Physical Description

Diagnostic Description

with intestine and simple mouth opening; epithelial nervous system; statocyst with 2 statoliths; no excretory apparatus; male genital pore in hind end; without female ducts and accessory apparatus
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Names and Taxonomy

Taxonomy

Habitat:   Flagellophora apelti- sublittoral to 80m North Sea & Adriatic.   Nemertoderma- sublittoral, Steinbock O 1930 fine mud at 250m.   Meara- intestine of Stichopus tremulus or in cavity of body?    Outer Appearance:   Size: Flagellophora- 0.8-1.2 mm   Meara- up to 3mm    Integument: Flagellophora & Meara - polygonal cells at base of cilia &   deeper ep. cells. Meara thick, cellular.   Nemertoderma- thick epithelial with vacuoles.   Meara- outer circ., inner longitudinal muscles,   only small adenal glands  Nervous System:   Flagellophora- internal- high brain in cross section.   Meara- neuropile at base of intestinal cells (like Nemertoderma),   swellings for 2 dorsolateral nerves- no inner nervous system   and brain less dev than Nemertoderma.  Statocyst:   2 statoliths. Statocyst muscles go out to longitudal muscles?   Steinbock O 1930 plate I.   Meara no statocyst muscles.   Meara & Nemertoderma statocyst - only sense organ.    Digestive Tract:   Flagellophora- no pharynx or mouth. "Koernerkolben" cells = mucous cells. Flagella organ.   Nemertoderma bathycola- Steinbock O 1930- refer to mouth at front end [= male pore]   Riedl RJ 1960 (citation)- defines with ventral mouth.   Karling TG 1974- shows ventral mouth.   Karling TG 1967 (citation)- illustration of sections to show cilia in digestive tract.   Karling TG 1967 (citation)- p 5,6, & 8 on gut.   Nemertoderma rubra- Faubel A 1976 (citation)- "typical pharynx simplex".   [glands and mouth are Koernerkolben?] no? but there are ones in digestive tract.     Meara- fleshy lips a little behind middle of ventral side and thickened neuropile for a sort of   psuedo-pharynx (Westblad E 1948 (citation)) intestine all through body with short   sub-lateral side ventricles. epithelial lining sort of cells- amoeboid cells   and "Koernerkolben"    Reproductive System: Faubel A 1983 (citation)- notes ciliated male tract (p. 26).     Flagellophora (female)- ovary- large bursa opening dorsally?   Meara (female)- ovary follicular- fills posterior part of bady.     Flagellophora (male)- ventral male pore- copulatory organ thickened and interal part of epithelial   layer and gland cells. no seminal vesicles- or antrum.   Meara (male)- testis follicular and fills (??) part of body. seminal vesicles thin walled (??).     Copulation by insemination - also spermatophores.     Spermatozoa- uniflagellate- see Tyler S, Rieger RM 1975 (citation) and Tyler S, Rieger RM 1977 (citation)   Hendelberg J 1977 (citation)- Nemertoderma- sp uncertain and Meara p 152, all have   middle piece and tail (uniflagellate).   both "modified spermatozoa" Franzen A 1956 (citation), Franzen A 1977 (citation)   "evolved from pimitive type of metazoan spermatozoa." helically coiled   middle piece in Meara etc- primitive single flagellum etc- differs from Acoela   see Hendelberg J 1977 (citation).    Ax 1961 (citation)- Discusses separation of this order from Acoela p 47 in diagram p 45.  Faubel A, Dorjes J 1978 (citation)- definition p 8.   "Archoophora with a digestive tract containing "Koernerkolben" cells, mouth opening simple,   nervous system epithelial aor subepithelial, statocyst with two or more statoliths, excretory   organ unknown, male genital pore in the posterior part of the body, uniflagellate spermatozoa."    Karling TG 1974 (citation)- discussion of the phylogeny of Turbellaria (See under Nermertoderma)  Rieger RM 1981 (citation)- on electron microscopy structure p 216, sperm 222, statocyst 220-221.  Doe DA 1981 (citation)- pharynges discussion. 

 Reuter M, Raikova OI, Gustafsson MKS 2001 (citation)- Phylogeny, neurons, muscles. Acoela and Nemertodermatida studies of neuroanatomy. Species used include:   Catenulida   Stenostomum leucops Duges 1828   Macrostomida   Macrostomum lineare Muller 1774   Acoela   Anaperus biaculeatus   Childia groenlandica Levinsen 1879   Faerla glomerata Westblad 1942   Paraphanostomum crassum Westblad 1942   Avagina incola Leiper 1902   Nemertodermatida   Nemertoderma westbladi Steinbock 1938   Mera stichopi Westblad 1949 

 Littlewood DTJ, Olson PD, Telford MJ, Herniou EA, Riutort M 2001 (citation)- Reviews recent molecular systematics on Acoela, Nemertodermatida, Catenulida and Rhabditophora, EF1 analysis and its limitations, etc. 

 Lundin K 1997 (citation)- "ultrastructure of the epidermal ciliary rootlets and associated structures in  species of the Nemertodermatida and Acoela". Species used: Meara stichopi, Nemertoderma westbladi,  Nemertoderma cf. bathycola, Convolutriloba retrogemma, Childia groenlandica, Paraphanostoma submaculatum,  Haploposthia virdis. 

 Ehlers U (citation)-"Frontal glandular and sensory structures in Nemertoderma (Nemertodermatida) and Paratomella (Acoela): ultrastructure and phylogenetic implications for the monophyly of the Euplathelminthes".  Nemertoderma sp. B, and Paratomella rubra used. 

 Ehlers U (citation)-"Frontal glandular and sensory structures in Nemertoderma (Nemertodermatida) and  Paratomella (Acoela): ultrastructure and phylogenetic implications for the monophyly of the  Euplathelminthes". Nemertoderma sp. B, and Paratomella rubra used. 

 Bush LF 1981 (citation)- Marine flora and fauna of the northeastern United States. Turbellaria: Acoela and  Nemertodermatida. 

 Tyler S, Rieger RM 1977 (citation)- "Ultrastructural evidence for the systematic position of the Nemertodermatida  (Turbellaria)." 

 Ruiz-Trillo I, Paps J, Loukota M, Ribera C, Jondelius U, Baguna J, Riutort M 2002 (citation)- "phylogenetic  analysis of DNA sequences from the myosin heavy chain type II (myosin II) gene from a large set of  metazoans, including acoels and nemertodermatids." Evolutionary significance.  

 Jondelius U, Ruiz-Trillo I, Baguna J, Riutort M 2002 (citation)- "The Nemertodermatida are basal bilaterians not members of Platyhelminthes." 

 Reuter M, Raikova OI, Jondelius U, Gustafsson MKS 2000 (citation)- "The brain of the Nemertodermatida (Platyhelminthes) as revealed by anti-5HT and anti-FMRFamide immunostainings." Species: Meara stichopi, Nemertoderma westbladi. 

 Lundin K, Sterrer W 2001 (citation)- Diagnosis of the Order Nemertodermatida. p 27 "Present structural, immunocytochemical and embryological evidence favours the idea that the Nemertodermatida and Acoela are sister taxa....". 

 Lundin K, Hendelberg J 1998 (citation)- "Is the sperm type of the Nemertodermatida close to that of the ancestral Platyhelminthes?" 

 Lundin K 2000 (citation)-"Phylogeny of the Nemertodermatida (Acoelomorpha, Platyhelminthes). A cladistic analysis." 

 Sterrer W 1998 (citation)- "New and known Nemertodermatida (Playthelminthes-Acoelomorpha) -- a revision." 

 Tyler S, Rieger RM 1977 (citation)- "Ultrastructural evidence for the systematic position of the Nemertodermatida (Turbellaria)."
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Source: Turbellarian Taxonomic Database

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