Cynolebias parnaibensis from the Canindé River drainage, Parnaíba River basin, northeastern Brazil, is described. It is considered to be a member of a clade endemic to the Caatinga. The clade is diagnosed, e.g., by a series of structural modifications of the pharyngeal jaw apparatus, which is related to the sound production exhibited by males during courtship behavior. The courtship sound of C. parnaibensis consists of a single pulse named as thump (duration 0.031-0.133s; interthump intervals 0.020-8.319s; dominant frequency 70.3-93.8 Hz). The new species is distinguished from all other congeners by a combination of 27-31 neuromasts around eye, 29-33 supraorbital neuromasts, 16-18 dorsal-fin rays and 19 anal-fin rays in males, 28-31 caudal-fin rays, 33-36 scales in the longitudinal series, 3+10 gill-rakers in the first branchial arch, absence of second pharyngobranchial teeth, absence of contact organs on the flank scales, 34-35 vertebrae, absence of teeth on vomer, and presence of transverse series of scales on the anal-fin base. 

Terra Tipica:

Brazil, Estado do Piauí, Município de Jacobina do Piauí, seasonal lagoon at the right side of the road between Conceição do Canindé and Jacobina do Piauí, 08°00’54"S 41°25’26"W, 19 May 2009

No data available but assumed not different from its congeners. Breeding Cynolebias attenuatus is not for inexperienced hobbyists. The species becomes relative large and need special attention in feeding and storing the eggs. Food demand is high as the species need to grow to adulthood within a few months and eggs need to be stored under very cool circumstances in wich a frigidaire could become a good tool. Reproduction is best with one male and a number of big females. Tank need at least contain 60 liters and provide shelter for the females as male can be very agressive.

Also females are known to be agressive to each other. Put a high container filled with neutral pH material like Coco peat or clay (or a mix of it) for spawning.

Eggs are 2.2 mm in diameter and need about 4 to 5 months to develop. Juveniles that grow faster than others should be separated from the smaller ones immediately as they prey on them.

Remarks :

As with almost all other species this one is not available under hobbyists.

Max. size 00.0 cm in males - fem.smaller.
Dorsal (average, male only ) 00.0,
Anal (average, male only ) 00.0,
D/A (average, male only ) 0.0,
LL scale count (average) 00.0
Pre- dorsal length to SL – 00.0 %
Depth to SL – 00.0 %
Vertebrae count (average) 00.0

Wilson J. E. M. Costa1, Telton P. A. Ramos, Luisa C. Alexandre and Robson T. C. Ramos. 2010. Cynolebias parnaibensis, a new seasonal killifish from the Caatinga, Parnaíba River basin, northeastern Brazil, with notes on sound producing courtship behavior (Cyprinodontiformes: Rivulidae). Neotropical Ichthyology, 8(2):283-288, 2010.