Marcus E 1950 (citation) pg. 102: 'Mecynostomum tenuissimum (Westbl.) (Fig. 14-15) occurs in gray mud in about 5m depth on the coast of the island of São Sebastião. The present specimens show some minor differences from the northern ones: the frontal glands (f) are a little more developed, scarce cutaneous glands (g) are present, the posterior retractors were not seen, but dorso-ventral muscles (h) in the same region. The bursa seminalis is absent, and not even masses of sperms were found behind the ovaries. Big cells (x) in the caudal ectocytium may be glandular and perhaps produce the secretion by which the animals stick to mud-particles. The nuclei (n) of the epicytium are depressed in the pre-oral region of the body.'
Marcus E 1950 (citation)- Describes species from Brazil and says this is synonymous with Mecynostomum tenuissimum (Westblad, 1946). Pg. 12, 102. Dorjes J 1968 (citation)- moves to Avagina (=Avagina tenuissima) pg. 86. Dorjes J 1972 (citation)- says does not belong here (in Avagina)- sets up Genus Proaphanostoma. Dorjes J, Karling TG 1975 (citation)- Lists Westblad species in Proaphanostoma- Swedish Museum of Natural History- North Sea. Also, moves Brazil species to genus Avagina (= Avagina marci n. sp.)
Notes for the valid (accepted) taxonomic name
Notes for Avagina marci
Dorjes J, Karling TG 1975 (citation)- Swedish Museum of Natural History. Marcus' specimens are not same as Mecynostomum tenuissimum to which Marcus assigned them- differences between the 2 species given.-----"Westblad (1946) described Aphanostoma tenuissimum; in 1948 the same author changed the genus name into Mecynostomum. Beside other criteria he mentioned the absence of cutaneous glands and the presence of a posterior retractor and an indistinct bursa or instead of this mass of sperms behind the ovaries. Marcus (1950) mentioned specimens of Mecynostomum tenuissimum from the coast of Brazil. He discussed as minor differences the presence of scarce cuteaneous glands and the absence of a posterior retractor and a and a bursa or a mass of sperms behind the ovaries. A revision and comparison of the entire material show distinct differences between Westblad's and Marcus' material. Westblad's specimens are characterized by the presence of a bursa, a posterior retractor, and the absence of cuteaneous glands. The specimens collected by Marcus show the opposite features, i.e. the presence of numerous cutaneous glands and the absence of a posterior retractor and a bursa or sperm mass. Another difference exits in the shape of the copulatory organ. It is thus necessary to regard the specimens collected by Westblad and Marcus as different species. Marcus' species belongs to the genus Avagina and its species name must be changed according to the article 49 in the International Code of Zoological Nomenclature."
Notes for Avagina marci
Avagina vagina and Proaphanostoma tenuissima may be synonymous or sibling species according to findings of M. Hooge. Differences in the female reproductive organs, which are most important in distinguishing the two, may be a matter of degree of development.
Notes for Avagina marciHooge M.D. & Rocha C.E.F. 2006 (citation) p. 12 - report this species from the coast of Sao Paulo, Brazil.
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