两个新的桃花水母形态度量学参数的建立及其在种类区分上的应用

ESTABLISHMENT OF TWO NEW MORPHOMETRICAL PARAMETERS OF CRASPEDACUSTA (LIMNOMEDUSAE: OLINDIDAE) WITH THEIR APPLICATION IN THE SPECIES VALIDATION

桃花水母属一些种类命名的有效性仍存在争议,本文建立了两个新的形态度量学参数,即触手密集度和平衡囊密集度,采用形态度量学方法对在我国采集到的索氏桃花水母、嘉定桃花水母、中华桃花水母和短手桃花水母进行了比较研究,并讨论这两个参数在种类区分上的应用。此外,利用Spearman秩相关系数检验桃花水母各形态学参数之间的相关性。结果表明,短手桃花水母和中华桃花水母在形态上没有明显的差异,可能与中华桃花水母为同一物种。嘉定桃花水母与中华桃花水母和索氏桃花水母在形态上均存在显著的差异,应该是一个有效种。桃花水母的触手数和平衡囊数均与伞径显著正相关,除嘉定桃花水母外,其他三种桃花水母的平衡囊密集度都与触手密集度显著正相关。

There 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, 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 modem molecular genetic approaches, is needed before any conclusive decisions can be made.