There are several types of spiders that have a white line on their backs. The two with the most definitive white stripes on their backs are the gray wall jumper, scientific name Menemerus bivittatus, and the pantropical jumper, scientific name Plexippus paykulli.
One very common spider with a white stripe down its back is the "Daddy Long-legs" or cellar spider, scientific name Pholcidae.
One more rare and exotic spider with a white stripe on its back is the redback spider, scientific name Latrodectus hasseltii. Native to Australia, the redback spider usually has an hourglass-shaped red mark on its back. But the juvenile female redback spider has white markings on its back. The redback spider is venomous but not deadly. A bite just causes severe pain for about a day, sometimes a bit longer. The redback spider is closely related to the black widow spider, which is commonly found throughout North America.