Stenostomum rosulatum Marcus, 1945

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

Stenostomum rosulatum Marcus, 1945

( Fig. 3B )

Description: Simple individuals 0.5–0.9 mm long. Two-zooid chains 1.2 mm long. Anterior end blunt. Small lateral ciliated pits. Body broader at mouth level. Body constriction between pharynx and intestine. Intestine-lacking region at posterior end. Body covered with cilia. Presence of semi-rigid sensory cilia, more abundant at both body ends. Rhabdites parallel to the axial axis. Colourless in life.

Anterior brain lobes deeply dentate, internal brain lobes associated with posterior lobes ( Marcus, 1945a); posterior lobes slender. One pair of light-refracting bodies with a single refractory element (type 2), associated with the posterior brain lobes.

Oral pore circular. Long sacciform pharynx with internal cilia and strong pharyngeal muscles. Clubshaped glands (type b) open between mouth and pharynx. Well-developed circular musculature can be observed in the posterior pharyngeal region. With muscles extending from pharynx to body wall. First region of the intestine with high, vacuolated cells, with contractile activity independent from the rest of the intestine, and separated from the posterior intestinal region by a marked constriction ( Marcus, 1945a). The rest of the intestine is homogeneous with irregularly arranged excretophores. The protonephridium becomes sinuous at the posterior end. Nephridiopore terminal.

Distribution: Tieté River, São Paulo, Brazil ( Marcus, 1945a).

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.