116 



bone (TS 145[1]). This condition is not present in other species of Phoxinus or the out- 

 groups (TS 145[0]). 



Epibranchial 2 (Fig.72A-F) articulates with pharyngobranchials 1 and 2+3 dorsally. and 

 ceratobranchial 2 ventrally. It is short, bar-shaped and has a concavity at its dorsoanteri- 

 or and dorsoposterior margins. In P. erythrogaster, phoxinus. and oreas. the dorsal portion 

 of the bone is constricted (TS 1 46[ 1 ] ). This condition is not present in other species of 

 Phoxinus or in the outgroups (TS 146[0]). The ventral margin of the epibranchial 2 is 

 deeply concave in P. eos (TS 147[ 1 ] ): the margin is not concave in other Phoxinus spe- 

 cies or in the outgroups (TS 147[0]). 



Epibranchial 3 (Fig.72A-F) articulates with pharyngobranchial 2+3 dorsally. and cerato- 

 branchial 3 ventrally. It is bar-shaped and forked at its dorsal portion. In Phoxinus neo- 

 gaeus, eos, cumberlandensis, erythrogaster. tennesseensis, brachyurus, oreas. and 

 issykkulensis. the posterior process of the dorsal forked structure is much shorter than the 

 anterior branch (TS 148[0]). In P. phoxinus, the posterior process is of the same length as 

 the anterior one (TS 148[1]). Therefore, two articular condyles to the pharyngobranchial 

 2+3 are formed in P. phoxinus. Moreover, there is a posterior process at the middle of the 

 bone's lateral side in P. phoxinus (TS 149[1]). The process is absent in other species of 

 Phoxinus and in the outgroups (TS 149[0]). 



Epibranchial 4 (Fig.72A-F) articulates with pharyngobranchial 4 (if any) dorsally, and ce- 

 ratobranchial 4 ventrally. In Phoxinus. this bone is bar-shaped with constriction at the 

 middle of its anterior and posterior margins. The ventral margin of epibranchial 4 is straight 

 in P. eos, tennesseensis, oreas. and cumberlandensis (TS 150[0]): it is deeply concave, 

 w ith two articulating facets contacting the dorsal side of ceratobranchial 4 in P. erythro- 

 gaster, neogaeus, brachyurus, phoxinus. and issykkulensis (TS 150[1]). The dorsal margin 

 of epibranchial 4 is deeply concave in P. neogaeus and phoxinus (TS 151[1]); the margin 

 is straight without concavity in other species of Phoxinus (TS 151 [0] ) and in the out- 

 groups. The posterior margin of epibranchial 4 bears a wide notch in P. cumberlandensis, 

 issykkulensis, oreas, erythrogaster, tennesseensis, brachyurus, eos. and in the outgroups 

 (TS 152[0]); the posterior margin is deeply concave in P. neogaeus and phoxinus (TS 

 152[1]). 



In P. erythrogaster and P. brachyurus. a dorsally directed elongated process is present at 

 the lateral side of epibranchial 4 (TS 1 53 [ 1 ] ). This process is absent in other species of 

 Phoxinus and in the outgroups (TS 153[0]). 



Ceratobranchials (Fig.73A-F). The ceratobranchials are the longest elements in the 

 branchial region, and consists of four pairs of bones, i.e.. ceratobranchials 1. 2. 3. and 4. 

 All ceratobranchials are elongated bar-shaped and bear cartilage at both dorsal and ven- 

 tral ends. Each ceratobranchial articulates with the same numbered epibranchial dorsally 

 and same numbered hypobranchial ventrally. except ceratobranchial 4 because hypobran- 

 chial 4 is absent. No variations with phylogenetic significance are present among the spe- 

 cies of Phoxinus. 



Hypobranchials (Fig.73A-F). Three paired small hypobranchials (1, 2 and 3) are pre- 

 sent in Phoxinus: they articulates with the same numbered ceratobranchials laterally. 



