Stenostomum glandulosum Kepner & Carter, 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 : 44

Stenostomum glandulosum Kepner & Carter, 1931

( Fig. 2A )

Description: Isolated specimens 0.6–0.8 mm long. Chains of up to 16 zooids which may reach 12 mm long. Anterior end very mobile and retractile. Large, superficial lateral ciliated pits. Presence of ciliated channels or grooves, dorsal or ventral, intimately connected to the brain ganglia. Rosette-shaped gland cells in the epidermis at the anterior end. Each rosette is formed by 2–4 refractive, toxic vesicles ( Kepner & Carter, 1931). Posterior end truncate. No rhabdites. Colour in life whitish.

Anterior lobes of the brain divided into small independent masses (‘metamerics’). One to three pairs of light-refracting bodies, formed by one or two spheres associated with the anterior brain lobes (type 2).

Oral pore very dilatable and surrounded by a layer of muscle. Long muscular pharynx. Numerous clubshaped glands (type b) open onto the pharynx and the oral pore. Intestine extended up to the caudal end. Intestinal epithelium folded, with excretophores. Nephridiopore terminal or subterminal.

Benthic species, either predatory ( Marcus, 1945b) or scavenger ( Kepner & Carter, 1931); mainly feeds on Stenostomum sp., rotifers, oligochaetes, etc.

Distribution: Virginia ( Kepner & Carter, 1931; Nuttycombe & Waters, 1938), North Carolina and Georgia ( Nuttycombe & Waters, 1938; Kolasa, 1991), USA; São Paulo, Brazil ( Marcus, 1945b); near Onverwacht, Surinam ( Van der Land, 1970); Poznan, Poland ( Kolasa, 1973); North of Europe, in laboratory aquaria ( Lanfranchi & Papi, 1978).

Discussion: Several features relevant for specific identification vary according to different authors. The absence of rhabdites was mentioned by Kepner & Carter (1931) and by Marcus (1945b). Nuttycombe & Waters (1938) mention the presence of relatively numerous fragile rhabdites in the anterior region and in lesser number in the rest of the body.

Kepner & Carter (1931) describe four pairs of lightrefracting bodies associated with the anterior brain lobes. Nuttycombe & Waters (1938) state that the number and position of the light-refracting bodies is variable and each one may be formed by two spheres. Marcus (1945b) found two or three pairs in the Brazilian specimens.

Figures

Figure 2. A, Stenostomum glandulosum. B, S. grande. C, S. hemisphericum. D, S. leucops. E, S. matarazzoi. Scale bars = 200 Mm.