Acropisthium mutabile Perty, 1852

Jung, Atef Omar and Jae-Ho, 2021, New record of 21 ciliate species (Protozoa, Ciliophora) from South Korea, Journal of Species Research 10 (3), pp. 301-320 : 310

12. Acropisthium mutabile Perty, 1852 ( Fig. 12 )

Material examined. Freshwater sample collected from a temporary puddle, after rainfall, on a footpath behind Gangneung-Wonju National University, Gangneung, Korea (37°46 ʹ 30 ʺ N, 128°51 ʹ 46.8 ʺ E) on 25 June 2020 .

Diagnosis. Size in vivo about 75 × 25 μm and after protargol impregnation (n = 5); body slenderly ellipsoidal with pointed posterior end; cytoplasm clear containing 1 oblong macronucleus surrounded by 1-3 micronuclei and scattered rod-shaped extrusomes; contractile vacuole located subterminally; 19 or 20 monokinetidal somatic kineties each curves anteriorly to right side forming subapical ciliary wreath; 3 dorsal brush rows consist of dikinetids and monokinetids; oral opening anteriorly and slightly curved to right side.

Distribution. Cosmopolitan.

Remarks. The Korean population of Acropisthium mutabile agrees very well with the description of Foissner (1984) in most aspects. Balantidion pellucidum Eber- hard, 1862 is the most similar species to A. mutabile . Both have densely arranged oralized somatic kinetids (subapical ciliary wreath), usually three dikinetidal dorsal brush rows, and rod-shaped extrusomes. However, they belong to different genera and can easily be separated from each other by the flat (vs. conical) oral bulge and the longitudinal (vs. curved) subapical ciliary wreath ( Foissner, 1984; Foissner et al., 1999).

Voucher slides. Two slides with protargol-impregnated specimens were deposited at the Nakdonggang National Institute of Biological Resources (NNIBRPR20124, NNIBRPR20125).

Figures

Fig. 12. Photomicrographs of Acropisthium mutabile from life (A, B) and after protargol impregnation (C, D). A, B. Ventral views showing the body shape, the subterminally located contractile vacuole, and the subapical ciliary wreath. C. Ventral view showing the nuclear apparatus and the somatic ciliature. D. Dorsal view showing the three dorsal brush rows. B1-3, dorsal brush rows; CV, contractile vacuole; CW, subapical ciliary wreath; MA, macronucleus; MI, micronucleus. Scale bars=20 μm.