119 



Fig.74: Pharyngeal bone and its teeth of Phoxinus in lateral (a) and dorsal (b) views. A: P. phoxinus 

 (CNUC uncat. 76.0 mm TL); B: P. cumberlandensis (KU 18934, 52.0 mm SL); C: P. eos (KU 12255, 

 43.0 mm SL). Scale bars = 1 mm. 



Generally, the pharyngeal bone in Phoxinus is "L'-shaped with expansion at the middle 

 of its ventral side. The expanded ventral surface bears several pits, to which masticatory 

 muscles are attached. These pits are well developed in Phoxinus. The pharyngeal teeth are 

 located at the dentigerous surface. The teeth are dorsally directed and function to chew 

 food with masticatory pad attached on the pharyngeal pad of the basioccipital bone. 

 Variations with phylogenetic significance including a few aspects of the pharyngeal bone 

 and teeth among Phoxinus species can be described as follows (Fig.74A-C): 



1. Posterior angle: This angle partially represents relationship between the posterior 

 edentulous process and the main span of the posterior limb. The smaller the angle, the 

 more anteriorly the posterior edentulous process bends. The angle is smaller in P. eos, 

 tennesseensis, and oreas (TS 1 59[ 1 ] ) than in other species of Phoxinus and in the out- 

 groups (TS 159[0]). 



2. Posterior edentulous process: The posterior edge of the posterior edentulous pro- 

 cess bears a flat plate-shaped structure with two small processes in P. cumberlandensis 

 (TS 160[1]) (Fig.74B); the structures is not present in other species of Phoxinus or in the 

 outgroups (TS 160[0]). 



