Uronema nigricans Florentin 1901
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
Hymenostomatida
Uronematidae
Uronema
Uronema nigricans

description: Uronema nigricans (Müller, 1786) Florentin, 1901
(Figs 2A, C, F, 3A–M, Table 1)
Uronema nigricans has been redescribed several times since its first recording. However, high-quality photomicrographs of protargol-stained individuals and SSU rDNA sequencing were not available previously. In this study, we determined an improved diagnosis and a detailed redescription based on previous and present data.
Improved diagnosis: Cell size ca. 20–50 μm × 10–25 μm in vivo with a truncated apical plate; pellicle thin and inconspicuously notched, with ridges located longitudinally along ciliary rows; 10–15 somatic kineties, somatic kinety 1 usually shortened, posterior end extending at about three fourths to four fifths of cell; oral apparatus typical of the genus, membranelle 1 clearly separated from other membranelles; freshwater and brackish water habitat.
Deposition of voucher slides: Two voucher slides (registration nos. LMJ2015120701-1 and LMJ2015120701-2) have been deposited in Laboratory of Protozoology, Ocean University of China, Qingdao, China.
Morphological description of Shenzhen population: Cell size in vivo about 30–40 μm × 12–20 μm. Cell shape elongate-elliptical in outline. Anterior end flat, with a prominent apical plate. Posterior part broadly rounded (Figs 2A, 3A–C, E). Buccal field about half body length and slightly concave. Pellicle thin and inconspicuously notched with ridges located longitudinally along ciliary rows (Figs 2A, 3A, E). No extrusomes detected in vivo. Cytoplasm colorless to slightly grayish, containing several bar-like crystals distributed in anterior and posterior portions. Well-fed individuals containing several to many grayish-green food vacuoles, leading to a dark gray body color at low magnifications (Figs 3A–E). Single contractile vacuole subcaudally positioned, about 3–4 μm in diameter when fully expanded, pulsating at intervals of 6–8 s (Figs 2A, 3A). Somatic cilia about 5–7 μm long in vivo, densely arranged (Figs 2A, 3A–E); single caudal cilium approximately 15–20 μm long (Figs 2A, 3A, C, D). Single spherical to oval macronucleus located centrally or slightly ahead of mid-body, about 10 μm in diameter in protargol preparations (Figs 2F, 3J–M). Locomotion by swimming moderately fast, but cells observed mostly crawling on substrates or resting on the bottom of petri dish when not disturbed.
aCV, coefficient of variation in %; Max, maximum; Mean, arithmetic mean; Min, minimum; n, number of individuals examined; SD, standard deviation; SK 1, the kinety on right of buccal field; SK mid, the middle kinety on dorsal side; SK n, the kinety on left of buccal field.
Somatic ciliature as shown in Figs 2C, F, 3F–M. Thirteen to fifteen somatic kineties (SKs) arranged longitudinally, forming a small glabrous area at anterior end (Figs 2C, F, 3J–M). Somatic kinety 1 (SK1, kinety on right of buccal field) usually shorter than other SKs, with posterior end terminating at about three fourths to four fifths of cell (Figs 2C, 3J, L). Somatic kinety n (SKn, kinety on left of buccal field) located slightly posteriorly with anterior end commencing at front part of membranelle 1 (M1) (Figs 2C, 3J, L). In general, each kinety composed of closely arranged dikinetids in anterior part and loosely arranged monokinetids posteriorly (Figs 2C, F, 3J–M). Dikinetids of some individuals extending to the posterior end, almost occupying four-fifths of SK. Somatic kinety 1 composed of 15–19 kinetids, including four to 14 dikinetids, while SKn composed of 15–20 kinetids, with three to 10 dikinetids (Figs 2C, 3J, L). The middle SK on the dorsal side comprising 12–15 kinetids (Figs 2F, 3K, M).
Buccal apparatus similar to its congeners (Figs 2C, 3I, L). Membranelle 1 (M1) single-rowed and positioned near apical plate, clearly separated from other membranelles. It consisted of 5 or 6 basal bodies arranged in one row and a central basal body slightly deviated to the left (towards SKn) (Figs 2C, 3I, J, L). Membranelle 2 (M2) almost equal to M 1 in length and composed of two or three longitudinal rows of basal bodies (Figs 2C, 3H, I, L). Membranelle 3 (M3) composed of about seven to nine basal bodies, forming a small patch (Figs 2C, 3I, L). Paroral membrane (PM) on right of shallow buccal cavity, composed of two rows of basal bodies in a zigzag pattern, and extending anteriorly to about middle portion of M2 (Figs 2C, 3H–J, L). Scutica observed usually consisting of two or three pairs of basal bodies with one or two basal bodies positioned posteriorly (Figs 2C, 3F, G, L).
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 19-21, DOI: 10.4467/16890027AP.17.003.6967, http://zenodo.org/record/8364376