Morphological Redescriptions and Molecular Phylogeny of Three Stentor Species (Ciliophora: Heterotrichea: Stentoridae) from Korea Author Taher, Md Abu Author Kabir, Ahmed Salahuddin Author Shazib, Shahed Uddin Ahmed Author Kim, Min Seok Author Shin, Mann Kyoon text Zootaxa 2020 2020-02-13 4732 3 435 452 journal article 24039 10.11646/zootaxa.4732.3.6 ea9ffdde-e6b1-4e98-a8aa-93c6a67591fe 1175-5326 3667262 76254E06-3555-4C8D-9B25-1DF8BD9C55ED Stentor coeruleus ( Pallas, 1766 ) Ehrenberg, 1831 ( Figs. 1 , 2 , Tables 1 , 2 ) Improved diagnosis: The Korean Stentor coeruleus population is highly contractile, cell size is 250–400 × 105–160 µm in vivo but can become more than 1000 µm during complete extension. 100–239 × 80–185 µm after protargol impregnation. They are trumpet-shaped when completely extended, but freely motile or contracted specimens are inverted pear-shaped. Under low magnification, specimens are blue green in color but at higher magnification cortical granules are reddish brown in the absence of symbiotic algae; a contractile vacuole is present on the left of the oral cavity. 55–65 somatic kineties are longitudinally arranged; 20–25 peristomial kineties are vertically arranged within adoral zone membranelles; 145–165 adoral membranelles comprise the peristome. The moniliform macronucleus is composed of 6–15 spherical nodules. Micronucleus and lorica were not observed in the present study. Locality and habitat: freshwater pond, Bugokji pond in Samrak-ri, Maam-myeon, Goseong-gun, Gyeongsangnam-do province , Korea ( 35°01′35.2′′N , 128°20′40.2′′E ). Voucher material: A slide with protargol-stained specimens was deposited in the National Institute of Biological Resources ( NIBR ), Incheon , Korea , with registration number NIBRPR0000109602. The slide includes many specimens, but the relevant specimens are marked by a black ink circle on the slide. FIGURE 1. Line diagrams of S . coeruleus from life (A–C) and after protargol impregnation (D, E). A. A representative specimen; B. Showing cortical granulation; C. Somatic cilia; D, E. Ventral and dorsal views of the voucher specimens, showing the somatic ciliature and the nuclear apparatus; AM, adoral membranelles; CG, cortical granules; MA, macronuclear nodules; PK, peristomial kinety; PM, paroral membrane; SC, somatic cilia; SK, somatic kinety. Scale bars: A=100 µm, C=10 µm, D, E=50 µm. Description: The freely motile cell is inverted pear-shaped and size ranges 250–400 × 105–160 µm (on average 325 × 125 µm ) ( Figs. 1A , 2B ). After extension, when cell relaxed, the body looks like trumpet-shaped and size ranges, 575–1050 µm in length and 120–135 µm in width in the peristomial area ( Fig. 1A ). The specimens shrink considerably after protargol impregnation, i.e., 100–239 × 80–285 µm (on average 165 × 116 µm ) ( Figs. 1D, E , 2 H–J). Greenish (due to limitations of microscope and camera, CG appears greenish-brown in pictures) cortical granules (~ 0.5 µm in diameter) irregularly arranged densely between somatic kineties ( Fig. 2D ). The transparent cortex makes cytoplasmic organelles easily identifiable ( Figs. 2B, E, G ). 55–65 somatic kineties composed of dikinetids longitudinally arranged parallel to the antero-posterior axis of cell ( Figs. 1D, E , 2D, J ). Each somatic cilium is 11–12 µm long ( Fig. 1C ). One contractile vacuole without any visible collecting canal located left of the buccal cavity about 38 µm in diameter during diastole ( Fig. 2E ). 20–25 peristomial kineties present in the peristomial region ( Figs. 1D, E , 2C, I ). The size of the peristomial cilia is similar to that of somatic cilia. The buccal cavity is clearly visible. Adoral zone of membranelles conspicuous, consisting of 145–165 membranelles ( Figs. 1D, E , 2C, I ). Adoral zone of membranelles surrounding the peristome ends at the buccal cavity ( Figs. 1A, D , 2B, C, I ). The breadth of adoral membranelles 12–13 µm long, feather-like extension is nearly 33 µm . The paroral membrane is typical of the genus, consisted of a single and continuous row of thin cilia, 20–35 µm long ( Fig. 2C ). Nuclear apparatus comprised of 6–12 spherical macronuclear nodules and each nodule are connected by macronuclear bridges; nodules are globular ( 20–22 µm in diameter in vivo ) to ellipsoidal ( 25–30 µm in length), usually located at the mid-body; however, the position of macronuclear nodules is not fixed ( Figs. 1E , 2G, H ). Micronucleus was not observed. Food vacuoles are 20–30 µm in diameter; contain bacteria and algae ( Figs. 1A , 2B ). Lipid droplets 1.5–3.5 µm in diameter scattered throughout the body ( Fig. 2E ). Holdfast organelle present at the posterior end of the cell ( Fig. 2F ).