Adult Science Fiction using the Tarzan legend as the template but the lead character is darker and very, very twisted and bizarre. Read 1983. Spoiler.

[Jay]

Lead character genetically superior to mortals, in conflict with another (or more?) like him, and SPOILER in a part of the narrative rips off or has his own penis ripped off, which regenerates. This was a paperback, bought at a petrol station in rural Australia in 1983, from memory the author (obviously a pseudonym) was a variation on William Burroughs.

[Kat]

Philip José Farmer wrote at least one reimagining of Tarzan, Tarzan Alive by Philip Jose Farmer, and knowing him it was likely to be pretty bizarre and/or dark. It's entirely possible one or more editions were published under/with the addition of a pseudonym. Any chance it's one of those?

[Kat]

OK I just looked into it a little more and I doubt that's it. But if you have some time to kill, here's a Goodreads list of Tarzan books that includes not just the ERB originals, but also retellings etc.:
https://www.goodreads.com/shelf/show/...
And here's a list of books in the ERB universe:
https://www.goodreads.com/list/show/1...
Maybe your book is on one of those lists?

[Genesistrine]

Yeah, it's by Philip Jose Farmer. I think it's the Nine series that has the ripped-off penis: maybe one of these two, Lord of the Trees / The Mad Goblin, they're kind of fiction-based-on-the-fictional-autobiographies of Tarzan and Doc Savage he wrote. The characters in those are called Lord Grandrith and Doc Caliban, if that helps.

The "autobiographies" are Tarzan Alive: A Definitive Biography of Lord Greystoke and Doc Savage knockoff Doc Savage: His Apocalyptic Life but I don't think either of these includes ripped-off penises. I'm for sure not going to read them again to check though.

[Kat]

A Feast Unknown is the first book in that series if you want to start there, Jay.