Deep Troglomorphy: New Arrhopalitidae (Collembola: Symphypleona) of Different Life Forms from the Snezhnaya Cave System in the Caucasus

Abstract

The Snezhnaya (=Snow) Cave System (depth −1760 m; total length 40.8 km), located in the West Caucasus, is inhabited by distinctly troglomorphic collembolan species from several families. Two new species of the family Arrhopalitidae occur in the deep parts of the system. Both are highly morphologically specialized; however, they evolved into different troglobiont life forms. Arrhopalites profundus sp. nov. with extremely long claws, lamellate mucro, and an enlarged sensory organ of third antennal segment lives exclusively in hygropetric and epineustonic habitats, whereas Pygmarrhopalites rystsovi sp. nov., with greatly elongated and multi-subsegmentated antennae and long legs, prefers open terrestrial spaces. The troglomorphy, as well as ecological life forms of the obligate cave-dwelling Arrhopalitidae, in general, are discussed and classified as neustonic-hygropetric, atmobiont, intrasubstrate, and intermediate troglomorphs.