Stonogobiops family photo: where does S. nematodes end and S. xanthorinica begin?

Stonogobiops is a popular group of aquarium fish collectively known as rayed shrimp gobies. The genus Stonogobiops includes the dracula goby, S. dracula, barber pole goby, S. nematodes, the yellowface goby, S. xanthorhinica, and the ever popular white ray shrimp goby, S.…