Uronema orientalis, Pan & Huang & Fan & Ma & Al-Rasheid & Miao & Gao, 2015

Pan, Xuming, Huang, Jie, Fan, Xinpeng, Ma, Honggang, Al-Rasheid, Khaled A. S., Miao, Miao & Gao, Feng, 2015, Morphology and Phylogeny of Four Marine Scuticociliates (Protista, Ciliophora), with Descriptions of Two New Species: Pleuronema elegans spec. nov. and Uronema orientalis spec. nov., Acta Protozoologica 54 (1), pp. 31-43 : 38-40

Uronema orientalis spec. nov. ( Fig. 4 ; Table 1 )

Diagnosis: In vivo about 40–55 × 20–30 μm with a truncated apical plate; buccal field about 50% of body length; consistently twenty somatic kineties; membranelle 1 (M1) one-rowed, divided into two parts: the anterior part (M1a) and the posterior part (M1b), comprising four and three basal bodies, respectively; contractile vacuole caudally positioned near ventral margin; contractile vacuole pore (CVP) positioned at end of the second somatic kinety; marine habitat.

Type locality: A beach near Sculpture Garden (36°4′N; 120°29′E), Qingdao , China .

Type slides: The holotype slide (registration number: PXM-2012041301) and one paratype slide (registration number: NHMUK 2013.8.15.2) with protargol stained-specimens are deposited in the Laboratory of Protozoology , OUC and the Natural History Museum, London, respectively .

Dedication and etymology: The species receives its name ‘ orientalis ’ from the locality where it was isolated.

Description: Size in vivo about 40–55 × 20–30 μm, elongate-elliptical in outline ( Figs 4A, E ). An- terior end flat, with an apical plate, dorsal posterior area broadly rounded ( Figs 4A, E ). Buccal field about 50% of body length ( Fig. 4A ). Pellicle smooth, with- out ridges ( Figs 4E–G ). Extrusomes bar-shaped, about 4 μm long, and sparsely arranged beneath pellicle. Cytoplasm colourless to grayish, containing several to many large (ca 5 μm across) food vacuoles and dumb- bell-shaped crystals, which are usually 4 μm long ( Figs 4A, I, J ). Single macronucleus oval to spherical, centrally located ( Fig. 4C ). Contractile vacuole moderately large, 5 μm in diameter, caudally positioned ( Figs 4A, J ). Somatic cilia about 10 μm long, densely arranged; single caudal cilium approximately 20 μm long ( Figs 4G, H ). Swimming moderately fast while rotating about main body axis, sometimes crawling on debris, or resting on the bottom.

Consistently twenty somatic kineties arranged longitudinally, which usually have monokinetids in the entire length of each row ( Figs 4B, C, K ). Buccal apparatus as shown in Figs 4D, K : M1 one-rowed, divided into two parts: the anterior part (M1a) and the posterior part (M1b) comprising four and three basal bodies, respectively. M2 composed of two longitudinal rows of basal bodies; M3 comprising three longitudinal rows ( Figs 4D, K ). Paroral membrane on right of buccal cavity terminating halfway along M2 ( Figs 4D, K ). Scutica consisting of four pairs of basal bodies ( Figs 4D, K ). Contractile vacuole pore positioned at the end of second somatic kinety ( Fig. 4L ).

SSU rRNA gene sequence: The SSU rRNA gene sequence of Uronema orientalis spec. nov. has been deposited in the GenBank database with the accession number, length and G+C content as follows: KF840517 , 1657 bp, 42.37%.

Remarks and comparison: Considering the morphology, infraciliature and habitat, three species have similarities with our new species: Uronema marinum Dujardin, 1841 , U. elegans Maupas, 1883 and U. heteromarinum Pan et al., 2010 .

Though Uronema marinum is similar to U. orientalis in body shape and the conspicuous extrusomes, it can be distinguished by the patterns of M1 (one row with 3–6 basal bodies in U. marinum vs. divided into two parts and comprising four and three basal bodies, respectively in U. orientalis ), the number of somatic kineties (12–14 vs. 20 in U. orientalis ), and the location of the contractile vacuole pore (at posterior end of kinety 2 in U. marinum vs. at posterior end of kinety 1 in U. orientalis ) ( Pan et al. 2010).

Compared with Uronema orientalis , U. elegans is distinguished by the ratio of body length to width (1.5: 1 vs. 2.5: 1 in U. orientalis ) and more somatic kineties (23–26 vs. 20) (Song et al. 2002).

Uronema heteromarinum differs from U. orientalis in having reticulate ridges on a notched pellicle and fewer somatic kineties (15–16 vs. 20 in U. orientalis ) ( Pan et al. 2010).

Figures

Fig. 4. Uronema orientalis spec. nov. in vivo (A, E–J), after protargol (B–D, K) and silver nitrate staining (L). A, E – ventral views of a typical cell; B, C – ventral (B) and dorsal (C) views of the same specimen, showing infraciliature and nuclear apparatus; D, K – detailed infraciliature of buccal area, arrowhead in (K) shows the gap between the anterior part and posterior parts of membranelle 1; F, G – ventral views, to show different body shapes; H – posterior region of cell, arrow points to caudal cilia, arrowheads show somatic cilia; I – ventral view, arrow refers to blue irregularly-shaped crystal, arrowhead indicates dumbbell-shaped crystal; J – ventral view, arrow shows contractile vacuole, arrowhead marks buccal field; L – ventral view, arrow shows contractile vacuole pore. M1, 2, 3 – membranelles 1, 2 and 3; M1a – the anterior part of membranelle 1; M1b – the posterior part of membranelle 1; Ma – macronucleus; PM – paroral membrane; Sc – scutica. Scale bars:A, B, C = 50 μm; E–G, J, K = 80 μm.