KENDALL ET AL.: ELH STAGES AND CHARACTERS 



19 



B 





Fig. 10. Apparent convergence in siphonophore-mimicking appendages on larval fish. (A) Loweina rara. 17.6 mm. Note lower pectoral fin 

 ray (Moser and Ahlstrom, 1970); (B) Carapussp., 3.8 mm (Padoa, 1956j). Note elongate dorsal fin ray; (C) Exterilium larva, 64 mm. Note trailing 

 gut (Moser, 1981); (D) Lopholus sp., 12.t mm. Note elongate dorsal and pelvic ray (Sanzo. 1940); and (E) Arnoglossus japonkus, 30.5 mm. 

 Note elongate dorsal ray (Amaoka, 1973). 



and of presumed functional significance primarily for planktonic 

 existence (Fig. 9). These latter features are of particular interest 

 in systematic studies of larval fish ontogeny. They include pig- 

 ment pattern, larval body shape, armature on head bones, and 

 precocious (early forming), elongate, or serrate fin spines. The 

 sequence and way of developing adult structures, such as the 

 skeleton and fin rays, are also useful larval characters. All of the 

 characters of the larvae— whether they are specialized larval 

 characters or merely characters observable in the larvae— may 

 have potential systematic value at some taxonomic level; how- 

 ever, the usefulness of most of the characters has not been eval- 

 uated (Tables 3 and 4). 



Among the most taxonomically useful larval characters, gen- 

 erally at the specific or generic level, is the pigment pattern. 

 Usually, each species has a distinct larval pigment pattern. In 

 some the number and placement of individual melanophores 



are diagnostic, while in others the location, shape, and size of 

 groups of melanophores are key characters. At a higher taxo- 

 nomic level, in the myctophiforms for example, the peritoneal 

 pigment blotches seem to indicate relationships on a suborder- 

 family level. Problems associated with the usefulness of pigment 

 patterns include 1 ) the widespread distribution of some patterns, 

 and 2) the variable state of melanophore contraction on larvae 

 of the same species. An example of the first problem is the 

 frequent occurrence of a row of small melanophores along the 

 ventral midline from just behind the anus to the tip of the tail. 

 Another example is a pigmented area midlaterally on the caudal 

 peduncle which occurs in numerous groups. A ventral spot at 

 the junction of the cleithra is also quite common. These are just 

 a few examples of widespread, presumably convergent pigment 

 patterns that limit the usefulness of pigment in systematic stud- 

 ies of larvae. The causes for the observed differences in degree 



