the difference between the sp 'Jumbo' and the leptosoma is not just size or body proportions.
the best way to see if a certain Cyprichromis (not pavo, zonatus or microlepidotus) is either a Jumbo or a regular leptosoma is to breed it
if the fry has a black and white dorsal fin: jumbo type
if it has yellow dorsal fin: leptosoma
There are no leptosoma with black fins. some do have small black spots or a small black stripe in the dorsal (the Isanga male for example), but the largest part of the dorsal is either white or a lightblue color, often with yellow parts.
many Jumbo type males have a black dorsal with a white edge or a dark dorsal with a black and white band.
females of the true leptosoma have yellowish fins, whereas jumbo females are light brown.
Jumbo females have 2 darker brown spots in the caudal, one in each lobe. the leptosoma female lacks these.
Jumbo females often have a black or dark or black and white band on the edge of the dorsal. leptosoma females lack these.
but the best way to see if it's a Jumbo Cyp or a leptosoma Cyp is the fry.
with fry there's no doubt.
this is also one of the best clues that we're dealing with 2 real species living all mixed up instead of a lot of variety in 1 species.
if you find 2 different types of similar but different fry in 1 location, you can be pretty sure you're dealing with 2 species of closely related fish living sympatric together.
"And he piled upon the whale's white hump the sum of all the rage and hate felt by his whole race. If his chest had been a cannon, he would have shot his heart upon it"