Thethuthinnang was a doe who was a part of Efrafa but was rescued by the Watership Down rabbits. She ended up being the mate of Bigwig. Thethuthinnang is one doe out of the other ten or eleven does from Efrafa. When they returned to Watership Down, she became Bigwig's mate. In the television series she was replaced and renamed as Spartina, but still became Bigwig's mate. Her name means "movement of leaves" in Lapine.
Thethuthinnang appears in the miniseries, and is voiced by Rosie Day.
Thethuthinnang is more prominent in this version, and is Hyzenthlay and Nettle's best friend. She appears to be the second youngest doe behind Vilthuril, being rather small, at least compared to Clover, and rather trusting, as shown when Clover tried and failed to get the does moved out of the sun. She speaks to her, and tells her it was worth a try, but Nettle quickly silences her. She also has faint white marks around her eyes, to distinguish her from Hyzenthlay.Thethuthinnang is shown ready to be marked, along with Hyzenthlay and Nettle. Captain Holly, Blackberry, and Bluebell, who have been captured by Captain Orchis, also join them. Later on, while Hyzenthlay is speaking with Orchis, Thethuthinnang apparently sings down the tunnels, to comfort her. However, Hyzenthlay tells her not to do so anymore, as all it does is annoy the guards, and cause trouble for them.
Thethuthinnang, along with Hyzenthlay, Nettle, Vilthuril, Clover, and the other does, digs out to the surface where Bigwig is waiting for them. Kehaar was supposed to come and help them escape, but he doesn't, so they decide to make a break for it. However, they are intercepted by Captain Campion and Sainfoin, along with a group of guards. Hyzenthlay attempts to tackle Campion, but Sainfoin quickly pins her to the ground. The does are then taken back to the deep burrows.
Hyzenthlay's stay of execution ends, and when she is taken to the electrical tower to be executed, Thethuthinnang begins singing a song. The other does join in, and manage to overpower Captain Chervil's attempts to shut them up. He makes it back up to the tunnel, and declares that he will have all of them punished, but Bigwig sneaks up behind him, and kills him. All of them easily escape, as Hyzenthlay had given Nettle (who was a spy) false information about an escape attempt on the opposite side of the warren. However, General Woundwort, along with every Efrafan guard, catches up to them, and corners them. Kehaar finally arrives just as Woundwort is about to kill Bigwig, and knocks him to the ground. He then starts swooping through the Efrafan guards, causing enough confusion for the rabbits to escape.
The Efrafans manage to track down the rabbits to Watership Down, and begin digging through the filled in burrows. Thethuthinnang battles the Efrafan guards by pulling soil from the ceiling, and making it fall on them. Later on, when Captain Holly is killed by Efrafans, Thethuthinnang mourns him, along with everyone else trapped in the Honeycomb. Hazel, Fiver, and Blackavar go to Nuthanger Farm to release the dog, and lead him back to the Efrafans. The plan is a success, though Fiver is attacked by the cat, and left behind. The dog then assaults the Efrafans, and kills Orchis, before turning his attention to Woundwort. They both jump at each other, before their shadows fade away, leaving Woundwort's fate ambiguous.
Thethuthinnang survives, and continues to live on Watership Down, though it is unknown who becomes her mate, although it is implied it is Fiver.