Euplotes octocarinatus Carter, 1972

Yeo, Jeong Hyeon & Jung, Pablo Quintela-Alonso and Jae-Ho, 2023, New record of five Euplotes species (Protozoa, Ciliophora) collected from South Korea, Journal of Species Research 12 (3), pp. 203-211 : 206

3. Euplotes octocarinatus Carter, 1972 ( Fig. 3 )

Material examined. Freshwater collected from ecological reservoir, Gyeongpo-dong , Gangneung-si, Gangwondo, Korea (37°46′57″N, 128°52′60″E) on July 23, 2020 .

Diagnosis. Body size 60.3-79.3 × 32.0-49.9 μm (on average 66.5 × 46.4 μm) after protargol impregnation, shape oval to ellipsoidal, 6 dorsal and 3 ventral ridges; one macronucleus C-shaped with a single small spherical micronucleus attached; 33-36 adoral membranelles; 9 frontoventral, 5 transverse, 2 caudal and 2 marginal cirri; invariably 8 dorsal kineties, of which the middle kinety composed of about 14-19 dikinetids; dorsal argyrome pattern in double- patella type.

Distribution. Worldwide ( Carter, 1972; Méndez-Sánchez et al., 2020).

Remarks. The characteristics of the Korean population correspond well with the type ( Carter, 1972) and Mexican populations ( Méndez-Sánchez et al., 2020).

Some species with silverline system of double- patella type in Euplotes (i.e., E. apsheronicus Agamaliev, 1966 , E. patella ( Müller, 1773) Ehrenberg, 1838 , E. zenkewitchi Curds, 1975 and E. elegans Kahl, 1932 ) also resemble E. octocarinatus . However, E. apsheronicus differs from E. octocarinatus in the number of dorsal kineties (9 vs. 8) and the habitat (marine vs. freshwater) ( Curds, 1975). Euplotes patella can be distinguished from E. octocarinatus by the body size (90-120 × 55-75 vs. 60-79 × 32-50) and the number of dorsal kineties (9 vs. 8) ( Foissner et al., 1991). Euplotes zenkewitchi differs from E. octocarinatus in the body size (80 × 50 vs. 60-79 × 32-50), the number of adoral membranelles (50-55 vs. 33-36), the number of dorsal kineties (10 vs. 8), and the habitat (marine vs. freshwater) ( Curds, 1975). Euplotes elegans differs from E. octocarinatus in the body size (65-118 × 33-63 vs. 60-79 × 30-50), the number of adoral membranelles (47- 64 vs. 33-36), the number of dorsal kineties (9-10 vs. 8), and the habitat (marine vs. freshwater) ( Schwarz et al., 2007).

Voucher slides. One slide with protargol-impregnated specimens (NNIBRPR25659) and one slide with wet silver nitrate-impregnated specimens (NNIBRPR25660) were deposited at the Nakdonggang National Institute of Biological Resources.

Figures

Fig. 3. Euplotes octocarinatus in vivo (A, B) and after protargol (C, D) and “wet” silver nitrate impregnation (E). A-D. Ventral (A, C) and dorsal (B, D) views of different specimens showing the infraciliature and nuclear apparatus. E. Dorsal argyrome of double-patella type. AZM, adoral zone of membranelles; CC, caudal cirri; DK, dorsal kineties; FVC, frontoventral cirri; MC, marginal cirri. Scale bars: 50μm.