Odonaticola pyriforma n. sp. (Apicomplexa: Eugregarinida: Actinocephalidae), parasitic in the alimentary canal of Brachythemis contaminata Fabricius, 1793 (Insecta, Odonata) from West Bengal, India

In the present study, a new species of septate gregarine, inhabiting Brachythemis contaminata Fabricius, 1793, a common dragonfly species in West Bengal, India, was identified and characterised. Mature trophozoites are solitary and pyriform. The epimerite complex extends up to 112 µm in length and includes a terminal, hat-shaped epimerite proper with 8–12 distinct, very deeply ovoid to narrowly ovoid petals without pointed apices and an oblong diamerite. Gamonts are isogamontic and also pyriform (~230 x 167 µm), with a broadly obpanduriform protomerite and a pyriform deutomerite. Gametocysts are more or less orbicular (~345 µm). Under SEM, both trophozoites and gamonts are found to be covered by longitudinal, undulating epicytic folds, except epimerite proper. An orbicular, retracted area with a central, roughly orbicular region devoid of epicytic folds is present at the anterior end of the gamont, measuring 24.7–40.6 µm in diameter. Tetrahedral configuration of the oocysts is prominent, characterised by a smooth surface and terminal projections with an apical, sucker-like structure. The above characteristics align this septate gregarine with the genus Odonaticola. The distinctive morphological traits, including pyriform trophozoites and gamonts and an epimerite proper with 8–12 distinct, ovoid petals without pointed apices, support its erection as a new species, Odonaticola pyriforma n. sp.