Trichototaxis marina Lu 2014

Trichototaxis marina Lu et al., 2014 Description (Figures 1, 2; Table 1) The November and April populations studied here are so similar that conspecificity is beyond reasonable doubt. Consequently, the description below includes data from both populations. Body size highly variable, but shape very similar in the two populations. Size 200– 360 × 40–80 μm, mostly 250 × 50 μm in life, and 178–328 × 53–118 μm for stained specimens (Table 1); ratio of length to width about 4–6: 1 in live specimens; flattened ca. 2:1 dorsoventrally with anterior and posterior portions thin. Body elongate elliptical and often sigmoidal in outline, anterior end wider than posterior one, widest at mid-body (Figures 1A, 2A–C), conspicuously reddish in colour at low magnification (Figure 2B, C, F). Pellicle very flexible and highly contractile (Figure 2D, F) and to some extent thigmotactic. Conspicuous furrows recognisable along cirral rows on ventral side (Figure 2G). Cortical granules not observed, but rice-shaped granules (1 × 0.5 μm, mitochondria?) densely arranged along cirral rows (Figure 2E). Many brick-reddish, weird pigment patches of variable size densely distributed under pellicle and in cytoplasm, which render cells red (Figure 2I), and often decreasing in number after some time at room temperature in raw culture. Endoplasm usually packed with numerous small (ca. 30% of body length in live cells (Figures 1A, 2A–C, F, G), its proximal part covered by a thick buccal lip (Figure 2H and J, arrow). Adoral zone composed of 45 to 80 (on average 63 and 74 in two populations) membranelles, with distal end extending far onto right ventral side (Figures 1B–D, 2A, D, G, K, N); cilia of apical membranelles about 10 μm long. Paroral membrane (Figures 1D, arrow, and 2K, N, P) about half length of endoral membrane (Figures 1B, arrow, and 2N, arrowhead), almost parallel to each other, the former dikinetidal and the latter monokinetidal (Figure 2K, P). Pharyngeal fibres conspicuous in vivo. Twelve to 23 frontal cirri, cilia of which are 10–15 μm long in vivo, arranged in a conspicuous bicorona (Figures 1B–D and 2N). Usually 1 buccal cirrus (rarely 2 or 3) (Figures 1B–D, 2K, N, arrow,P, arrowhead); cilia ca.10 μm long, located adjacent to right posterior third of paroral membrane. Invariably 2 frontoterminal cirri near distal end of adoral zone (Figures 1B–D, 2K, N). Midventral complex composed of 39–75 pairs of cirri (including 2 pretransverse ventral cirri), arranged in a zig-zag pattern, running in a slightly sigmoid pattern along ventral surface and extending to posterior portion of body (Figures 1B–D, 2K–O). Cirri about 10 µm long, base of right midventral cirrus (about 2 × 6 basal bodies) conspicuously larger than that of left cirri (2 × 3 basal bodies; Figure 2L). Usually 6 (sometimes 5 or 7; 8 in two of (Continued) 35 specimens) transverse cirri, cilia of which are ca. 20 μm long, arranged in a J-shaped pseudo-row (Figures 1B–D, 2K, O). Total number of fronto–ventral–transverse cirri highly variable, ranging from 94 to 178 for two populations. Ciliary fibres of cirri, especially transverse cirri, conspicuous after protargol staining (Figure 2K, M). Table 1. (Continued). *all cirri derived from frontoventral-transverse cirral anlagen. Abbreviations: CV, coefficient of variation, in %; DK, dorsal kinety; LMR, left marginal row; Max, maximum; Mean, arithmetic mean; Min, minimum; n, number of specimens examined; PT, pretransverse ventral cirri; RMR, right marginal row; SD, standard deviation; SE, standard error of the mean. Invariably 1 right marginal row; on average 2 or 3 left marginal rows for November and April populations, respectively (Figures 1A–D, 2K). Cilia of marginal cirri ca. 12 μm long, each cirrus usually containing 2 × 6 basal bodies (Figure 2L). The innermost left marginal row composed of about 68 (November population) or 89 (April population) densely packed cirri, commencing more or less at level of mid-region of buccal field, and ending at posterior end of body. The next left marginal row consisting of 23–52 sparsely distributed cirri, starting behind level of the innermost row, and terminating at about posterior two-thirds of body; sometimes one or more cirri in this row resorbed, forming several gaps; most cells of the April population having the third left marginal row, which is comprised of about 21 loosely arranged cirri and located at mid-body. Right marginal row starting adjacent to right of frontoterminal cirri, composed of 46–104 cirri, running along right body margin, and terminating at the rear end of body (Figures 1B–D, 2K). Six to 8 bipolar dorsal kineties (Figure 1D), with cilia 3 μm long in vivo. Numerous (usually more than 100) macronuclear nodules, scattered throughout body; each spherical to ovoid, varying between 3 and 8 μm in length (Figures 1E, 2K, L, Q), having usually 1 central nucleolus (rarely 2 to 5) (Figure 2R); micronuclei numbering 2–14, each spherical to ellipsoidal (Figures 1E, 2L and Q, arrowheads, R, arrow) and 3–9 μm long. Locomotion by crawling moderately without pause on debris or on bottom of Petri dish or by swimming in water when disturbed. Cells usually very thigmotactic to the substrate. Deposition of specimens. A voucher slide (registration number: HX20230418-1) with protargol-stained specimens has been deposited in the Marine Biological Museum, Chinese Academy of Sciences, Qingdao, China. Ecological data. Water temperature 14.2°C and 16.5°C, pH 8.2 and 8.2, salinity 34.5‰ and 34.7‰, DO (Dissolved oxygen) 7.38 mg /L and 7.87 mg /L for November and April populations, respectively.
Published as part of Ghaffar, Abdul, Bai, Yang & Hu, Xiaozhong, 2023, First record of two urotsylid ciliates (Protozoa: Ciliophora: Spirotrichea) from Japan expanding the circumscription of species, pp. 724-743 in Journal of Natural History (Oxford, England) (Oxford, England) 57 (9 - 12) on pages 726-730, DOI: 10.1080/00222933.2023.2206586, http://zenodo.org/record/8071692
{"references":["Lu X, Gao F, Shao C, Hu X, Warren A. 2014. Morphology, morphogenesis and molecular phylogeny of a new marine ciliate, Trichototaxis marina n. sp. (Ciliophora, Urostylida). Eur J Protistol. 50: 524 - 537. doi: 10.1016 / j. ejop. 2014.08.002"]}