Family Siphonosomatidae

1. Rectum with multiple rectal caecae or diverticulae ........................................................................... ......................................................... Siphonosoma cf. vastum (Selenka & Bülow in Selenka, 1883)

– Rectum without multiple rectal caecae or diverticulae and dorsal retractor muscles originate anterior to ventral pair ................................................. Siphonosoma cumanense (Keferstein, 1867)