Analisi cariologica e morfologica di alcune popolazioni di Macrobiotus hufelandi (Tardigrada) della Valsesia
Four populations with a different sex ratio of the tardigrade Macrobiotus hufelandi are recognized in an alpine valley. This difference is due to the presence of three biotypes (diploid, triploid and tetraploid biotype). Ameiotic thelitokous parthenogenesis is present in the triploid and tetraploid biotypes, while the diploid biotype is bisexual. Two types of eggs, probably related to the biotypes, are identified by morphologic analysis of egg shell.