Frontonia paramagna, Chen, Ying, Zhao, Yan, Pan, Xuming, Ding, Wenqiao, Al-Rasheid, Khaled A. S. & Qiu, Zijian, 2014
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publication ID |
https://doi.org/ 10.11646/zootaxa.3827.3.7 |
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publication LSID |
lsid:zoobank.org:pub:14CD03DB-1613-4BCA-984E-58F5AD607A60 |
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DOI |
https://doi.org/10.5281/zenodo.5662315 |
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persistent identifier |
https://treatment.plazi.org/id/B92B0438-BE43-7242-FF65-FEA50B9CFE39 |
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treatment provided by |
Plazi |
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scientific name |
Frontonia paramagna |
| status |
sp. nov. |
Frontonia paramagna spec. nov.
Diagnosis. Freshwater Frontonia about 400–610 × 110–160 Μm in vivo; dorsoventrally slightly flattened with conspicuously small buccal cavity; about 179–201 somatic kineties; three vestibular and six to seven postoral kineties; peniculi 1–3 each with four kinetid rows; single ellipsoidal macronucleus; one contractile vacuole located equatorially on the right margin; extrusomes spindle-shaped.
Type slides. A silver carbonate-impregnated slide containing the holotype specimen is deposited in the Laboratory of Protozoology, Ocean University of China (CY 20111229 -1). Three silver nitrate slides containing paratype specimens are deposited in the Laboratory of Protozoology, Ocean University of China (CY 20111229 -2, 3, 4).
Type locality. A puddle in a freshwater wetland in Harbin (N45°52′ 02.67″, E126°32′ 56.23″), Heilongjiang Province, China.
Etymology. The prefix “para-” refers to the species being similar to Frontonia magna .
Morphological and Ultrastructural description. Table 1 View TABLE 1 and Figures 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 : Size huge and varied, in vivo about 400–610 × 110–160 Μm, but mostly 500–550 Μm in length; ratio of length: width about 3.5:1. Body shape constant, long ellipsoidal in outline; left margin straight while right margin slightly convex ( Figs. 1 View FIGURE 1 A, 1B, 1C, 1D 2A,2B). Both ends rounded with the front end wider and slightly bent to the right. Dorsal-ventral side slightly flattened. Single ellipsoidal macronucleus, positioned at body centre ( Figs. 1 View FIGURE 1 G, 2K). Single contractile vacuole, about 100 Μm in diameter, positioned in mid-body right of cell median; one contractile vacuole pore located on right dorsal surface ( Figs. 1 View FIGURE 1 A, 1D, 1G, 2A, 2C). Most of the extrusomes spindle-shaped, about 5 Μm long, densely arranged beneath cortex ( Figs. 1 View FIGURE 1 E, 2I, 2J, 3C, 3F). The other two types of extrusomes were observed for the first time ( Figs. 1 View FIGURE 1 E, 3D, 3E). Cytoplasm is transparent, colourless to slightly grey. Cytoplasm filled by many yellow and grey food vacuoles, with different diameters, as well as dark granules and crystals containing bacteria, diatoms and other small ciliates ( Figs. 1 View FIGURE 1 A, 2A, 2B). 180–199 somatic kineties. somatic cilia about 8 Μm long ( Figs. 1 View FIGURE 1 F; 1G). Locomotion by revolving moderately rapidly on substrate or by swimming in water about long body axis. Buccal cavity small and shallow, approximately triangular in outline, occupying about 1/10 of body length ( Figs. 1 View FIGURE 1 A, 1D, 1F; 1H, 2F, 2G, 2H, 2L, 3A, 3B). Three short vestibular kineties (VK1–3) on the right of the buccal cavity running from the anterior vertex to the postoral suture of the cavity, with dense kinetosomes ( Figs. 1 View FIGURE 1 H; 2F, 2H). Three peniculi deeply located on the left wall of cavity: peniculi 1 and 2 (P1, 2) about equally long and close to each other, peniculus 3 (P3) slightly separated from P1, 2 and curved to right. Each peniculus composed of four rows of kinetosomes ( Figs. 1 View FIGURE 1 F, 1H; 2H, 2L, 2M). Peniculus 3 composed of four shorter kineties, of which the right two are complete and the left two shortened ( Figs. 1 View FIGURE 1 H; 2H, 2L). Single paroral membrane (PM) on right edge of the buccal cavity runs from anterior of the buccal overture to the posterior edge. Argentophilic line (AL) positioned parallel to VK ( Figs. 1 View FIGURE 1 H; 2F, 2H).
Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were combined to study the subpellicular ultrastructure of F. paramagna spec. nov. Three types of extrusomes were evident, including a spindle trichocyst, another new type of trichocyst and a mucocyst. A large number of spindle trichocysts with a cap-like structure were distributed densely in the specimens ( Figs. 3 View FIGURE 3 C, 3F). The other two types of extrusomes, however, were rare and could be observed only by TEM. The mucocysts were an elongated oval-shape, about 2 Μm long and with transverse microfilaments on their surface, and can emit micro-mesh ( Fig. 3 View FIGURE 3 D). The new type of trichocyst were about 5 Μm long, in the shape of a long rod with a dark, flat, front end, and appeared mainly around the oral apparatus ( Fig. 3 View FIGURE 3 E).
This investigation also revealed a three layered fibre system beneath the pellicle. The first layer of fibre was close to the pellicle, with a diameter of about 0.12 Μm. The fibres of the second layer were densely wrapped around the extrusomes ( Figs. 3 View FIGURE 3 F, 3G); while the fibres of the third layer were loose, covering most of the subpellicular structures and adjoined the cytoplasm.
Finally, the VK in the oral apparatus were observed by SEM. This showed that a membranous structure was wrapped around the root of each VK to form a coarse columnar structure, with interwoven fibres linking these columnar structures to the VK ( Fig. 3 View FIGURE 3 H).
SSU rRNA gene sequence and phylogeny of Frontonia paramagna spec. nov. (Table 3 and Figure 4 View FIGURE 4 ). The newly sequenced SSU rRNA gene of Frontonia paramagna spec. nov., with a length of 1,667 bp, has been deposited in the GenBank database with accession number JQ868786 View Materials . The genetic similarity and number of nucleotide differences between the new species and its congeners has been set out in Table 3, showing details of the molecular differences between this new species and other comparable species. Each of the SSU rRNA gene sequences of the species available from GenBank for genus Frontonia have similarities with this new species ranging from 91.1% to 98.6% with 22 to 147 nucleotides difference from other congeneric species (Table 3). The phylogenetic trees generated through both Bayesian Inference ( BI) and Maximum Likelihood (ML) methods had similar topologies, therefore, they were combined into a single consensus tree ( Fig. 4 View FIGURE 4 ). The new species Frontonia spec. nov. clustered together with Frontonia sp. / vernalis with high support (100% ML, 1.00 BI) and then formed a clade with F. leucas (100% ML, 1.00 BI). The clade became the sister group with the clusters of F. tchibisovae / lynni / mengi / magna , also with high support (100% ML, 1.00 BI). But genus Frontonia did not form a monophyletic group since Frontonia sp. ( FN667825 View Materials ) and F. didieri were separated and clustered with Paramecium and Apofrontonia species instead of with their congeners (68% ML, 0.99 BI).
TABLE 1. Morphometric data of Frontonia paramagna spec. nov. Data based on randomly selected specimens with silver impregnation. Measurements in Μm. CV, coefficient of variation in %; Max, maximum; Mean, arithmetic mean; Min, minimum; SD, standard deviation.
| Characters | Min | Max | Mean | SD | CV | n |
|---|---|---|---|---|---|---|
| Body length | 318 | 362 | 340.8 | 13.0 | 3.7 | 15 |
| Body width | 96 | 124 | 113.0 | 7.6 | 6.8 | 15 |
| Number of somatic kineties | 180 | 200 | 189.7 | 6.3 | 3.3 | 15 |
| Number of vestibular kineties | 3 | 3 | 3.0 | 0 | 0 | 15 |
| Number of postoral kineties | 6 | 7 | 6.5 | 0 | 0 | 15 |
| Number of ciliary row in peniculus 1 | 4 | 4 | 4.0 | 0 | 0 | 15 |
| Number of ciliary row in peniculus 2 | 4 | 4 | 4.0 | 0 | 0 | 15 |
| Number of ciliary row in peniculus 3 | 4 | 4 | 4.0 | 0 | 0 | 15 |
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