Macrophthalmus ( Macrophthalmus ) abbreviatus Manning & Holthuis, 1981, a new natural host for Hematodinium perezi infection

Recent reports have shown that wild crabs may be important hosts involved in the transmission and spread of the parasitic in cultured marine crustaceans. Therefore, monitoring the prevalence of infections in wild crabs is necessary to develop effective strategies for the prevention and control of disease. Here we report a wild crab species, ( ) Manning & Holthuis, 1981, as a new natural host for sp. infection. It is one of the common wild crab species dwelling in the ponds or waterways connected to the polyculture ponds located on the coast of Rizhao or Weifang, Shandong Peninsula, China. According to the results of PCR detection and phylogenetic analysis targeting the internal transcribed spacer 1 (ITS 1) region, these sp. isolates were identified as and fell into the genotype II category within . A high monthly prevalence of infection was observed during the 2021-2022 field survey, ranging from 33.3% to 90.6% in originating from Weifang (n=304 wild crabs) and from 53.6% to 92.9% in those from Rizhao (n=42 wild crabs). Artificial inoculation infection experiments demonstrated that could be infected by , and massive cells and typical histopathological changes were observed in the hepatopancreas and gill tissues of the infected crabs. To our knowledge, this is the first report of as a new natural host for infection. Results in the present study extend the known host spectrum for this emerging parasite pathogen, and also provide valuable information for epidemic surveillance of the disease as well.