Convoluta henseni Bohmig, 1895

(Fig. 7)

Material. Living specimens in squeeze preparation; whole mount for fluorescence imaging of musculature.

Locality. São Sebastião Channel, São Paulo, Brazil, from plankton (23°50’S, 45°24’W).

Description. Mature specimen ~ 600 m in length and ~ 300 m wide (Fig. 7 A). Anterior and posterior ends rounded. Lateral edges inrolled. Epidermis completely ciliated. Body with conspicuous green zoochlorellae endosymbionts, and a few scattered rhabdoids with red coloration. Mouth opening on ventral surface, middle of body.

Ovaries paired, ventral. Testes paired, lateral to ovaries. Separate male and female gonopores, female anterior to male. Female gonopore opens to vagina leading to bursa; bursa with nozzle ~ 20 m in length (Fig. 7 B). Male gonopore leads to short, muscular, glandular penis (Fig. 7 B). Penis invaginated into seminal vesicle filled with sperm that surrounds penis (Fig. 7 B).

Remarks. Convoluta henseni occurs in large numbers in São Sebastião channel when there is a current from the South. It is often collected simultaneously with another planktonic acoel, Adenopea cenata (Marcus, 1955) .