Stenostomum uronephrium Nuttycombe, 1931

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 : 49-50

Stenostomum uronephrium Nuttycombe, 1931

( Fig. 3E )

Description: Individuals of 1–4 zooids. Two-zooid chains 0.8–0.9 mm long, up to 1.8 mm in the Brazilian forms. Body cylindrical, ventrally flattened, gradually tapering. Anterior end blunt. Small, rounded, antero-lateral ciliated pits. Posterior end with a long intestine-lacking tail (1/3–1/2 of the total body length). Long, semi-rigid cilia concentrated at both ends of the body. Vacuolar epidermal cells, with rhabdites. Colour in life whitish. Some of the studied individuals with anastomosed pigment accumulations.

Anterior brain lobes smooth. A pair of lightrefracting bodies at mouth level, with few spheres in a vesicle (type 2), associated with the posterior brain lobes.

Subapical oral pore, generally with circular outline. Tubular pharynx, with small glands (type a) uniformly distributed on the pharynx. Sphincter between the pharynx and intestine. Presence of excretophores. The protonephridium becomes sinuous at the caudal end. Nephridiopore terminal.

Distribution: Georgia, USA ( Nuttycombe, 1931; Kolasa, 1991); São Paulo and São Paulo State, Brazil ( Marcus, 1945b); Poland ( Kolasa, 1977); Finland, Russia, Germany ( Lanfranchi & Papi, 1978); Paraná River, Argentina ( Noreña-Janssen, 1995); Los Talas, Berisso, Buenos Aires, Argentina, April 1999, January and February 2000.

Discussion: In contrast to the observations for South American specimens, Nuttycombe (1931) does not mention the presence of a sphincter between the pharynx and the intestine.

Figures

Figure 3. A, Stenostomum paraguayense. B, S. rosulatum. C, S. simplex. D, S. tenuicauda. E, S. uronephrium. F, S. virginianum. Scale bars = 200 Mm.