Eupotes balteatus ( Dujardin, 1841 ) Kahl, 1932

Pan, Ying, Li, Liqiong, Shao, Chen, Hu, Xiaozhong, Ma, Honggang, Alrasheid, Khaled A. S. & Warren, Alan, 2012, Morphology and Ontogenesis of a Marine Ciliate, Euplotes balteatus (Dujardin, 1841) Kahl, 1932 (Ciliophora, Euplotida) and Definition of Euplotes wilberti nov. spec., Acta Protozoologica 51 (1), pp. 29-38 : 30-33

Eupotes balteatus ( Dujardin, 1841) Kahl, 1932 ( Figs 1A–P , 2A–F ; Table 1)

Improved diagnosis: Small to medium-sized marine Euplotes , 30–80 µm × 20–60 µm in vivo; buccal field about 2/3 of cell length, with about 35 adoral membranelles; constantly 10 frontoventral, five transverse, two caudal and two widely separated left marginal cirri; eight dorsal kineties with about 15 dikinetids in mid-dorsal rows. Dorsal silverline system doubleeurystomus type.

Morphological description of Qingdao population: Body size highly variable, usually 30–80 µm × 20–60 µm in vivo ( Table 1; Fig. 1A–D, L ). Body generally broadly oval in outline, sometimes with a narrow anterior end. Both margins smooth except for a small projection at the right anterior end. Dorsoventrally highly flattened, ventral side somewhat concave, dorsal side convex, without distinct ridges or grooves ( Fig. 1N ). Each dorsal cilium surrounded by 7 to 9 ellipsoid granules forming a rosette beneath the pellicle ( Fig. 1F, M ). Cytoplasm colorless, usually with numerous crystals and food vacuoles of different sizes making cell appear opaque or dark gray in vivo ( Fig. 1A–C, L ). Macronucleus generally C-shaped, somewhat variable among individuals ( Fig. 1J, P ). Micronucleus oval, usually attached to mid-region of macronucleus ( Fig. 1P ).

Adoral zone approximately 55–85% of the body length, composed of 28–43 membranelles, the bases of which are up to 8–10 µm in length. Paroral membrane thin and long, lying parallel to main body axis and to the right of the posterior portion of the adoral zone of membranelles (AZM). Contractile vacuole about 8 µm in diameter, located posteriorly near the right body margin ( Fig. 1C, L ).

Locomotion typically by moderately fast crawling or incessant jerking on substrate. Most active when near dense growths of bacteria.

Cirri on the ventral side relatively fine with cilia about 14 µm long in vivo ( Fig. 1A, D, L ). Constantly ten frontoventral cirri (FVC), among which cirrus VI/2 is nearer to cirrus V/2 than to cirrus V/3, the other seven frontoventral cirri located in frontal area of body ( Fig. 1K, O ). Constantly five strong transverse cirri, cilia of which are about 30 µm long; cirrus VI/1 is located slightly higher than cirrus II/1 ( Fig. 1K, O ). Two fine, widely separated marginal cirri. Anterior marginal cirrus and leftmost transverse cirrus located at about the same level ( Fig. 1K, O ). Two fine caudal cirri ( Fig. 1O ). Invariably eight dorsal kineties that extend entire length of body. First and last dorsal kineties usually positioned near the edge on the ventral side, the middle ones consist of 12–16 dikinetids ( Fig. 1O, P ).

Dorsal silverline system irregular double- eurystomus type, i.e. distances from the silverline to both neighboring ciliary rows about equal ( Figs 1H , 4F ) with moderately dense silverline grids on ventral side ( Figs 1I , 4E ).

Figures

Fig. 1A–P. Euplotes balteatus from life (A–G, L–N), after protargol (J, K, O, P) and silver nitrate (H, I) impregnation. A – ventral view of a typical individual; B – ventral view of a well-fed specimen; C – dorsal views showing general body shape; D – ventral view to demonstrate the arrangement of cirri; E, F – details of cell (ventral view), arrow and arrowhead in E indicate the left marginal cirri and paroral membrane respectively; arrows in F mark the dorsal cilia; G – arrows denote the transverse cirri; H, I – silverline system on dorsal and ventral sides respectively; J – macronucleus (arrows); K – infraciliature on ventral side; L – ventral view of a representative individual, arrow indicates the contractile vacuole; M – sub-pellicular rod-like structures around dorsal cilia; N – lateral view, to show the flattened body shape; O, P – ventral and dorsal views, to show the infraciliature and nuclear apparatus. CC – caudal cirri, LMC – left marginal cirri, Ma – macronucleus, Mi – micronucleus, PM – paroral membrane. Scale bar: 40 µm.

Fig. 2A–L. Morphogenesis of Euplotes balteatus after protargol impregnation. A, B – ventral view and macronucleus of the same specimen at an early stage to show the appearance of frontoventral transverse cirral anlagen, the developing oral primordium and macronuclear replication bands (arrows); C, D – slightly later divider, ventral view and macronucleus of the same specimen, indicating 5 FVT-cirral streaks (arrowheads) and the enlarging oral primordium; arrows point to the replication bands; E, F – ventral and dorsal views of the same specimen to show the marginal cirral anlagen (arrowheads), cirrus I/1 anlage and the newly formed dorsal kinety anlagen (DKA, macronuclear replication bands (arrows)); G, H – ventral and dorsal views of the same specimen, showing the fragmentation of the cirral anlagen, the formation of cirrus I/1 anlage for the opisthe (arrow), the UM-anlage for the opisthe and the development of the anlagen both of the marginal cirri (arrowheads) and of the dorsal kineties; I, J – ventral and dorsal views of the same middle-stage divider to show the completion of the cirral development, the differentiation of the caudal cirri (double arrowheads), the development of cirrus I/1 for the opisthe (arrow) and the marginal cirri (arrowheads); K, L – ventral and dorsal views of a late divider, showing the migration of the cirri, the development of the dorsal kineties and the dividing macronucleus. Arrowheads indicate the marginal cirri and arrows point to the caudal cirri. FVTA – frontoventral-transverse anlagen, Ma – macronucleus, DKA – dorsal kinety anlagen, MCA – migratory cirral anlagen, UMA – undulating membrane anlagen, MC – migratory cirri, OP – oral primordium. Scale bar: 30 µm.

Fig. 4A–K. Euplotes balteatus and Euplotes wilberti nov. spec. from life (A, G), after protargol (D, J, K) and silver nitrate (B, C, E, F, H, I) impregnation. Arrows point to the marginal cirri. A – ventral view of Euplotes balteatus, to show the ventral ciliature (from Kahl 1932); B, C – ventral and dorsal views of Euplotes balteatus, showing the silverline systerm (from Tuffrau 1964); D – Euplotes balteatus, to show variations in the shape of the macronucleus; E, F – ventral and dorsal views showing the silverline system; G–K – Euplotes wilberti nov. spec., to show the live morphology (G), silverline system (H, I), infraciliature (J, K) and macronucleus (K) (from Song and Wilbert 2002). Scale bar: 30 µm.