1. any of a genus of a large, harmless lizards found in marshes in the West India and Central America
2. a Caribbean lizardfish
The lizard is spelled with two "L"s "Galliwasp. It can also be spelled as Gallywasp, but you are right it is a long bodied, lizard from the Central Americas, and the West Indies.
The word is very similar to gall wasp, which are really wasps that produce very distinctively shaped galls ( an uncommon swelling caused by friction, and injury) on oaks and other plants.