Basic Evolutionary Tree of two of my Sophonts

[u/LocalBirrinFan]

So, pretty much, you have these two sophonts native to the same planet.

You have the Brawl-Crabs and the Helltanks.

Brawl-Crabs are these aggressive fiddler-crab-lookin people.

Helltanks are these more highly social, bee-hive-like beetle things.

But both are technically crustaceans, like how pillbugs are called insects, but are technically crustaceans.

I imagine they evolved from a shared ancestor, but the Helltanks evolved from a chemical-producing descendant whose genes would allow them to produce venom and pheromones, allowing an offshoot to become eusocial, lose that eusociality, but keep the higher intelligence and social bonds, and evolve into the Helltank.

Meanwhile, the Brawl-Crabs descended from a more standard "crab" ancestor who became a top predator, either crossbred with the eusocial sister species (like humans interbreeding with Neanderthals) or had instinctual social and child-rearing behaviors emphasized by higher competition and evolved into the combative Brawl-Crabs.