118 



In all Phoxinus species and in the outgroups. except P. erythrogaster, basibranchial 1 

 (Fig.75A-F) is bar-shaped and slightly concave at the lateral margin (TS 155[0]). In P. 

 erythrogaster, the basibranchial 1 is wedge-shaped and its anterior portion is narrower 

 than its posterior portion (TS 155 [1]). 



Basibranchial 2 (Fig.73A-F) articulates with the posterior margin of basibranchial 1 ante- 

 riorly, the anterior margin of the basibranchial 3 posteriorly, and the medial margin of hy- 

 pobranchial 1 and 2 laterally. It is a slender bar-shaped bone with a slightly concave lateral 

 side. The anterior and posterior ends are broader than the middle of the bone in all Pho- 

 xinus species and in the outgroups (TS 156[0]). except P. issykkulensis in which the bone 

 is tapering anteriorly and sharp at the anterior end (TS 156[1]). 



Similar to basibranchials 1 and 2 described above, basibranchial 3 (Fig.73A-F) articulates 

 with the posterior end of basibranchial 2 anteriorly, mesial of hypobranchial 2 and 3 an- 

 terolaterally and posteriorly respectively. It is also similar to the basibranchial 2 in shape. 

 It varies in size relative to the basibranchial 2. It is much longer (about two times ) than 

 the basibranchial 2 in P. phoxinus (TS 157[1]); it is almost of the same length of the ba- 

 sibranchial 2 in other species of Phoxinus and the outgroups (TS 157[0]). 



In P. neogaeus, eos, and issykkulensis. an elongated cartilage is present at the posterior 

 end of basibranchial 3 which articulates with ventral side of the epibranchial 4 (TS 158[1]). 

 The cartilage is less developed in P. neogaeus than that in P. issykkulensis and eos. The 

 cartilage is very small in other species of Phoxinus and the outgroups (TS 158[0] ). 



Pharyngeal bones and pharyngeal teeth (Fig.74A-C). The pharyngeal bones bea- 

 ring pharyngeal teeth are located posteriorly to the forth gill arch. It is the fifth ceratob- 

 ranchial (Gasowska 1979, Chen 1986b). In cyprinids. the shape of the pharyngeal bones 

 shows a great variation, from very slender (e.g.. Eiythroculter ilishaefonnis - Yi & Wu 

 1964) to very broad (e.g.. Cyprinus caipio). The pharyngeal teeth on the pharyngeal bone 

 vary in rows and shape in cyprinids. One (e.g.. Rhodens sericeus). two (e.g.. P. phoxinus). 

 three (e.g.. Schiz.othorax prenanti). even four rows {Tetrostichodon - see Cao 1964) of 

 pharyngeal teeth are present in cyprinids. The teeth vary from slender (e.g.. Acantho- 

 rhodeus peihoensis) to strong (e.g.. Mylophaiyngodon piceus). Almost no book or paper 

 on the taxonomy of cyprinids does not consider the pharyngeal bone and teeth as some 

 of the most useful characters in the identification of genera or species within the family 

 (e.g.. Nichols 1943. Wu 1964, 1977). The phylogenetic significance of the pharyngeal 

 bone and the teeth of cyprinids has been discussed by many ichthyologists (e.g.. Jurine 

 1821. Koh 1931. Chu 1935. Girgis 1952. Nikolsky 1963. Peyer 1963. Eastman 1970. Chen 

 1986a, 1987a, b). Jurine (1821) was the first one describing the pharyngeal bone and teeth 

 of minnows {Cyprinus carpio). Chu (1935) was credited as the first know n to study the 

 pharyngeal bones and teeth of cyprinid systematically. Eastman & Underhill (1973) stu- 

 died the intraspecific variation of the pharyngeal tooth formula. 



The terms used herein for pharyngeal bones and teeth follow Chu 1 1935) and Eastman 

 (1970), except the meaning of the posterior angle. The posterior angle (Fig. 74) used herein 

 is the angle between the main span of the posterior limb and the posterior edentulous 

 process (Fig. 74). 



