Gonorynchiformes: Development and Relationships 

 W. J. Richards 



THE Gonorynchiformes is a small group of fishes which have 

 been allied with the clupeiforms or salmoniforms and most 

 recently have been placed as a lineage, within the ostariophysan 

 group, which includes also the Cypriniformes, Characiformes, 

 and Siluriformes (Fink and Fink, 1981). The group is comprised 

 of seven genera classified in about four or five families. The 

 most widely known species is Chanos chanos Forsskil placed 

 in the monotypic family Chanidae. The Gonorynchidae is a 

 marine family of one genus Gonorymchus and several species 

 found in tropical waters of all but the western Atlantic and 

 eastern Pacific. The remaining twelve or so species are African 

 freshwater forms in the genera Kneria. Parakneria. Grassei- 

 chthys and Phractolaemus, which may represent two or three 

 families. The eariy life history of Chanos is very well known 

 because of the extensive culturing; Gonorymchus is poorly known. 

 The early life histories of the freshwater species are unknown. 

 Pellegrin (1935) notes that young specimens of Cromeria nt- 

 lotica have a superficial resemblance to young Albula. It is ap- 

 parent that this resemblance is to the shape of juveniles and not 



to a leptocephalus stage. Several subsequent papers have erro- 

 neously reported that Pellegrin said that Cromeria resembled 

 larval Albula. 



Development 



The early life history of Chanos chanos, the milkfish, has been 

 described by Delsman (1926d, 1929b). Since Chanos is an im- 

 portant aquaculture organism, several recent papers have de- 

 scribed various aspects of development, among them the de- 

 scription by Liao et al. (1979) is the most complete. Miller et 

 al. (1979) provides a good account for separating them from 

 common marine larvae. To summarize, the eggs and larvae 

 superficially resemble clupeids and engraulids but differ in sev- 

 eral trenchant characters. The eggs as described by Delsman 

 ( 1 929b) are spherical, 1 .2 mm in diameter, lack oil droplets and 

 have a weakly segmented yolk which may be similar to the 

 granular yolks seen in ostariophysans. Yolk-sac larvae have me- 

 lanophores scattered over the body and fin folds and a myomere 

 formula of 34 -I- 10 (preanal and postanal). As development 



Fig. 71. Lateral and ventral views from top to bottom: Chanos chanos. 1 1.7 mm SL from Kumano, Tanegashima collected August 19, 1978, 

 drawn by J. C. Javech; and Gonorymchus abrevialus. 12.8 mm SL from R/V Shoyo Maru station 25, 35°05'N, 144°24.3'E. collected on November 

 10, 1963; drawn by J. C. Javech. 



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