A New Cheiracanthid Acanthodian Species from the Aruküla Regional Stage (Middle Devonian, Givetian) of the Eastern Main Devonian Field

A new cheiracanthid acanthodian species, Cheiracanthus flabellicostatus sp. nov., is described based on scales found in the beds of the Aruküla Regional Stage of Siverskiy and Zaitsevo localities of the Leningrad Region. It is distinguished from other members of the genus in the presence of a V-shaped eminence in the medial part of the scale crown and 8–10 large ribs branching into smaller ribs in the anterior part of the crown; large lacunas are observed at crossings of circular and ascending canals in the middle part of the scale neck.