Stenostomum cryptops Nuttycombe & Waters, 1935

Stenostomum cryptops Nuttycombe & Waters, 1935 View in CoL

( Fig. 1E View Figure 1 )

Description: Isolated specimens, 0.4–0.5 mm long. Chains of up to six zooids ( 3 mm long). Anterior end blunt. Body constriction behind the ciliated pits. Tapering posterior end. Large, deep dorso-lateral ciliated pits. Uniformly ciliated epithelium. Scarce semirigid sensory cilia. Rhabdites uniformly distributed. Colour in life white.

Brain large and elongated. Anterior brain lobes divided into small independent masses (‘metamerics’). A pair of light-refracting bodies formed of small spheres included in a vesicle ( type 2) associated with the anterior brain lobes.

U-shaped oral pore. Short muscular pharynx. Small pharyngeal glands ( type a) in the anterior region, elongated glands ( type b) in the posterior region. Welldeveloped pharyngeal sphincter. An intestinal caecum with granulose epithelium, dorsal to the pharynx. High intestinal epithelium. Excretophores laterally placed. Nephridiopore terminal or subterminal.

Distribution: Georgia, USA ( Nuttycombe & Waters, 1935; Kolasa, 1991); São Paulo, Brazil ( Marcus, 1945b).

Discussion: At variance with the single pair of lightrefracting bodies described by Marcus (1945b), Nuttycombe & Waters (1935, 1938) describe a second pair, associated with the posterior lobes and larger than the first pair.