Plagiopyla frontata Kahl, 1931

Jung, Atef Omar and Jae-Ho, 2022, New record of five anaerobic ciliate species from South Korea, Journal of Species Research 11 (2), pp. 108-116 : 113-114

4. Plagiopyla frontata Kahl, 1931 ( Fig. 4 )

Material examined. Marine water sample collected from Anin Beach , Gangdong-myeon , Gangneung-si, Gangwon-do, Republic of Korea (37°44′4″N, 128°59′25″E) on 14 June 2021 .

Diagnosis. Size in vivo 80-120 × 40-60 μm and about 100 × 55 μm after protargol impregnation (n = 5); body oval to ellipsoidal, dorsoventrally flattened, anterior and posterior end rounded; 50-60 somatic ciliary rows; about 10 caudal cilia along left posterior margin; buccal opening slit-like, at right ventral side extending transversely to left and curving upwards in mid-region; frontal region (between anterior cell margin and upper oral lip) about 1/6 of body length; striated band on dorsal side commences at level of oral opening and forms a hook-like structure and ends near mid-body; one globular to elliptical macronucleus slightly anterior to mid-body, one micronucleus attached to macronucleus; cytoproct on posterior third of dorsal side, 1-3 dense ciliary rows left of cytoproct slit; extrusomes curved, 3-4 μm long in vivo; contractile vacuole terminal.

World distribution. Germany, Denmark, Australia, and South Korea ( Kahl, 1931; Fenchel, 1968; Fenchel et al., 1995; Esteban et al., 2000; Nitla et al., 2018).

Remarks. Plagiopyla frontata was studied a few times, but a complete characterization of the species is lacking ( Kahl, 1931; Fenchel, 1968; Fenchel et al., 1995; Esteban et al., 2000; Nitla et al., 2018). The Korean population of P. frontata agrees very well with previous descriptions,

especially that of the type population ( Kahl, 1931). Esteban et al. (2000), who studied P. frontata from Australia, also mentioned that their population is almost identical to the type population. Within the marine Plagiopyla species, P. frontata is most similar to P. ovata , which was described recently from marine water in China ( Li et al., 2021). However, they can be separated by the body shape (oval to ellipsoidal vs. obovate), the shape of extrusomes (curved vs. straight), the length of the frontal region anterior to upper lip (1/6 vs. 1/4 of body length), and the shape of buccal cavity tube (straight vs. curved upwards in its mid-region). The curved extrusomes were also found in the freshwater species, P. megastoma (Smith, 1898) Kahl, 1931 , P. ramani Nitla et al., 2018 , and P. narasimhamurtii Nitla et al., 2018 ( Nitla et al., 2018).

Voucher slide. One slide with protargol-impregnated specimens was deposited at the National Institute of Biological Resources (NIBRPR0000111070).

Figures

Fig. 4. Plagiopyla frontata in life (A-E) and after protargol impregnation (F-H). A, B, E. Dorsal (A) and ventral (B, E) views showing the body shape, the striated band (arrow), and the oral apparatus. C. Ventral view of the oral region showing the oral tube curving upwards in the middle and the curved extrusomes (arrows). D. The caudal cilia and the terminal contractile vacuole. F-H. Dorsal (F, H) and ventral (G) view, showing the somatic ciliature, the striated band (arrows), and the dense ciliary rows left of cytoproct. BC, buccal cavity; CC, caudal cilia; CV, contractile vacuole; CY, cytostome; DC, dense ciliary rows; FV, food vacuole; MA, macronucleus. Scale bars 30μm (A, B, E) and 20μm C, D, F-H).