Establishment of two new morphometrical parameters of Craspedacusta (Limnomedusae : Olindidae) with their application in the species validation

here are still arguments on the validity of some Craspedacusta species. In the present study, C. sowerbyi C. kiatingi. C. sinensis and C. brevinema were compared by using the morphometry, including two new morphometrical parameters established and applied in the species validation, i.e. the density of tentacles and statocysts. The two parameters were calculated as the number of tentacles, and of statocysts in the medusa divided by the diameter of its umbrella. In addition, the correlation between pairs of morphological characters for the above four species were analyzed by using the Spearman rank correlation coefficient. C. brevinema and C. sinensis were similar in many aspects of their morphology and morphometrics; however, C. Kiatingi was Significantly different from C. sowerbyi, and also from C. sinensis in the two new morphometrical characters. Spearman correlation test indicated that either the number of tentacles or the number of statocysts was significantly positively correlated with the diameter of umbrella for the four Craspedacusta species. Significant positive correlations were found between the density of tentacles and of statocysts for the three species, i.e. C. sowerbyi I C. sinensis and C. brevinema. It is suggested that C. brevinema is probably a synonym of C. sinensis, and that C. kiatingi is a valid species. However, further study on the relationships and validity of Craspedacusta species and subspecies described in China, with modern molecular genetic approaches, is needed before any conclusive decisions can be made