Didinium gargantua Meunier 1910

6. Didinium gargantua Meunier, 1910

(Fig. 6)

Material examined. Marine water (salinity 31‰) taken from Songji Lake, Oho-ri, Jugwang-myeon, Goseonggun, Gangwon-do, Korea (N38°20 ʹ 11 ʺ, E128°30 ʹ 58 ʺ) on April 28, 2017.

Diagnosis. Body size 55-60 × 35-40 μm in vivo; clubshaped; prominent proboscis; single contractile vacuole terminally located; proboscis extrusomes densely packed, length about 10 μm; colorless globules conspicuous, about 1.0 × 0.7 μm in size; spindle shaped cytoplasmic extrusomes sparsely scattered; number of somatic kineties associated with number of anterior and posterior ciliary girdles; anterior girdle kineties about 85 in number; posterior girdle kineties about 75 in number; 3 dorsal brush rows at anterior and posterior ciliary girdles; single macronucleus C or sausage shaped; marine habitat.

Distribution. China, U.S.A., Weddell Sea, Korea (this study).

Remarks. The Korean population of Didinium gargantua Meunier, 1910 can be separated from the population in the Weddell Sea by its body size (55-60 × 35-40 μm vs. 70-200 × 50-120 μm), and the number of somatic and ciliary girdle kineties (75-85 vs. 50-75) (Petz et al., 1995). The Korean and U.S.A. populations of D. gargantua also have different body sizes (55-60× 35-40 μm vs. 70-100 × 40-80 μm), and numbers of somatic and ciliary girdle kineties (75-85 vs. 55-60) (Alekperov et al., 2007 /8).

Didinium gargantua can be separated from D. nasutum (Müller, 1773) Stein, 1859 by body size (55- 60 × 35-40 μm vs. 80-200 × 60-140 μm), the number of dorsal brush rows (3 vs. 5), the position of the contractile vacuole (terminal vs. subterminal), and habitat (saline water vs. freshwater; Foissner et al., 1995).

Voucher slides. Two slides, including protargol-impregnated specimens, were deposited at the National Institute of Biological Resources, Korea (NIBRPR0000107904, NIBRPR0000107905).