Phytomonas vermiformis sp. n. (Kinetoplastea, Trypanosomatidae), a parasite of the shieldbug Peribalus strictus vernalis (Hemiptera, Pentatomidae)

A new species of dixenous trypanosomatids, Phytomonas vermiformis sp. n., was discovered in the gut and salivary glands of the vernal shieldbug Peribalus (P.) strictus vernalis (Wolff, 1804) in the Novgorod Region and in Krasnodar Krai of the Russian Federation. Phylogenetic analysis based on SSU rRNA gene revealed a high level of similarity between the European isolates of P. vermiformis sp. n. and the isolate G24 (TU76) from the bug Aeptus singularis Dallas, 1851 (Pentatomidae) in Ghana. In insect hosts, the cells of P. vermiformis sp. n. were represented by two morphotypes: promastigotes and endomastigotes. Both morphotypes were found in the gut, the dominant one being represented by worm-like promastigotes with long flagella. Very long promastigotes with the body twisted several times along its length were noted in the hemolymph. Some of them had long flagella, while others had no flagella at all. Promastigotes and small endomastigotes were detected in salivary glands. Endomastigotes of P. vermiformis sp. n. were also found in the homogenate obtained from inflorescences of nettle Urtica dioica L., on which the shieldbugs aggregated in autumn. In culture, the cells of P. vermiformis sp. n. were represented by promastigotes and endomastigotes. Large virus-like particles (VLP) of two morphotypes were found in the cytoplasm of P. vermiformis sp. n. This is the first report of these particles in trypanosomatids. VLP1 had a diameter of about 260 nm, possessed an icosahedral capsid and were localized in the central part of the cytoplasm. VLP2, spheroid particles about 210 nm in diameter, were mainly localized at the periphery of the cell in the submembrane zone.