Cyanocharax, Malabarba & Weitzman, 2003

Malabarba, Luiz R. & Weitzman, Stanley H., 2003, Description Of A New Genus With Six New Species From Southern Brazil, Uruguay And Argentina, With A Discussion Of A Putative Characid Clade (Teleostei: Characiformes: Characidae), Comun. Mus. Ciênc. Tecnol. PUCRS 16 (1), pp. 67-151 : 95-97

Cyanocharax , new genus

Type species: Cyanocharax macropinna , new species

Distinguishing characters. Characters that allow the recognition of Cyanocharax are summarized as (1) the presence of two unbranched and eight branched dorsal-fin rays; (2) absence of insemination; (3) absence of caudal- and anal-fin glands or specialized organs; (4) the presence of one unbranched and six branched pelvic-fin rays; (5) presence of a clearly anterior mouth with unspecialized teeth, as well as the absence of a ventrally-located mouth with modified maxilla, premaxilla and dentary bones; (6) the number of branched anal-fin rays, ranging from 21 to 35; and (7) the incompletely toothed maxilla, with 2 to 8 teeth.

Cyanocharax is distinguished from most characid genera (except Attonitus , Boehlkea , Bryconacidnus , Bryconamericus , Caiapobrycon , Ceratobranchia , Creagrutus , Hemibrycon , Hypobrycon , Knodus , Microgenys , Monotocheirodon , Odontostoechus , Othonocheirodus , Piabarchus , Piabina , Rhinobrycon , and Rhinopetitia ), by the presence of a derived dorsal fin with ii,8, instead of ii,9 or higher number of rays.

Cyanocharax species can be recognized and distinguished from glandulocaudines, Attonitus and Monotocheirodon by the absence of the insemination, that is present in those taxa, as well as by the lack of modified caudal organs as described for the glandulocaudine tribes ( Weitzman & Menezes, 1998).

A reduced number of pelvic-fin rays (i,6) differentiate Cyanocharax from Attonitus , Bryconacidnus , Bryconamericus , Ceratobranchia , Creagrutus , Hemibrycon , Hypobrycon , Odontostoechus , Othonocheirodus , Piabina , Rhinobrycon and Rhinopetitia , all of which have i,7 pelvic-fin rays.

The presence of a clearly anterior mouth with unspecialized teeth, as well as the absence of modified maxilla, premaxilla, and dentary bones distinguishes Cyanocharax from Attonitus (as diagnosed by Vari & Ortega, 2000), Caiapobrycon (as diagnosed by Malabarba & Vari, 2000), Ceratobranchia (as diagnosed by Chernoff & Machado-Allison, 1990), Creagrutus and Piabina (as diagnosed by Vari & Harold, 1998), and Hypobrycon (as diagnosed by Malabarba & Malabarba, 1994; and Silva & Malabarba, 1996). Although not cladistically diagnosed, the genera Bryconacidnus , Microgenys , Monotocheirodon , Odontostoechus , Othonocheirodus , Piabarchus , Rhinobrycon , and Rhinopetitia are all characterized by the specialized mouth placed anteroventrally or ventrally with modified teeth and maxilla, premaxilla and dentary bones, features not shared with the species of Cyanocharax .

Cyanocharax is further distinguished from Monotocheirodon , Odontostoechus , and Othonocheirodus by the presence of two tooth series in the premaxilla (versus one in Monotocheirodon , Odontostoechus and Othonocheirodus ).

The 21 to 35 branched anal-fin rays further distinguish Cyanocharax from Caiapobrycon (8 to 10 branched anal-fin rays), Attonitus (11 - 17), Ceratobranchia (11 - 19), Rhinobrycon (11 - 14), Bryconacidnus (total of 14- 17 anal-fin rays), and Creagrutus (8-18) ( Malabarba & Vari, 2000).

Cyanocharax is distinguished from Boehlkea and Hemibrycon by the incompletely toothed maxilla, with 2 to 8 teeth (versus almost to completely toothed in Boehlkea , with 11 -21 teeth, and 6-20 teeth in Hemibrycon ). It is distinguished from Knodus by the absence of scales covering the proximal region of the caudal-fin rays.

The genera Bryconamericus - 51 species, Hemibrycon - 19 species and Knodus - 16 species lack a diagnosis based on putatively apomorphic characters, and their species are so morphologically diverse that the limits among those genera have long been considered uncertain. Although the characters given to distinguish Cyanocharax from the above three genera apply for most of their species, our comparisons herein were primarily concerned with distinguishing Cyanocharax from the type species of each genus.

Key to the species of Cyanocharax

1. - Lateral line usually complete. Anal-fin origin clearly posterior to vertical through dorsal-fin origin. Anal-fin distal border concave in males......... ..................................................................................................................................2

1 ’ - Lateral line never complete (interrupted, or with alternated series of perforated and non perforated scales). Anal-fin origin nearly along vertical through dorsal-fin origin. Anal-fin distal border convex or nearly straight in mature males..................................................................................................... 4

2 - Anal fin black pigmented, with distal tip ofanterior lobe unpigmented. Adipose fin black in preserved mature males and females............................ 3

2 ’ -Anal fin unpigmented, without distinctive marks. Adipose fin not pigmented in preserved mature males and females.................... C.alburnus

3 - Eleven to 13 scale rows between dorsal-fin origin and pelvic-fin origin............................................................................................................ C. itaimbe 3 ’ - Ten to 11 scale rows between dorsal-fin origin and pelvic-fin origin.. C. dicropotamicus

4 - Anal fin with one row of 7- 13 small scales covering basal part of unbranched anal-fin rays and anterior 7- 13 branched anal-fin rays................... ................................................................................................................. C. tipiaia

4 ’ - Anal fin with one row of more than 12 small scales covering basal part of unbranched anal-fin rays and anterior 12 -20 branched anal-fin rays or all branched anal-fin rays ............................................................................... 5

5 - Distal border of anal fin in mature males nearly straight. Body scales in longitudinal series 37-39 (usually 37-38) .............................. C. lepiclastus

5 ’ - Distal border of anal fin in mature males strongly convex ( Figs. 7 , 8). Body scales in longitudinal series 36-38 (usually 36-37)............................... 6

6 - Branched anal-fin rays, 23-30 (usually 25-28). Anal fin with basal sheath of scales, consisting of 1 row with 12- 18 small scales, covering bases of unbranched rays and first 12 to 18 branched rays .. C. alegretensis

6’ - Branched anal-fin rays, 28-35 (usually 29-33). Anal fin with basal sheath of scales, consisting of one row with 20-28 small scales, covering anterior 22 branched rays, to all anal-fin base ........................ C. macropinna

Figures

Figure 7. Left view of the anal fin of a male of Cyanocharax alegretensis showing the distribution of the anal-fin hooks (MCP 11232,39.3 mm SL).