ИСТИНА

Two new species of Cossura were found in material collected during deep-water sampling in frame of CONGOLOBE project. These species were described using light and scanning electron microscopy. Cossura sp. A has 15-17 thoracic chaetigers; prostomium longer than wide, with widely rounded anterior margin, posterior prostomial ring rapidly expands, the same length as peristomium, without mid-ventral notch; branchial filament attached to midlength of chaetiger 3; pygidium divided by vertical cleft, with three cirri. Cossura sp.A is similar to C.brunnea Fauchald, 1972 by attachment of branchial filament, number of thoracic chaetigers, shape and location of chaetae, and differs by the shape of prostomium which is widely rounded anteriorly in Cossura sp.A and broadly triangular in C.brunnea; furthermore Cossura sp. A is uniformly pale whereas C.brunnea has dark pigmentation. C.keablei Zhadan, 2015 differs by having the midventral notch in posterior prostomial ring and by having more (22-26) thoracic chaetigers. The whole body of Cossura sp. B including chaetae is covered by thick mucous sheath similar to tunic of flabelligerids. Cossura sp.B has 16-19 thoracal chaetigers; prostomium conical, branchial filament arising from posterior part of chaetiger 2. Cossura sp. B resembles C.longocirrata Webster & Benedict, 1887 by the position of branchial filament, shape of prostomium, number of thoracic chaetigers, shape and distribution of chaetae; it differs by having thick mucous sheath. This charachter seems to be unique for Cossuridae.