FUIMAN: OSTARIOPHYSI 



127 



Fig. 6 1 . Egg of Clenolucius hujela ( 1 8 hours poslfertilization) show- 

 ing the membranous pedestal by which the egg attaches to plants. Pho- 

 tograph by H.-J. Franke. 



coastal marine waters (the latter by a few characids, cyprinids, 

 and aspredinids, as well as all ariid and plotosid catfishes). The 

 presence of a Webenan apparatus has overshadowed the suite 

 of remaining diagnostic characters for the group which includes 

 an axe-shaped endochondral portion of the metapterygoid, an- 

 teriorly bifurcate pelvic girdle, second hypural fused to the com- 

 pound terminal centrum, and elongate olfactory tracts (all de- 

 tailed by Fink and Fink, 1981). Additional characters include 

 a pheromone-mediated alarm reaction and homy dermal pro- 

 jections called unculi (Roberts, 1982b). 



According to the classification of Fink and Fink (1981), the 

 orders of Ostariophysi (their Otophysi) are: Cypriniformes, 

 Characi formes, and Siluriformes (the latter including Siluroidei 

 and Gymnotoidei). Cypriniforms (with over 1,800 species in 5 

 families) uniquely share peculiarities of the following: kineth- 

 moid bone, palatine-mesopterygoid articulation, fifth cerato- 

 branchial, and lateral process of the second vertebral centrum. 



They lack jaw teeth and an adipose fin. They are found in North 

 America, Eurasia, and Africa. Characiforms (comprising at least 

 1,000 species in 14 families) are characterized by multicuspid 

 teeth, a prootic foramen, dorsomedial opening in the posttem- 

 poral fossa, enlarged lagenar capsule, and a gap between the 

 compound terminal centrum and hypural 1. They occur in Af- 

 rica, South America, and southernmost North America. Silu- 

 roids (with about 2,000 species in 3 1 families) are distributed 

 nearly worldwide. Although quite diverse morphologically, they 

 commonly lack scales and several bones (including the sym- 

 plectic, subopercle, and separate parietals). They show consid- 

 erable fusion of portions of the first five vertebrae and pectoral 

 and dorsal fin rays. The electrogenic gymnotoids are character- 

 ized by an extremely long anal fin and substantial reductions or 

 losses, such as the loss of dorsal and pelvic fins, and palatine 

 and ectopterygoid bones. They are confined to South America 

 and southernmost North America. 



Development 



Knowledge of the early life history stages of ostariophysans 

 is rather spotty and concentrated on fishes from a few geographic 

 regions. Major descriptive works cover portions of the Soviet 

 Union (Kryzhanovskii, 1949; Kryzhanovskii et al., 1951; Kob- 

 litskaia, 1981), Japan (Okada, 1960; Nakamura, 1969), and the 

 United States (Jones et al., 1978; Snyder, 1981; Auer, 1982; 

 Fuiman et al., 1983). Most of these works concentrate on cy- 

 priniforms. Additional descriptive data are available as indi- 

 vidual papers on Indian major carps (Cyprinidae) and Indian 

 siluroids (reviewed by Jhingran, 1975). African and South 

 American ostariophysan eggs and larvae remain little known. 



Of the six families of cypriniforms, nothing is known of the 

 eggs and larvae of the families with fewest species, Gyrinocheili- 

 dae and Psilorhynchidae. Catostomids are known well. Cypri- 

 nids, cobitids, and homalopterids are known to a lesser degree. 

 Scattered notes are available for nine characiform families but 

 only a few descriptions of ontogeny exist. Brief descriptions of 

 larvae of representatives from seven families of siluroids are 

 available, and notes on eight additional families exist. Photo- 

 graphs of larvae of two gymnotoids. Eigenmannia virescens anA 

 Aptewnotus leptorhynchus are published (Kirschbaum and 

 Westby, 1975; Kirschbaum and Denizot, 1975; Kirschbaum, 

 1984) but without morphological descriptions. Most informa- 

 tion on ostariophysan larvae deals with external morphology. 

 Osteological studies are few (Bertmar, 1959; Hoedeman, 1960a- 

 d). 



Eggs 



Ostariophysan eggs vary considerably in their morphology 

 and the habitat they occupy. Most are spherical, demersal, 1 to 

 5 mm in diameter, with pale yellow, somewhat granular yolk 



Table 26. Larval Characters of Major Groups of Ostariophysans. 



Cypnniformes 



Characiformes 



Siluroidei 



Gymnotoidei 



Size at hatching (mm XL) 



Yolk-sac shape 



Gap between yolk sac and anus 



Barbels: 



Presence 



Timing of development 



Size at finfold absorption (mm TL) 



2-10 



pyriform or tubular 



absent 



present or absent 



late or early 



15-25 



2-5 

 elliptical 

 present 



absent 

 10-20 



3-8 

 elliptical 

 present 



present 

 early 

 11-23 



elliptical 

 absent 



absent 

 15 



