Cynolebias gibberosus, Berg, 1897

Castello, Hugo Patricio & Lopez, Rogelio Bartolome, 1974, Cynolebias alexandri, a new species of annual killifish from Argentina, with notes on C. bellottii, Tropical Fish Hobbyist 23 (1), pp. 34-40 : 34-35

Cynolebias gibberosus

—A new synonym of C. bellottii

Two specimens of an annual killifish from Cachari (Partido de Azul, Provincia de Buenos Aires) were described in 1897 under the name Cynolebias gibberosus by the Argentine ichthyologist Carlos Berg. They were very similar in color and scale disposition to the Argentine pearl fish, Cynolebias bellottii .

The original specimens (type material), a male and a female, were distinguished by Berg from C. bellottii as having a very curved dorsal profile anterior to the dorsal fin and 11 to 13 spinous tubercles protruding through the scales and skin in the same area. Cynolebias gibberosus was never again recorded from new specimens, although it was included in several lists of fishes from Buenos Aires Province. This type material is in our collection under the numbers M.A.C.N. 5172 (male) and 5177 (fe- male).

For several years we have been collecting the pearl fishes in temporary ponds situated on both sides of the road that connects Villa Elisa with Punta Lara on the shore of the La Plata river, 50 km south of Buenos Aires.These ponds are inhabited by such lesser known killifishes such as C. elongatus and C. nigripinnis and other fishes such as Corydoras paleatus (tachuela), Cnesterodon decemmaculatus (madrecita), the airbreathing fresh water eel Synbranchus marmoratus (anguilla criolla), Callichthys callichthys (cascarudo), and small tetras (mojarritas).

The pearl fishes were kept in aquaria and fed daily with live foods (Daphnia, Tubifex, or chironomid larvae).If live food was not provided for them, in a few days the fish became thin, emaciated, and often infected with “ich;” they died shortly afterward. Raising the temperature sometimes stopped the white-spot infection, but if the pearl fish were not properly fed again with abundant food, their vertebral column became bowed.

As we were very interested in the evolution of this process, adult male and female C. bellottii were placed in the large aquaria of the Animal Physiology Laboratories at Buenos Aires University. They were given an inadequate supply of food from the beginning of the experiment. In a three month period we observed the following symptoms: bowed vertebral column, emaciation, and exophthalmos. Finally, we observed the neural spines appearing through the skin in the predorsal area.

After reading a paper by Walford and Liu (1965), we became aware of the fact that C. adloffi is also a short lived species that undergoes senility changes in about a year. Specimens lose their equilibrium and the branchial epithelium degenerates; they show hyperplasia of thyroid tissues, melanism, and other illnesses such as tuberculosis. The same authors (Liu and Walford. 1969) observed that the pathological symptoms increased with age in C. bellottii, emaciation, equilibrium disturbances and spinal curvature being the major gross symptoms. In comparing these deformed specimens with the type material of C. gibberosus , even though the latter were badly preserved in alcohol, we were able to prove that C. gibberosus was based on deformed specimens of C. bellottii, probably collected in a temporary pond after a long period of aging, and dis playing symptoms of lordosis and kyphosis. Cynolebias gibberosus Berg, 1897 , thus becomes a synonym of Cynolebias bellottii Steindachner, 1881 .