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Endotransformations and aberrations of the life cycle in the evolutionary history of trypanosomatids (Kinetoplastea: Trypanosomatidae) are analyzed. We treat the term «endotransformations» as evolutionarily fixed changes of phases and/or developmental stages of parasites. By contrast, we treat aberrations as evolutionary unstable, periodically arising deformations of developmental phases of trypanosomatids, never leading to life cycle changes. Various examples of life cycle endotransformations and aberrations in representatives of the family Trypanosomatidae are discussed.

The development of generative elements of Schistosoma mansoni mother sporocysts (MS) was examined by histological methods. About 20 large cells, on average, determined as germinal cells (GC) were found in the miracidium. These cells formed a C-shape cellular aggregation (a band) beginning in the caudal part of the larva, and reaching the nerve ganglion in the anterior part. At the level of the 3d tier of epithelial plates of the miracidium, this band shifted to the external body wall, bypassing the zone of excretory channels. Apparently, this shift resulted in the subdivision of a single pool of GC into two structurally associated groups. A group of several undifferentiated cells (UC) was also revealed in the caudal part of the body. After the metamorphosis of the miracidium into sporocysts, GC had increased in size and on the 3d day started to divide, forming first embryos of daughter sporocysts. During the same time, germinal masses were being formed in the subtegumental area of the MS body. Since this time point, proliferation of UC occured only in germinal masses. A part of UC also differentiated there into GC. These cells formed sporocystoid embryos, developing as far as the germinal ball, and then came out into the sporocyst schizocoel (approximately in 10 days p. i.). Thus, in S. mansoni, the formation of generative elements into MS occurs in two stages. Primary GC are formed during the development of the miracidium into the egg, whereas secondary GC develop in germinal masses of the sporocyst.

The data on the black fly fauna of the tribe Simuliini (Diptera: Simuliidae) of the Sakha Republic (Yakutia) comprising available literature, collections of the Zoological Institute RAS, and new material collected in Yakutia were analyzed. Three new species were recorded in the fauna of the Sakha Republic: Archesimulium polare Rubzov, 1940, A. splendidum Rubzov, 1940, and A. tumulosum Rubzov, 1956. Distribution of eleven black fly species was clarified. Processing of the collected material confirmed the presence of 9 black fly species previously known from Yakutia. On the whole, the fauna of the region comprises 27 black fly species.

The article provides a list of 30 species of the family Tabanidae, recorded in Belgorod Province. Forest and forest-steppe species dominate (60%), being found at edges of oak forests, deciduous and mixed forests, and in mesophytic meadows. These species are distributed over the entire area of the region. The fraction of taiga-forest species in the region is small (10%). These species are found in western and northern areas where large forests and sphagnum bogs are present. The fraction of steppe species constitutes 13.3%, these species are found mainly in eastern and south-eastern parts of the Province, where areas of steppe and cretaceous outcrops are found. Desert species (6.7%) and a single Mediterranean coastal species were also recorded in the region. Mass emergence of horseflies in Belgorod Province begins in June and lasts until mid-August.

Samples of Zooplankton collected in waters of the Prostor Gulf (Iturup Island) were examined. Metacercariae of Brachyphallus crenatus were found in copepods Pseudocalanus newmani and Acartia longiremis. This is the first record of the second intermediate hosts of this species in the North Pacific.

Adult trematodes Paralecithodendrium chilostomum (Mehlis, 1831) were detected in the roundleaf bat Hipposideros sp. and in the African sharptooth catfish Clarias gariepinus from Tana Lake, Ethiopia. The catfish is an accidental host for P. chilostomum. This is the first record of P. chilostomum from Ethiopia. The description and figures of P. chilostomum from both host species, Hipposideros sp. and Clarias gariepinus are given.

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