Trachelophyllum brachypharynx Levander, 1894

Jang, Seok Won, Vďačný, Peter, Shazib, Shahed Uddin Ahmed & Shin, Mann Kyoon, 2015, Morphology, Ciliary Pattern and Molecular Phylogeny of Trachelophyllum brachypharynx Levander, 1894 (Litostomatea, Haptoria, Spathidiida), Acta Protozoologica 54 (2), pp. 123-135 : 125-127

Trachelophyllum brachypharynx Levander, 1894

1894 Trachelophyllum brachypharynx – Levander, Acta Soc. Fauna Flora fenn. 12: 66, Taf. III, Fig. 1 [reproduced here as Fig. 35 ] (original description).

1930 Trachelophyllum brachypharynx Levander, 1894 – Kahl, Tierwelt Dtl. 18: 115, Fig. S. 104, 5 [reproduced here as Fig. 36] (revision).

Improved diagnosis (Korean population): Size about 380 × 40 μm in vivo, slightly contractile. Shape very narrowly fusiform, with a slightly to distinctly narrowed neck, gradually merging into a broadened trunk. Two ellipsoidal macronuclear nodules usually connected by a fine strand, with two to three broadly ellipsoidal micronuclei close to or attached to macronuclear nodules. Contractile vacuole terminal and comparatively small. Extrusomes filiform, slightly curved and with pointed ends, 30 µm long in vivo. On average, 24 ciliary rows, two anteriorly differentiated into an isostichad dikinetidal dorsal brush: row 1 composed of 40 dikinetids on average, row 2 of 33 dikinetids on average. Lepidosomes hat-shaped and about 4 × 3.7 µm in vivo.

Type locality: Levander(1894) discovered T.brachypharynx in brackish water from the Finnish shore.

Voucher material: Three slides with protargol-impregnated Korean specimens have been deposited in the Natural Institute of Biological Resources ( NIBR), Incheon, South Korea with the following registration numbers NIBRPR0000105674. The relevant specimens are marked with ink circles on the backside of the slides .

Gene sequence: The 18S rRNA gene sequence of the Korean population has been deposited in GenBank with the accession number KJ680555. The sequence is 1543 nucleotides long and has a GC content of 43.1%.

Etymology: Not given in the original description. The name is a composite of the Greek prefix brachy - (βραχυ-; short) and the Latin noun pharynx, referring to the short cytopharynx of the species. Because the species epithet stands in apposition to the generic name [Article 11.9.1.2 of ICZN (1999)], its ending need not agree in gender with the generic name with which it is combined and must not be changed to agree in gender with the generic name [Article 34.2.1 of ICZN (1999)].

Description of Korean population: Size in vivo about 330–445 × 35–45 µm, usually near 380 × 40 μm; morphometric data from protargol-impregnated specimens indicate shrinkage of body length by about 12% and inflation of body width by about 20% ( Table 2). Body flexible, up to 2:1 flattened dorsoventrally, and slightly contractile especially in neck region; both con- traction and extension occur slowly, thus exact body shape and size difficult to determine. Shape very narrowly fusiform both in vivo and after protargol impregnation, but prepared specimens appear stouter on average due to length shrinkage and width inflation (see above), i.e., body length:width ratio 9.7: 1 in vivo while 8.3:1 after protargol impregnation. Anterior end rather conspicuous due to pin-shaped to conical oral bulge and slightly broadened neck region below it, forming a head-like structure ( Figs 2–4 , 22, 24 ). Neck distinctly narrowed and usually slightly curved in extended specimens, while more or less inconspicuous in contracted ones; gradually merges into broadened trunk. Posterior body end typically narrowly rounded, sometimes point- ed ( Figs 1, 5, 13–21, 27, 29, 30 ).

Nuclear apparatus in middle trunk region; typically composed of two macronuclear nodules and several micronuclei. Macronuclear nodules broadly to narrowly ellipsoidal, on average ellipsoidal, with a length width ratio of 1.3–3.6:1, with an average near 2:1 both in vivo and after protargol impregnation; size about 32 × 17 µm in vivo, while 48 × 25 µm after impregnation; usually distinctly apart and connected by a fine strand, very rarely abutting (in one out of 30 specimens analyzed). Nucleoli numerous, small to medium-sized, rounded to narrowly ellipsoidal, evenly distributed over macronuclear nodules, well recognizable after protargol impregnation. Two to three micronuclei attached to macronuclear nodules at varying positions, rarely slightly distant from them, broadly ellipsoidal, i.e., approximately 4 × 3 µm in size after protargol impregnation ( Table 2; Figs 1, 5, 14–20 , 26–28, 30 ).

Contractile vacuole in rear end, comparatively small with respect to body size, i.e., about 14 µm across dur- ing diastole; sometimes a defecation vacuole near by ( Figs 1, 13–17, 19, 20 , 27, 29, 30 ). Extrusomes about 30 × 0.7 µm long in vivo, filiform with pointed and slightly curved ends, attached to oral bulge and scattered throughout cytoplasm, usually heavily impregnated with the protargol method used, rarely with small darker granules in weakly impregnated specimens ( Figs 5, 8, 9, 11 , 22, 23, 25 ). Cortex about 1 µm thick and flexible, without granules, covered by mucilaginous layer difficult to recognize in vivo and almost indistinguishable in protargol preparations; lepidosomes hat-shaped and about 4 × 3.7 µm in size ( Figs 10 , 29 ), no other lepidosome types were recognized due to the lack of SEM observations. Cytoplasm colourless, usually turbid, packed with lipid droplets about 1–10 µm in diameter ( Figs 21, 27, 28 ). The organism glides slowly on the surface of microscope slide and swims by rotation about the main body axis.

Cilia about 13 µm long in vivo; arranged in an average of 24 meridional, equidistantly spaced rows; anterior end of somatic kineties not curved in oral region and thus forming an enchelyodonid pattern; some rows shortened anteriorly or posteriorly ( Table 2; Fig. 5 ). Dorsal brush three-rowed and isostichad, i.e., row length difference <30%. Brush rows 1 and 2 dikinetidal; about 95 µm and 80 µm long, respectively, after protargol impregnation; composed of an average of 40 and 33 dikinetids, respectively; dikinetids more densely spaced in anterior brush portion than in posterior portion; associated with 5 µm long, slightly inflated bristles becoming rod-like in protargol preparations. Brush row 3 monokinetidal throughout, bearing about 1 µm long stumps; with a short anterior dikinetidal tail in a single malformed specimen ( Table 2; Figs 6, 7, 12 , 31, 32 ).

Oral bulge rather conspicuous because distinctly set off from body proper; pin-shaped in extended specimens, while conical in contracted cells; not covered by lepidosomes ( Figs 2–4, 11 , 21, 22, 24, 27, 28, 30 ). Pharyngeal basket not recognizable in vivo and in protargol preparations. Circumoral kinety at base of oral bulge, composed of comparatively widely spaced, more or less oblique dikinetids situated on top of somatic ciliary rows ( Figs 6, 7 , 25, 32 ).

Figures

Figs 1–20. Trachelophyllum brachypharynx, Korean specimens in vivo (1–4, 8, 10–16) and after protargol impregnation (5–7, 9, 17–20). 1 – ventral view of a representative specimen; 2–4 – the pin-shaped oral bulge becomes conical in contracted specimens; 5 – ventral view of the ciliary pattern and nuclear apparatus of a typical specimen; 6, 7 – dorsal view of the ciliary pattern in the anterior body portion of a normal (6) and abnormal (7) specimen. Typically, only brush row 1 and 2 are composed of dikinetids, while brush row 3 is monokinetidal throughout. In the abnormal specimen, brush row 3 also commences with a dikinetidal part but the brush is deformed (asterisk); 8, 9 – ex- trusomes are about 30 µm long in vivo and are filiform with pointed and slightly curved ends (8). When weakly impregnated, they display some small darker granules; 10 – lepidosomes are hat-shaped and about 4 × 3.7 µm in size; 11 – detail of the anterior body portion showing the conical oral bulge, the long filiform extrusomes, and the hat-shaped lepidosomes; 12 – the dorsal brush consists of three-rows. The first two rows are dikinetidal and bear 5 µm long, slightly inflated bristles, while the third row is monokinetidal and associated with 1 µm long stumps; 13–20 – variability in body shape and size as well as nuclear apparatus. Drawn to scale. B1–3 – dorsal brush row 1–3, CK – circumoral kinety, CV – contractile vacuole, E – extrusomes, F – fiber, L – lepidosomes, MA – macronuclear nodules, MI – micronucleus, OB – oral bulge, SC – somatic cilia. Scale bars: 50 µm (6, 7) and 100 µm (1, 5, 13–20).

Fig. 35. Original drawing of Trachelophyllum brachypharynx, length 350–400 µm (from Levander 1894). Fig. 36. Redrawing of T. brachypharynx, length 400 µm (from Kahl 1930).

Figs 21–32. Trachelophyllum brachypharynx, Korean specimens in vivo (21–24, 27–29) and after protargol impregnation (25, 26, 30–32). 21, 27, 28, 30 – overview showing the narrowly fusiform body, the nuclear apparatus composed of two macronuclear nodules, and the turbid cytoplasm packed with many small granules and some lipid droplets; 22, 24, 25 – detail of the anterior body end showing the pin-shaped to conical oral bulge studded with extrusomes; 23 – extrusomes are about 30 µm long in vivo and are filiform with pointed and slightly curved ends; 26 – the nuclear apparatus is typically composed of two ellipsoidal macronuclear nodules that are distinctly separate and connected by a fine strand. The arrowhead denotes an ellipsoidal micronucleus; 29 – detail of the rear body end showing the single posterior contractile vacuole and hat-shaped lepidosomes (arrowhead) forming a mucilaginous layer around the cell; 31 – dorsal view of the ciliary pattern in the anterior body portion of a typical specimen. The dorsal brush is composed of two isostichad dikinetidal rows and a single monokinetidal row; 32 – dorsal view of the ciliary pattern in the anterior body portion of a malformed specimen whose brush row 3 also commences with a dikinetidal part (arrowheads) similar to the first two brush rows. B1–3 – dorsal brush row 1–3, CK – circumoral kinety, CV – contractile vacuole, E – extrusomes, F – fiber, FM – fecal mass, MA – macronuclear nodules, OB – oral bulge, SK – somatic kinety. Scale bars: 10 µm (29), 30 µm (22, 26, 31, 32), 50 µm (24, 25), and 100 µm (21, 27, 28, 30).