Morphological, histological, and molecular aspects of Myxobolus zaikae n. sp., a parasite of the roach Rutilus rutilus, in Lake Baikal

Abstract

A new myxobolid species, Myxobolus zaikae n. sp., was found in the connective tissue near the kidney and liver blood vessels of the common roach Rutilus rutilus, while fish myxosporean fauna were being investigated in Lake Baikal, Russia. The parasites were studied on the basis of spore morphology as well as with histological and molecular methods. Mature spores of M. zaikae n. sp. are round or ellipsoidal in the frontal view and lemon-shaped in the lateral view, measuring 11.37 ± 0.11 µm (10.2-14.0 µm) in length, 10.29 ± 0.10 µm (9.6-11.0 µm) in width, and 6.3 ± 0.08 µm (5.8-7.1 µm) in thickness (mean ± SD; n = 50). Polar capsules are equal and pyriform, measuring 4.5 ± 0.07 µm (3.4-5.2 µm) in length and 2.9 ± 0.03 µm (2.6-3.3 µm) in width. Polar capsules contained polar filaments coiled with 5 to 6 turns. Phylogenetic analysis showed that this newly described species clusters with other myxobolid species infecting the connective tissue of different organs from Palearctic cyprinid fish.