474 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



Fig. 261. {A)Coryphaemd!ie—Coryphaenahippurus. 8.5 mm SL; (B) Rachycenlridae—Rachycenlroncanadum. 9.0 mm SL; (C)Echeneididae- 

 Echeneis sp., 8.8 mm SL; (D) Caristiidae— Canif/i« sp., 10.1 mm SL; (E) Bramidae— firaAjja dussuimeri, 6.5 mm SL, from Mead (1972). 



range from in the Congrogadidae to 19 in the Sillaginidae, the 

 most common numbers being 8-14. 



One of the most variable aspects of percoid physiognomy is 

 the form and composition of the dorsal fin. Even the most 

 consistent feature, the presence of spines, does not characterize 

 all percoids. Absence of dorsal spines in six percoid families 

 appears to have originated by at least two different mechanisms. 

 In Bathyclupea, it is obvious that the spines have been lost 

 because the spinous pterygiophores are still present and the soft 

 rays occupy a position posterior to them. In Coryphaena, how- 



ever, Potthoff (1980) showed that although the anteriormost 3- 

 4 pterygiophores bear soft rays, they are of the type that normally 

 support spines. This suggests that the absence of spines in Cory- 

 phaena is the result of transformation, rather than loss, of pre- 

 existing elements. Absence of spines in the Bramidae, Caristi- 

 idae, some cepolids and some congrogadids is also probably the 

 result of transformation. 



Spines are present anteriorly in the dorsal fin of all other 

 percoids, ranging from 1 in some malacanthids and pseudo- 

 chromids to XXI in some acanthoclinids. Dorsal soft rays range 



Fig. 262. (A) Chaetodontidae— unidentified, 10 mm, from Burgess (1978); (B) C\ae\oAon\\Aae—Forcipigerlongiroslris. 17 mm TL, from 

 Kendall and Goldsborough (191 1); (C) Chaetodontidae— C/jWotom sp. or Coradion sp., 6.5 mm SL, from Leis and Rennis (1983); (D) Scato- 

 phagidae— 5ca/o/7AagMi argiis, 10 mm SL from Weber and de Beaufort (1936); (E) Scombropidae — 5fom/)TOpi hoops. 6.2 mm SL, from Uchida 

 et al. (1958); (F) Lethrinidae— Z.e?/!n>ii/i nematacanlhus, 6.1 mm SL, from K. Mori (unpubl.); (G) CepoMiae—Acanthocepola sp., 9.7 mm SL, 

 from Okiyama (1982b); (H) Priacanlhidae — unidentified. 4.6 mm SL. from Leis and Rennis (1983); (I) Priacanthidae— /'nacanr/iMisp., 10.9 mm 

 SL, from Leis and Rennis (1983); (J) PenXace^toUd&c — Pseudopentaceros richardsoni. 15 mm SL. 



