Cothurnia ceramicola

Lu, Borong, Li, Lifang, Hu, Xiaozhong, Ji, Daode, Al-Rasheid, Khaled A S & Song, Weibo, 2019, Novel contributions to the peritrich family Vaginicolidae (Protista: Ciliophora), with morphological and phylogenetic analyses of poorly known species of Pyxicola, Cothurnia and Vaginicola, Zoological Journal of the Linnean Society 187 (1), pp. 1-30 : 25

COMMENTS ON COTHURNIA CERAMICOLA

( FIG. 12 ; TABLES 4, 5)

The lorica of our population is much larger than Kahl’s (95–105 vs. 60) and with relatively distinct annular ridges compared to the slight ridges in Kahl’s form (from the drawing). We think these are population-dependent differences, because unstriated, partly striated and completely striated loricas were found in a single species in another vaginicolid genus, Platycola ( Warren & Carey, 1983) . Our population matches Kahl’s form with respect to the marine habitat, having a lorica that is cylindroid in shape, slightly narrower towards the top and 1/4 to 1/3 of the body projects outside the lorica ( Kahl, 1933). It also shares an obviously striated endostyle, as well as a clearly striated and truncated-cone shaped mesostyle ( Fig. 12L ). Therefore, we identify it as Cothurnia ceramicola .

Precht (1935) described several populations, also collected from Kiel, that match perfectly with Kahl’s population and they are clearly conspecific, except for one form that was found from Gonothyraea loveni (Allman, 1859) where Precht put a question mark after the specific name, because the double-layered part of the lorica was considerably larger and the body protruded less ( Fig. 12M ). We think these are population-dependent differences. Felinska (1965) reported a form under C. ceramicola , but this identification is suspect, because her population differs distinctly from Kahl’s form by the narrowed aperture, the larger double-layered proportion (more than 1/3 vs. less than 1/4) and the much larger span of the annular ridges ( Fig. 12N ). The lorica of Küsters’ population is longer than Kahl’s (67–102 μm vs. 60 μm) and our population is more similar to Küsters’ population than to that of Kahl in the lorica size ( Fig. 12O ) ( Küsters, 1974). Song (1992) described a form of C. ceramicola isolated from the surface of Penaeus chinensis (Osbeck, 1765) , but the identification is doubtful: its lorica is clearly elliptical (vs. invariably cylindroid), has a smooth pellicle (vs. clearly striated pellicle) and a stalk of about 10 μm long (vs. 3–9; Song, 1992). Sun et al. (2009) recorded a population of C. ceramicola in the Yellow Sea, which corresponds closely with our population. They are conspecific, the only difference being that the P3 is composed of two rows of kinetosomes, although this is probably an illusion caused by the overlapped row 2 and row 3 ( Fig. 12Q ). Shen & Gu (2016) depicted a species as C. ceramicola , but this was probably a different species, because of its occurrence in freshwater ( Fig. 12R ).

Cothurnia ceramicola is mostly characterized by its marine habitat, annulated wall and combination of endostyle–mesostyle-stalk. Based on these characters, three closely similar species should be compared, i.e. C. curvula Entz, 1884 , C. harpactici Khal, 1933 and C. fibripes Kahl, 1933 . Cothurnia curvula can be separated from C. ceramicola by the curved anterior portion of the lorica (vs. straight), the obviously narrowed aperture (vs. equal to the lorica width) and the small proportion of the body that projects through the aperture (just the peristomial lip vs. 1/6–1/3 of the body length; Fig. 12S ) ( Entz, 1884). Cothurnia harpactici is close in size to C. ceramicola , but its stalk is much longer (15 μm vs. 3–5 μm; Fig. 12T ) ( Kahl, 1933; Precht, 1935; Warren & Paynter, 1991). Cothurnia fibripes is different from C. ceramicola in its distinctly shorter body length (60 μm vs. 95–100 μm) ( Kahl, 1935). Furthermore, its lorica is plumper than C. ceramicola (shape quotient 2.0 vs. 2.9–3.3) with a much narrower aperture (15 μm vs. 30–34 μm; Fig. 12U ).

Figures

Figure 12. Different isolates of Pyxicola pusilla (A–H) and its similar species (I–K), different isolates under the names of Cothurnia ceramicola (L–R) and its similar species (S–U), different isolates under the names of Vaginicola tincta (V–Z) and its similar species (Z1–Z4). A, Cothurnia pusilla sensu Wrześniowski, 1866. B, Cothurnia furcifer sensu Hutton, 1878. C, Pyxicola affinis sensu Kent, 1882. D, Pachytrocha cothurnoides sensu Kent, 1882. E, Caulicola valvata sensu Stokes, 1895. F, Pyxicola carteri sensu Sommer, 1951. G, Pyxicola eforiana sensu Tucolesco, 1962. H, after Shen & Gu, 2016. I, Pyxicola carteri (from Kent, 1882). J, Pyxicola operculigera (from Kent, 1869). K, Pyxicola psammata (from HadŽi, 1940). L, after Kahl, 1933. M, after Precht, 1935. N, after Felinska, 1965. O, after Küsters, 1974. P, after Song, 1992. Q, after Sun et al., 2009. R, after Shen & Gu, 2016. S, Cothurnia curvula (from Entz, 1884). T, Cothurnia harpactici (from Kahl, 1933). U, Cothurnia fibripes (from Kahl, 1933). V, Vaginicola tincta after Ehrenberg, 1838. W, after Kahl, 1935. X, after Stiller, 1971. Y, after Vucetich & Escalante, 1979. Z, after Shen & Gu, 2016. Z1, Vaginicola ceratophylli (from Penard, 1922). Z2, Vaginicola lagena (from Vucetich & Escalante, 1979). Z3, Vaginicola plicata (from Shen, 1980). Z4, Vaginicola festivus (from Shen & Gu, 2016). Scale bars = 30 μm.