I don't know. It just seems to broad and vague. There are plenty of mammals, birds, and reptiles (maybe not many birds) that put humans on edge, while there are many invertebrates that humans would be very comfortable around (many mollusks, arthropods like bees or butterflies, not sure about fungi since we are naturally supposed to avoid fungi). How individuals react to these aliens is also completely subjective, for example one Human might just find bats and snakes much more settling than bees or butterflies. There are just people who are afraid of spiders but would have any snake slither around them, or the other way around, I know people who are completely comfortable around large spiders and scorpions but show them a rat snake and they piss themselves (I am one who hates spiders but is really comfortable around snakes). Then there is the fact that the alien you are looking at is intelligent, which will change so much of how you perceive it. Is an intelligent spider less scary than an unintelligent one, because you think it can control itself? Or is an intelligent spider more scary because it is intelligent? Basically, the matter of intelligence can either incite more fear, or incite reassurance due to the expectation that an intelligent being will control itself.
Marine vs Terrestrial also has some different reactions (since some of the alien portraits clearly look like they belong under the sea). I don't know about other people, but something being from the sea, even if it is directly related to a similar land animal, completely changes how I react to it. Crabs don't scare me like insects and spiders do, JUST because they live in the ocean, and this includes Japanese Spider Crabs. Meanwhile I won't touch a sea snake with a 10 foot pole because those things are damn dangerous. Speaking of crabs, there is also a matter that we are less afraid of animals we know to eat. I don't think many are going to get creeped out by an alien that looks like a shrimp, and might try to convince them that marinara sauce baths are "customary human tradition".
TL;DR it is completely subjective to individual how they react to aliens based on phenotype, even with collectivists since fears are unconscious. One spider might just have a soft spot for fungi, while another has one for birds, while another actually finds their own kind the most unsettling to look at.