Lembadion lucens Kahl 1931
Creators: name: Liu, Mingjian
name: Li, Lifang
name: Qu, Zhishuai
name: Luo, Xiaotian
name: Al-Farraj, Saleh A.
name: Lin, Xiaofeng
name: Hu, Xiaozhong
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Chromista
Ciliophora
Oligohymenophorea
Peniculida
Lembadionidae
Lembadion
Lembadion lucens

description: Lembadion lucens (Maskell, 1887) Kahl, 1931 (Figs2B, D, E, 4A–K, Table 1)
Although Lembadion lucens had been redescribed using silver staining methods several times, its SSU rDNA sequence remained unavailable. Moreover, it had never been found in China. Based on all data available, the species is now redescribed below.
Improved diagnosis: Cell size approximately 45–80 μm × 20–50 μm in vivo; cell shape oval to long ellipsoidal; large and wide buccal field, occupying about 60– 90% of body length; single contractile vacuole centrally positioned near right margin of cell; 25–35 somatic kineties; single kidney- or L-shaped macronucleus; seven to 10 caudal kinetosomes arranged into two rows, with cilia about 20–30 μm in length; freshwater habitat.
Deposition of voucher slides: Two voucher slides (registration nos. QZS2013102408 and LXT2013102407) have been deposited in Laboratory of Protozoology, Ocean University of China, Qingdao, China.
Morphological description based on Zhanjiang population: Cell size in vivo about 45–70 μm × 20–40 μm. Ratio of length to width approximately 3:2 to 2:1. Cell shape constant, oval to long elliptical in outline. Anterior part slightly narrowed with a prominence, and posterior part rounded (Figs 2B, 4A). Ventral side deeply concave, while dorsal side prominently convex (Fig. 4D). Buccal field extremely large and wide, about 30–45 μm long and 20–35 μm wide, occupying three-fourths to four-fifths of body length, with buccal cilia about 20 μm in length (Figs 2B, 4A, B). Somatic cilia approximately 8 μm long in vivo and densely arranged along long axis of body (Figs 2B, 4B). Caudal cilia about 20 μm long (Figs 2B, 4B). Pellicle thin with rectangular meshes arranged on middle and posterior parts of cell’s surface. Each mesh has single somatic cilium inserted centrally. Extrusomes not detected. Endoplasm colorless to grayish, containing several to numerous food vacuoles and bar-like refractile granules. Many small spherical lipid droplets located beneath pellicle (Figs 4A–C). Single contractile vacuole, about 7 µm in diameter when fully expanded, positioned at mid-body near right margin of cell on dorsal side (Figs 2B, 4C). Collecting canal not detected. Single kidney-or L-shaped macronucleus subequatorially positioned, right side of median line, about 15–30 μm × 5–15 μm in size (Figs 2D, E, 4F, H). One spherical micronucleus closely associated with macronucleus, approximately 2.5 μm in diameter (Fig. 4H). Locomotion achieved by swimming moderately fast while rotating about main body axis continuously without pause.
Ciliature as shown in Figs 2D, E, 4E–K. About 25–30, usually 28, almost bipolar SK observed. Each SK composed of dikinetids in middle portion and monokinetids at both ends (Figs 2D, E, 4F, G, J). Middle somatic kinety on dorsal side consisting of about 21–27 basal bodies, of which four to six dikinetids (Figs 2E, 4G, J). Number of dikinetids gradually increasing from middle somatic kinety, in both left and right directions, to approximately eight to 12 dikinetids (Figs 2D, E). Somatic kinety 1 (kinety on right of buccal field) composed of about 14–23 basal bodies. Basal bodies of caudal cilia arranged into two rows, distributed at posterior part of cell: row on dorsal side consisting of five or six basal bodies, while another row on ventral side composed of two or three basal bodies (Figs 2D, 4I).
Buccal apparatus typical of genus, containing one adoral membranelle (AM) and two paroral membranes (PMs) (Figs 2D, 4F). Adoral membranelle composed of seven rows of densely packed basal bodies located on left margin of buccal cavity. Inner three rows (apart from SKn) almost identical in length while outer rows shortened gradually (Figs 2D, 4F, K). Two PMs positioned on right margin of buccal cavity. Kinetids in outer PM (near SK1) arranged in zigzag pattern and longer than inner one, while inner PM seems to be composed of single row of kinetids (Figs 2E, 4F). Small bald area presents below posterior end of buccal apparatus, between SKn (kinety on left of buccal field) and SK1 (Figs 2D, 4E, K). Two pairs of basal bodies close to posterior end of SKn (Figs 2D, 4K).
Silverline system visible in vivo and after protargol staining, typical for genus, composed of longitudinally arranged silverlines located between SKs, and horizontally arranged silverlines connecting two neighboring longitudinal ones at mid and posterior part of the body, forming rectangular meshes where somatic cilia inserted centrally (Fig. 4E).
description: Published as part of Liu, Mingjian, Li, Lifang, Qu, Zhishuai, Luo, Xiaotian, Al-Farraj, Saleh A., Lin, Xiaofeng & Hu, Xiaozhong, 2017, Morphological Redescription and SSU rDNA-based Phylogeny of Two Freshwater Ciliates, Uronema nigricans and Lembadion lucens (Ciliophora, Oligohymenophorea), with Discussion on the Taxonomic Status of Uronemita sinensis, pp. 17-37 in Acta Protozoologica 56 (1) on pages 23-24, DOI: 10.4467/16890027AP.17.003.6967, http://zenodo.org/record/8364376