Metromonas grandis Larsen and Patterson 1990

Lee, Won Je, 2015, Small Free-Living Heterotrophic Flagellates from Marine Sediments of Gippsland Basin, South-Eastern Australia, Acta Protozoologica 54 (1), pp. 53-76 : 67-68

Metromonas grandis Larsen and Patterson 1990 ( Fig. 4i )

Observation: Cells are leaf shaped, 5 to 11 µm long and dorso-ventrally flattened. One side of the cell appears folded. The cells have two flagella of unequal length. The long flagellum is 1.5 to 2.5 times the cell length and trails behind the cell when gliding. The shorter flagellum is inactive, less than 2 µm long, and inserts to the right of the major flagellum and is always present. The nucleus lies near the flagellar insertion. The cells attach to the substratum with the longer flagellum and move with a nodding action – like a pendulum. Relatively common.

Remarks: This species was reported from marine sites in Australia, Brazil, Fiji, Hawaii and Turkey (Aegean Sea), and cell length reported was 5 to 12 µm ( Larsen and Patterson 1990; Tong et al. 1998; Lee and Patterson 2000; Al-Qassab et al. 2002; Lee 2002b, 2006b; Aydin and Lee 2012). Generally, the current observations are in agreement with those of Larsen and Patterson (1990) and Lee and Patterson (2000; p. 552, Fig. 26f). Metromonas grandis is distinguished from M. simplex by its cell shape, slightly larger size and folded margin. The cell shape and folded margin may be good diagnostic characters for this species. This species usually co-occurs with M. simplex . According to Lee (2002b), Skvortzov (1957) reported 9 new Ancyromonas species with one long flagellum, but these species may be gliding stages of Metromonas . The short flagellum in Metromonas is easy to overlook.

Figures

Fig. 4. a – Carpediemonas membranifera; b – Kipferlia bialata; c – Discocelis saleuta, note a short flagellum; d – Metopion fluens, showing general appearance of cell, note shorter flagellum (arrow); e–f – Kurnaimonas celeris nov. spec., showing general appearance of cell; g – Pseudophyllomitus granulatus; h – Helkesimastix faecicola, showing general appearance and note short flagellum (arrow); i – Metromonas grandis, showing general appearance of cell and note the folded margin on the left side and short flagellum (arrow); j – Metromonas simplex, showing general appearance of cell and note short flagellum (arrow); k – Kiitoksia kaloista, showing two flagella and note short flagellum (arrow); l – Sinistermonas sinistrorsus nov. spec., showing general appearance of cell, and note flagellar insertion and beating pattern of anterior flagellum; m – Telonema subtilis, showing general appearance; n – Protist ‘1’. All micrographs are DIC images. Scale bar: 5 µm for all figures.