200 



ONTOGENY AND SYSTEMATICS OF RSHES-AHLSTROM SYMPOSIUM 



."//,/., 



Fig. 105. Giganturidae. (Upper) Larva oi Rosaura indica. 8.4 mm SL (=holotype oi Rosaura rotunda from Tucker, 1954). (Lower) Adult 

 Rosaura indica. 182 mm SL (from Berry and Perkms, 1966). 



to differentiate in larvae as small as 5.5 mm SL. but the ventral- 

 most pectoral rays are the last fin rays to be formed). The pelvic 

 fins appear just below the dorsal-fin origin and do not greatly 

 shift in relative position until transformation. A dorsal finfold 

 connects the incipient dorsal fin with the caudal fin in small 

 larvae, but loses this connection in larvae larger than 6 mm SL. 

 and shrinks in extent but remains as a highly visible adipose fin 

 until transformation, when it is resorbed. 



Peritoneal pigment sections. — A single peritoneal pigment sec- 

 tion characterizes the larvae of both species. This section lies 

 just above and posterior to the dorsal transverse limb of the 

 intestine. The section is never paired as in synodontoids and 

 remains proportionately constant in size throughout larval life 

 and is represented in adults as a small, intensely-black oval 

 pigment patch above the stomach (growth of the section ap- 

 parently ceases at about the onset of transformation, but the 

 section apparently remains in both juveniles and adults of both 

 species). The dense brown or black pigment enclosing the gut 

 is not derived from this peritoneal pigment section, as is true 

 for many "inioms" (see Johnson, 1 982) but develops separately 



dunng transformation (as in Aleptsaurus and Omosudis, Was- 

 sersug and Johnson. 1976). 



Other pigmentation. — \n both species pigmentation in larvae 

 occurs in three areas (other than the peritoneal section), the 

 eyes, over the optic lobes, and on the sides of the body posterior 

 to the dorsal-fin base. In some but not all pre-transformation 

 specimens of Gigantura, very small punctate melanophores ap- 

 pear over the still otherwise essentially transparent lateral ab- 

 dominal body wall. 



Gut morphology.— The stomach is enlarged and sac-like. The 

 mtestine leaves the pyloric region of the stomach, descends 

 round the left margin of the abdominal cavity, crosses trans- 

 versely upon the ventral body wall, reascends the right side and 

 then turns again, descending abruptly and obliquely down and 

 posteriad to the vent. 



Transformation —Changes during transformation are numer- 

 ous and striking: (A) Body shape. The body changes in shape 

 from short, rotund and deep, rather as in some ceratioid larvae 



