1. Anterior part of body is very sharp-pointed.................................................... S. stenocephalus - Anterior part of body is not sharp-pointed................................................................. 2 2. Cephalic setae length more than or equal to head diameter.................................................... 3 - Cephalic setae length less than head diameter.............................................................. 4 3. Length of spicules along arc is equal to cloacal body diameter...................................... S. macramphis - Length of spicules along arc is more than cloacal body diameter..................................... S. longisetosa 4. Diameter of amphideal fovea is less than or equal to 75% corresponding body diameter............ S. parvamphis sp. n. - Diameter of amphideal fovea is more than 75% corresponding body diameter..................................... 5 5. c’ = 4.5.................................................................................... S. abyssalis - c’> 4.5....................................................................................... S. ornata