Hemigrammus newboldi

description

Description: Morphometric data presented in Table 4. Body compressed, moderately elongate. Largest specimen examined 46.8 mm SL; greatest body depth slightly anterior to dorsal-fin origin. Dorsal profile of head and body convex from snout tip to dorsal-fin origin. Profile along base of dorsal fin straight and inclined posteriorly; moderately convex to adipose fin; concave along dorsal margin of caudal peduncle. Ventral profile of head and body convex from anterior tip of dentary to anal-fin origin; straight along anal-fin base; concave along ventral margin of caudal peduncle. Mouth terminal, jaws equal. Posterior tip of maxilla anterior to vertical through middle of orbit. Premaxillary teeth in two rows. Outer row with 4 * (30) or 5 (11) tricuspid teeth, inner row with 5 * (30) tri- to pentacupid teeth. Dentary with 4 * (41) large pentacuspid teeth followed by a series of 7 (3) diminutive conical teeth (Fig. 20). Central median cusp of all teeth longer than lateral cusps. First gill arch with 3 (2) rakers on hypobranchial, 12 (2) rakers on ceratobranchial, 1 (2) on intermediate cartilage, and 7 (2) rakers on epibranchial. Supraneurals 4 (3), obliquely oriented anteriorly. First sup

Taxonomic study of Moenkhausia cotinho Eigenmann, 1908 and Hemigrammus newboldi (Fernández-Yépez, 1949) with the description of two new species of Moenkhausia (Teleostei: Characiformes: Characidae)

diagnosis

Diagnosis. Hemigrammus newboldi is distinguished from all congeners, except H. hyanuary Durbin, H. schmardae (Steindachner), H. levis Durbin and H. vorderwinkleri Géry, by the presence of a single humeral blotch and a blotch on the base of the caudal fin (vs. humeral blotch absent or presence of two humeral blotches, and blotch on caudalfin base absent). It differs from H. hyanuary, H. schmardae and H. vorderwinkleri in having more perforated scales along the lateral line (9 to 16 vs. 6 – 9 respectively). It is distinguished from Hemigrammus levis by the deeper body (27.2 – 37.5 % vs. 22.9 – 29.8 % SL) and the shorter longitudinal stripe extending from the vertical through the dorsalfin origin to the caudal peduncle (vs. longitudinal stripe extending from the humeral spot to the caudal peduncle) and by the absence of hooks on the anal-fin rays of mature males (vs. mature males with hooks on the anal fin rays).

Taxonomic study of Moenkhausia cotinho Eigenmann, 1908 and Hemigrammus newboldi (Fernández-Yépez, 1949) with the description of two new species of Moenkhausia (Teleostei: Characiformes: Characidae)

discussion

Remarks. Ramirezella newboldi was described by Fernández-Yépez (1949) as a new genus and species from the drainage of Río Apure, Río Orinoco basin, Venezuela. Later, Taphorn (1992: 221) claimed that there were no characters to justify the proposition of a new genus, and although suggesting that Ramirezella should be considered a synonym of Hemigrammus, the author also mentioned that H. newboldi could be included in the genus Moenkhausia, based on its similarity with M. cotinho which, according to Eigenmann (1917), presented a gradation from incomplete to complete lateral line. As discussed above (see Geographic variation under the account of Moenkhausia cotinho), specimens of M. cotinho presents a complete lateral line throughout its distribution range, except from a few specimens from the Guyana. In addition, H. newboldi differs from M. cotinho in the relatively longer pectoral fin, with the tips of the longest rays extending beyond the pelvic-fin origin (vs. tips of pectoral-fin rays reaching at most the pelvic-fin origin), in the presence of conical teeth in the posterior portion of the dentary (vs. teeth tricuspid); in the absence of a reticulate color pattern of body (vs. reti

Taxonomic study of Moenkhausia cotinho Eigenmann, 1908 and Hemigrammus newboldi (Fernández-Yépez, 1949) with the description of two new species of Moenkhausia (Teleostei: Characiformes: Characidae)

distribution

Distribution. Hemigrammus newboldi occurs in drainages of the upper portion of the Amazon basin and in the Río Orinoco basin in Colombia and Venezuela, in 9 of the regions proposed by Dagosta & de Pinna (2017) for the Amazon and neighboring regions (17. Juruá, 18. Ucayali, 19. Marañon-Nanay, 20. Napo-Ambyiacu, 21. Putumayo, 22. Japurá, 39. Lower Orinoco, 40. Upper Orinoco, 41. Apure) (Fig. 21).

Taxonomic study of Moenkhausia cotinho Eigenmann, 1908 and Hemigrammus newboldi (Fernández-Yépez, 1949) with the description of two new species of Moenkhausia (Teleostei: Characiformes: Characidae)