Bioacoustics of Chilodontopsis simplex

Remarks. To our knowledge, since the establishment of the genus Chilodontopsis Blochmann, 1895 , about 16 nominal species had been assigned to the taxon, and several have been either recognized as a junior synonym (e.g. C. planicaudata Song & Wilbert, 1989 ), or transferred into other genera (e.g. Nassula oblonga (Maupas, 1883) Kahl, 1931 , Chilodonella bengalensis (Ghosh, 1921) , Zosterodasys transverses ( Kahl, 1928 ) Foissner et al. , 1994 , and Nassulopsis elongata ( Kahl, 1931 ) Foissner et al. , 1994 ; for details see Kahl 1931 and Foissner et al. 1994 ). We therefore accept 11 species of Chilodontopsis (see Figs. 27–37 ), including: C. depressa (Perty, 1852) Blochmann, 1895 , C. vermiformis Deroux, 1978 , C. kurensis Alekperov, 1985 , C. muscorum Kahl, 1931 , C. acuta Ozaki & Yagiu, 1941 , C. caudata Kahl, 1933 , C. hisioensis Ozaki & Yagiu, 1941 , C. nemerosa Ozaki & Yagiu, 1941 , C. ovalis Biernacka, 1963 , C. pseudonassula ( Penard, 1922 ) and C. simplex Ozaki & Yagiu, 1941 (for references see Alekperov 1985 ; Biernacka 1963 ; Blochmann 1895 ; Deroux 1978 ; Foissner 1984 ; Foissner et al. 1994 ; Kahl 1931 , 1933 ; Ozaki & Yagiu 1941 ; Penard 1922 ). Character Min Max Mean SD SE CV n Abbreviations: CV = coefficient of variation in %, Max = maximum, Mean = arithmetic mean, Min = minimum, n = number of individuals examined, SD = standard deviation, SE = standard error of mean. Cell length 92 160 152 380 127.3 240.5 14.64 61.55 2.77 11.5 11.85 25.6 28 27 Cell width 52 68 84 136 63.2 92.2 9.38 17.01 1.77 14.8 3.47 18.4 28 24 Length of macronucleus 26 56 52 128 41.5 85.0 7.53 17.73 1.64 18.1 3.48 20.9 21 26 Width of macronucleus 20 12 40 40 27.4 24.3 5.40 7.87 1.18 19.7 1.54 32.4 21 26 Number of ventral kineties 30 47 45 77 36.2 64.0 4.24 8.17 1.00 11.7 1.83 12.8 18 20 Number of dorsal kineties 23 42 38 63 30.3 56.9 4.75 5.41 1.12 15.7 1.21 9.5 18 20 Number of somatic kineties 59 105 78 138 66.6 121.0 5.28 9.39 1.24 7.9 2.00 7.8 18 22 Number of nematodesmal rods 11 15 13 18 11.8 16.3 0.70 0.96 0.15 5.9 0.20 5.9 21 23 Number of dikinetids in synhymenium 45 65 90 130 55.3 88.5 10.84 17.77 2.49 19.6 4.44 20.1 19 16 Diameter of cytostome 3 4 5 10 4 5.7 0.43 1.68 0.13 10.8 0.43 29.5 12 15 Length of cyrtos 40 56 70 112 51.6 88.9 14.31 16.81 6.40 27.7 4.66 18.9 5 13 In 1941, Ozaki and Yagiu established the species Chilodontopsis simplex , with describing some important living features, for example, cell size on average 110 × 45 µm, single macronucleus measuring 29 × 11 µm, with one large, irregularly shaped contractile vacuole which is always located near the posterior region of the left side of the cell ( Fig. 34 ; Ozaki & Yagui 1941 ). The authors also pointed out that the species had no “postoral ciliary line”, which most probably referred to the synhymenium. We argue that the absence of synhymenium is either a character of a genus other than Chilodontopsis , or a mis-observation, and we assume the latter is the case. Since no redescription with infraciliature features has been available for this species so far, our population of C. simplex is identified based on the living features (e.g. cell shape and size, with one contractile vacuole) and marine habitat ( Ozaki & Yagui 1941 ). Compared with the four species (i.e. Chilodontopsis depressa , C. vermiformis , C. kurensis and C. muscorum ) for which the infraciliature is known, C. simplex most resembles the freshwater species C. kurensis in terms of cell size and shape ( Fig. 29 ; Table 2 ; Alekperov 1985 ). Nevertheless, C. simplex has more somatic kineties (59–78 vs. 50–60), fewer nematodesmal rods (11–13 vs. 20), and higher ratio of synhymenium length to cell length (1:1 vs. 1:3), hence can be recognized ( Alekperov 1985 ). Chilodontopsis depressa and C. vermiformis can be distinguished from C. simplex by their smaller cell size (50–80 vs. 90–160 μm in length), and having fewer somatic kineties (27– 42 vs. 59–78) ( Figs. 27, 28 ; Table 2 ; Foissner et al. 1994 ; Deroux 1978 ). Chilodontopsis muscorum differs from C.