Trunk up to 2.0 mm long (Pelagopleura australis). Mouth wide. Spiracles small and circular, at both sides of the rectum. Endostyle short. Stomach with postcardial caecum curved ventrally. Intestine wide, arising from the anterior part of the stomach. Rectum pear-shaped and dorso-ventral. Gonads valve-shaped, parallel to the genital wall. Tail with stellar amphichordal cells, arranged into 3 groups on one side and into 2 groups on the other, musculature broad.