HENSLEY AND AHLSTROM: PLEURONECTIFORMES 



687 



probably plesiomorphic for flatfishes. Some genera show spines 

 in the otic region of the neurocranium; these are possibly ple- 

 siomorphic for bothoids. All known pleuronectine larvae lack 

 elongated dorsal-fin rays. However, this state is not limited to 

 this group and a phylogenetic interpretation of it would be pre- 

 mature. In short, at present, we know of no character states that 

 are unique to pleuronectine larvae or that can confidently be 

 interpreted as apomorphic. 



Egg characters 



Except in certain groups, eggs of flatfishes are still too poorly 

 known to be of much value in phylogenetic studies. One char- 

 acter of pleuronectiform eggs was used by Regan (1910) and 

 Norman (1934) to interpret phylogeny, the presence of one oil 

 globule in bothid eggs to separate them from those of pleuro- 

 nectids which lack oil globules. We now have more information 

 about the occurrence of oil globules in flatfish eggs, and the 

 distribution of these character states is not exactly that predicted 

 by the Regan-Norman model (preceding article, this volume). 

 The obvious pattern here is that bothoids have 0-1 and soleoids, 

 rhombosoleines, and Mancopsetta multiple oil globules. There 

 are published exceptions to this. Watson and Leis (1974) iden- 

 tified three types of eggs with multiple oil globules as those of 



bothids. However, these authors expressed some doubt about 

 the identifications of at least two of these egg types. These eggs 

 are probably some other group (poecilopsettines or samarines?). 

 Brownell (1979) identified some eggs which lacked oil globules 

 as the soleid Heteromycteris capensis. This is the only soleid we 

 are aware of that lacks multiple oil globules. 



It is probably premature to use the oil-globule character for 

 phylogenetic information until eggs from other groups are known. 

 However, it is interesting and possibly significant that the so- 

 leoids, rhombosoleines, and Mancopsetta are so sharply sepa- 

 rable from the bothoids in this character. One oil globule appears 

 to be the most common state in the eggs of percomorph fishes 

 (based on accounts in Watson and Leis, 1974; Russell, 1976; 

 Fritzsche, 1978; Hardy, 1978b; Johnson, 1978; and Brownell, 

 1979). This may indicate that this state is plesiomorphic for 

 pleuronectiforms. Corollaries of this would be that oil globules 

 were lost in most pleuronectines, and multiple oil globules de- 

 veloped in a line leading to the soleoids, rhombosoleines, and 

 Mancopsetta. 



(D.A.H.) Department of Marine Sciences, University of 

 Puerto Rico, Mayaguez, Puerto Rico 00708. 



