Occurrence and characterization of Trichomitus batrachorum (Protista, Trichomonadidae) from Rhinella marina (Amphibia, Bufonidae) in the Philippines

Trichomonad isolation from amphibians is new in the Philippines as trichomonad studies in the country are few, limited only to mammals, reptiles and birds. Moreover, there are very few studies on amphibian-associated trichomonad ultrastructure and morphology. Trichomitus batrachorum (Ts. batrachorum) was isolated from Rhinella marina fecal samples and identified using SEM and TEM for ultrastructural study and 18S rRNA gene sequencing. A 37.5% prevalence of Ts. batrachorum from R. marina was observed based on in vitro culture and molecular analysis. Characteristics of this coprozoic trichomonad that provided distinctive features for classification included body size and shape, three anterior flagella and a recurrent flagellum, lamelliform undulating membrane, type A costa periodicity, V-shaped parabasal body, well-developed pelta, shape and location of organelles such as the nucleus, blepharoplast, axostyle, comb-like organelle, hydrogenosomes and the observation of a pseudocyst stage. DNA sequence analysis corroborated these results, and generated phylogenetic trees with high bootstrap support further proved the identity of the isolate. The few identified trichomonads in the Philippines exhibit the capability for adaptation to new hosts and it is possible they have zoonotic potential. These findings contribute to the existing trichomonad data sets in the country. This is the first ultrastructural study of Ts. batrachorum species isolated from a toad.