Complex sentence: The bluespotted stingray has a flat disc-like rhomboid body averaging in diameter and in length; and their coloring is a dark green with blue spots with a light white underbelly also known as countershading.
Split into simpler sentences: The bluespotted stingray has a flat disc-like rhomboid body up to in diameter and in length. Their coloring is a dark green with blue spots with a light white underbelly also known as countershading.