In September 2021,the goldfish (C.auratus) cultured at two adjacent ornamental fish farms in Tongzhou District of Beijing suffered from sporidiosis,and displayed dorsolateral humps or swollen abdomen,which lost their ornamental value and caused a small number of deaths.In order to identify the specie of parasite and enrich its epidemiological data,the lesion tissues from dorsolateral humps and hepatopancreas of diseased fish were collected.Morphological observation and spores measurement were carried out.18S rDNA gene of the parasites was then cloned,sequenced and analyzed.The results showed that the morphological characteristics of the spore was pyriform in shape,and two polar capsules arranged in an octagonal shape at the front which accounts for about half of the entire length of the spore.The measured data of the spores were 17.58 μm and 18.09 μm in average length,11.02 μm and 11.82 μm in average width,and there were 7-9 loops of polar filaments,which were similar to those of M.wulii. The partial sequences of 18S rDNA gene of the parasites had the highest homology with M.wulii based on blast from GenBank,and the similarity was more than 99%.In addition,in the constructed phylogenetic tree by 18S DNA gene,the isolated spore was also clustered with the M.wulii.Therefore,it was confirmed that the parasites caused goldfish sporidiosis in these two cases were both M.wulii,and this was the first report that M.wulii parasitized in goldfish muscle.

The nacre color is the main factor that determines the color of the cultivated pearls.The nacre color trait has become an important target trait of the genetic improvement of the pearl oyster,but the measurement of the nacre color is difficult,which seriously limits the efficiency of pearl mussel breeding.Using 1-year-old red,blue,golden and white strains of juvenile H.cumingii as experimental materials,the color parameters L,a and b values were obtained by the X-Rite ColorEye XTH spectrophotometer,while correlation analysis,principal components analysis,and regression analysis were performed on each color parameter to explore the correlation between nacre color and shell color.The results showed that the nacre color and the shell color of the four H.cumingii strains were significantly correlated,and the correlation between the nacre color and the shell color of the red and blue strains was relatively stronger.The L,a and b values of nacre color in red and blue strains were all significantly correlated with at least one color parameter in shell color.Among them,the a value of nacre color in red strains had the strongest correlation with the b value of shell color,with the correlation coefficient as -0.557 (P<0.01).The L value correlation between the nacre color and the shell color was the strongest in the blue strain,and the correlation coefficient was 0.533 (P<0.01).The L value of the shell color in the golden strain was significantly correlated with the a and b values of the nacre color (P<0.05),and the correlation coefficients were 0.331 and 0.335,respectively.In the white strain,only the a value had a very significant correlation between the nacre color and the shell color (P<0.01),and the correlation coefficient was 0.286.This study reveals that the nacre color is correlated with the shell color in these four H.cumingii strains of juvenile mussels,which is of great significance for guiding the early selection of nacre color of H.cumingii.