A new species, Aphanomyces salsuginosus sp. nov., isolated from ice fish Salangichthys microdon
2010
Takuma, Daisuke | Sano, Ayako | Wada, Shinpei | Kurata, Osamu | Hatai, Kishio
A species of Aphanomyces was isolated from the ice fish Salangichithys microdon living in brackish water in Japan. White cotton-like growth was found on the heads and fins of the fish. Hyphae penetrated into the dermal layers, subcutaneous tissues, muscular layers, and cartilaginous tissue of the mandible and maxilla; these hyphae were associated with cellular debris and lesions in host tissue. White fluffy colonies from subcultures of these growths were isolated on glucose-yeast agar plates with 0.5% sodium chloride (NaCl). These isolates consisted of delicate, slightly wavy, and moderately branched hyphae. Zoosporangia were isodiametric with the vegetative hyphae. Oogonia were abundant and approximately 21-33 μm in diameter, with irregular short papillae. Generally they were spherical or subspherical and only rarely pyriform. Individual oogonia usually contained a single oospore, which was spherical and 19-27 μm in diameter, with a large shiny vesicle. Antheridial branches, when present, were usually androgynous; however, they were sometimes monoclinous or diclinous. The optimal growth temperature of the isolates was 20°C, and cultures grew well at low salinity (0-0.5% NaCl). Phylogenic analysis based on the internal transcribed space 1-5.8S-ITS 2 of the ribosomal RNA gene indicates that these isolates will be an as-yet unidentified species of Aphanomyces.
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