I 



117 



Fig. 73: Dorsal view of cera- 

 tobranchials, hypobranchials. 

 and basibranchials of Phoxi- 

 nus. A: P. phoxinus (CNUC 

 uncat., 76.0 mm TL); B: P. 

 eos (KU12255, 43.0 mm SL); 

 C: P. cumberlandensis (KU 

 18934, 52.0 mm SL); D: P. is- 

 sykkulensis (P- 10696, 42.4 

 mm SL); E: P. oreas (KU 

 3259. 55.0 mm SL); F: P. 

 erythwgaster (KU 5773, 51.5 

 mm SL). Scale bars = 1 mm. 



Hypobranchials 1 and 2 (Fig.73A-F) are small bones. No variation with phylogenetic sig- 

 nificance is present among Phoxinus species. 



Hypobranchial 3 (Fig.73A-F) is a slender bone tapering ventrally. The left and right hy- 

 pobranchials 3 are close to each other at their ventral ends, forming an arch-like struc- 

 ture. Basibranchial 3 runs through the arch (Chen 1986b). Variation exists in size of the 

 hypobranchial 3 relative to the basibranchial 2. In P. phoxinus and issykkulensis, hypo- 

 branchial 3 is elongated and its length is almost equal to that of basibranchial 2 (TS 

 1 54[ 1 ]). In other species of Phoxinus, this bone is much shorter than that of basibranchial 

 2 (TS 154[0]), which is similar to the condition in the outgroups. 



Basibranchials (Fig.73A-F). Bones included are three single basibranchials (1, 2 and 

 3, from anterior to posterior) and placed mesially between the right and left hypobran- 

 chials. 



