The answer is class.
A class is a higher category in biological taxonomy that includes one or more orders. Classes are typically defined by shared characteristics such as body plan, mode of reproduction, and habitat. For example, the class Mammalia includes all mammals, which are characterized by having hair or fur, mammary glands, and a four-chambered heart.
Orders are a lower category than classes and include one or more families. Families are a lower category than orders and include one or more genera. Genera are a lower category than families and include one or more species.
Species are the basic unit of biological classification. A species is a group of organisms that can interbreed and produce fertile offspring.
In conclusion, the answer to the question “__ being a higher category, is the assemblage of families which exhibit a few similar characters” is class.