@article {1766, title = {Triploid planarian reproduces truly bisexually with euploid gametes produced through a different meiotic system between sex.}, journal = {Chromosoma}, volume = {123}, year = {2014}, month = {2014 Jun}, pages = {265-72}, abstract = {

Although polyploids are common among plants and some animals, polyploidization often causes reproductive failure. Triploids, in particular, are characterized by the problems of chromosomal pairing and segregation during meiosis, which may cause aneuploid gametes and results in sterility. Thus, they are generally considered to reproduce only asexually. In the case of the Platyhelminthes Dugesia ryukyuensis, populations with triploid karyotypes are normally found in nature as both fissiparous and oviparous triploids. Fissiparous triploids can also be experimentally sexualized if they are fed sexual planarians, developing both gonads and other reproductive organs. Fully sexualized worms begin reproducing by copulation rather than fission. In this study, we examined the genotypes of the offspring obtained by breeding sexualized triploids and found that the offspring inherited genes from both parents, i.e., they reproduced truly bisexually. Furthermore, meiotic chromosome behavior in triploid sexualized planarians differed significantly between male and female germ lines, in that female germ line cells remained triploid until prophase I, whereas male germ line cells appeared to become diploid before entry into meiosis. Oocytes at the late diplotene stage contained not only paired bivalents but also unpaired univalents that were suggested to produce diploid eggs if they remained in subsequent processes. Triploid planarians may therefore form euploid gametes by different meiotic systems in female and male germ lines and thus are be able to reproduce sexually in contrast to many other triploid organisms.

}, keywords = {Animals, Chromosomes, Female, Germ Cells, Male, Meiosis, planarians, reproduction, Triploidy}, issn = {1432-0886}, doi = {10.1007/s00412-013-0449-2}, author = {Chinone, Ayako and Nodono, Hanae and Matsumoto, Midori} } @article {1726, title = {Spermatogenesis, spermiogenesis and sperm structure in Crenobia (Planaria) alpina (Dana)}, journal = {Z Zellforsch Mikrosk Anat}, volume = {97}, year = {1969}, month = {1969}, pages = {549-63}, keywords = {Animals, Cell Division, Cell Nucleus, Cytoplasm, Flagella, Male, Microscopy, Phase-Contrast, Spermatozoa, Staining and Labeling, Turbellaria}, issn = {0340-0336}, author = {van der Linden, A G} } @article {1708, title = {Anatomical deviation of male organs of land planarians from Rio de Janeiro, Brazil, with description of two new species of Cratera (Platyhelminthes, Tricladida).}, journal = {Zootaxa}, volume = {3931}, year = {2015}, month = {2015 Mar 11}, pages = {27-40}, abstract = {

Two new land planarian species, collected in the State of Rio de Janeiro, Brazil, are described. Their external aspect is similar to that of Imbira marcusi Carbayo et al., 2013 and Pseudogeoplana theresopolitana (Schirch, 1929), respectively. The analysis of the internal organs, however, revealed they belong to the genus Cratera. The male copulatory organs of one species is very different from any other geoplaninid, for the penis papilla holds a large, distal cavity receiving the ejaculatory duct and, furthermore, the papilla projects vertically downwards from the roof of the male atrium. Thus we consider it as a new species, Cratera cuarassu sp. nov. The second species differs from its congeners in that the dorsal insertion of the penis papilla is anterior to the ventral one, and in that the female atrium is narrowed in the anterior portion. The species was found in the type locality of Pseudogeoplana theresopolitana (Schirch, 1929) and compares well with it in the external features. However, since its internal organs are unknown and the type material of the species is seemingly lost, we describe it as Cratera anamariae Carbayo, sp. nov.

}, keywords = {Animals, Brazil, Genitalia, Male, Male, planarians}, issn = {1175-5334}, doi = {10.11646/zootaxa.3931.1.2}, author = {Carbayo, Fernando and Almeida, Ana Laura} }