94 



Dorsally, two anteroposteriorly directed parallel crests (Figs.54B, 55A-D) are present on 

 the mesial portion of the dorsal side of the basioccipital's dorsal portion. These two par- 

 allel crests articulate with the ventral side of the exoccipital to form a canal-like structure 

 (see the description of the exoccipital above) (Figs.49A-B, 50). The crests run from the 

 middle to the posterior end of the dorsal portion of the basioccipital. Variation of the crest 

 includes the space between the anterior ends of the left and right crests, and the extent of 

 the development of the crest. The crest is high and the space between the anterior ends 

 of the left and right crests is narrow in P. cumberlandensis (TS 91 [1]; Fig.55C); whereas 

 the crest is lower and the space is broad in other Phoxinus species (TS 91[0]). In P. erythro- 

 gaster, the crest is short, and placed at the middle of the dorsal side of the dorsal porti- 

 on (TS 92[1]; Fig. 55 A). In other Phoxinus, the crest is elongated extending from the 

 middle to the posterior margin of the dorsal side of the dorsal portion (TS 92[0]; Fig.55B- 

 D). 



As described above, three parts can be recognized for the pharyngeal process in most spe- 

 cies of Phoxinus, i.e., the pharyngeal pad, the anterior process (lacking in some species, 

 see below) located at the anterior margin of the pharyngeal pad, and the posterior pro- 

 cess. The pharyngeal pad is a plate-like structure contacting the masticatory pad at its ven- 

 tral side. The pharyngeal pad is concave; its margin extends anteriorly forming the anterior 

 process in some species, its posterior margin extends forming the posterior process. Va- 

 riations were observed in size and shape of the pharyngeal pad, the anterior process, and 

 the posterior process. The pharyngeal pad is well developed, semi-ellipsoidal, elongated 

 and relatively narrow, the length between the anterior and posterior margins (the anterior 

 and posterior processes not included) is longer than the width between the left and right 

 margins of the pad, the ventral concavity is deep in P. tennesseensis, oreas, and cumber- 

 landensis (TS 93 [1]). In other Phoxinus species, the pharyngeal pad is less developed, se- 

 mi-round, short and relatively wide, its length is shorter than its width, and the concavity 

 is shallow (TS 93[0]). 



The anterior process is long and narrow in P. cumberlandensis (Fig.55C), whereas the an- 

 terior process is short and broad in P. oreas, tennesseensis, issykkulensis, and phoxinus; it 

 is less developed in P. eos (Fig.54D) and very small, almost absent in P. erythrogaster 

 (TS 94[0]; Fig.55A). In P. brachyurus and neogaeus, the anterior process is absent, and 

 the anterior margin of the pharyngeal pad is concave (TS 94[1]). Besides the main ante- 

 rior process mentioned above, two small anterior processes are present at the lateral part 

 of the anterior margin of the pharyngeal pad in P. phoxinus (TS 95 [1]) (Fig.l3C). The la- 

 teral processes are absent in other species of Phoxinus (TS 95 [0]). The posterior process 

 is broader and stout in P. neogaeus, oreas, cumberlandensis, and tennesseensis (TS 96 

 [1]). This process is relatively high and narrow in other Phoxinus (TS 96[0]). 

 In the outgroups, the anterior margin of the dorsal portion is straight or slightly convex 

 without concavity; the concavity at the ventral side of the dorsal portion is elongated and 

 rectangular; the crest on the dorsal side of the dorsal portion of the basioccipital is straight, 

 and the space between the anterior ends of the crests is wide; the pharyngeal pad is rela- 

 tively small and short; the anterior process is not present on the anterior margin of the 

 pharyngeal margin (no lateral process present at the lateral portion of the anterior mar- 

 gin), and the posterior process is narrow. 



