DESCRIPTION OF AN ITALIAN POPULATION OF STYLONYCHIA HARBINENSIS (CILIOPHORA, OXYTRICHIDAE) BASED ON MORPHOLOGY AND SSU RDNA

The genus Stylonychia Ehrenberg, 1830 is largely confined to freshwater with species of S. mytilus complex and S. pustulata being the most common ones. Berger (1999) in his detailed revision of the oxytrichids included eleven species within the genus however, only four of them were described in detail (Wirnsberger et al., 1986). The Stylonychia mytilus complex includes four species: S. mytilus, S. lemnae, and the last two species added Stylonychia ammermanni (Gupta et al., 2001) from Delhi region of Yamuna River, India, and Stylonychia harbinensis (Shi et al., 2004) from Harbin (Heilongjiang Province, China). The latter being previously included in the revision of Berger (1999) although considered as a nomen nudum since the species had been poorly described at that time. As with other genera including cryptic and sibling species, the morphological identification of species within the genus Stylonychia is known to be difficult due to the lack of conspicuous and unambiguous differences, and to the fact that most of the descriptions (including Stylonychia harbinensis) are only morphological but do not provide any molecular data. In the present study we provide a comprehensive redescription of Stylonychia harbinensis, isolated from soil samples of paddy fields collected from the area of Parona (Lombardia, Italy), combining morphology, morphogenesis, and molecular phylogeny.