4. Allotricha mollis Sterki, 1878

(Fig. 4)

Material examined. Brackish water (salinity 1.0‰) taken from the River Gyeongpocheon, Unjeong-dong, Gangneung-si, Gangwon-do, Korea (N37°47 ʹ 20 ʺ, E128° 54 ʹ 34 ʺ) on December 22, 2016 .

Diagnosis. Body size 270-300 × 85-105 μm in vivo; elliptical shape; flexible; acontactile; colorless; contractile vacuole on left side above mid-body; yellow to green cortical granules ca. 1 μm in diameter; about 65 adoral membranelles; 3 frontal cirri; 1 buccal cirrus; 4 frontoventral cirri; 3 postoral ventral cirri; 2 pretransverse cirri; 5 transverse cirri; 1 left marginal row with 37-43 cirri; 3 right marginal rows composed of 11-19 cirri in row 1, 32-33 cirri in row 2, 34-36 cirri in row 3; 8 dorsal kineties including 3 fragmented kineties; 3 caudal cirri; 2 macronuclear nodules, 7-10 micronuclei.

Distribution. Austria, Germany, Switzerland, U.S.A., Korea (this study).

Remarks. Allotricha mollis Sterki, 1878 is different from A. antarctica Berger, 1999 . It has a larger body size (270-300 × 85-105 μm vs. 90-125 × 40-70 μm), and the arrangement of the transverse cirri (straight vs. hooklike), the number of adoral membranelles (60-82 vs. 30- 37), and their habitat (freshwater vs. terrestrial soil) separate these two species (Berger, 1999).

Voucher slides. Two slides, including protargol-impregnated specimens, were deposited at the National Institute of Biological Resources, Korea (NIBRPR0000107894, NIBRPR0000107895).