Diversity, altitudinal distribution and assemblages of Orthoptera in North-Western Tuva (the Ak-Sug River Basin), Russia
The species diversity of Orthoptera, their altitudinal distribution patterns and the main types of theirs assemblages are described for the Ak-Sug River Basin (the north-western part of the Tyva Republic in South Siberia) for the first time. 30 species have been found, namely 2 species of Tettigoniidae, 2 of Tetrigidae, and 26 species of Acrididae. Tetrix tartara (I. Bolivar, 1887) has been found in Tuva for the first time (based on larvae determination). Schmidtiacris schmidti (Ikonnikov, 1913) has been found in North-Western Tuva for the first time too. In general, the orthopteran species diversity decreases upwards. However, some sharp transformations in altitudinal distribution of the species are revealed on the altitudes about 1400 and 1600 m a.s.l. At least several main clusters of the local orthopteran assemblages can be discriminated: (1) some assemblages of the dry openings at the upper part of the forest altitudinal belt; (2) of the wet habitats near the timber-line, with dominance of Chorthippus montanus (Charp.); (3) of the short-grass tundras on the high altitudes (above 2000 m a.s.l.); (4) of the meadow-steppe ecosystems of the middle altitudes; (5) of the lower flood-plains on the altitudes between 1400 and 1600 m a.s.l.; (6) of the dry steppes (including the semi-desert ones) in the lower part of the Ak-Sug River Basin; (7) of the flood-plains and the lower terraces with dominance of Chorthippus karelini (Uv.) and Ch. fallax (Zub.); (8) of the flood-plains and the lower terraces without Orthoptera during our studies.