49 



Tab.l: Number (N) of primary lamellae of the olfactory organ in some species of Phoxinus with dif- 

 ferent standard length. 



Species 



SL(mm ) 



N 



Species 



SL(mm) 



N 



P. cumberlandensis 



23.5 



4 



P. neogaeus 



27.0 



5 





42.0 



10 





34.5 



8 





48.7 



10 





48.4 



8 





50.9 



9 









P. eos 



' 26.4 



7 





52.0 



11 





31.1 



7 











41.5 



9 



P. oreas 



29.5 



9 





41.8 



9 





33.5 



9 





45.0 



10 





41.8 



1 1 











43.1 



10 



P. erythrogaster 



23.0 



^4 





51.0 



12 





26.0 



6 





53.4 



13 





30.1 



8 











. 40.3 



10 



P. phoxinus 



27.4 



8 





46.5 



12 





46.8 



10 





48.5 



12 





48.0 



14 





50.2 



12 





60.1 



16 



Axis: Based on the shape of the axis, Chen ( 1988b) described six patterns of axes in cy- 

 prinids: i.e.. Y. linear, elongated ellipsoidal, shorted ellipsoidal, bottle, and spindle pat- 

 terns. Chen (1988b) proposed the elongated ellipsoidal pattern as plesiomorphic in 

 cyprinids because this pattern is the condition present in most cyprinids. from which the 

 shortened ellipsoidal, and linear patterns have derived independently. 

 Based on the number of primary lamellae and the shape of the axis. Yamamoto (1982) 

 described eight types of olfactory organs in teleosts, lettered from A to H. Types F and G 

 of the olfactory organ (Yomamoto 1982) are present in cyprinids. Chen & Arratia (1994) 

 proposed 11 types (lettered from A to K) of olfactory organs in actinopterygians. 

 Extending from the anterior margin of the olfactory organ to the posterior portion of the 

 organ, the axis is located at the middle portion of the olfactory organ in Phoxinus. Based 

 on the criteria used by Chen (1988b). three morphological types of the axis can be de- 

 scribed in Phoxinus as the following: 



Elongated ellipsoidal type The axis is a narrow and elongated ellipse. This type is 

 present in Phoxinus phoxinus, oreas, erythro gaster, issykkulensis, tennesseensis, and 

 brachyurus (TS 7[0]; Fig.21A. B). 



Linear type The axis is elongated, narrow and slender. This type is present in Phoxi- 

 nus eos (TS 7[1]; Fig.21C). 



Shorted ellipsoidal type The axis is wider, relatively short and elliptic in shape. This 

 type is present in P. cumberlandensis and neogaeus (TS 7 [2]; Fig. 2 IE). 

 The elongated ellipsoidal type is present in the outgroups. According to the hypothesis on 

 the relationships among different types of axes in cyprinids proposed by Chen (1988b) 



