Instagram photo under investigation by U.S. Marine Corps. (Screenshot of Instagram post via Task and Purpose)

A Marine reservist lost a rank Friday, more than three months after he shared a photo on social media of Marines posing with their boots in the shape of a swastika.

Pfc. Anthony Schroader, with 4th Air Naval Gunfire Liaison Company based in West Palm Beach, Florida, was reduced in rank to private, Marine officials confirmed. The punishment was first reported by Task and Purpose on Tuesday.

Marine Corps Forces Reserve began investigating Schroader after Max Uriarte, creator of the popular Marine-themed comic strip "Terminal Lance," posted an exchange he had with the then-private first class on Instagram. Schroader shared a photo of what appears to be four Marines twisting their boots into a swastika shape.

Uriarte, who's Jewish, Tweeted a screengrab of the photo April 26, calling on leaders to investigate the matter. Uriarte later removed the post once Marine officials confirmed they were looking into it, Task and Purpose reported at the time.

Schroader's command declined to detail his punishment, saying only that "appropriate administrative action was taken."

"Because these are internal administrative actions, I am unable to disclose specific details," said Maj. Roger Hollenbeck, a Marine Corps Forces Reserve spokesman.

The other Marine personnel in the image have not been identified, he added.

Schroader is at least the fourth Marine to be investigated for allegedly posting racist photos and videos on social media in recent months.

In June, officials said Lance Cpl. Mason Mead, an infantry assault Marine with 1st Battalion, 3rd Marines, would be discharged after admitting to advocating supremacist ideology. Mead shared several Nazi-themed posts on Twitter and another showing himself in blackface.

In February, two members of 3rd Marine Aircraft Wing were under investigation after a Snapchat video emerged showing them in black face masks and making disparaging racial comments.

-- Gina Harkins can be reached at gina.harkins@military.com. Follow her on Twitter @ginaaharkins.