Amphileptus salignus, Chen, Ruimin, Lin, Xiaofeng & Warren, Alan, 2011

Chen, Ruimin, Lin, Xiaofeng & Warren, Alan, 2011, A new pleurostomatid ciliate, Amphileptus salignus n. sp. (Protozoa, Ciliophora), from mangrove wetlands in southern China, Zootaxa 3048, pp. 62-68 : 63-65

Amphileptus salignus n. sp.

( Figs. 1–23 ; Table 1)

Diagnosis. Large brackish water Amphileptus 180–360 μm long in vivo; lanceolate body shape; two ellipsoidal macronuclei and one micronucleus; 24–29 right and 4 left somatic kineties; several contractile vacuoles positioned ventrally in posterior 3/4 of cell and usually one near dorsal margin; two types of extrusomes, the longer one barshaped and mostly arranged along the oral slit, the other short-bar-like packed under the pellicle.

Type slides. The holotype slide (registration number: CRM 090401 -01) of protargol-impregnated specimens is deposited in the Laboratory of Protozoology, South China Normal University, China. One paratype slide (registration number: NHMUK 2010:11:4:1) is deposited in the Natural History Museum, London, U.K.

Type locality. Futian mangrove wetland in Shenzhen (22°31'49"N; 113°59'45"E), China.

Etymology. The Latin word salignus refers to the cell shape which is like the leaf of a willow ( Salix ).

Morphological description. Cells size highly variable, 180–360 × 55–65 μm in vivo, mostly 200–300 μm in length. Body slightly contractile, shaped like the leaf of willow with posterior end bluntly pointed and neck region, which is about 20% of body length, usually curved slightly to dorsal side ( Figs. 1, 4, 5 , 10, 11 ). Cell laterally compressed about 3 to 4:1; right side flat, left side slightly vaulted in mid-body region and with four longitudinal furrows that are conspicuous at high magnifications ( Fig. 11 ). Right side densely ciliated, cilia 8–10 μm in length, ciliary rows forming a distinct anterior suture that is detectable in vivo. Left somatic cilia sparsely distributed and difficult to detect in vivo: dorsal brush conspicuous, cilia about 2–3 μm long ( Fig. 5 ).

Numerous tiny (<0.5 μm across), colourless dot-like cortical granules densely packed beneath pellicle between ciliary rows on both sides of cell ( Figs. 3 , 18 ). Cytoplasm colourless to slightly brown-grayish, often with numerous shining globules (1–2 μm across), which render main part of body more or less opaque, especially at low magnifications ( Figs. 1, 5 , 10 ). Two kinds of extrusomes ( Figs. 2 , 16, 17, 21–23 ): type I 8–18 μm long in vivo, barshaped, densely arranged in oral area and some distributed in cytoplasm ( Figs. 1, 2, 9 , 10, 16, 17, 23 ); type II short bar-like, about 2 μm long, packed under the pellicle and some scattered in cytoplasm ( Figs. 2 , 16, 17, 21, 22 ), not observed in stained specimens. Food vacuoles few in number, about 4 μm across. Two to seven contractile vacuoles (CV), about 6–12 μm in diameter, largest usually subterminally located, one near dorsal margin at posterior part, the others distributed unevenly along ventral margin in posterior 3/4 of body ( Figs. 1, 4, 5 , 10, 19 ).

Two spherical to ovoid macronuclear nodules located in mid-body, size 30–60 × 18–36 μm after fixation, often appearing as two large transparent areas in vivo ( Figs. 1, 5 , 10, 11 ). Single spherical micronucleus between two macronuclear nodules, undetectable in vivo, about 3 μm in length after protargol impregnation.

Movement by swimming with moderately slow rotation around longitudinal axis or by gliding on substrate.

Infraciliature typical of genus ( Figs. 6–8 ). Two densely ciliated perioral kineties (PK1, PK2): PK1 on left of oral slit, extending to posterior end of cell, about half of kinety length consisting of monokinetids and half dikinetids ( Figs. 6, 8 ); PK2 right of oral slit, composed of closely spaced dikinetids in anterior half and monokinetids posterior half ( Figs. 6, 8 ).

Right somatic kineties closely spaced, 24–29 (mean 27) including PK2, anterior end of each intermediate kinety shortened forming a distinct anterior suture ( Fig. 7 ). Four densely ciliated left somatic kineties, including the left perioral kinety and the dorsal brush kinety, all of which reach anterior end of cell; dorsal brush extending 1/3 of cell-length and composed of regularly spaced dikinetids ( Fig. 8 ). Well-developed nematodesmata, all of which originate from kinetosomes of right perioral kinety, extending along cytopharynx and into cytoplasm ( Figs. 6 , 13 ).

Characters Min Max Mean CV SD n Body length in µm 190 350 257.5 0.2 45.7 20 157 360 278.0 0.2 51.0 22 Body width in µm 43 78 56.9 0.2 9.9 20 32 56 47.7 0.1 5.9 22 Number of right somatic kineties a 24 29 27.4 0 1.2 19 24 29 28.0 19 1.7 20 Number of left somatic kineties b 4 4 4 0 0 20 4 4 4 0 0 21 Number of macronuclear nodules 2 2 2 0 0 20 1 1 1 0 0 14 Length of micronucleus in µm 1.5 4 2.9 0.2 0.7 17 3 6 4.6 0.2 1.0 14

Length of extrusomes in µm 8 18 12.6 0.3 3.5 11 11 18 14.7 0.2 2.2 20

a Includes perioral kinety 2; b Includes both perioral kinety 1 and dorsal brush kinety. Max, maximum; Mean, arithmetic mean; Min, minimum; n, number of cells measured; SD, standard deviation. CV, coefficient of variation in %.

Figures

FIGURES 1 – 9. Amphileptus salignus n. sp. from living cells (1 – 5) and after protargol impregnation (6 – 9). (1) Right view of a typical specimen with pointed posterior end. (2) Two kinds of extrusomes. (3) Cortical granules distributed between ciliary rows. (4) Left views, to show variations in body shape and in the number and distribution of contractile vacuoles. (5) Left view, note the dorsal brush. (6) Left-ventral view showing the detailed structure around the cytostome including the well-developed nematodesmata. (7 – 8) Infraciliature of right (7) and left (8) sides of the same specimen, arrows in Fig. 7 mark the suture. (9) Macronuclear nodules and distribution of the longer extrusomes, the shorter kind of extrusomes were not observed after protargol impregnation. CV: contractile vacuole, DB: dorsal brush, Ex: extrusome, Ma: macronuclear nodules, PK 1 – 2: perioral kineties 1 and 2. Scale bars in (1, 4) — 100 µm, in (2) – 10 µm, in (7, 8) — 80 µm.

FIGURES 10 – 23. Photomicrographs showing the morphology of Amphileptus salignus n. sp. from living cells (10 – 11, 16 – 22) and after protargol impregnation (12 – 15, 23). (10) Right view of a typical individual, arrows mark the extrusomes, arrowheads mark the contractile vacuoles. (11) Left view, arrowheads mark the longitudinal ridges. (12) To show the oral structure, arrowheads mark perioral kinety 1, arrow marks perioral kinety 2. (13) To show the nematodesmata (arrowheads). (14) Left view of anterior portion, arrows show the dorsal brush. (15) The distribution of macronuclear nodules (arrows) and long extrusomes (arrowheads). (16, 17) Two kinds of extrusomes, arrowheads show the shorter ones, arrows show the longer ones. (18) Cortical granules (arrowhead). (19) To show the contractile vacuoles, arrowhead marks the one positioned near the dorsal side. (20) To show dorsal cilia (arrowheads) and dorsal brush (arrow). (21) Anterior region of cell, arrowheads point to the shorter extrusomes. (22) Mid-region of cell, arrowheads indicate the shorter extrusomes. (23) To show the longer extrusomes. Scale bars in (10, 11) — 100 µm, in (16, 17) — 20 µm.