I don't have a taxonomic specialization, and I'm happy with that. I've worked with or dug deeply in to the literature on hardwood forest trees, midges, several groups of birds, frogs, rotifers, primates and Hydra (the polyp, not the mythical beast). I've probably read more of the literature on beetles in the family Melyridae than any other non-entomologist who knows almost nothing about beetles.
I've now gotten to the point in my career where I am organizing a research group and serving on people's committees, and suddenly and unintentionally, I'm all into crustaceans. I'm supervising a post-doc and a doctoral student and on the committee of another student all working on different Daphnia projects. Daphnia are the model organism for crustaceans. I've got another post-doc working on barnacles (which despite their outward appearance as adults, are very much crustaceans, and go through not one but two amazing metamorphoses before ending up attached to ships, rocks or whales). This particular barnacle, Balanus improvisus was first described by Darwin (1854) in his giant book on barnacles that he wrote to procrastinate publishing On the Origin of Species (1859).
I've still got projects on Neurospora a fungus best known for ruining your bread, on Hydra, and on primates (including humans) going, but most of my time at the moment is crustacean focused. I suppose I will have to learn the basics of carcinology. Yes, that does come from the same root as carcinogen and carcinoma.