Taxonomic note on a rare fish infecting freshwater mould Achlya ambisexualis Raper 1939 (Achlyaceae) isolated from Chandraprabha dam, Uttar Pradesh, India

Abstract

Achlya spp. are oomycetous water moulds, responsible for freshwater fish diseases causing great economic losses. An Achlya sp. implicated in significant fungal infections of both live and dead fish as well as their eggs, has been isolated from the water and soil samples collected from Chandraprabha dam (Chandauli District, Uttar Pradesh, India) employing standard baiting method. Based on morphological characterisation, the strain was identified as Achlya ambisexualis Raper 1939 (Saprolegniales, Oomycetes). It is a dioecious species, characterised by the presence of an achlyoid type of spore dehiscence from both primary and secondary sporangia, differentiated by its oospheres predominantly maturing into eccentric oospores, generally 1-18 per oogonium and gemmae cylindrical in both antheridial and oogonial mycelia. In India, this species was recorded from a single collection in the past but lack proper description and illustrations. The present study describes and illustrates this species for the first time in India and hoped to be beneficial for ichthyopathologists and researchers as A. ambisexualis is known as a necrotroph or parasite of fishes and their eggs.