Orthodonella gutta ( Cohn, 1866 ) Kahl, 1931

Lin, Xiaofeng, Gong, Jun & Song, Weibo, 2004, Morphological studies on a new species of Orthodonella, with redescription of O. gutta (Cohn, 1866) Kahl, 1931 (Protozoa: Ciliophora: Synhymeniida) from coastal water off Qingdao, China, Journal of Natural History 38 (16), pp. 2001-2011 : 2007-2009

Orthodonella gutta ( Cohn, 1866) Kahl, 1931

( figures 3, 5–7, 10, 11 , 29–36 ; table 1)

To the authors’ knowledge, no investigations based on modern methods have been carried out since this species was reported. Thus, a detailed redescription of both living morphology and infraciliature is supplied here.

Improved diagnosis

Marine Orthodonella in vivo about 140–200 6 60–100 M m; body widely ellipsoidal with contractile beak-like anterior end; 62–74 (mean 66) somatic kineties with ca 41–48 ventral and 20–26 dorsal; synhymenium consisting of 43–70 dikinetids; 11–14 pharyngeal rods; one to several contractile vacuoles distributed in caudal area of cell; numerous cortical granules tiny and colourless; one ovoid macronucleus.

Sample sites

This population was collected from an open scallop-farming pond ( Chlamys farreri ) (salinity about 29, pH 7.3, water temperature about 8 ‡ C) off Qingdao.

Neotype specimens

Since no type specimens, treated with silver impregnation, have been deposited, one neotype, a protargol-impregnated slide, is deposited in the Natural History Museum , London, UK (registration number 2003:3:27:2) and one neoparatype, No.

All measurements are in M m.

(?), accounted from drawings, data not given.

Gong-00-12-22, protargol-impregnated specimen, has been deposited in the Laboratory of Protozoology, Ocean University of China.

Description of the Qingdao population

Cells in vivo generally larger than Orthodonella apohamatus , about 140–200 6 60–100 M m in size (N ~3). Body ellipsoidal with considerably tapering anterior end ( figures 7 , 31, 32 ). Unlike the new species described above, its pellicle is relatively flexible and the body is highly changeable with conspicuous contraction, especially the pointed anterior portion: from strongly bending to left (keeping this beak-like shape when still) to stretching straight forward ( figure 3 ). Cilia about 3–6 M m in length. Cortical granules tiny (ca 0.5 M m across), colourless and densely arranged between kineties ( figures 5 , 34 ). Cytostome (Cyst) rounded, in anterior fifth to sixth near right margin ( figures 7, 10 ; figures 35, 36 , arrows). Nematodesmata about 20–40 M m in length, consisting of 11–14 pharyngeal rods. Cytoplasm colourless, often containing numerous greasy globules (1–2 M m across) ( figures 6, 7 , 31–33 ). Food vacuoles usually with diatoms ( figures 7 , 31, 32 ). Four contractile vacuoles (3–8 M m across) (N ~3) distributed at posterior part of cell ( figures 7, 10 ). Macronucleus ovoid, 28–40 6 10–28 M m in size after impregnations ( figures 7, 11 , 29, 30 ).

Movement as in O. apohamatus , slow, with the anterior part swinging as it looks for food.

Infraciliature as shown in figures 10, 11 , 29–30 . Synhymenium composed of 43–70 (mean 53) dikinetids ( figures 10 , arrow). In total 62–74 (mean 66) somatic kineties including about 20–26 (mean 23) on dorsal and 41–48 (mean 44) on ventral side; conspicuously more densely arranged on ventral side than dorsal. Preorally about seven kineties curving around cytostome and separated by it ( figure 10 , arrowheads); postorally meridional.

Figures

FIGS. 1–11. Morphology and infraciliature of Orthodonella apohamatus nov. spec. (1, 2, 4, 8, 9) and O. gutta (3, 5–7, 10, 11) from life (1, 3, 5–7) and after protargol impregnation (2, 4, 8, 9–11). (1) Ventral view of a typical individual. (2) Ventral view, to show the synhymenium (arrows) and nuclear apparatus. (3) To demonstrate the form-transfiguration of the same individual. (4) To show different body shapes and sizes among individuals. (5) Cortical granules. (6) Oil globules. (7) Ventral view of an extended individual. (8, 9) Dorsal and ventral view of the same specimen, to show the general infraciliature, arrow indicates the synhymenium and arrowheads show the ‘broken’ kineties. (10, 11) Dorsal and ventral view of the same specimen, to show the general infraciliature, arrow indicates the synhymenium and arrowheads show the ‘broken’ kineties. CV, contractile vacuole; Cyst, cytostome; Ma, macronucleus; Mi, micronucleus. Scale bars: 40 Mm.

FIGS. 29–36. Photomicrographs of Orthodonella gutta from life (31–34) and after protargol (29, 30, 35, 36). (29, 30) Ventral and dorsal view of the same specimen, to show the infraciliature, arrow refers the synhymenium. (31, 32) Dorsal view, to show the formtransfiguration of the same individual. (33) To show oil globules. (34) Cortical granules. (35) To demonstrate the cytostome (arrow). (36) To show the end of pharyngeal rods (arrow). Scale bar: 50Mm.