The scientist found a new species in a rainforest the species of small and green in color she examined one of its many cells and found that the cell have a nucleus but no cell wall to watch animal kingdom does the species most likely belong to

The species mentioned in the given question most likely come under the animal kingdom as the species exhibits no cell wall and has many cells, that is, it is multicellular. In the Kingdom Animalia, the general characteristics exhibited by the species is that they are multicellular, are eukaryotic species with the true nucleus, and possess cells with no cell wall.  

The species found in the rainforest would be an animal as if it had a cell wall, then the species would generally come under the category of fungi or plant. The species of animals found on the planet comes in different size and colors, and exhibit cells with organelles that do many activities essential for their existence.