''Ellobiopsis'' 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 ...

unicellular A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...

ectoparasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

s causing disease in crustaceans. This genus is widespread and has been found infecting

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s from both marine and freshwater ecosystems. parasitism has been seen to interfere with fertility in both sexes of copepods.

Taxonomy and History

The ''Ellobiopsis''

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, ''Ellobiopsis chattoni,'' was first described in 1910 by Caullery after being isolated from an infected

found in the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

. ''Ellobiopsis'' was first classified as a

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

, but observation of a

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

forming

organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as Organ (anatomy), organs are to th ...

concluded that the ''Ellobiopsis'' was not a part of this group.

Phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

based on small subunit (SSU) ribosomal DNA places ''Ellobiopsis'' in the Alveolata. In the family Ellobiopsidae, the most closely related genus is ''Thalassomyces''. Three

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

have been defined in this genus: ''Ellobiopsis chattoni'' Caullery (1910), ''Ellobiopsis elongata'' Steuer (1932) ''and Ellobiopsis fagei'' Hovasse (1951). These species are characterized by morphology of their reproductive structures and their ability to infect species specific hosts.

Description

Morphology

During dispersal, unflagellated spores of ''Ellobiopsis'' land on the surface of potential hosts. Once in contact with a host, the cell body of the organism grows and takes on an oval shape. A rhizoid pierces the host

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

to root the parasite in the copepod tissue. The cell body constricts in the center and differentiate into trophomere and gonomere, proximal and distal to the host body. The cell forms a conical shape. The number of gonomeres is distinguishes species. The cell body has been seen to grows to a length of 700 μm and a width of 350 μm.

Life cycle

The

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

life cycle of ''Ellobiopsis chattoni'' begins with a spore that lands on the surface of a host appendage. A stalk attaches the parasite to the host and it uses an organelle for penetration, called a rhizoid, of the cuticle and to root itself in the host tissue. As the cell grows the root is used for absorption, causing damaging to the local host tissue. Once established at a specific size, approximately 400 μm, the cell body begins to partition itself in half. The half not attached to the host becomes the gonomere and the half attached to the host is named the trophomere. As the gonomere and trophomere partitioning continues to partition, the spore begins to form in the gonomere and it takes on a granulated texture. The pre-spores are released from the reproductive body and form spores for dispersal to the next host.

Host records

* ''E. chattonii'' — '' Acartia clausi'', '' Calanus helgolandica'', '' Calanus finmarchicus'', '' Centropages typicus'', '' Clausocalanus arcuicornis'', '' Ctenocalanus vanus'', '' Euchaeta marina'', '' Euchaeta wolfendeni'', '' Metridia longa'', '' Pleuromamma gracilis'', '' Pleuromamma borealis'', ''

Portunus pelagicus ''Portunus pelagicus'', also known as the blue crab, blue swimmer crab, blue manna crab and flower crab is a species of large crab found in the Indo-Pacific, including off the coasts Indonesia, Malaysia, Cambodia, Thailand, the Philippines, and V ...

'', '' Pseudocalanus elongatus'', '' Pseudocalanus minutus'', '' Undinula vulgaris'' * ''E. elongata'' — '' Clausocalanus arcuicornis'', '' Ctenocalanus vanus'', '' Cosmocalanus darwini'', '' Euchaeta marina'', '' Gaetanus antarcticus'', '' Gaetanus curvicornis'', '' Penaeopsis retacuta'' * ''E. fagei'' — '' Clausocalanus arcuicornis''

References

{{Taxonbar, from=Q5366096 Alveolata genera Parasitic alveolates