New Contribution to the Morphology and Taxonomy of Four Marine ...

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158 W. Song et al. Table 5. Morphometric data of Cyrtohymena marina (Kahl, 1932). All data are based on protargol impregnated specimens. Measurements in µm Character Min Max Mean SD SE CV n Length of body 133 170 152.8 12.19 3.52 8.0 12 Width of body 53 75 62.8 7.46 2.15 11.9 12 Length of buccal field 55 70 61.4 5.72 1.81 9.3 10 Number of membranelles 32 42 37.0 3.28 0.95 8.9 12 Number of frontal cirri* 8 8 8 0 0 0 >30 Number of ventral cirri 5 5 5 0 0 0 >30 Number of transverse cirri 5 5 5 0 0 0 >30 Number of left marginal cirri 17 21 18.1 1.45 0.46 8.0 12 Number of right marginal cirri 19 25 21.9 2.18 0.69 10.0 12 Number of caudal cirri 2 3 2.6 0.54 0.20 20.8 7 Number of macronuclei 2 2 2 0 0 0 >30 Length of macronuclei 19 29 23.3 3.32 0.89 14.2 14 Width of macronuclei 13 19 15.5 2.01 0.64 12.9 14 Number of micronuclei 2 5 2.8 1.09 0.36 39.3 9 Number of dorsal kineties** 4 4 4 0 0 0 12 * Including buccal cirrus; ** short fragment on anterior-right cell margin not included (see text) ules, oval to elongate in shape, ca 5 x 3 µm in size, scattered within cytoplasm and difficult to observe in vivo; micronuclei ovoid, several in number (Fig. 15). Locomotion relatively slow, crawling without pause on debris or on bottom of Petri dish. Buccal apparatus as shown in Fig. 13. Adoral zone of membranelles (AZM) extending to about 1/4 of body length in fixed specimens, bases of membranelles up to 8-12 µm long, cilia ca 15 µm long in vivo. Distal end of AZM extends to right margin of cell and bends considerably posteriad. Paroral membrane short (arrow in Fig. 13), lies parallel to long endoral membrane. Pharyngeal fibres conspicuous after protargol impregnation, about 50 µm long (Fig. 14). Most somatic cirri relatively fine. Bicorona consisting of about 7 pairs of slightly enlarged frontal cirri, which curve to left margin of cell. Two small frontoterminal cirri often difficult to recognize (FTC, Fig. 13). Single buccal cirrus (double-arrowhead in Fig. 13) small, situated beside mid-point of paroral membrane. Midventral rows terminating subcaudally about 20 µm anterior to transverse cirri, giving the appearance of a narrowed longitudinal furrow at low magnification. Usually 4 transverse cirri, rather fine and inconspicuous, positioned at posterior end of cell (Fig. 14), but projecting only slightly beyond posterior body margin when viewed in vivo (Fig. 9). Cirri in both marginal rows rather densely distributed; anterior portions of right marginal row extending to about distal end of adoral zone of membranelles. Posterior end of marginal rows clearly separated (Figs 9, 14). Usually 4 (seldom 5) dorsal kineties in both populations, each comprising ca 30 pairs of basal bodies; cilia about 3-8 µm long. Caudal cirri absent (Fig. 15). Comparison and discussion. Several morphotypes of marine Pseudokeronopsis with yellow, yellow-brownish or orange-red colour and slender body shapes have been previously reported. These include: P. carnea, P. rubra, P. flava and P. flavicans (Cohn 1866, Entz 1884, Möbius 1888, Morgan 1926, Kahl 1932, Rühmekorf 1935, Foissner 1984, Wirnsberger et al. 1987). Three of these, P. carnea, P. rubra and P. flava, have previously been redefined using modern methods (Foissner 1984, Wirnsberger et al. 1987). Several workers have noted that species identification in Pseudokeronopsis is often difficult (Kahl 1932, Jerka-Dziadosz and Janus 1972, Borror and Wicklow 1983, Foissner 1984, Wirnsberger et al. 1987, Hu and Song 2000). This is because the body shape, the morphogenetic pattern, the infraciliature and the cell colour (even the arrangement of pigments) of many taxa are very similar. In the light of the body shape and size, general ciliary pattern, the cell colour as well as most of the morphometric data, Pseudokeronopsis flavicans is extremely difficult to distinguish from P. flava as described by Wirnsberger et al. (1987) (Fig. 20). We do not
On four marine hypotrichs 159 consider them conspecific mainly because, according to the redescription of Wirnsberger et al. (1987), the latter seems to have no specialisation of the “cortical granules” as observed in P. flavicans, i.e. blood-cell-like granules and the colour of “pigments” (bright yellowbrownish vs. yellow). Other differences include the fact that P. flava is smaller (140-250 vs. 200-300 µm long), has fewer frontal cirri in the bicorona (ca 9 vs. ca 14) and transverse cirri (1-3 vs. 3-6) (Table 3), and is less slender (ratio of length to width about 3-5:1 vs. 5-6:1) than P. flavicans. In addition, Wirnsberger et al. (1987) emphasized that there is always a conspicuous gap (ca 30 µm) between the posterior end of midventral rows and the transverse cirri in P. flava, while in P. flavicans the gap is less conspicuous (
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