Sorry I don't spend my time looking at weird male reproductive systems of monotremes. In fact, I don't look at any male reproductive systems other than my own. But don't let my preferences stop you.
Don't mind if I do.
I'll elaborate on what I mean btw: monotremes use intrauterine insemination to avoid their sperm being washed out of the female cloaca by regular excretions (as it's all pretty much one chamber), so the male's penis is shaped to the female's reproductive tract. Male echidnas' penis look like a four toed foot and platypi's look like a lopsided hairy cactus...with retractable tentacles at the tip.
And btw, female platypi's ovaries are the same as bird ovaries, only the left ovary is functional (which is why the male has a penis with two, lopsided prongs). So you can add yet another trait of a different animal family to something the playtpus does.