Rhabditophora (from ''rhabdito''-,

rhabdite Rhabdites (from Greek, ''rhabdos'', rod) are rodlike structures in the cells of the epidermis or underlying parenchyma in certain turbellarians, and in the epidermis of nemertea Nemertea is a phylum of animals also known as ribbon worms or ...

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

-φορος ''phoros'' bearer, i.e., "rhabdite bearers") is a subphylum (previously a class) of

flatworms Platyhelminthes (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called ...

. It includes all

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 ...

flatworms (clade

Neodermata Neodermata is a clade of rhabditophoran flatworms containing the parasitic groups Trematoda, Monogenea and Cestoda. Description All neodermatans are parasites, in many groups having a free-swimming larval stage. The most striking feature uniti ...

) and most free-living species that were previously grouped in the now obsolete class

Turbellaria The Turbellaria are one of the traditional sub-divisions of the phylum Platyhelminthes (flatworms), and include all the sub-groups that are not exclusively parasitic. There are about 4,500 species, which range from to large freshwater forms mo ...

. Therefore, it contains the majority of the species in the phylum

Platyhelminthes Platyhelminthes (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called f ...

, excluding only the catenulids, to which they appear to be the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

. The clade Rhabditophora was originally erected by Ulrich Ehlers in 1985Ehlers, U. (1985) ''Phylogenetic relationships within the Platyhelminthes''. ''In'' S. Conway Morris; J. D. George; R. Gibson; H. M. Platt (Eds.), ''The origins and relationships of lower invertebrates''. Oxford, Clarendon Press, p. 143-158. based on morphological analyses and its

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

was later confirmed by molecular studies.

Description

Rhabditophorans are characterized by the presence of lamellated

s, rodlike granules secreted in the cells of the

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ...

and consisted of concentric

lamella Lamella (: lamellae) means a small plate or flake in Latin, and in English may refer to: Biology * Lamella (mycology), a papery rib beneath a mushroom cap * Lamella (botany) * Lamella (surface anatomy), a plate-like structure in an animal * Lame ...

e. They are absent in the clade

, most likely due to a secondary loss of this feature because their epidermis is turned into a

syncytium A syncytium (; : syncytia; from Greek: σύν ''syn'' "together" and κύτος ''kytos'' "box, i.e. cell") or symplasm is a multinucleate cell that can result from multiple cell fusions of uninuclear cells (i.e., cells with a single nucleus), i ...

in adult forms. Duogland adhesive system

Another important

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy sh ...

of the group is the duo-glandular adhesive system. It is a structure of the epidermis containing three different cell types: anchor cells, adhesive glands and releasing glands. The adhesive glands secrete an adhesive substance that attaches the anchor cells to a surface, while the releasing glands secrete a substance able to release the anchor cells from surfaces. This systems allows rhabditophorans to adhere and release quickly from the substrate, even several times in a second. The secretory organs of rhabditophorans, the

protonephridia The nephridium (: nephridia) is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidneys (which originated from the chordate nephridia). Nephridia remove metabolic wastes from an animal's body. Nephridia co ...

, also have a unique anatomy in which the

flame cell A flame cell is a specialized excretory cell found in simple invertebrates, including flatworms ( Platyhelminthes), rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney ...

s and tube cells present a series of cytoplasmic projections that overlap, forming a two-cell 'weir'.

Systematics

The following orders are recognised in the subphylum Rhabditophora: *Class ? **** Order

Bothrioplanida ''Bothrioplana'' is a genus of freshwater flatworms, the sole genus in the family Bothrioplanidae and order Bothrioplanida. Description Species of ''Bothrioplana'' are small organisms, usually measuring 2–3 mm in length, but reaching up to 7 ...

**** Order

Fecampiida Fecampiida is an order of flatworms in the class Rhabditophora. It is a considerably recent clade, erected after molecular studies. Description The order Fecampiida, as currently defined, was erected based on molecular studies. They all are pa ...

**** Order Gnosonesimida **** Order

Polycladida The Polycladida represents a highly diverse clade of free-living marine flatworms. They are known from the littoral to the sublittoral zone (extending to the deep hot vents), and many species are common from coral reefs. Only a few species are fo ...

**** Order

Prolecithophora The ''Prolecithophora'' are an order consisting of an estimated 300 species of small (typically 0.2 – 12 mm, one species up to 50 mm), active, aquatic flatworms. The order lacks a common English name. Most species are shaped like an e ...

**** Order Prorhynchida **** Order

Proseriata Proseriata is an order of free-living flatworms in the class Rhabditophora with over 400 species described worldwide. Description Proseriate flatworms are minute aquatic organisms, usually with an elongate body. There are no strong synapomorph ...

**** Order

Rhabdocoela Rhabdocoela is an order of flatworms in the class Rhabditophora with about 1700 species described worldwide. The order was first described in 1831 by Christian Gottfried Ehrenberg. Most of rhabdocoels are free-living organisms, but some live sym ...

**** Order

Tricladida Planarians (triclads) are free-living flatworms of the class Turbellaria, order Tricladida, which includes hundreds of species, found in freshwater, marine, and terrestrial habitats.pp 3., "Planarians (the popular name for the group as a whole ...

*** Superorder

Macrostomorpha Macrostomorpha is a clade of free living flatworms in the group Rhabditophora. Description Species of Macrostomorpha are characterized by having the necks of the viscid gland and releasing gland emerging in a common collar of anchor cell microvi ...

****** Genus ''

Bradynectes Macrostomorpha is a clade of free living flatworms in the group Rhabditophora. Description Species of Macrostomorpha are characterized by having the necks of the viscid gland and releasing gland emerging in a common collar of anchor cell microvi ...

'' ****** Genus ''

Myozona Macrostomorpha is a clade of free living flatworms in the group Rhabditophora. Description Species of Macrostomorpha are characterized by having the necks of the viscid gland and releasing gland emerging in a common collar of anchor cell microvi ...

'' ***** Family Haplopharyngidae ***** Family Macrostomidae **** Order Dolichomicrostomida * Superclass

(''

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s'') ** Class

Cestoda Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies co ...

*** Subclass

Cestodaria Cestodaria is one of two subclasses of the class Cestoda Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like w ...

**** Order Amphilinidea **** Order

Gyrocotylidea Gyrocotylidea is an order of Cestoda (tapeworms). Members of this order are parasites of vertebrates, living in the coelom The coelom (or celom) is the main body cavity in many animals and is positioned inside the body to surround and contai ...

*** Subclass

Eucestoda Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass being Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Ce ...

**** Order Bothriocephalidea **** Order Caryophyllidea **** Order Cathetocephalidea **** Order

Cyclophyllidea Cyclophyllidea (the cyclophyllid cestodes) is the order of Cestoda (tapeworm). It is the largest and most diverse order of Cestoda (tapeworm), encompassing species that infect all classes of terrestrial tetrapods including humans and domesticate ...

**** Order Diphyllidea **** Order Diphyllobothriidea **** Order Lecanicephalidea **** Order Litobothriidea **** Order

Onchoproteocephalidea Onchoproteocephalidea is an order of flatworms belonging to the class Cestoda. Families: * Onchobothriidae * Prosobothriidae * Proteocephalidae Onchoproteocephalidea ''incertae sedis or is a term used for a taxonomy (biology), taxono ...

**** Order Phyllobothriidea **** Order Rhinebothriidea **** Order

Spathebothriidea Spathebothriidea is an order of Cestoda (tapeworms). Members of this order are gut parasites Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another org ...

**** Order Tetrabothriidea **** Order Tetraphyllidea **** Order

Trypanorhyncha ''Trypanorhyncha'' is an order of cestodes, a type of flatworm. Some species infect gamefish, such as sciaenids, during the parasitic worm's plerocercoid stage, and are commonly called spaghetti worm because of their appearance, approximating ...

** Class

Monogenea Monogeneans, members of the class Monogenea, are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they ...

*** Subclass

Monopisthocotylea The Monopisthocotylea are an inferior class of parasitic flatworms in the class Monogenea.WoRMS (2019). Monopisthocotylea. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=119219 on 2019-02-08 Yamaguti, S. (1963). Systema Helmi ...

**** Order

Capsalidea Capsalidea is an order of parasitic flatworms in the class Monogenea Monogeneans, members of the class Monogenea, are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do ...

**** Order

Dactylogyridea Dactylogyridea is an order of parasitic flatworms in the class Monogenea.WoRMS (2018). Dactylogyridea. Accessed at: http://marinespecies.org/aphia.php?p=taxdetails&id=517897 on 2018-08-09 Families * Amphibdellatidae Carus, 1885 * Ancylodisc ...

**** Order

Gyrodactylidea Gyrodactylidea is an order of monogenean parasitic flatworms in the subclass Monopisthocotylea The Monopisthocotylea are an inferior class of parasitic flatworms in the class Monogenea.WoRMS (2019). Monopisthocotylea. Accessed at: http://www.m ...

**** Order

Monocotylidea The Monopisthocotylea are an inferior class of parasitic flatworms in the class Monogenea.WoRMS (2019). Monopisthocotylea. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=119219 on 2019-02-08 Yamaguti, S. (1963). Systema Helmi ...

**** Order

Montchadskyellidea The Monopisthocotylea are an inferior class of parasitic flatworms in the class Monogenea.WoRMS (2019). Monopisthocotylea. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=119219 on 2019-02-08 Yamaguti, S. (1963). Systema Helmi ...

*** Subclass

Polyopisthocotylea Polyopisthocotylea is a subclass of parasitic flatworms in the class Monogenea.WoRMS (2023). Polyopisthocotylea. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=119220 on 2023-12-21Yamaguti, S. (1963). Systema Helminthum Volu ...

**** Order

Chimaericolidea Chimaericolidae is a family of monogenea Monogeneans, members of the class Monogenea, are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate h ...

**** Order

Diclybothriidea Diclybothriidea is an order of monogenea Monogeneans, members of the class Monogenea, are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate ...

**** Order Lagarocotylidea **** Order

Mazocraeidea Mazocraeidea is an order of flatworms in the subclass Polyopisthocotylea within the class Monogenea. The species of this order have various structures in the clamps of their posterior attachment organ, including additional sclerites in the Gas ...

**** Order

Polystomatidea Polystomatidae is a family of flatworms belonging to the class Monogenea Monogeneans, members of the class Monogenea, are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and ...

** Class

Trematoda Trematoda is a class of flatworms known as trematodes, and commonly as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is a mol ...

*** Subclass

Aspidogastrea The Aspidogastrea (Ancient Greek: ' “shield”, ' “stomach/pouch”) is a small group of flukes comprising about 80 species. It is a subclass of the trematoda, and sister group to the Digenea. Species range in length from approximately on ...

**** Order

Aspidogastrida Aspidogastrida is an order of trematodes in the subclass Aspidogastrea The Aspidogastrea (Ancient Greek: ' “shield”, ' “stomach/pouch”) is a small group of flukes comprising about 80 species. It is a subclass of the trematoda, and ...

**** Order

Stichocotylida ''Stichocotyle'' is a monospecific genus of trematodes, in the monospecific family Stichocotylidae, which is itself in the monotypic order Stichocotylida. It comprises the single species ''Stichocotyle nephropis'', which is an internal parasite o ...

*** Subclass

Digenea Digenea (Gr. ''Dis'' – double, ''Genos'' – race) is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms (known as ''flukes'') with a syncytial tegument and, usually, two suckers, one ventral and one or ...

**** Order

Diplostomida Diplostomida is an order of trematodes in the subclass Digenea. It is synonymous with Strigeatida Poche, 1926. Families Order Diplostomida *Suborder Diplostomata **Superfamily Brachylaimoidea Joyeux & Foley, 1930 ***Brachylaimidae Joyeux & Foley ...

**** Order

Plagiorchiida Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few significant parasites of humans. The following families are placed here, ...

References

{{Taxonbar, from=Q3428991 Protostome classes