' "fLimnAi! «.i->-':r^i««^ 



323 



diffuse band extending across the preoperculum and operculum above the lower 

 margin of the eye. Upper half of operculum with dense, weakly-defined 

 submarginal band and a diffuse, light yellow margin. Underside of head generally 

 unpigmented except for scattered melanophores on skin over posterior edges of 

 lateral branchiostegals, and a series of 15-20 star-like clusters surrounding irregular, 

 superficial lateralis canals and pores on chin overlying dentary (Fig. 1). 



Specimens collected in clear- or blackwater rivers are much darker than 

 individuals from more turbid habitats. In these specimens the coloration on the 

 dorsum may be steel-blue to nearly black, and the dark pigmentation extends over a 

 much greater portion of the body than in Whitewater specimens. The top and sides 

 of the head and the upper half of the body may also have a number of small, round, 

 black spots similar to those found inpofystictus. ' 



Gunther (1864) remarked that young specimens have brown spotting on the 

 body. Some smaller specimens in the present study were observed to have irregular, 

 rather faint blotches (FMNH 58136, USNM 247251). There were no recently 

 collected juvenile specimens in the material examined during this study, hence no 

 detailed information can be provided concerning possible ontogenetic differences in 

 coloration pattern (see comments in A. marmoratus account). 



Live specimens sometimes have blood red pigment in the fins and on the 

 venter; adequate information on life colors was not available to me, and it remains 

 unknown whether the red pigment, occasionally mentioned in the literature 

 (Steindachner 1910, Puyo 1949), is present year round or only seasonally. 



