484 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



Table 120. Continued. 



Aphredoderus. gobies and some flatfishes, and the mechanism 

 of growth of the posterior field is not understood. As shown by 

 the authors mentioned above, there is extensive diversity in 

 configuration and processes of formation of marginal and sub- 

 marginal ctenii, and this diversity undoubtedly holds useful 

 phylogenetic information. 



The third major scale type found among percoids is the cy- 

 cloid scale (Cy in Table 1 20), characteristic of most groups below 

 the Percomorpha. Although the cycloid scales of some percoids 

 may represent a plesiomorphic state, they are clearly secondary 

 in a number of families where they occur only in some members 

 (acanthoclinids, acropomatids, apogomds, ephippidids, pem- 

 pheridids, percichthyids, sciaenids and serranids). Cycloid scales 

 also characterize all members of two groups of percoid families. 



each of which probably comprises a monophyletic lineage. The 

 cirrhitoid fishes (Aplodactylidae, Cheilodactylidae, Chironem- 

 idae, Cirrhilidae, and Latrididae) have large cycloid scales of 

 similar morphology, and the carangoid fishes (Carangidae, Cor- 

 yphaenidae, Nematistiidae, Rachycentridae and Echeneididae) 

 have very small adherent cycloid scales. Cycloid scales char- 

 acterize five other families of moderate size, Ambassidae, Ce- 

 polidae. Congrogadidae, Leiognathidae and Opistognathidae. 

 Otherwise, cycloid scales are restricted to a few monotypic fam- 

 ilies and tncertae sedis genera (Bathyclupeidae, Caristiidae, Di- 

 nolestidae, Drepamdae, Enoplosidae, Lactanidae, Menidae, Po- 

 matomidae, Scombropidae and Siniperca). The widespread 

 occurrence of true ctenoid scales in the Percoidei, including most 

 of the less specialized forms, and the distribution of cycloid 



