''Merocystis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

in the

phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature f ...

Apicomplexa.

History

This genus was created in 1911 by DakinDakin WJ (1911) Notes on a new coccidian ''Merocystis kathae'' (n. gen. et sp.,) occurring in the renal organ of the whelk. Arch. Protist XXIII: 1115 He discovered this parasite - ''Merocystis kathae'' - in the renal organ of the whelk (''

Buccinum undatum ''Buccinum undatum'', the common whelk or the waved buccinum, is a large, edible marine gastropod in the family Buccinidae, the "true whelks".Fraussen, K.; Gofas, S. (2014). Buccinum undatum Linnaeus, 1758. Accessed through: World Register of M ...

''). Its life cycle has been studied in some detail by other workers. A second species was described - ''Merocystis tellinovum'' - by Buchanan in 1979 but this has since been moved to the genus ''

Pseudoklossia ''Pseudoklossia'' is a genus in the phylum Apicomplexa. Species in this genus infect marine molluscs, although one species (''Pseudoklossia microcosmi'') infects in an ascidian worm. The life cycle is heteroxenous (requires at least two hosts) ...

''.

Taxonomy

There is one species known in this genus.

Description

The life cycle follows a seasonal course. The earliest stages may appear in the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

any time between March and June. Growth proceeds and sexual differentiation takes place but mature

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce t ...

s are not found until November, when the first stages of sporogony are first found. Mature spores containing sporozoites are formed in January and become increasingly common up to May. Degenerating stages of spores are common in summer. The earliest stages within the renal organ are 10

µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

in diameter. To the naked eye the later stages of the parasite have the appearance of a rounded milky white dot. The trophozoites appear opaque and occasionally granular.

Schizogony Fission, in biology, is the division of a single entity into two or more parts and the regeneration of those parts to separate entities resembling the original. The object experiencing fission is usually a cell, but the term may also refer to how ...

occurs in the host cell. Morphological sexual differentiation is not detectable until growth is almost complete. The microgametocyte divides into 32 nuclei. At this stage cleavage of the

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...

brings about the formation of

uninucleate {{Short pages monitor