I'd directly contact the editor of the journal and accuse the author of plagiarism, proving to the editor that my work was utilized without citation.

I'd directly contact the editor of the journal and accuse the author of plagiarism, proving to the editor that my work was utilized without citation.

If the publication in question meets your criteria of knowing your previous work and that it is published, perhaps Kirk suggestion of plagiarism is the best course of action.

However, what if they known that you are studying something and publish ahead of you?

In this case, João, I think there is nothing you can do about it. A good thing that you can do now is to upload your data in biorxv years before submitting the research to a journal. So there is proof that you have done it before other people.

If your paper was published before the final editorial process of the work in question (say, 2 months before?), than it should have been added as a citation during the editorial process. If your paper was published before the initial submission of the work, than it also should have cited as well, and definitely not sold as "new".

In any way, a letter to the editor is warranted. The adequate actions to take are up to her/him. At least a corrigendum is necessary. A retraction might be too severe, but if there was plagiarism, than that is definitely the right course of action.

I'll second the opinions of others that contacting the editor is the appropriate course to follow. Lay the case out in sufficient detail that the editor can forward it to the authors for their response. I am sure this editor will be surprised and chagrined that his/her editorial process admitted false claims to the scientific literature. S/he should take appropriate steps, including a retraction (most severe) or at least an acknowledgement to the readers of Neotropical Primates that your work had priority

I know how you feel. Recently, an early review/perspective was published about a hot and novel topic. And they did not cite my paper, which was among the first in the field, and was published by the exact same journal one year before. In this case, I contacted the corresponding author and told him about it.

Be very careful in deciding whether you should take action or just leave it to be perceived by other peers. There is a lot of politics involved in scientific collaborations and grant applications, and too often the most aggressive players are well connected.

Failure to cite my work has occurred several times with me and usually I keep it quiet. Most of the times the overlap becomes evident to others on the area, which affects the image of the wrongdoer.