part of part_of end organ ligula The portion of the sucker-free end-organ of the hectocotylus of many incirrate octopods that is generally elongate and longitudinally grooved. The ligula in octopodids is often spatulate in shape with transverse ridges. Spermatophores transferred along the sperm groove of the hectocotylus presumably enter the ligula which assists in their transfer to the female. Details of the use of the ligula are unknown. surface structure reproductive structure male anatomical structure