''Haemohormidium'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of parasitic

alveolates The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major unranked clade or superphylum within Eukaryota. They are currently grouped with the Stramenopiles and Rhizaria among the protists with tubulocristat ...

in the

phylum In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead ...

Apicomplexa The Apicomplexa (also called Apicomplexia; single: apicomplexan) are organisms of a large phylum of mainly parasitic alveolates. Most possess a unique form of organelle structure that comprises a type of non-photosynthetic plastid called an ap ...

. They have two hosts in their life cycle: the

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

hosts are

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

and the invertebrate vectors are

leech Leeches are segmented parasitism, parasitic or Predation, predatory worms that comprise the Class (biology), subclass Hirudinea within the phylum Annelida. They are closely related to the Oligochaeta, oligochaetes, which include the earthwor ...

es.

Taxonomy

The genus was created in 1910 by Henry who described the type species, ''Haemohormidium cotti'', in the short spined sea scorpion ('' Myxocephalus scorpius'') and the long spined sea scorpion ('' Taurulus bubalis''). Its nature was unclear until the electron microscopic studies revealed its relationship to the Apicomplexia. Henry in 1913 abandoned the name but the genus was validated by Wenyon in 1926. The species in the genus '' Babesiosoma'' were initially incorporated into this genus in 1969 but have subsequently been demerged. Some authors consider this genus to be synonymous with ''

Dactylosoma ''Dactylosoma'' is a genus of parasitic alveolates of the phylum Apicomplexa. Species in this genus have two hosts in their life cycle: the vertebrate host is a fish or amphibian (possibly also reptiles) and the invertebrate host is a glossiphon ...

''. Henry also in 1910 described a second genus - '' Haematractidium'': this is now considered synonymous with ''Haemohormidium''. It seems that the taxonomy of this group may yet undergo further revision.

Description

Species in this genus have * a single boundary membrane * may have closely apposed nuclei with

nucleoli The nucleolus (; : nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis. The nucleolus also participates in the formation of signal recognition particles and plays a ro ...

* cytoplasmic dense material of variable structure * the apical complex lacks a

conoid In geometry a conoid () is a ruled surface, whose rulings (lines) fulfill the additional conditions: :(1) All rulings are parallel to a plane, the '' directrix plane''. :(2) All rulings intersect a fixed line, the ''axis''. The conoid is a rig ...

Host records

* ''H. beckeri'' — Laval's eelpout ('' Lycodes lavalaei''), Vahl's eelpout ('' Lycodes vahlii'') * ''H. cotti'' — short spined sea scorpion ('' Myxocephalus scorpius''), long spined sea scorpion ('' Taurulus bubalis'') * ''H. terranovae'' —

America The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

n plaice (''

Hippoglossoides platessoides The American plaice, American sole or long rough dab (''Hippoglossoides platessoides'') is a North Atlantic flatfish that belongs, along with other right-eyed flounders, to the family Pleuronectidae. In the northwest Atlantic (''H. p. platessoide ...

'')

References

Apicomplexa genera {{Apicomplexa-stub