Urotricha cyrtonucleata Martin & Montagnes 1993

Body ovoid, anterior end slightly truncated, 45 (35-55) µm long and 32 (25-45) µm wide. Oral cavity with cytopharyngeal fibres (basket, CB), 25% of body length (Fig 1,5,6); circumoral ciliature oblique (Fig 1, OD); the brosse consists of 3 adoral rows of dikinetids (AO), AO1 consists of 2 rows of 5-6 kinetosomes, AO2 and AO3 consist of 2 rows of 8-9 kinetosomes (Fig 1,7); however, this character is difficult to observe and is not visible in Lugol?s fixed material. 46-52 somatic kineties of 35-40 monokinetids, 3 of the kineties end prior to the brosse; last 20% of the body unciliated except for 3 caudal cilia (Fig 1). One elongate macronucleus, positioned around the oral cavity (Fig 1,5,6).

Urotricha cyrtonucleata has not been described from UK waters yet. However, we find large Urotricha species that match these general characteristic features and one of them may be U. cyrtonucleata. As observation of the brosse is required to identify these ciliate species, and this structure cannot be seen in Lugol?s fixed material, we recommend that Urotricha is identified only to the genus level from Lugol?s fixed samples.

Nanoflagellates

Cell ovoid, anterior slightly truncated, most of the cell with short (3-4 µm long) cilia, posterior 20% of the cell unciliated except for 3 caudal cilia; oral cavity centric, with funnel-shaped cytopharyngeal fibres (basket); one elongate macronucleus, positioned around the cytopharynx

Temperature: 10 ºC Salinity: 22-25 ?

Fast swimming