66 



ABC D 



Fig. 34: Dorsal view of gas 

 bladder of Phoxinus. A: P. eos 

 (KU 4578, 41.8 mm SL); B: 

 P. phoxinus (KU 22853, 56.3 

 mm SL); C: P. oreas (DU 

 field no. B-58-3, 59.9 mm 

 SL); D: P. tennesseensis (UT 

 5274, 50.0 mm SL); E: P. 

 cumberlandensis (UT 

 44.3096, 51.3 mm SL); F: P. 

 cumberlandensis (ANSP 

 138356, 33 mm SL); G: P. 

 neogaeus (KU 14254, 51.8 

 mm SL); H: P. brachyurus 

 (MCZ 3006, 75.9 mm SL). 



E F G H Scale bars = 1 mm - 



The condition in P. erythrogaster is plesiomorphic because it is similar to that in the out- 

 groups, and other conditions are proposed to be apomorphic. 



The constriction of the gas bladder is long and narrow in P. phoxinus and neogaeus (TS 

 32[2]; Fig.34B, G). It is shorter and broader in P. oreas, brachyurus, erythrogaster, cum- 

 berlandensis, and tennesseensis (TS32[1]; Fig.34C). It is very short, almost absent in P. 

 issykkulensis and eos (TS 32[0]; Figs.33B, 34A). A very short constriction is present in 

 the outgroups, and also in young specimens of Phoxinus species. Length of the constric- 

 tion increases ontogenetically, as shown by P. cumberlandensis (Fig.34E, F). The polari- 

 ty of this transformation series (TS 32) is therefore interpreted as very short [0] — » short 

 [1] - long [2]. 



The pneumatic duct connects to the anterior portion of the posterior chamber in P. eos, 

 brachyurus, issykkulensis, and tennesseensis (TS 33[1]; Fig.34A). In other species of Pho- 



