95 



Presence of the anterior process of the pharyngeal process is previously proposed as an 

 apomorphic character at the genus level for Phoxinus (see p. 34). Absence of the process 

 in Phoxinus may have resulted from loss or is a reversal of the presence of the process. 

 Therefore, the absence of the process is hypothesized an apomorphic character state within 

 Phoxinus. 



The viscerocranium is located ventrally to the neurocranium. The regions included in the 

 viscerocranium are the upper and lower jaws, hyoid region, Suspensorium, opercular re- 

 gion, and branchial region. 



Upper jaw 



As in all cyprinids, the upper jaw in Phoxinus consists of two paired bones: premaxilla 

 and maxilla. 



Premaxilla (Fig.56A-E). The premaxilla is an elongated, narrow plate-like bone bearing 

 an ascending process at its anterior portion which contacts with the same process of other 

 premaxilla. The premaxilla tapers posteriorly; therefore, its posterior portion is narrower 

 than its anterior portion. The morphology of the premaxilla varies inter- and intraspecifi- 

 cally. 



Maxilla (Figs.57A-C, 58A-E). In cyprinids, the maxilla is a paired elongated plate-like 

 bone. Five processes can be recognized from the maxilla (Ramaswami 1955a). Following 

 Chen (1986b), these five processes were named as the anterior process, anterior ascen- 

 ding process, anteromedial process, posterior ascending process, and posterior process 

 (Fig.57C). These processes show variations among the Phoxinus species. 

 The anterior process (Fig.57C) is the most anterior portion of the maxilla. It is broad and 

 blunt in P. erythro gaste r, issykkulensis, phoxinus, oreas, and neogaeus (TS 97[ 1 ]); it is 

 narrow and sharp in P. brachyurus, cumberlandensis, tennesseensis, and in the outgroups 

 (TS 97 [0]). 



The anteromedial process is the process located at the medial side of the anterior process 

 (Figs.57A-C, 58A-E). The anteromedial process is broad, blunt, and well developed in P. 



Viscerocranium 



Fig. 56: Premaxilla in lateral 

 view of Phoxinus. A: P. pho- 

 xinus (CNUC uncat, 76.0 

 mm TL); B: P. cumberlan- 

 densis (KU 18934, 51.5 mm 

 SL); C: P. oreas (KU 3259, 

 55.0 mm SL); D: P. erythro- 

 gaster (KU 5773, 51.5 mm 

 SL); E: P. eos (KU 12255, 

 43.0 mm SL). Scale bars = 1 



E 



mm. 



