Just "Erotica" is enough. No subcategory is necessary.
The genre you assign is shorthand for who you expect will read the book. In your case, this is not women: I believe most erotic fiction written for women is about a female MC with whom the female reader can "identify", at least in the sense of wanting to share vicariously in the MC's sexual adventures and explorations.
With a male MC, presumably written from a male point of view, this novel would appeal to men. Men are a much smaller audience for written erotica; they are typically not as language-oriented as women and have an unlimited supply of visual erotica to sample on the Internet. However, that does not mean you can't successfully sell it.
Genre is about your audience, not the mix of styles in your work or anything else. The agent/publisher wants to know where or how to sell the work, who the typical buyers are going to be. The only genre that really matters is the main reason people buy your story: Is it for the sex scenes, or is it for the mystery? Only one can be the primary reason.
For example, I write sci-fi and fantasy. Both of those contain erotic scenes and references, because I think those are part of adult life, and I write for an adult audience.
Sci-Fi is when the story revolves around scientific accomplishment, disaster, etc, the invented science is why people are reading. They can skim or skip my erotic scenes, and not be disappointed in the ending. Typically I think those erotic scenes make the characters feel more real, and deepen the relationships they have, so I don't think the story is as powerful without them. But it's still a good story if the reader wants to skip to the end of the scene after reading about the opening kiss.
But it sounds like in your story, the erotic adventure is what the reader is really reading for, and if it was missing, you'd have a short mystery. I think your readership has to be Erotica. Most erotic novels have some excuse for moving characters around and meeting new people, that's kind of essential to having lots of sexual encounters.
I suspect your mystery is of secondary importance and you don't want to include that in your genre label at all. I suspect you aren't going to get any more readers of this book because you wrote a great mystery. Mystery readers probably are not going to enjoy a book that is heavily focused on erotic scenes. Not because they are prudes, they like it fine if their favorite detective has a romantic interest and gets laid, but they are looking for something that immerses them in a mental puzzle, not a masturbation aid.
But if you classify it as just "Erotica," you aren't going to get any returns of your book because it also had a murder mystery in it, or a heist, or legal drama or whatever. Erotica readers expect there to be some plot like that to carry the MC into various situations. If anything, a cover blurb would tell the story: "John's search for his brother's killer leads him into a subculture of sexual clubs, fetishists and new experiences he'd never imagined."