Schellackia is a genus of parasitic protozoa

Protozoa

Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...

 within the phylum

Phylum

In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....

 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...

. The genus was described in 1919 by Reichenow. Species in this genus infect reptile

Reptile

Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s and amphibian

Amphibian

Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s.

The type species is Schellackia bolivari.

Life cycle

The parasite undergoes asexual replication in the cells of the intestine

Intestine

In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...

. This is followed by the formation of macrogametocytes and microgametocytes which undergo sexual recombination. The fertilized zygote

Zygote

A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...

 undergoes a series of divisions which result in sporozoites that invade the erythrocytes.

These cells are taken up in a blood meal of a mite

Mite

Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...

 where development of the parasite does not continue. The mite acts strictly as a passive vector. Lizard

Lizard

Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...

s eat the mites and become infected when the parasite emerges from the erythrocytes in the lizard's (or toad's) stomach.

In some species orofaecal transmission occurs without the necessity of a passage through a mite.

The parasites may be seen in a stained blood smear. The parasites deform the erythrocytes into cresents and are visible as oval, pale staining bodies within the cell.

The sporozoites possess rhoptries

Rhoptry

A rhoptry is a specialized secretory organelle. They are club-shaped organelles connected by thin necks to the extreme apical pole of the parasite. These organelles, like micronemes, are characteristic of the motile stages of Apicomplexa protozoans. They can vary in number and shape and contain...

, microneme

Microneme

Micronemes are cellular organs, or organelles, possessed by Apicomplexa protozoans that are restricted to the apical third of the protozoan body. They are surrounded by a typical unit membrane. On electorn microscopy they have an electron-dense matrix due to the high protein content...

s, apical rings and other structures typical of the members of this phylum.