The objective of this work was to accomplish the micromorphological characterization of the causal agent of the algal spot in ‘Amrapali’ mango trees. Therefore, ‘Amrapali’ mango leaves exhibiting symptoms of algal spots were used for making microscope slides, on which the pathogen somatic and reproductive structures were measured. The dimensions obtained for sporangiophores and sporangia were 245.5-545.6 × 10.5-19.1 μm and 21.4-34.2 × 16.3-24.7 μm, respectively. Descriptions based on symptoms and micromorphology indicated that the algae are Cephaleuros virescens, since this morphological data corroborates with literature descriptions. Besides, the algae had already identified by DNA sequencing as C. virescens.