Clevelandella hastula ( Kidder, 1937 )

PECINA, Lukáš & VĎAČNÝ, Peter, 2020, Morphological versus molecular delimitation of ciliate species: a case study of the family Clevelandellidae (Protista, Ciliophora, Armophorea), European Journal of Taxonomy 697, pp. 1-46 : 12-13

Clevelandella hastula ( Kidder, 1937)

Figs 4–5

Description of Vietnamese population

Size in vivo about 75–105 × 25–35 μm, usually 90 × 30 μm, as calculated from some in vivo measurements and morphometric data; length:width ratio ranging from 2.6:1 to 3.5: 1 in protargol preparations ( Table 2). Body spear-shaped, widest at mid-portion, i.e., about at level of contractile vacuole. Anterior end pointed; posterior body portion differentiated into a conspicuous, long peristomial projection; left side distinctly curved at level of proximal end of adoral zone of membranelles and hence forming a lobe above the base of peristomial projection ( Figs 4 A–N, 5A–H). Macronucleus located in anterior second fourth of body; ellipsoidal, with a length:width ratio of 1.3–1.7: 1 in protargol preparations; 15–23 × 11–15 μm in size after protargol impregnation; filled with innumerable globular structures (presumably nucleoli) 0.7–1.8 μm in diameter after protargol impregnation, well observable in vivo and in some protargol preparations. Karyophore absent. Micronucleus invariably attached to anterior side of macronucleus; almost globular to broadly ellipsoidal with a length:width ratio of 1.0–1.7:1; about 4–6 × 3–4 μm in size after protargol impregnation ( Table 2; Figs 4 A–L, 5B–F). Contractile vacuole just above base of peristomal projection near left body margin, i.e., at level of proximal end of peristomial funnel ( Fig. 4A, L ). Cortex flexible, no cortical granules recognizable. Cytoplasm colorless; finely granulated; refractile bodies concentrated in cytoplasm anteriorly to macronucleus, recognizable in vivo and after protargol impregnation; cytoplasm posterior to macronucleus contains some free (symbiotic?) bacteria and/or archaea and food vacuoles about 2.5–4.0 μm across with prey prokaryotes ( Figs 4A , 5 B–F). Swims slowly; dies quickly on microscope slides, possibly due to presence of oxygen; body shape changes in dying and strongly squeezed cells, i.e., left margin loses a small notch at level of the base of peristomial projection ( Fig. 5 F–H).

Somatic ciliature holotrichous; cilia about 4.0–6.0 μm long in vivo and very narrowly arranged. Approximately 80 ciliary rows narrowly spaced over entire body surface and about 25 ciliary rows running onto peristomial projection. Peristomial ciliary rows in a form of strongly oblique lines in ventral view, while in a form of shallow arcs in dorsal view ( Figs 4 M–N, 5G–H). Almost all body ciliary rows begin from a whorl (posterior suture) on left body side about at level of proximal end of peristomial funnel, i.e., near location of contractile vacuole ( Figs 4 M–N, arrowheads, 5G–H, asterisks) to radiate over ventral and dorsal sides toward right body margin; some kineties shortened anteriorly or posteriorly. Right suture extends from base of peristomial projection to anterior body end; formed by obliquely abutting ventral and dorsal ciliary rows ( Fig. 4M , arrow).

Peristomial projection conspicuous because it occupies on average 38% of body length and measures 23–34 × 9–15 μm after protargol impregnation. Peristomial opening situated on left ventral side of peristomial projection, roughly triangular and relatively large, i.e., about 17% of body length and 11–15 × 9–12 μm in size after protargol impregnation ( Figs 4 A–M, 5A–G). Peristomial funnel approximately 34 μm long in protargol preparations. Adoral zone extends slightly obliquely from distal end of peristomial projection across right side of peristomial funnel to terminate about at level of base of peristomial projection; occupies 36% to 50% of body length; composed of on average 32 membranelles; cilia of distalmost membranelles about 8 μm long in vivo and projecting out of peristomial funnel ( Table 2; Figs 4A, L , 5 B–G). Paroral membrane diplostichomonad, i.e., composed of two rows of basal bodies; runs in parallel with adoral zone on opposite side of peristomial funnel; commences about at level of proximal end of peristomial opening and terminates near cytostome at proximal end of peristomial funnel ( Figs 4L , 5E ). Pharyngeal fibres originate from proximal end of adoral zone and paroral membrane, run transversely leftwards forming a conical funnel about 12 μm long in vivo.

Figures

Fig. 4. Clevelandella hastula (Kidder, 1937). Vietnamese specimens isolated from Panesthia angustipennis cognata Bey-Bienko, 1969 from life (A) and after protargol impregnation (B–N). A. Ventral view of a representative specimen, length 90 μm. B–K. Variability of body shape and size as well as of the nuclear (shaded grey) and oral (shaded yellow) apparatus. L. Semi-schematic diagram, showing the general body organization. M–N. Ciliary pattern of ventral and dorsal sides. Arrow marks the right suture and black arrowheads denote the position of the ciliary whorl (posterior suture). Scale bars = 30 μm.

Fig. 5. Clevelandella hastula (Kidder, 1937). Vietnamese specimens isolated from Panesthia angustipennis cognata Bey-Bienko, 1969 from life (A, F–H) and after protargol impregnation (B–E). A–E. Ventral view of specimens with well-preserved body shape. Arrows mark the proximal end of the peristomial opening, black arrowheads mark the proximal end of the adoral zone of membranelles. F. Ventral view, showing general organization of body. G–H. Ciliary pattern of ventral and dorsal sides. Conspicuous cilia of adoral membranelles emerge out of the peristomial opening in (G).Asterisks indicate the position of the ciliary whorl (posterior suture), arrow marks the proximal end of the peristomial opening. Scale bars = 30 μm.