New Record of Two Apokeronopsis Species(Ciliophora: Urostylida: Pseudokeronopsidae) from Korea

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  • ABSTRACT

    The morphology of the two marine hypotrichous ciliates Apokeronopsis bergeri and A. ovalis, isolated from the Yellow Sea, Korea, are described based on live and protargol-impregnated specimens. It is the first time that these species have been recorded in Korea. In addition, the small subunit ribosomal RNA gene was sequenced for comparison with the public database. The genus Apokeronopsis has recently been established in the family Pseudokeronopsidae, and the two congeners of the Korean population share the following characteristics:one row of one or more buccal cirri; usually two frontoterminal cirri; midventral complex composed of two distinctly separated rows; one left and one right marginal row; number of transverse cirri, more than eight;absence of caudal cirri; two types of cortical granules. Apokeronopsis bergeri differs from A. ovalis primarily in body shape (fusiform vs. oval form), size (usually 260×80 μm vs. 160×55 μm), type II cortical granules(oval vs. round shape; yellow-green vs. mostly colourless and only a few yellow-green in colour), and morphometric data (75-106 vs. 53-70 in adoral membranelles; 37-47 vs. 24-36 in frontal cirri; 9-15 vs. 1-2 in buccal cirri), as well as molecular data (2.87% of pairwise distance).


  • KEYWORD

    Apokeronopsis bergeri , Apokeronopsis ovalis , marine ciliate , morphology , SSU rRNA gene , Korea

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  • [Table 1.] Morphometric characterization of Apokeronopsis bergeri
    Morphometric characterization of Apokeronopsis bergeri
  • [Fig. 1.] Morphology and infraciliature of Apokeronopsis bergeri and A. ovalis from live (A-D G H) and after protargol impregnation(E F I J). A-F Apokeronopsis bergeri: A Ventral view of live arrow indicates the contractile vacuole; B Two types of densely distributed granules arrow and arrowhead show the granules respectively; larger granules scattered throughout the body ventral(C) and dorsal (D) views; E F Infraciliature of ventral (E) and dorsal (F) sides arrow in (E) to show frontoterminal cirri; G-J Apokeronopsis ovalis: G Ventral view of live arrow indicates the contractile vacuole; H Densely distributed granules arrow and arrowhead show the two types of granules respectively; I J Infraciliature of ventral (I) and dorsal (J) sides arrow in (I) to show frontoterminal cirri. AZM adoral zone of membranelles; BC buccal cirri; DK dorsal kineties; EM endoral membrane; LMR left marginal row; Mamacronuclei; MVR midventral row; PM paroral membrane; RMR right marginal row; TC transverse cirri. Scale bars: 100 μm.
    Morphology and infraciliature of Apokeronopsis bergeri and A. ovalis from live (A-D G H) and after protargol impregnation(E F I J). A-F Apokeronopsis bergeri: A Ventral view of live arrow indicates the contractile vacuole; B Two types of densely distributed granules arrow and arrowhead show the granules respectively; larger granules scattered throughout the body ventral(C) and dorsal (D) views; E F Infraciliature of ventral (E) and dorsal (F) sides arrow in (E) to show frontoterminal cirri; G-J Apokeronopsis ovalis: G Ventral view of live arrow indicates the contractile vacuole; H Densely distributed granules arrow and arrowhead show the two types of granules respectively; I J Infraciliature of ventral (I) and dorsal (J) sides arrow in (I) to show frontoterminal cirri. AZM adoral zone of membranelles; BC buccal cirri; DK dorsal kineties; EM endoral membrane; LMR left marginal row; Mamacronuclei; MVR midventral row; PM paroral membrane; RMR right marginal row; TC transverse cirri. Scale bars: 100 μm.
  • [Fig. 2.] Morphology and infraciliature of Apokeronopsis bergeri from live (A-D) and after protargol impregnation (E-G). Dorsal (A B)and ventral (C D) views of live (B) arrow indicates the contractile vacuole; C Body shape slightly contractile and flexible; D Arrow and arrowhead indicate the two types of granules respectively; Dorsal (E) and ventral (F G) views of protargol-impregnated specimen(E) arrows mark the invariable three dorsal kineties; F Frontal cirri (bicorona) and one row of buccal cirri; G General ciliature of the specimen usually 200 densely scattered macronuclear nodules. Scale bars: 100 μm.
    Morphology and infraciliature of Apokeronopsis bergeri from live (A-D) and after protargol impregnation (E-G). Dorsal (A B)and ventral (C D) views of live (B) arrow indicates the contractile vacuole; C Body shape slightly contractile and flexible; D Arrow and arrowhead indicate the two types of granules respectively; Dorsal (E) and ventral (F G) views of protargol-impregnated specimen(E) arrows mark the invariable three dorsal kineties; F Frontal cirri (bicorona) and one row of buccal cirri; G General ciliature of the specimen usually 200 densely scattered macronuclear nodules. Scale bars: 100 μm.
  • [Table 2.] Morphometric characterization of Apokeronopsis ovalis
    Morphometric characterization of Apokeronopsis ovalis
  • [Table 3.] Pairwise distance of SSU rRNA gene sequences among Apokeronopsis congeners were calculated using the Kimura twoparameter distance
    Pairwise distance of SSU rRNA gene sequences among Apokeronopsis congeners were calculated using the Kimura twoparameter distance
  • [Fig. 3.] Morphology and infraciliature of Apokeronopsis ovalis from live (A-F) and after protargol impregnation (G-L). Dorsal (A F)and ventral (C-E) views of live (C) arrow indicates the contractile vacuole; B-D Body shape slightly contractile and flexible; E FArrow and arrowhead mark the two types of granules respectively; double-arrowhead indicates the dorsal cilia; Ventral (G-I K L)and dorsal (J) views of the protargol-impregnated specimen; G General ciliature of the specimen; H Two frontoterminal cirri arrows indicate cirri near the distal end of the adoral zone; I Arrow denotes macronuclear nodules; J Arrows indicate dorsal kineties usually three; K Frontal (bicorona); L J-shaped transverse cirri. Scale bars: 100 μm.
    Morphology and infraciliature of Apokeronopsis ovalis from live (A-F) and after protargol impregnation (G-L). Dorsal (A F)and ventral (C-E) views of live (C) arrow indicates the contractile vacuole; B-D Body shape slightly contractile and flexible; E FArrow and arrowhead mark the two types of granules respectively; double-arrowhead indicates the dorsal cilia; Ventral (G-I K L)and dorsal (J) views of the protargol-impregnated specimen; G General ciliature of the specimen; H Two frontoterminal cirri arrows indicate cirri near the distal end of the adoral zone; I Arrow denotes macronuclear nodules; J Arrows indicate dorsal kineties usually three; K Frontal (bicorona); L J-shaped transverse cirri. Scale bars: 100 μm.