Rhynchoclevelandella nipponensis ( Kidder, 1937 )

Kotyk, Michael, Bourland, William A., Soviš, Matyáš, Méndez-Sánchez, Daniel, Škaloud, Pavel, Varadínová, Zuzana Kotyková & Čepička, Ivan, 2024, Morphology maưers: congruence of morphology and phylogeny in the integrative taxonomy of Clevelandellidae (Ciliophora: Armophorea) with description of six new species, Zoological Journal of the Linnean Society 202 (1), pp. 1-51 : 19-20

Rhynchoclevelandella nipponensis ( Kidder, 1937)

( Fig. 21D–F, J, K ; Supporting Information, Table S22)

Rhynchoclevelandella nipponensis was detected and morphologically characterized in a single host population (PAC), never in high abundance.

Description based on PAC population: Medium-sized Clevelelandellidae (on average 82 × 33 µm in vivo, range 67–100 × 27–42 µm; on average 65 × 25 µm in protargol preparations, range 47–83 × 20–31 µm). Slender spade-shaped (L/W about 2.6) with long posterior peristomial projection (about 31% of cell length). Anterior right and left margins of body proper straight or concave. Macronucleus broadly ellipsoidal ( Fig. 21J , K) to broadly teardrop-shaped ( Fig. 21D , F), obliquely oriented to right of midline, prominent numerous globular nucleoli in vivo. Karyophore extremely inconspicuous, attached to posterior of macronucleus ( Fig. 21K ). Micronucleus ellipsoidal ( Fig. 21F , K), relatively large, about 5.5 µm across. Somatic cilia limited to approximately anterior 64% of cell length. Circumperistomial kineties only sparsely ciliated. Free right sutural kinetofragments not identified, presence of inconspicuous kinetofragments not completely excluded due to suboptimally oriented cells in protargol preparations. Adoral zone extends about 47% of cell length on average, composed of an average of 23 membranelles (range 20–25). POM unstudied.

Remarks: Overall morphology corresponds with original description and drawing by Kidder (1937) except (i) the ciliature: while Kidder (1937) depicts the cell as fully ciliated, we show that only the anterior two-thirds of the cell are ciliated and (ii) the macronuclear shape varies from broadly ellipsoidal ( Fig. 21K ) to broadly teardrop-shaped ( Fig. 21D , F, J).

Regarding measured characteristics (Supporting Information, Table S22), our population is slightly shorter than that of Kidder (1937) and Yamasaki (1939).

A notch sometimes forms at the base of peristomial projection ( Fig. 21F , J)—rarely in vivo but frequently in protargol-stained cells, creating a R. hastula -like appearance. However, R. nipponensis can be mostly distinguished from R. hastula by: length (approx. 65 µm vs. 85 µm), length/width ratio (approx. 2.6 vs. 3.4), number of adoral membranelles (approx. 23 vs. 26), and characteristic curvature of the most posterior third of peristomial opening in larger cells of hastula ( Fig. 21L , M). Very small cells of both species (e.g. Fig. 21D , N) can be rather indistinguishable.

Figures

Figure 21. Rhyncholevelandella sp.2 (A–C, G–I) from ASS. Rhynchoclevelandella nipponensis (D–F, J, K) from PAC.Rhynchoclevelandella hastula (L–T) from PGW. In vivo (A–F, L–O) and after protargol impregnation (G–K, P–T). A, ventral view (optical section) showing margin of the peristomial overture (black arrowhead) and adoral membranelles (black arrow). B, ventral view.C, ventral view showing cilia of circumperistomial kineties (white arrowhead). D, ventral view showing anterior margin of peristomial overture (black arrowhead). E, same cell showing ventral kineties (asterisk).F, ventral view showing contractile vacuole (white arrowhead), the relatively large micronucleus