The Hiver Queens are the space spiders. And everybody knows that space cats aren't nearly silly enough for SotS! Especially not when we have lizard-monkeys, squid-dolphins, bird-dragons, Tasmanian Devils, and weasel-pedes. So, you need to make them much more interesting, and give them a scientifically-plausible-but-tactically-interesting-FTL-drive.
Really, this is all a joke. Just ask the Jumbwars, they'll gladly tell you. Or they would, if they weren't laughing at your corpse. SolForce first encountered the Jumbwars on a planet that the Travelers left uncolonized, even though it was well within their habitation standards.
The first alien encounter team didn't come back. Neither did the second one. For the third team, they allowed some SolForce marines to escort the team. What they found was several green cows peacefully chewing cud on an arboreal world, and an overabundance of tree-houses. There was no sign of the previous teams, or of any hostile creatures. Then they noticed that the bovine-looking creatures' cud was dripping out of their mouths. And it was RED
What constitutes a sense of humor in a plant? How does a plant communicate? In the case of the Jumbwars, the answer is by digestion and perception of light. All communication is done by light, and the Jumbwars can see in a far greater range of frequencies than most other sentient species. So, when they first saw how the light of their homeworld hit the aliens, they found it hilarious. And since it is quite possible to "graze" on each other with little to no lasting damage, they quite "frequently chew on their neighbor's thoughts" quite literally. Unfortunately, this wasn't pleasant or remotely funny to their visitors. The Jumbwars, however, found it hilarious.
In a similar manner, they find war to be similar to a musical comedy. The beautiful lights of weapons, the sounds of explosions, and even the sight of a devastated forest is all done for the giggles. When you live for thousands of years, and your children WILL survive most weapons if buried into the soil deep enough, war ceases to have the effect it does on other less survivable species. It even becomes... funny.FTL Drive and Research
Not surprisingly, the Cows (as the humans call them) use a form of light-based FTL travel. A Charge-drive ship collects solar energy from a nearby star and uses this to generate a field in which the normal laws of relativity do not apply, similar to the Tarkan Drive although it operates on different principles. The effect of this is that when within a short distance from any luminescent body, they can absorb enough energy to expand this field and therefore travel faster for a short period of time. For their basic Fission Drive, this translates to each ship having a "base" STL speed, which is increased by 1 light year per turn up to a maximum of 2 turns. Each turn spent traveling in space, their speed slowly "degrades" by 0.2 light years per turn.
Research-wise, they have a high affinity for laser and mass-driver weapons, but not defenses. They also are not adept at developing weapons that do a high amount of climate damage. As plant creatures, they are of course very likely to be able to survive in areas of high CO2 concentration with high humidity and heat as well. They are the only race other than the Liir that have basic colonizers that can terraform the planets they inhabit, although in the case of the Jumbwars, this is because their existence actually terraforms the planet instead of them bringing parts of their planets with them. Their populations grow relatively slowly, but they have a large number of colonists on their ships. (It's very easy to store seeds in small places compared to grown individuals).
Their ships are made mostly of artificially petrified organic components. In other words, the basic structure is first grown, then infused with metals to form the ship hulls / structural components.
And THAT is how you make a SotS suggestion race. Take something done in other sci-fi, in this case, intelligent plants, then turn the typical assumptions of such a race (peaceful, humorless) on its rear end, throw in a themed FTL drive (light-based), and some research likes and dislikes, and voila! Instant SotS race (or good enough for a few giggles, and one that the Devs MIGHT actually consider for SotS III: Enter the Veggies!!!!!).