Studies Of Species Diversity Of Protozoa In West Lake,Hangzhou And Morphology Of A New Peritrich Genus/Species

A preliminary study on the diversity of the Protozoa community as well as the water quality of the West Lake in Hangzhou has been investigated. An overall evaluation on the water quality has been maken according to the general index of the Protozoa community and the physical and chemical parameters of the water—temperature, pH, dissolved oxygen (DO), biochemical oxyfen demand (BOD5), chemical oxygen demand (CODCr), total phosphorus (TP) and total nitrogen (TN) though the investigation of six sampling sites from September,2006to February,2007.According to the physical and chemical parameters, the water temperature varies obviously form7.0℃to25.8℃, while pH appears between7.33and9.18, the water is alkalescent, and it presents a high DO (3.92～12.31mg/L), low BOD5(0.77～5.38mg/L) and CODCr (4.51～32.0mg/L), a little high TP (0.017～0.283mg/L)and very high TN(1.00～5.88mg/L).81species of algae and60species of protozoa have been found during the investigation, including3species of flagellate,10species of sacrodinas and47species of ciliates. The individual abundance of algae and protozoa is very high (up to94560000ind/L in sampling site3in middle of October). The diversity index was0.315～4.973in six sampling sites during6months. The dominant species were Oscillatoria amphibia、Euglena viridis and Strbilidium gyrans which often appear in the high nutrition water. According to the above data, this water area should belong to the high nutrition type and should be recognitioned.A new colonial sessilid peritrich genus, Pseudepistylis, is established. Pseudepistylis n. gen. belongs to the family Epistylididae,(i.e. colonial with a non-contractile stalk and peristomial disc not borne on a stalk) but has oral ciliature that makes less than two turns on the peristome before entering the infundibulum and a reticulate silverline system. Morphology, infraciliature and silverline system of the type species Pseudepistylis songi n. sp., isolated from a freshwater pond near Wenzhou, China, have been investigated both in vivo and following silver impregnation. The new species is characterized by small colony size of only one to eight zooids borne upon a slender, dichotomously branched stalk. Zooids are bell-shaped, in vivo approximately220×140μm, with wide peristomial lip that are invariably reflected aborally, single contractile vacuole at the dorsal wall of the infundibulum, and C-shaped macronucleus. The pellicle of contracted zooids shows several large, characteristic folds. The silverline system is reticulate with at least137silverlines between the peristomial area and the aboral ciliary wreath and approximately77between the aboral ciliary wreath and the scopula. The haplokinety and polykinety complete approximately one and one-quarter turns of the peristome before entering the infundibulum. Within the infundibulum the kineties of infundibular polykinety2(P2) terminate at different levels between P1and P3. The myoneme system is also described.