ULTRASTRUCTURE OF AN ANTENNAL SENSE ORGAN OF A CAVE-DWELLING TERRESTRIAL ISOPOD, TITANETHES ALBA

The triangular scales of the antennae of Titanethes alba (Koch) contain seven sensory cells. One unit is mechanosensitive and ends at the base of the seta; the remaining six units are probably chemoreceptive and extend up to the tip of the seta that displays a pore. The mechanosensitive unit differs from the other six but does not display characteristic features of usual crustacean mechanosensitive cells. It displays a tubular body at its distal end and a ribbon-like ciliary root. Some hypotheses are proposed to explain these unusual observations.