Diego Rivera appears in two photographs taken in his studio, both dated in 1915; his hair was very short at the time.
In the first, he is seated at a table reading a newspaper. The studio is somewhat reminiscent of the one in the photograph in question here in terms of its layout and décor, but there are no specific elements in common between the two pictures.
In the second photograph, Rivera is standing, paintbrush and palette in hand, proudly posing in front of his painting titled Zapatista Landscape.[1] This was precisely the piece which, in mid- or late 1915, caused the rift with Picasso, when Rivera accused him of stealing his technique for painting foliage. To mimic Rivera’s pose, in September or October[2] Picasso had his photograph taken in the same position, in similar attire—white shirt, necktie, and dark pants—standing in front of his painting Man Seated in Shrubbery. Later on, Picasso altered the painting, turning it into Seated Man,[3] in which most of the foliage supposedly copied from Rivera had disappeared.
This second picture of Rivera allows us to confirm without much of a doubt that he is indeed the painter in the photograph in question: the same shaved head, close-cropped beard, the same narrow necktie and drooping trousers.
During this period, Diego Rivera was living with the Russian-born painter Angelina Beloff,[1] who had arrived in France in 1909. She had met Diego Rivera in Bruges, where he was traveling at the time. Rivera went back to Mexico in July 1910, and upon his return to France in late 1912 they moved in together. Angelina and Diego had a child—a boy whom they named Dieguito. The child was born on August 11, 1916, and died fourteen months later.
There are photographs of Angelina and portraits by Rivera. One of them shows her breastfeeding her child, who is clearly not a newborn: therefore, the picture must have been taken in late 1916 or early 1917. Angelina’s face has the same features and expression as that of the woman in our initial photograph.
[1] The French version of Wikipedia provides the following summary: « Angelina Petrova Beloff, née à Saint-Pétersbourg le 23 juin 1879 et morte à Mexico le 30 décembre 1969, est une artiste mexicaine d'origine russe, peintre pleinairiste, graveuse, illustratrice de livres et auteure pour le théâtre de marionnette » (Angelina Petrova Beloff, who was born in Saint Petersburg on June 23, 1879 and died on December 30, 1969, was a Russian-born Mexican artist, plein air painter, printmaker, book illustrator, and marionette show creator.) https://fr.wikipedia.org/wiki/Angelina_Beloff, accessed on 3/30/2020.
[1] John Richardson, A Life of Picasso - Volume II : 1907-1917, London, Jonathan Cape, 1996, p. 412.
[2] Ibid.
[3] Pierre Daix and Joan Rosselet, Le cubisme de Picasso – Catalogue Raisonné, Neuchâtel, Ides et Calendes, 1979, p. 355 DR 889, see John Richardson, A Life of Picasso - Volume II: 1907-1917, London, Jonathan Cape, 1996, pp. 412-15.