Plagiopyla flontata Kahl 1931

Li, Ran, Zhuang, Wenbao, Feng, Xiaochen, Al-Farraj, Saleh A., Schrecengost, Anna, Roưerova, Johana, Beinart, Roxanne A. & Hu, Xiaozhong, 2023, Molecular phylogeny and taxonomy of three anaerobic plagiopyleans (Alveolata: Ciliophora), retrieved from two geographically distant localities in Asia and North America, Zoological Journal of the Linnean Society 199 (2), pp. 493-510 : 499-501

Plagiopyla flontata Kahl 1931

( Figs 6 , 7 ; Table 3)

1931 Plagiopyla flontata Kahl, Tierwelt Dtl. , 21, fig. 45.10.

1933 Plagiopyla flontata Kahl, Tierwelt N , fig. 9.3.

2000 Plagiopyla flontata Esteban et al. , J. Nat. Hist., 34, figs 34–37.

2007 Plagiopyla flontata Jankowski, Russian Acad. Sci. , p. 792 (revision).

2019 Plagiopyla flontata Nitla et al. , Zool. J. Linn. Soc., 186, p. 35 (revision).

2022 Plagiopyla flontata Omar & Jung, J. Spec. Res. , 11, fig. 4.

Although Plagiopyla flontata has been known for a long time, most descriptions lack molecular and infraciliature data. Based on the previous and current information, the improved diagnosis is provided here.

Improved diagnosis: Cell size 55–120 × 30–67 μm in vivo, shape slim ellipsoidal. Length to width ratio about 2: 1 in vivo; 40–68 somatic kineties. Striated band about 32 μm long and 3 μm wide, extending down to below midbody. One nearly spherical macronucleus and one spherical micronucleus. Two or three dense ciliary rows. Extrusomes 4–6 μm long, curved or straight. Region above oral opening about 17% of cell length, perpendicular to the oral opening. Tube-like buccal cavity about 60% of cell width, extending transversely to leħ.

Voucher slides: Three protargol slides (registration numbers: LR2020121301-01, LR2020121301-02, LR2020121301-03) with voucher specimens were deposited in the Laboratory of Protozoology, Ocean University of China, ºingdao, China.

Description of Chinese population: Body size 70–100 × 30–40 μm in vivo and 60–90 × 25–40 μm aħer protargol staining, with the ratio of length to width about 2:1. Cell slim ellipsoidal, acontractile, dorsoventrally flaưened ( Figs 6A, E, F , 7A, B ). Cytoplasm colourless, containing several food vacuoles and many fat globules ( Figs 6A , 7A, B, E ). One macronucleus, nearly spherical, 17–29 × 14–22 μm in vivo, located below oral opening ( Figs 6A, E, F, H , 7A, E, L, M ). Single globular micronucleus, about 3 μm in diameter, enveloped by macronucleus ( Figs 6A, E, F, H , 7I ). Extrusomes relatively short, 4–6 μm long, mainly distributed under the cortex, curved or straight shaped ( Figs 6B, C , 7E, H ). Extruded extrusomes about 20 µm long, slender, needle-shaped with one end slightly inflated. Single contractile vacuole located near posterior end of cell with two pores ( Figs 6G , 7D ). Striated band 28–42 µm long, 2–4 µm wide, extending below midbody ( Figs 6G, I , 7G, M ). Cytoproct located on dorsal side of cell ( Figs 6G , 7F ). Swims slowly by rotating around main longitudinal axis of cell.

Somatic cilia 11–14 µm long, densely and evenly distributed on the cell surface forming 56–68 longitudinal kineties (23–32 ventral kineties, 26–42 dorsal kineties) mainly composed of monokinetids, except for several kinetosomes irregularly and densely arranged near loop of striated band ( Figs 6H, I , 7L, M ). Dorsal kineties including 16–28 dorso-leħ kineties and 10–14 dorso-right kineties that form a suture at the posterior end of the cell. Seven to nine rigid caudal cilia, 11–14 µm long ( Fig. 6A ). Two or three dense ciliary rows located leħ to cytoproct ( Figs 6G, I , 7M ).

Oral opening wide-belt shaped, surrounded by two lip-like structures without nose-like protuberance on right side ( Figs 6A, D, E, H , 7L ). Region above oral opening 15–18% of cell length, outline perpendicular to oral opening ( Figs 6A, E, F, H , 7A, B ). Tube-like buccal cavity short, extending transversely to leħ, about 60% of cell width ( Figs 6D–F , 7A, J, K ). Upper oral lip kineties 3–5 µm long. Gap between upper oral lip kineties and somatic kineties 2–4 µm ( Figs 6H , 7L ); 52–58 oral kineties on cell surface and extending inwards ( Figs 6D, H , 7J–L ).

Molecular data and phylogenetic analyses

Twenty-one newly obtained SSU rRNA gene sequences were deposited in the GenBank database with length (bp), GC base content, accession numbers, and origin information shown in Table 1. Sequence identities and max BLAST scores are shown in the Supporting Information, Table S1.

The topologies of the phylogenetic trees from ML and BI analyses were almost identical, therefore only the ML tree topology is shown here ( Fig. 8 ). All members of the family Plagiopylidae cluster together with maximum support (100% ML, 1.00 BI) and comprise two clades. In Clade I, ML analysis shows that the Chinese population of Plagiopyla flontata (SHAZIKOU OP114648) groups with four American populations (PJ7 OP186392, NARRIV13 OP186393, NAPAT2B OP186394, NAPAT2 OP186395), then clusters with another sequence of P. flontata (Z29440). However, these six P. flontata sequences are parallel to each other in BI analysis. Two sequences of P. nasuta (Z29442, KY563719) form a fully supported subclade, which is sister to the P. flontata subclade group. In Clade II, 10 newly obtained Plagiopyla species sequences (BI27A OP186391, BI29B OP186390, BLAPTMUD OP186389, GB33B OP186388, GOOSE1A OP186387, JUDRED OP186385, JUD8 OP186386, NINISW OP186384, SAÞ1B OP186383, and SAÞ1B3 OP186382) group together with P.ovata (MW762810) forming a strong branch (100% ML, 1.00 BI), then followed by P. ramani (KY563720), P. rariseta (BAINIDI OP114647), and P. narasimhamurtii (KY563721) with P. mystax (AF527757), respectively, with low support (19%, 35%, 41%) in ML analysis, whilethesefoursequencesgrouptogetherinBIanalysis. Plagiopyla species (FJ875150) is sister to other sequences in Clade II in both analyses. The family Trimyemidae is also a fully supported monophyletic group. Five Trimyema foissneri (TANGDAO OP114646, NINIBRI4 OP186378, JUDFA OP186379, JUD81 OP186380, and JUD11A OP186381) sequences cluster together with maximum support (100% ML, 1.00 BI) and together are sister to the assemblage containing T. compressum (AB285526, Z29438), T. finlayi (MF074215), and Trimyema species (Z29441) with moderate support (86% ML, 0.89 BI).

Figures

Figure 6. Drawings of Plagiopyla frontata from life (A–C, E, F) and after protargol staining (D, G–I). A, ventral view of a representative individual, arrowheads show caudal cilia. B, tangential section of the cortex, arrowhead marks straight extrusome, arrow indicates curved extrusome. C, extruded extrusomes with one end slightly inflated (red arrowheads). D, details of oral region, showing oral opening and buccal cavity (arrow). E, F, different cell shapes. G, dorsal view of a compressed cell, showing position of striated band, cytoproct (black arrow), dense ciliary rows (red arrow), and contractile vacuole pores (red arrowheads). H, ventral view to show somatic and oral kineties, arrowhead indicates gap between upper oral lip kineties and somatic kineties. I, dorsal view to show somatic kineties, arrow indicates striated band, arrowhead shows dense ciliary rows, double-arrowhead shows several irregularly and densely packed kinetosomes located near loop of striated band. Abbreviations: CV, contractile vacuole; Ma, macronucleus; SB, striated band. Scale bars: 35 μm (A, E, G, H); 10 μm (C).

Figure 7. Photomicrographs of Plagiopyla flontata in vivo (A–H) and aħer protargol staining (I–M). A, ventral view of a slightly compressed cell, arrow marks buccal cavity. B, representative individual, arrow shows oral opening, arrowhead indicates contractile vacuole.C, extruded extrusomes with one end slightly inflated (arrowheads).D, contractile vacuole pores (red arrowheads). E, ventral view of a compressed cell, arrows show straight extrusomes, arrowheads show curved extrusomes. F, details of dorsal side, arrowhead shows cytoproct. G, right side of a compressed cell showing striated band (arrowhead). H, details of extrusomes.I, macronucleus and micronucleus (white arrowhead). J, K, oral region, showing buccal cavity under different focal planes. L, M, ventral (L) and dorsal (M) views of the same individual, showing somatic and oral kineties, red arrow indicates gap between upper oral lip kineties and somatic kineties, black arrow shows striated band, black arrowhead shows dense ciliary rows, red arrowhead indicates several polykineties located near loop of striated band. Abbreviation: Ma, macronucleus. Scale bars: 35 μm.

Figure 8. Maximum likelihood (ML) tree inferred from the small subunit rRNA gene sequences, revealing the positions of the 21 newly obtained sequences (red font). Numbers near branches indicate ML bootstrap values and BI posterior probabilities. Black circles represent full support (ML/BI, 100/1.00) in both analyses. Disagreements in topology between ML and BI are marked with asterisks.The scale bar corresponds to 2 changes per 100 nucleotide positions.Abbreviation:sp = species.