44 



Hypothesis 3: Cavender & Coburn (1987) described the character of anteriorly positio- 

 ned anal pterygiophores and proposed a monophyletic group including Phoxinus, Semoti- 

 lus, Couesius, and Hemitremia based on this character. All these genera belong to the base 

 of the Chub clade (Coburn & Cavender 1992). See "Monophyly of the Hemitremian clade 

 and its position in the family Cyprinidae" for the discussion about this hypothesis. 

 Hypothesis 4: Instead of using breast tuberculation, Schmidt (1989) applied the anterior 

 placement of the anterior anal pterygiophores discovered by Cavender & Coburn (1987) 

 and proposed Phoxinus the sistergroup of Semotilus. However, this character is widely 

 distributed among a few other genera, as discussed by Cavender & Coburn (1987), Co- 

 burn & Cavender (1992), and herein. 



NON-OSTEOLOGICAL MORPHOLOGY 



The morphological description and comparison among the species of Phoxinus are pre- 

 sented as two sections, the non-osteological and osteological morphology. In both sec- 

 tions, a brief review of the structure in cyprinids will be presented, followed by a detailed 

 description of the structure in Phoxinus and the outgroup taxa (i.e., Eupallasella, Rhyn- 

 chocyphs, and Lagowskiella). Finally, a comparison among Phoxinus species and the out- 

 groups, and a discussion on the polarity of the transformation series (TS) are presented. 

 The number of transformation series in the Osteology is continuous with those in this sec- 

 tion, and corresponds to the transformation series numbers in Appendices II and III. 

 Intraspecific variation will be discussed only in a few cases. Because of the ontogenetic 

 variation of certain structures, the description and comparison among the species is based 

 on similar-sized adult specimens. In a few cases young specimens are also used to obtain 

 ontogenetic information. 



External Morphology 



Mouth (Fig.l9A-C) 



The mouth in cyprinids shows significant variation, such as mouth shape, width of the 

 mouth opening (mouth gape), relative length of the upper and lower jaws, and morpho- 

 logy of the lower jaw. The mouth can be almost vertical (e.g., Toxabramis houdemeri), 

 oblique (e.g., Erythroculter dabryi), or horizontal (e.g., Xenocypris fangi) (Wu 1964). The 

 shape of the mouth can be partially demonstrated by degree of the mouth angle: the smaller 

 the angle, the more horizontal the mouth; the larger the angle, the more oblique the mouth. 

 The mouth gape can be large enough to reach below the middle of eye (e.g., P. neogaeus), 

 or very small only approaching the anterior margin of the nasal opening (e.g., 

 Plagiognathops microlepis) (Yang 1964). 



In most cyprinids, the lower and upper jaws are almost equal in length (or the lower jaw 

 is slightly shorter or longer than the upper one) (e.g., Notropis spp., Xenocypris yunna- 

 nensis); however, a much longer lower jaw (than the upper one) (e.g., Luciobrama macro- 

 cephaius), or a much longer upper jaw (e.g., Varicorhinus tungting) are also present in 

 some species of the family. In most cyprinids, the structure of the mouth is relatively sim- 



