Hemibrycon divisorensis Bertaco, Malabarba, Hidalgo & Ortega, 2007

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. 737-737 : 737-

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https://doi.org/ 10.1590/S1679-62252010000400005

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Hemibrycon divisorensis Bertaco, Malabarba, Hidalgo & Ortega, 2007


Hemibrycon divisorensis Bertaco, Malabarba, Hidalgo & Ortega, 2007 View in CoL

Hemibrycon divisorensis was recently described by Bertaco et al. (2007), from the upper río Ucayali drainage, Peru, and only an updated diagnosis is presented here.

Diagnosis. Hemibrycon divisorensis is distinguished from its congeners by the presence of a wide black asymmetrical spot covering the base of caudal-fin rays and extending along entire length of caudal-fin rays 9 to 12-13 (except H. surinamensis ), and by the presence of a black band in the lower half of the caudal peduncle from the region above the last anal-fin rays to the caudal-fin base. Furthermore, it is distinguished from its

V. A. Bertaco & L. R. Malabarba 767

Cis-Andean congeners by the number of scale rows below lateral line (4-5 vs. 5-9), except H. mikrostiktos and H. surinamensis . It differs from H. mikrostiktos by the number of branched anal-fin rays (24-30 vs. 18-21), and from H. surinamensis by the number of scale sheath along anal-fin base (17-22 vs. 12-17), and by the number of cusps in the inner row of the premaxilla teeth (5-7 vs. 4-5).

Taxonomic status of Boehlkea orcesi (Böhlke, 1958) , new combination

Hemibrycon orcesi was described by Böhlke (1958) based on the holotype and three paratypes from río Macuma, Província de Santiago-Zamora, Ecuador.According to Böhlke, the species was proposed provisionally in Hemibrycon because the lobes of the caudal-fin were scaled and disagree with Eigenmann’s definition for Hemibrycon . In 1962, Géry also suspected that H. orcesi could belong to a new genus related to Hemibrycon , but clearly different from it.

The type specimens of H. orcesi possess the caudal fin scaled or with scale marks to proximal half of lobes, a character not found in Hemibrycon species. In all type specimens some body scales are lacking and are not in good conditions of preservation, thus it is not possible to know if the lateral line is incomplete or complete. Böhlke (1958: 27) when describing a lateral line complete to H. orcesi commented that “though all lateral line counts were interrupted by areas where scales were missing”. Also, Böhlke commented “although the caudal scalation of all the present specimens is damaged to some extent, some specimens (most notably the holotype) still possess scales which extend more than half-way out on the caudal lobes”.

Differently of the genera belonging to the Stevardiinae sensu Mirande (2009, 2010 ), the species of Hemibrycon and Boehlkea share a large number of teeth in the maxilla, as observed in the types of H. orcesi (13-14 uni- to pentacuspid teeth) and in the only species of Boehlkea , B. fredcochui Géry (14-15 uni- to tricuspid teeth). Boehlkea differs from Hemibrycon by the presence of scales in the caudal fin lobes, lateral line interrupted, and smaller total number of vertebrae (36 vs. 38-43). Besides lobes of caudal fin scaled, H. orcesi possess other features uncommon for Hemibrycon species , as the short lateral line (34 to 35 vs. 39-58 scales); smaller number of vertebrae (36 to 37 total vertebrae); and color pattern of dorsal, anal and ventral fins, densely pigmented. Recently, this species was redescribed in Hemibrycon from ríos Macuma and Pastaza, in Ecuador by Román-Valencia et al. (2007), but according with characters commented here its is considered as belonging to Boehlkea .

We have analyzed the holotype and one paratype of Boehlkea fredcochui , and the caudal-fin presented small scales to half of upper and lower lobes, lateral line interrupted with 14 perforated scales plus 23 remaining scales (last scales perforated or unperforated), and 37 scales in the longitudinal series. Further, B. orcesi differs from B. fredcochui by number of the branched anal-fin rays (17-18 vs. 24-25), pelvic-fin rays (8 vs. 7), lateral line scales (34-35 vs. 37), and scale rows above of the lateral line (6-7 vs. 5), color pattern, and by some body measurements.

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