Anokkostenostomum tuberculosum ( Nuttycombe & Waters, 1938 ) Noreña & Damborenea & Brusa, 2005

Noreña, Carolina, Damborenea, Cristina & Brusa, Francisco, 2005, A taxonomic revision of South American species of the genus Stenostomum O. Schmidt (Platyhelminthes: Catenulida) based on morphological characters, Zoological Journal of the Linnean Society 144 (1), pp. 37-58 : 54

Anokkostenostomum tuberculosum ( Nuttycombe & Waters, 1938) comb. nov.

( Fig. 5D )

Stenostomum tuberculosum Nuttycombe & Waters, 1938

Description: Chains with two zooids 0.72 mm long. Neither solitary individuals nor longer chains were observed. Anterior end blunt. A small, apparently tactile, tubercle in the ventral cephalic end is characteristic of this species. Small, antero-dorsal ciliated pits. Constriction posterior to the ciliated pits. Intestinelacking region at the posterior end. Densely ciliated ventral epithelium (long cilia). The cilia on the dorsal epithelium are inconspicuous. Semi-rigid sensory cilia irregularly arranged along body. Slender rhabdites. Live specimens yellowish-white, darker at the pharyngeal region because of the presence of glands and musculature. Anterior brain lobes divided into small independent masses (‘metameric’). No light-refracting bodies.

Oral pore V-shaped. Short muscular pharynx associated with elongated unicellular glands (type b), which open onto the whole length of the pharynx. Pharynx with refractory corpuscles. Anterior end of the intestine overlying the posterior part of the pharynx. Intestinal wall dentate. No excretophores. Nephridiopore terminal.

Distribution: Virginia and Georgia, USA ( Nuttycombe & Waters, 1938; Kolasa, 1991); São Paulo and interior of São Paulo State ( Marcus, 1945b), Brazil; margins of the Suriname River near Paramaribo, Surinam ( Van Der Land, 1970); Poznan, Poland ( Kolasa, 1973); Germany, Finland ( Lanfranchi & Papi, 1978); Los Talas, Berisso, Buenos Aires, Argentina, January and April 1999. This species has not been previously recorded in Argentina.

Discussion: Unlike the material found in Argentina, Marcus (1945b) describes chains of up to four zooids (1 mm) for Brazilian specimens. The South American specimens show refractory corpuscles in the pharynx. This feature was not mentioned by Nuttycombe & Waters (1938).

Figures

Figure 5. A, Anokkostenostomum pegephilum. B, A. pseudoacetabulum. C, A. saliens. D, A. tuberculosum. E, A. ventronephrium. Scale bars = 100 Mm.