Strombidium conicum

Swims slowly in spirals; may swim oral region down towards bottom of dish, moves rapidly forward -backward for 1-2 cell lengths, apparently searching for food

Aged and stressed forms of S. conicum (Fig 4) resemble Strombidium (Laboea) acuminatum as described by Leegaard (1915). S. conicum, S. chlorophilum and other undescribed but very similar species may form a species complex.

Mixotrophic, chloroplast-retention, pennate and centric diatoms, nanoflagellates

Temperature: 4-20 ºC; eurythermal Salinity: 15-29 ?; euryhaline

Body conical with rounded top: ice cream cone shape, widest near anterior third, 65 (40-110) µm long and 35 (25-60) µm wide (Fig 1,2,3,6); posterior part with faint longitudinal stripes (trichites; Fig 1,6,7); anterior collar; trichites rod-shaped (13-20 µm long), arranged in a funnel-shape and insert in hexagonally packed arrays anterior to the girdle (Fig. 1,6,7); ventral gap without trichites probably, where girdle kinety is interrupted. Shallow acentric oral cavity (Fig 1,6,7); APZ distinctly separated from VPZ (Fig 1a, 7); 30-37 ciliated kinetids as paroral kinety on the right side in the oral cavity; VPZ extends almost to the girdle into the oral cavity (Fig 7). Girdle kinety supraequatorial (in anterior third), completely surrounding the cell in a shallow furrow, 50-100 stubby cilia (Fig 1,6,7); ventral kinety clearly separate from girdle kinety, to the right of the oral cavity, with 10-40 ciliated kinetids (Fig 1a).

Cell conical with rounded top (ice cream cone shape), posterior part with faint longitudinal stripes (trichites); small anterior collar; APZ dinstinctly separated from VPZ; one macronucleus, variable in shape, centrally or anterior-left located; girdle kinety supraequatorial, ventral kinety clearly separate from girdle