NEW CASES OF PARTHENOGENESIS AND POLYPLOIDY IN THE GENUS RAMAZZOTTIUS (TARDIGRADA, HYPSIBIIDAE) AND A HYPOTHESIS CONCERNING THEIR ORIGIN

Specimens of the genus Ramazzottius Binda and Pilato, 1986 (Eutardigrada, Hypsibiidae) were obtained from 2 moss and 1 lichen sample(s) collected in the Emilian Apennine Mountains. R. tribulosus was only found in one sample, whereas R. oberhaeuseri was found in all three. The first species had only diploid specimens, with 6 bivalents during the first meiotic division; the second had only females showing various polyploid cytotypes in addition ot the diploid bisexual cytotype cited for this area. One of the triploid and the tetraplid cytotypes were characterized by the presence of univalents at oocyte metaphase. In contrast, another cytotype had "bivalents" in triploid number. Though the large number of cytotypes found in a single sample may be attributed to chance, it is better explained by an in loco origin, at least in some cases.