CTENELLA-AURANTIA, NEW GENUS AND NEW SPEC IES OF MEDITERRANEAN TENTACLED CTENOPHORE (CTENELLIDAE FAM NOV) WITHOUT COLLOBLASTS, BUT WITH LABIAL SUCKERS

Ctenella aurantia gen. et sp.nov. is a small Mediterranean tentacled c tenophore. its ovoid and flattened body is opaque and yellow-orange, w ith red-pigmented areas. Comb rows are arranged in pairs from the apex to the oral third of the body. The tentacular sheaths situated at the end of the oral third of the body open medially; they terminate in an aboral open groove which can close up around the unramified tentacles . The gastrovascular system is simple and follows the axis of the body ; it has no peripheral canals but two long apical canals project into the aboral zone. The mouth forms a sagittal slit bordered by two thick lips, each bearing a sucker on its internal wall. The species also po ssesses very distinctive cytological features, notably the absence of colloblasts on the tentacles and the consistent presence of exogenic c nidocysts that are embedded in the gastrovascular wall. The muscular c ells of the oral zone have no sarcomeres, but have both fine and thick myofilaments that are arranged alternately. The species is very disti nctive, both in its cytological characteristics and its general organi zation. It is tentatively classified in the order Cydippida, and its r elationship to some other species is mentioned.