Which organism is incorrectly matched with its characteristic?

The organism Hymenolepis nana is a cestode (tapeworm), and while it is known for having an egg that is oval-shaped, it is not described as having a striated shell. The correct characteristic of the eggs of Hymenolepis nana includes their thick, transparent shell and the presence of polar filaments, rather than striations. Striated shells are typically associated with different types of eggs in parasitology, particularly in some other helminths or protozoans, which can lead to confusion when matching characteristics with specific organisms.

In contrast, the other options correctly describe their respective organisms. Chilomastix mesnili is accurately described with its characteristic shepherd's crook and lemon shape, which helps in identification during microscopic examination. Plasmodium malariae's "band troph" designation refers to the unique form of the trophozoite stage, while Wuchereria bancrofti is known for the presence of sheathed microfilariae, which is critical for diagnosing lymphatic filariasis. Each of these characteristics plays a significant role in identifying these organisms in clinical or laboratory settings.