Anokkostenostomum pseudoacetabulum ( Nuttycombe & Waters, 1935 ) 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 : 52

Anokkostenostomum pseudoacetabulum ( Nuttycombe & Waters, 1935) comb. nov.

( Fig. 5B )

Stenostomum stuhlmanni Böhmig, 1897

S. pseudoacetabulum Nuttycombe & Waters, 1935

Description: Adult individuals 0.75–2.5 mm long. Two- to eight-zooid chains. Anterior region elongated. Reduced lateral ciliated pits. Body cylindrical, with a constriction before the mouth and sometimes another constriction at the level of the pharyngeal sphincter. Body tapering caudally. Intestine-lacking region at the posterior end that becomes thinner, forming a typical dorsal appendage. The ciliated epidermis forms a regular cover, except at the posterior end where cilia are scarce. Longer sensory cilia in the posterior region. Epidermis with regular vacuoles and short rhabdites. Colour in life yellowish-white.

The anterior brain lobes differentiate into small independent masses (‘metameric’). No light-refracting bodies.

Oral pore and pharynx resemble a trematode acetabulum, appearing as a body projection in lateral view. The pharynx is posteriorly expanded and forms a cup onto the apical end of the intestine. The mouth and first third of the pharynx can be invaginated, proboscis-like. The pharyngeal glands are uniform (type a) in the whole pharynx. A sphincter between pharynx and intestine. No excretophores. Nephridiopore at the base of the caudal appendage.

Distribution: Georgia, USA ( Nuttycombe & Waters, 1935, 1938; Kolasa, 1991); São Paulo and Paraná State, Brazil ( Marcus, 1945b); near Paramaribo, Surinam ( Van Der Land, 1970); Konin Lakes, Poland ( Kolasa, 1977); Germany ( Lanfranchi & Papi, 1978); Los Talas, Berisso, Buenos Aires, Argentina, February 1999 and February 2000. This species has not been previously recorded in Argentina.

Figures

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