Visconte Maggiolo also spelled Maiollo and Maiolo, was an Italian cartographer and sailor.

He was born in Florence

Florence

Florence is the capital city of the Italian region of Tuscany and of the province of Florence. It is the most populous city in Tuscany, with approximately 370,000 inhabitants, expanding to over 1.5 million in the metropolitan area....

 and was a fellow sailor

Sailor

A sailor, mariner, or seaman is a person who navigates water-borne vessels or assists in their operation, maintenance, or service. The term can apply to professional mariners, military personnel, and recreational sailors as well as a plethora of other uses...

 of explorer Giovanni da Verrazzano. He died of malaria

Malaria

Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

in 1530.

In 1527, he created a map depicting Verrazzano's travels. This map had a major error, as Giovanni did not accurately describe the North American continent. This error was not to be fixed for over a century.