Aphanomyces sinensis sp. nov., isolated from juvenile soft-shelled turtle, Pelodiscus sinensis, in Japan

Abstract

A species of Aphanomyces was isolated from juvenile soft-shelled turtles, Pelodiscus sinensis, cultured in Japan. Typically, an infected turtle showed small whitish maculae on the carapace. Many hyphae were observed in the epidermis. The hyphae were isolated using glucoseyeast (GY) agar plates. The morphological characteristics were very similar to those of Aphanomyces laevis, but a clear nuclear spot was observed in the center of the oospore in the strains isolated from the soft-shelled turtles. The optimal growth temperature for the isolates was 25-30°C and the optimum pH was 6-9. Experimental infection tests with isolates produced small whitish maculae on the carapace, and soft-shelled turtles artificially infected with the zoospores showed high mortality, especially in the highdose group. Phylogenetic analysis based on the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) indicated that the isolates from the soft-shelled turtles were unidentified species of Aphanomyces. As a result, the strain was described as a new species, Aphanomyces sinensis.

Fifty years of marine mycology

“…Various Fusarium spp. have been reported to cause disease of prawns (Khao et al 2005), tiger prawn (Khao et al 2004), infections of the eggs of loggerhead sea turtle (Sarmiento-Ramirez et al 2010), Aphanomyces sinensis infections of juvenile soft-shelled turtle (Takuma et al 2011) and various fungi causing skin infections of southern right whale (Reeb et al 2011). Algae susceptible to fungal infections include: the red algae Bangia, Palmaria, Polysiphonia and Porphyra (Pueschel and Vandermee 1985;Müller et al 1999;Sekimoto et al 2008a, b), and the brown algae Cystoseira, Halidrys, and Pylaiella (Alongi et al 1999;Gachon et al 2006;Harvey and Goff 2010).…”

The signal crayfish (Pacifastacus leniusculus) in Lake Tahoe (USA) hosts multiple Aphanomyces species

“…Recent studies contributing to knowledge of Aphanomyces diversity come from Japan (e.g., Takuma et al, 2010Takuma et al, , 2011Takuma et al, , 2013 and Europe (e.g., Ballesteros et al 2006;Diéguez-Uribeondo et al, 2009;Wolinska et al, 2009;Viljamaa-Dirks and Heinikainen, 2019), which apparently reflects the distribution of researchers rather than diversity of the genus. The closest known relative to A. astaci was detected in one individual signal crayfish in Central Europe during molecular screening for the pathogen in invasive North American crayfish populations in Czechia (Kozubíková et al, 2009;Diéguez-Uribeondo et al, 2009).…”

Skin Microbiota Was Altered in Crocodile Lizards (Shinisaurus crocodilurus) With Skin Ulcer

“…Aphanomyces belongs to the family Saprolegniaceae and class Oomycetes, and are the pathogens of epizootic ulcerative syndrome, mainly characterized by ulcer and granuloma (41)(42)(43)(44)(45)(46). They are listed as class II animal diseases in China and are harmful to fish, crustaceans, reptiles, and crops (41,(47)(48)(49). In reptiles, Aphanomyces has caused a mycosis outbreak in Chinese soft-shelled turtle in Japan in 2007-2009 (47).…”