Aspidisca polypoda ( Dujardin, 1841 ) Kahl, 1932

Choi, Jung Min, Jung, Jae-Ho & Kim, Jung-Hoon Kang and Young-Ok, 2020, New record of four ciliates (Protozoa, Ciliophora) collected from rocky intertidal pools of South Korea, Journal of Species Research 9 (4), pp. 455-461 : 456-457

1. Aspidisca polypoda ( Dujardin, 1841) Kahl, 1932 ( Fig. 2 )

Material examined. Marine water (temperature 11.5°C; salinity 34.0; pH 8.6) collected from Jeongdongjin Harbor , Jeongdongjin-ri , Gangdong-myeon , Gangneung-si, Gangwon-do, South Korea (37°41′09″N 129°02′32″E) on April 23, 2012 ( Fig. 1 ; St. 1) .

Diagnosis. Body size 22-40 × 21-35 μm, length:width ratio about 1.3: 1 in vivo; 30-40 × 22-32 after protargol impregnation; outline bean-shaped with snout-like November 2020 Choi et al. Four new ciliate records from Korea 457 anterior portion; 8 prominent dorsal ridges; 1 inverted U-shaped macronucleus; contractile vacuole below transverse cirri; adoral zone of membranelles split into anterior and posterior part and each with 4-5 and 9-11 membranelles respectively; 7 frontoventral cirri; 6 transverse cirri including almost conjoined leftmost 2 cirri; 4 dorsal kineties each with about 8, 9, 9, 9 basal bodies, from left to right, respectively.

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Distribution. Antarctica, France, Germany, Russia, and Korea.

Remarks. Aspidisca polypoda is easily distinguished by seven or eight conspicuous dorsal ribs ( Dujardin, 1841), which coincides with this Korean population. Our population differs from the Antarctic population by basal body number of dorsal kineties 1-4 (ca. 8, 9, 9, 9 vs. ca. 4, 5, 6, 6, respectively) that might be caused by a distinct sampling localities/habitats ( Song and Wilbert, 2002).

Among the other congeners with similar morphology to A. polypoda , A. steini Buddenbrock, 1920 is distinguishable from A. polypoda based on the number of dorsal ridges (absent or four vs. eight). Aspidisca cicada (Müller, 1786) Claparède & Lachmann, 1858 differs by pattern of frontoventral cirri (lynceus- arrangement vs. polystyla-arrangement) ( Wu and Curds, 1979; Song and Wilbert, 1997).

Voucher slides. Two slides with protargol-impregnated specimens was deposited at National Institute of Biological Resources (NIBRPR0000110829) and Korea Institute of Ocean Science and Technology (KIOST), respectively.

Figures

Fig. 2. Photomicrographs of Aspidisca polypoda from living specimens (A-D), protargol impregnated specimens (E, F), and illustrations (G-J). A. Ventral view showing posterior part of the adoral membranelles (arrowhead). B. Eight distinctive ridges (arrowheads) and contractile vacuole (arrow). C. Anterior part of the adoral membranelles (arrowhead). D. Separated into two parts of leftmost transverse cirri (arrowhead). E, F. Ventral and dorsal view of stained specimens. G-J. Illustrations showing main characteristics.AZM 1 and 2, adoral zone of membranelles 1 and 2; CV, contractile vacuole; DK, dorsal kineties; FVC, frontoventral cirri; MA, macronucleus; TC, transverse cirri. Scale bars: 20μm.

Fig. 1. Map of the sampling stations in South Korea. Each station (marked with red circles) located at three intertidal zones of the Korean Peninsula (St. 1-3) and Baekdo Island (St. 4).