Aconoidasida

The Aconoidasida are a class

Class (biology)

In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...

 of apicomplexa

Apicomplexa

The Apicomplexa are a large group of protists, most of which possess a unique organelle called apicoplast and an apical complex structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or...

n parasites created by Mehlhorn et al in 1980.

Organisms of this phylum bear a tip at one end of their outer membrane. This apical complex includes vesicles called rhoptries and micronemes, which open at the anterior of the cell. These secrete enzymes that allow the parasite to enter other cells. The tip is surrounded by a band of microtubules, called the polar ring. Among members of the class Conoidasida

Conoidasida

Conoidasida is a class of protists.The class was defined in 1988 by Levine and contains two subclasses - the coccidia and the gregarines. All members of this class have a complete, hollow, truncated conoid...

there is also a funnel of rods called the conoid. The class Aconoidasida, by contrast, lack this funnel of rods (a-, from the Greek negative prefix="lacking")