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Micrathena sagittata or or Micrathena sexspinosa.
Micrathena sagittata is a species of spider belonging to the family Araneidae. It is found in the eastern United States and throughout Central America. This is a striking spider with a distinctive arrow-shaped abdomen which is largely yellow, with black depressions above and variable red and black patterning below. Males are up to 5 millimetres (0.20 in) in length (excluding legs), but females are much larger at around 9 millimetres (0.35 in). The males lack spines. They leave a hole in the center of their web to assist in motion.
With this shot is kinda hard to ID, it would be easier if you had a dorsal view too. In any case it's an Arrow-shaped spider either Micrathena sagittata or Micrathena sexspinosa.