Well I was checking the Slayer Guide and in the boxes, there was Sumona and what monsters she would give as Slayer tasks, I looked and I didn't see Spiritual Warriors, which I just got as my Slayer task. Here is proof if you need it.

 

http://www.tip.it/runescape/?page=slayer_guide.htm#Slayerassign

 

Pollnivneach (Sumona) Assignments

 

* Aberrant Spectres

* Abyssal Demons

* Aquanites

* Banshees

* Basilisks

* Black Demons

* Blue Dragons

* Bloodvelds

* Cave Crawlers

* Cave Horrors

* Dagannoths

* Dust Devils

* Elves

* Fire Giants

* Gargoyles

* Greater Demons

* Hellhounds

* Iron Dragons

* Kalphites

* Kurasks

* Nechryaels

* Red Dragons

* Scabarite minions

* Spiritual Mages

* Spiritual Warriors

* Terror Dogs

* Trolls

* Turoths

* Warped Tortoises

 

You must have missed it.

Thanks for your submission :D, however like JoeDaStudd already said, it is in the list.

For any questions feel free to pm me or any other crewbie :)