... Reinvestigation and new evaluation of representatives from the genera Semigordionus, Euchordo... more ... Reinvestigation and new evaluation of representatives from the genera Semigordionus, Euchordodes, Pan tachordodes, Dacochordodes and Spinochordodes (Nematomorpha) Fernanda Zanca** and Andreas Schmidt-Rhaesa"". ... 1992, de Villalobos & Zanca 2002). ...
We reinvestigate five African species of the genus Chordodes in order to certify the taxonomic de... more We reinvestigate five African species of the genus Chordodes in order to certify the taxonomic descriptions and verify the species status. By scanning electron microscopy, we demonstrate characteristic cuticular patterns for the species Chordodes africanus, C. hawkeri, C. sandoensis and C. schoutedeni. The fifth species, C. butensis, is synonymized with C. africanus, because no differences were detected.
Three species of the freshwater genus Noteochordodes (Nematomorpha) have been reported from Argen... more Three species of the freshwater genus Noteochordodes (Nematomorpha) have been reported from Argentina. In this reinvestigation Neochordodes talensis is included into Noteochordodes on the basis of its cuticular structure. The ultrastructural study of the ...
Paragordius is a genus of Gordiida with a worldwide distribution, but with a scarce specific dive... more Paragordius is a genus of Gordiida with a worldwide distribution, but with a scarce specific diversity. Seventeen species of the genus Paragordius have been described so far. In many cases, as with the other genera of Gordiida, the original descriptions of the species are insufficient due to the limitations of the techniques employed. In this work the holotype of P. andrasii and P. esavianus and specimens of P. esavianus and P. varius are redescribed by scanning electron microscopy (SEM), the intraspecific variations of the cuticle are showed. The distribution for P. esavianus, P. varius and P. andrasii is pointed out and the position of P. flavescens is discussed. Keywords: Paragordius, Gordiida, Nematomorpha, scanning electron microscope.
Two questions are of interest concerning the male reproductive system in Gordiida: (1) is the epi... more Two questions are of interest concerning the male reproductive system in Gordiida: (1) is the epithelium surrounding the testis continuous or discontinuous and (2) is the type of spermatozoon as described at the transmission electron-microscopical level for the two species of Gordius typical for all Gordiida? An examination of the South American species Pseudochordodes bedriagae has allowed us to add new information to this poorly studied phylum. Testicular tubes are large, filled with spermatozoa, and surrounded by a continuous epithelium. The epithelial cells that line the posterior testes occasionally overlap, and their cytoplasm is narrow and contains dense granules, abundant endoplasmic reticulum, and vesicles. The plasma membrane possesses microvilli with many filaments. This epithelium rests on a basement membrane. The spermatozoa in P. bedriagae resemble the known spermatozoa of two Gordius species but differ in presenting a uniform halo layer of less dense chromatin that surrounds the dense chromatin in the nucleus. The finding that a similar type of spermatozoa occurs in both genera (Pseudochordodes and Gordius) makes it likely that it is present in all other Gordiida and is therefore an autapomorphy of the Gordiida.
A total of 687 adult nematomorphs of four species of Gordiida: Chordodes brasiliensis (393 specim... more A total of 687 adult nematomorphs of four species of Gordiida: Chordodes brasiliensis (393 specimens), Noteochorododes cymatium (47 specimens), N. talensis (162 specimens) and Pseudochordodes dugesi (85 specimens) were collected during a period of 1 year from El Simbolar stream, Argentina. Free-living worms were abundant during autumn and spring, but their number decreased during winter and summer. Males were shorter and significantly more abundant than females. The presence of N. cymatium, N. talensis and P. dugesi was correlated with water temperature and these species were most abundant in winter and spring. The presence of C. brasiliensis was correlated with flow rate and pH; this species was more abundant in autumn and winter. These four species are sympatric.
Six species of the genus Chordodes from Africa were investigated in order to certify their taxono... more Six species of the genus Chordodes from Africa were investigated in order to certify their taxonomic descriptions and verify the species status. Scanning electron microscopy demonstrated that the female of Chordodes congolensis has seven types of areoles, while the females of C. ferox have six and the male and females of C. madagascariensis have four and five areolar types, respectively.
... Reinvestigation and new evaluation of representatives from the genera Semigordionus, Euchordo... more ... Reinvestigation and new evaluation of representatives from the genera Semigordionus, Euchordodes, Pan tachordodes, Dacochordodes and Spinochordodes (Nematomorpha) Fernanda Zanca** and Andreas Schmidt-Rhaesa"". ... 1992, de Villalobos & Zanca 2002). ...
We reinvestigate five African species of the genus Chordodes in order to certify the taxonomic de... more We reinvestigate five African species of the genus Chordodes in order to certify the taxonomic descriptions and verify the species status. By scanning electron microscopy, we demonstrate characteristic cuticular patterns for the species Chordodes africanus, C. hawkeri, C. sandoensis and C. schoutedeni. The fifth species, C. butensis, is synonymized with C. africanus, because no differences were detected.
Three species of the freshwater genus Noteochordodes (Nematomorpha) have been reported from Argen... more Three species of the freshwater genus Noteochordodes (Nematomorpha) have been reported from Argentina. In this reinvestigation Neochordodes talensis is included into Noteochordodes on the basis of its cuticular structure. The ultrastructural study of the ...
Paragordius is a genus of Gordiida with a worldwide distribution, but with a scarce specific dive... more Paragordius is a genus of Gordiida with a worldwide distribution, but with a scarce specific diversity. Seventeen species of the genus Paragordius have been described so far. In many cases, as with the other genera of Gordiida, the original descriptions of the species are insufficient due to the limitations of the techniques employed. In this work the holotype of P. andrasii and P. esavianus and specimens of P. esavianus and P. varius are redescribed by scanning electron microscopy (SEM), the intraspecific variations of the cuticle are showed. The distribution for P. esavianus, P. varius and P. andrasii is pointed out and the position of P. flavescens is discussed. Keywords: Paragordius, Gordiida, Nematomorpha, scanning electron microscope.
Two questions are of interest concerning the male reproductive system in Gordiida: (1) is the epi... more Two questions are of interest concerning the male reproductive system in Gordiida: (1) is the epithelium surrounding the testis continuous or discontinuous and (2) is the type of spermatozoon as described at the transmission electron-microscopical level for the two species of Gordius typical for all Gordiida? An examination of the South American species Pseudochordodes bedriagae has allowed us to add new information to this poorly studied phylum. Testicular tubes are large, filled with spermatozoa, and surrounded by a continuous epithelium. The epithelial cells that line the posterior testes occasionally overlap, and their cytoplasm is narrow and contains dense granules, abundant endoplasmic reticulum, and vesicles. The plasma membrane possesses microvilli with many filaments. This epithelium rests on a basement membrane. The spermatozoa in P. bedriagae resemble the known spermatozoa of two Gordius species but differ in presenting a uniform halo layer of less dense chromatin that surrounds the dense chromatin in the nucleus. The finding that a similar type of spermatozoa occurs in both genera (Pseudochordodes and Gordius) makes it likely that it is present in all other Gordiida and is therefore an autapomorphy of the Gordiida.
A total of 687 adult nematomorphs of four species of Gordiida: Chordodes brasiliensis (393 specim... more A total of 687 adult nematomorphs of four species of Gordiida: Chordodes brasiliensis (393 specimens), Noteochorododes cymatium (47 specimens), N. talensis (162 specimens) and Pseudochordodes dugesi (85 specimens) were collected during a period of 1 year from El Simbolar stream, Argentina. Free-living worms were abundant during autumn and spring, but their number decreased during winter and summer. Males were shorter and significantly more abundant than females. The presence of N. cymatium, N. talensis and P. dugesi was correlated with water temperature and these species were most abundant in winter and spring. The presence of C. brasiliensis was correlated with flow rate and pH; this species was more abundant in autumn and winter. These four species are sympatric.
Six species of the genus Chordodes from Africa were investigated in order to certify their taxono... more Six species of the genus Chordodes from Africa were investigated in order to certify their taxonomic descriptions and verify the species status. Scanning electron microscopy demonstrated that the female of Chordodes congolensis has seven types of areoles, while the females of C. ferox have six and the male and females of C. madagascariensis have four and five areolar types, respectively.
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Papers by Fernanda Zanca