Cynodon Agassiz, 1829

TOLEDO-PIZA, MÔNICA, 2000, The Neotropical Fish Subfamily Cynodontinae (Teleostei: Ostariophysi: Characiformes): A Phylogenetic Study and a Revision of Cynodon and Rhaphiodon, American Museum Novitates 3286, pp. 1-1 : 1-

Genus Cynodon Agassiz, 1829

Cynodon Agassiz, 1829: 77 (type species Cynodon gibbus ).

Cynodon Cuvier, 1829: 312 .

Camposichthys Travassos, 1946: 132 (type species Cynodon gibbus by original designation).

DIAGNOSIS: Cynodon is diagnosed by the synapomorphies listed in Monophyly of Cynodon under Phylogenetic Reconstruction. Externally, Cynodon can be easily distinguished from other cynodontines by its relatively long anal fin with 60 or more branched rays in comparison to less than 50 in Rhaphiodon and Hydrolycus . The anal­fin origin in Cynodon is located approximately at the vertical through the middle of the body length, almost reaching the tips of the pelvic­fin rays; in Hydrolycus and Rhaphiodon the anal­fin origin is located far posterior to the vertical through the middle of the body.

DISTRIBUTION: Rios Amazonas, Tocantins, Capim, and Río Orinoco basins; Demerara River and Essequibo River drainage in Guyana; Rio Pindaré drainage, Maranhão State, Brazil.

REMARKS: The nomenclature of Cynodon and Rhaphiodon has been the subject of debate by many authors including Campos (1945), Travassos (1946), Kottelat (1988), Eschmeyer and Bailey ( 1990), Eschmeyer ( 1990), and Whitehead and Myers (1971), as a consequence of problems arising from differences in the interpretation of the works of Agassiz ( 1829) and Cuvier ( 1829). A petition was submitted to the International Commission on Zoological Nomenclature proposing the conservation of the usage of these genus names (acknowledgment of receipt appeared in Bull. Zool. Nomen (54): 77 under Case 3041 by M. Toledo­Piza and K. J. Lazara) and publication and ruling of the case are awaited.

Key to species of Cynodon Agassiz, 1829

1. Branched pelvic­fin rays 8; band of dark pigmentation covering caudal­fin base ( fig. 21 ) ................................ 2

– Branched pelvic­fin rays 7; no band of dark pigmentation covering base of caudal fin ( fig. 24 ); orbital diameter 30.1–34.4 of HL (Rio Amazonas and its tributaries between mouths of Rios Içá and Tapajós; Essequibo River drainage and Demerara River in Guyana; upper portions of Río Orinoco basin in Venezuela)...................................... C. septenarius , new species

2. Orbital diameter 24.9–33.8 of HL (mean 29.2), branched anal­fin rays 68–80 (2 specimens with 65 rays) (Rio Amazonas and Río Orinoco basins, Rupununi River in Guyana, Rio Tocantins drainage and Rio Pindaré system, state of Maranhão, Brazil)....................................... C. gibbus

– Orbital diameter 29.8–34.4 of HL (mean 31.8), branched anal­fin rays 63–67 (upper Maroni River, French Guiana).............................. C. meionactis (see below)

COMMENTS ON CYNODON MEIONACTIS

I examined one paratype ( MNHN 1998­ 400 ) and one nontype specimen of C. meionactis ( MNHN 1998­ 1769 ) . Dr. M. Jégu checked characters of the holotype ( MNHN 1998­ 0397 ) . I concluded that C. meionactis

Figures

Fig. 21. Cynodon gibbus, neotype, MZUSP 6539, 146.4 mm SL, Brazil, Amazonas, Lago Manacapuru.

Fig. 24. Cynodon septenarius, new species, holotype, MZUSP 32590, mm SL, Brazil, Amazonas, Rio Tefe´, Supiã­Pucu.