I am thinking it is a male and will soon develop full pouch in a month or two.
It could be H. Erectus since some look different. Where did you get and what name was it under?
Some are labeled Lined seahorse, Black Seahorse, and a few other names. I would be concerned about the whitish color on the tail spikes. Unless it is flash reflection.
Looks can be deserving-- I have had seahorse that seemed to be female for over a year and drop a pouch. :crazy1: I am just looking at how the belly has a small slope and not a round one.
Here is a pic of a young females from a few years ago.
I think yours and this one would be close in age.