I've been doing a bit more digging for those that are interested

about 50 years ago I believe Nicaraguensis was actually seen as 3 or maybe 4 species. Which were all in the old Cichlasoma or Heros family and they were Nicaraguensis, Spilotum, Baleatum and possibly Unimaculatum.
I found this paper from the 1970s that I believe is when three of the forms were classed under Nicaraguensis and managed to translate it using a mix of Acrobat and Google to get a reasonable translation out. One thing I've not worked out is where each 'species' came from, they mention the locations and the old names but not how they relate to each other? Interesting read if you want it. Any spanish speakers would be really interesting to see what you think of it?
https://tropicalstudies.org/rbt/attachments/volumes/vol22-1/10-Lopez-Peces.pdf
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Also found what I think is the latest research on them which is interesting too
https://www.researchgate.net/profil...h-Diagnoses-For-The-Genus-And-Its-Species.pdf
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H.Unimaculatum is actually referenced as the valid name here but a few other places I've seen disagree with this in the years since and still use Nicaraguensis. They also group Neets into Hypsophyrs which I'm not sure I'm on board with and again a few other places have the same issues. The link to put Nemoatopus in Hypsophyrs is both fish share a similar body shape (again not sure I agree) and they only have a single spike bone at the front of the dorsal fin where as other cichlid species have two. Interestingly they do say they think that C.Spilotum could be its own species and deserves more research.
One thing to mention on both studies is I believe they did the study on preserved specimens rather than living specimens so potentially I do feel they could have missed something like the body markings etc as discussed above with the recent Ram and Oscar species.
I can't find any research past this but will keep looking, I don't think as a family or species Hysophrys is fully explained yet. I think given they are such unique fish in terms of behaviour - burrowing with their heads for nests, their unusual relationship with P.Dovii, only cichlid with non adhesive eggs and their pretty unique appearance not just in terms of colour but also shape I do think they are 'worthy' of further research and proper classifications. Really wish I had the know how or at least the funds to contact people in the know haha.
Though someone here might find it interesting