANSP 139696 . MCP 14971, 11 unsexed 17.1-31.7 mm SL, río Apure, San Fernando de Apure, formerly ANSP 150111 . VENEZUELA , PORTUGUESA: USNM 349419 , 7 unsexed 29.9- 33.0 mm SL, río Las Marias, quebrada Seca (town) approximately 45 min. upstream by car from hwy. 5, 22 Km NNW Guanare. Río Orinoco basin, VENEZUELA , BOLIVAR: ANSP 181136 , 30 (1 male 32.8 mm SL, 29 unsexed 26.2-33.5 mm SL), caño Caiman, at crossing of Caicara - Puerto Ayacucho hwy, 19.2 km W of Ciudad Bolivar-Caicara highway, formerly ANSP 159904 .

Diagnosis. The anterior position of the adipose fin, at vertical through last 2 nd or 3 rd anal-fin ray insertions in O. splendida ( Fig. 12 ) is noticeably distinct from all other Odontostilbe species, including the sympatric O. pulchra ( Fig. 1 ) and O. pao ( Fig. 23 ), in which the adipose fin is positioned at vertical through last anal-fin ray insertion. Odontostilbe splendida further differs from O. pulchra by a group of morphometric characters in males: snout pointed and longer in O. splendida (24.1-26.9% HL) vs short and blunt in O. pulchra (18.0-26.0% HL) ( Fig. 5 ), shorter pectoral-fin length (20.9-23.5% SL in O. splendida vs 21.3-26.4% SL in O. pulchra ) ( Fig. 13 ), smaller anal-fin base (24.9-26.8% SL vs 26.0-31.4% SL) ( Fig. 14 ), shorter caudal peduncle length (11.5- 13.0% SL vs 12.5-16.0% SL) ( Fig. 15 ), longer snout-pelvic fin origin distance (45.1-48.7% SL vs 42.3-47.9% SL) ( Fig. 16 ), and longersnout-analfinorigindistance (63.7-68.6% SL vs 58.6-64.0% SL) ( Fig. 17 ). Additionally, mature males of O. splendida are remarkably distinguished by the presence of hooks on 1 st to 6 th- 7 th anal-fin rays, vs hooks on 1 st to 22 nd anal-fin branched rays in O. pulchra . Mature males of O. splendida usually have the 2 nd unbranched dorsal-fin ray elongate, not present in O. pulchra . Females and immature specimens, and not well-developed males of O. splendida and O. pulchra , have overlapping ranges in many of the ratios cited above, and can be differentiated by the following characters:(1) presence of 3-4 (mostly 3) maxillary teeth in O. splendida , vs 2-3 (mostly 2) in O. pulchra ; 36 lateral line scales (one specimen 35) in O. splendida vs 33-37, mostly 34-35 lateral line scales in O. pulchra . The number of gill rakers counts on lower branch differ O. splendida (averaging 11) from O. fugitiva (usually 12) ( Fig. 18 ).

Description. Morphometric data are given in Table 2 . Largest male 36.4 mm in.SL, largest female 41.6 mm in SL. Body elongate and compressed. Body of males slightly more compressed and elongate than females. Greatest body depth at dorsal-fin origin. Snout short, somewhat pointed in males. Head profile pointed, gently convex to straight from snout to posterior tip of supraoccipital bone. Predorsal profile slightly convex to straight between posterior tip of supraoccipital bone and dorsal-fin origin, straight on dorsal-fin base, and then slightly convex to straight from end of dorsal-fin base to caudal peduncle. Ventral profile convex from mouth tip to anal-fin origin. Analfin base straight. Caudal peduncle slightly longer than deep.

Head relatively small. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal. Maxilla obliquely positioned ending at vertical through anterior border of eye, and at horizontal on inferior border of eye. Premaxillary teeth 5-6, bearing 8-11 cusps; central cusp longest ( Fig. 19 ). Maxilla with 3-4 (mainly 3) teeth bearing 5-9 cusps, decreasing cusp number toward posterior tip of maxilla. Dentary teeth 9-10, gradually decreasing in size, anterior 5-6 teeth large bearing 7-8 cusps, 1 medium-sized tooth with 5-6 cusps, and posterior teeth small, conic or with 2-5 cusps. Smaller cusps of dentary teeth overlap cusps of adjacent tooth.

Dorsal-fin rays ii,9 (31). Dorsal-fin origin slightly posterior to mid body length, and slightly posterior to pelvic-fin origin. Second unbranched dorsal-fin ray slightly elongate in some males (not in holotype), extending beyond dorsal-fin distal profile. Anal-fin rays iv(6), or v (25), 19 (9), 20(16), 21(5), or 22(1). Anal-fin distal border concave, anterior 6-7 branched

rays longest. Pectoral-fin rays i(31), 9(2), 10 (9), 11(16), or 12(3). Pelvic-fin rays i(31), 6(1), or 7 (30). Unbranched pelvic-fin ray longest ray in mature males, extending beyond origin of anal fin. Lateral skin border of unbranched pectoral-fin ray and unbranched pelvic-fin ray slight thickened in males. Principal caudal-fin rays 19(31). Procurrent caudal-fin rays: dorsal 10(1), 11(4), 12(14), 13 (9), or 14(3), ventral 9(3), 10(17), 11 (10), or 12(1). Anterior 1 or 2 ventral procurrent caudal-fin rays sometimes laterally expanded or bifurcated. Caudal-fin ray flaps ventrally on 4 th- 8 th branched rays of upper lobe, dorsally on 13 th -16 th branched rays of lower lobe. Adipose-fin at vertical through last 2 nd or 3 rd anal-fin ray insertions.

Males with acute retrorse hooks on posterior border of pelvic- and anal-fin rays. One or two paired or unpaired hooks per segment of lepidotrichia, at distal half-length of last unbranched anal-fin ray, and 1 st to 6 th- 7 th branched anal-fin rays. One or two unpaired long hooks per segment of lepidotrichia along almost entire length of 1 st to 7 th branched pelvic-fin rays, reaching distal tip of fin ray (except on 1 st branched pelvic-fin ray, on midlength portion). One or two unpaired hooks per segment of lepidotrichia on anterior border of branchings of pelvic- and anal-fin rays.

Scales cycloid: lateral line complete 35(1), or 36 (26); predorsal row 10 (10), or 11(20); scale rows between lateral line and dorsalfin origin 6 (28), or 7(2); scale rows between lateral line and analfin origin 4 (15), or 5(15); scale rows around caudal peduncle 14 (29). Triangular modified scale on pelvic-fin base extends posterior covering 2-3 scales. Scales on anal-fin base 6 or 7.

Cleared and stained specimens (3), and radiographs (8): supraneurals 4; precaudal vertebrae, including Weberian apparatus, 16(3), or 17(8); caudal vertebrae 17(3), 18(7), or 19(1); gill rakers, upper 5(1), or 6(2), lower 10, 11, or 12 (2-3 on hypobranchial). Alcohol specimens (22): gill rakers, upper 5(2), 6 (18), or 7(2), lower 11 (21), or 12(1). Upper gill rakers with none to 3 denticles on anterolateral border; lower gill rakers with 1-4 recurved denticles on anterolateral border; and posteriormost lower gill raker with none to 7 recurved denticles on posterior border, and 3 denticles on anterior border ( Fig. 20 ). Denticulation mainly on basal portion of gill rakers.

Color in alcohol. General ground body color pale yellow or pale orange. Dorsal part of body darker with chromatophores more concentrate on scales border, from head to caudal peduncle. Dark chromatophores along all dorsal-fin rays. Pectoral fin with chromatophores along 1 st unbranched pectoralfin ray and 1 st branched fin rays. Pelvic fin clear.Anal fin with dark chromatophores on central branched anal-fin rays, except at tips of last unbranched fin rays and 1 st branched fin ray; hyaline in holotype. Adipose fin clear. Caudal fin almost entirely covered with diffuse dark chromatophores along fin rays, except clear areas on base of caudal-fin lobes just behind caudal-fin spot (chromatophores very faded in type material). Rounded brown to black spot on base of caudal fin, usually reaching upper border of caudal peduncle.

Dark chromatophores on snout, upper lip, anteriormost portion of maxilla, and 1 st to 2 nd infraorbitals. Top of head on frontals and parietals pigmented, deep-lying dark chromatophores over brain membranes below frontals and parietals, and fontanels. Body with faint dark and silver midlateral stripe, beginning behind pseudotympanum, above lateral line, and reaching caudal spot. Guanine on eye iris, opercle, isthmus, and 2 nd to 5 th infraorbital. Presence or not of scattered chromatophores on pseudotympanum area. Below lateral line, belly faint usually unpigmented, chromatophores above anal-fin base area forming 10 to 11 chevron shaped markings (faint scattered chromatophores in type material).

Sexual dimorphism. Males have hooks on anal and pelvicfin rays, and slight elongation of dorsal- and pelvic-fin rays, in contrast to the absence of these features in females (see description). A gill gland (Burns & Weitzman, 1996) is found in mature males of Odontostilbe splendida . The gill gland is present on the first gill arch, including about 7 to 9 anterior branchial filaments ( Fig. 20 ). Males usually have longer snout length, and caudal peduncle length ( Fig. 21 ).

Distribution. Río Orinoco basin ( Fig. 22 ).

Etymology. Refers to the Latin word splendidus, meaning splendid, grand, admirable.

Ecological notes. Field notes of type material indicate bottom with mud and sand, and water depth nearly 3 feet.

Figures

Fig. 12. Holotype of Odontostilbe splendida,ANSP 181040, male 32.7mm SL (top), and paratypeANSP 181041, female 32.1 mm SL (bottom).

Fig. 1. Odontostilbe pulchra, syntype MNHN 0000-9593, female 28.7 mm SL (top), a specimen INHS 40101, male 32.3 mm SL from Trinidad(middle top), and specimensMCP 38863, male 28.6 mm SL (middle bottom), andfemale 32.5 mm SL (bottom) from río Orinoco basin.

Fig. 23. Holotype of Odontostilbe pao, MCNG 54497, male 29.3 mm SL.

Fig. 5. Snout length as a function of head length for males of Odontostilbe pulchra, against O. splendida, and O. pao.

Fig. 13. Pectoral-fin length as a function of standard length for males of Odontostilbe pulchra, against O. splendida.

Fig. 14. Anal-fin base as a function of standard length for males of Odontostilbe pulchra, against O. splendida.

Fig. 15. Caudalpeduncle length as a function of standard length for males of Odontostilbe pulchra, against O. splendida.

Fig. 16. Snout-pelvic fin origin as a function of standard length for males of Odontostilbe pulchra, against O. splendida.

Fig. 17. Snout-anal fin origin as a function of standard length for males of Odontostilbe pulchra, against O. splendida.

Fig. 18. Lower gill rakers counts of Odontostilbe pulchra, Odontostilbe fugitiva (data from Bührnheim & Malabarba, 2006), and of two new species Odontostilbe splendida, and Odontostilbe pao.

Fig. 19. Dentition of Odontostilbe splendida, paratypeANSP 181041, female 32.1 mm SL:right side premaxilla (top), maxilla (middle), and dentary (bottom), lateral view. Scanning electron micrographs (SEM).

Fig. 20. First gill arch of Odontostilbe splendida, MCP 38862, male 29.7 mm SL: left side, lateral view, showing gill gland (top), in detail gill rakers on upper branchial branch (middle), and gill rakers on lower branchial branch (bottom). Scanning electron micrographs (SEM).

Fig. 21. Caudal peduncle length as a function of standard length for males against females of Odontostilbe splendida.

Fig. 22. Distribution of Odontostilbe splendida (triangles), and Odontostilbe pao (square). Symbols can represent more than one lot, and more than one locality.