Ms. Iturbide made the photo after happening upon Zobeida Díaz at a farmer’s market while living with the Juchitán of southeastern Oaxaca in 1979. It took several tries — the iguanas kept moving around, falling off, reducing her subject to laughter — but on her contact sheet, Ms. Iturbide found her “Nuestra Señora de las Iguanas (Our Lady of the Iguanas),” an image so arresting that 40 years later, its popularity is still growing.

In Mexico, “Nuestra Señora” is on murals, posters, postcards and road signs to Juchitán, and rendered into a life-size bronze sculpture in the Juchitán town square. It covers a brick building wall in East Los Angeles. It has gone viral. Fans have taken the rich black-and-white image and recreated it into graphic art, self-portraits, YouTube videos.

No wonder Ms. Iturbide says the image “is no longer mine.”

Nor is that iconic image her only claim to fame. In a long and varied career, Ms. Iturbide, 76, has done deep dives into her beloved country. She has documented the Seri Indians of Sonora, goat-slaughter festivals among the Mixtec of Oaxaca, funeral rites, cultural practices, complex landscapes, birds, herself.