Stentor muelleri Ehrenberg, 1831

Taher, Md Abu, Kabir, Ahmed Salahuddin, Shazib, Shahed Uddin Ahmed, Kim, Min Seok & Shin, Mann Kyoon, 2020, Morphological Redescriptions and Molecular Phylogeny of Three Stentor Species (Ciliophora: Heterotrichea: Stentoridae) from Korea, Zootaxa 4732 (3), pp. 435-452 : 439-440

Stentor muelleri Ehrenberg, 1831

( Figs. 3–5 , Tables 1 , 2 )

Improved diagnosis. Body size 205–570 × 60–180 µm in vivo (on average 365 × 135 µm), 500–1200 × 60–150 µm when extended, about 70–190 × 35–140 µm after protargol impregnation. Body slender trumpet-shaped to conical when extended, colorless cortical granules scattered throughout whole body, contractile vacuole with connecting canal located in anterior left margin adjacent to peristome, 9–15 peristomial kineties, 30–80 somatic ciliary rows, 5–14 moniliform spherical macronuclear nodules located at mid-body, 7–20 micronuclei located around macronuclear nodules. Mucilaginous lorica present.

Locality and habitat. Freshwater pond, Gonggeomji in Yangjeong-ri, Gonggeom-myeon, Sangju-si, Gyeongsanbuk-do, Korea (36°30′45.0′′N, 128°09′42.5′′E).

Voucher material. A slide with protargol-stained specimens was deposited in the National Institute of Biological Resources ( NIBR), Incheon, Korea, with registration number NIBRPR0000110185. The slide contains many specimens, but relevant specimens are marked by black ink circles on the slide.

Description. Cell size 205–570 × 60–180 µm in vivo (on average 365 × 135 μm in vivo) ( Fig. 4A ), when fully extended they are 500–1200 µm in length and 60–150 µm in width in the peristomial area ( Fig. 4D ) usually about 70–190 × 35–140 µm in protargol impregnated specimens ( Fig. 5A ). Body slender trumpet-shaped when fully extended, and inverted pear-shaped in contracted specimens ( Fig. 4A, D , 5A ). The specimens appear dark and colorless under lower magnification ( Fig. 4D, E ). A small individual of S. muelleri has some brown or yellowish color spots scattered throughout the body, most likely caused by crystals or foods ( Fig. 4A ). Colorless cortical granules scattered between somatic kinety rows, round or oval-shaped 0.5–0.8 µm in diameter ( Fig. 4F ). Cortex thin and translucent, which makes cytoplasmic organelles identifiable ( Fig. 4A ). 30–82 longitudinal rows of somatic cilia on surface of body parallel to the antero-posterior axis ( Fig. 3D, E , 4F , 5A ). Somatic cilia arise from dikinetids, 7–13 µm long ( Fig. 3C, D , arrowhead, 4F). Mitochondria (?)- type organelles were also spread on the pellicle ( Fig. 4G ). One contractile vacuole with a long collecting canal, located left of the peristome, 30 µm in diameter during diastole ( Fig. 3A , 4H ). Peristomial area contains 9 to 15 peristomial kineties, size of peristomial cilia alike somatic cilia ( Fig. 3D , 4B , 5A, B ). Buccal pouch absent. Adoral zone of membranelles composed of 120–225 membranelles ( Fig. 3D , 4B , 5B ). The longest adoral membranelles are 10–20 µm long. The paroral membrane is typical of the genus, consisted of a single and continuous row of thin cilia, 25–50 µm long surrounding peristome ( Fig. 3D , 5A, C ). Nuclear apparatus consists of a moniliform macronucleus with 5–14 spherical nodules almost 5–25 µm in diameter in vivo ( Fig. 3A, E , 4A , 5B ). Seven to 20 spherical micronuclei, 1–4 µm in diameter in vivo located near macronuclear nodules ( Fig. 4C , 5B ). Cells usually live inside of mucilaginous lorica ( Fig. 4D , arrowhead) composed of sand grains and other sticky particles, with length 150–700 µm. Food vacuoles are 4–35 µm in diameter; containing bacteria and diatoms as food ( Fig. 3A ). Lipid droplets, 2–10 µm in diameter, scattered throughout body. Cell has a holdfast organelle that assists with attachment to the substrate of benthic bottom or basement of lorica ( Fig. 4A , arrowhead).

Figures

FIGURE 3. Line diagrams of S. muelleri 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; Arrowhead in (D) point to basal bodies of somatic cilia; AM, adoral membranelles; AZM, adoral zone of membranelles; CG, cortical granules; MA, macronuclear nodules; MI, micronuclei; PK, peristomial kinety; PM, paroral membrane; SC, somatic cilia; SK, somatic kinety. Scale bars: A=100 µm, C=10 µm, D, E=50 µm.

FIGURE 4. Photomicrographs of S. muelleri from life (A–F). A. Ventral view of a representative specimen, showing macronuclear nodules and position of contractile vacuole; B. Indicating buccal ciliature; C. Section showing macronuclear nodules and micronuclei; D, E. Showing specimens in extended form; F. Cortical granulation and somatic cilia; G. Indicating mitochondria (?); H. Anterior part of live specimen, showing contractile vacuole with collecting canal; Arrowhead in (A) indicating holdfast organelles; Arrowhead in (D) indicating lorica; Arrowheads in (G) point to mitochondria (?); Arrowheads in (H) indicating collecting canal; AZM, adoral zone of membranelles; CV, contractile vacuole; CG, cortical granules; MA, macronuclear nodules; MI, micronuclei; PK, peristomial kineties, SC, somatic cilia, SK, somatic kineties. Scale bars: A=100 μm, D=200 μm, C=10 μm.

FIGURE 5. Photomicrographs of S. muelleri after protargol impregnation (A–D). A, B. Ventral views of representative specimens, showing ciliature and nuclear apparatus; C. Showing paroral membrane; D. Basal bodies of somatic cilia; Arrowheads in (D) point to basal bodies of somatic cilia; AM, adoral membranelles; AZM, adoral zone of membranelles; MA, macronuclear nodules; MI, micronuclei; PM, paroral membrane; PK, peristomial kineties; SK, somatic kineties. Scale bars: A=50 μm, B=10 μm.