Cymbopleura natellia Glushchenko, Kulikovskiy & Kociolek, 2021

Glushchenko, Anton, Gusev, Evgeniy, Maltsev, Yevhen, Kociolek, John Patrick, Kuznetsova, Irina & Kulikovskiy, Maxim, 2021, Cymbopleura natellia - a new species from Transbaikal area (Russia, Siberia) described on the basis of molecular and morphological investigation, PhytoKeys 183, pp. 95-105 : 95

Cymbopleura natellia Glushchenko, Kulikovskiy & Kociolek sp. nov.

Figs 1 , 2 , 3 , 4

Holotype.

Slide no B209 in collection of MHA, Main Botanical Garden Russian Academy of Science, Moscow, Russia, represented here by Fig. 2J .

Reference strain.

Strain B209, isolated in sample No. 11.2.

Type locality.

Russia, Eastern Siberia, Buryatia, Zagza River, 52°31.656'N, 107°05.114'E.

Description.

LM (Figs 1 and 2 ). Cells solitary. A single chloroplast is present per cell. The chloroplast has two lobes, that underlie the valve face, and they are connected by a wide isthmus (Fig. 1 ). Valves subelliptical, dorsiventral with moderately convex dorsal margin and slightly convex ventral margin, often almost straight near the valve centre. Ends are bluntly rostrate. Length 17.6-23.5 μm (20.5 ± 1.6; n = 30), width 8.7-9.5 μm (9.1 ± 0.2; n = 30). Length-to-width ratio 1.97-2.52. Central area more or less pronounced, rounded, 1/3 to the valve breadth. Axial area narrow, more often weakly expands to central area, less often - almost not expanded beyond the median line of the valve. Raphe filiform near the center, lateral towards the apices, with proximal raphe ends deflected ventrally, tipped with weakly inflated pores. Striae finely punctate, radiate, becoming subparallel and condensing towards to the ends, 13-15 in 10 μm (14 ± 0.7; n = 30) at the central part, 18-20 in 10 μm (19 ± 0.7; n = 30) near the ends. Areolae difficult to resolve in LM (Fig. 2 ).

SEM, external view (Fig. 3 ). Valve face is flat. Central area formed by shortened striae. Striae uniseriate, extending to valve face towards mantle on both the dorsal and ventral margins, composed of very small, elongate, lineolate areolae, 30-35 in 10 μm (32.5 ± 1.3; n = 30). Proximal raphe endings are slightly expanded, unilaterally curved. Distal raphe fissures unilaterally curved opposite the proximal raphe ends, extending onto the valve mantle.

SEM, internal view (Fig. 4 ). The raphe slits close to proximal endings are arcuate. Proximal raphe endings weakly deflected to the dorsal margin. Distal raphe ends terminated small helictoglossae. Areolae arranged in a series with narrow vimines, compared to the wide interstriae (virgae), occlusions absent but tectullae present.

Etymology.

New species is dedicated to our friend Natella Otarovna Gabuadze.

Distribution.

As yet known only from the type locality.

Sequence data.

Partial 18S rDNA gene sequence comprising V4 domain sequence (GenBank accession number MZ503642).

Molecular investigation

The phylogenetic analyses were conducted using a single gene dataset (Fig. 5 ). Sequences of Cymbopleura species as well as Cymbella , Gomphonema , Placoneis and another pennate diatom species were included in the phylogenetic analyses. According to the maximum likelihood (ML) and Bayesian Inference (BI) phylogenetic analyses, Cymbopleura natellia sp. nov. (the strain B209) appeared most closely related to the strain 22 vi092D of Cymbopleura naviculiformis (Auerswald ex Heiberg) Krammer 2003 with high statistical support (ML 94; BI 0.99) and other Cymbopleura strains (Fig. 5 ). We should point out, however, that Cymbopleura is non-monophyletic in these analyses, with two strains of Cymbopleura inaequalis and an unidentified Cymbopleura strain (D213 001 MK300893) having a closer relationship with some Cymbella species than Cymbopleura strains.

Figures

Figure 1. A-H Cymbopleura natellia Glushchenko, Kulikovskiy & Kociolek, sp. nov. LM, DIC. Strain B 209. Size diminution series. Live cells with chloroplast structure. Scale bar: 10 μm.

Figure 2. A-R Cymbopleura natellia Glushchenko, Kulikovskiy & Kociolek, sp. nov. LM, DIC. Strain B 209, slide no B 209. Size diminution series. Holotype (J). Scale bar: 10 μm.

Figure 3. A-D Cymbopleura natellia Glushchenko, Kulikovskiy & Kociolek, sp. nov. SEM. Strain B 209. External view A, B the whole valve C central area D valve end. Scale bars: 5 μm (A, B); 1 μm (C, D).

Figure 4. A-C Cymbopleura natellia Glushchenko, Kulikovskiy & Kociolek, sp. nov. SEM. Strain B 209. Internal view A the whole valve B central area C valve end. Scale bars: 5 μm (A); 1 μm (B, C).

Figure 5. Phylogenetic position of Cymbopleura natellia B 209 (indicated in bold) based on Bayesian inference for the partial 18 S rDNA gene. Total length of the alignment is 439 characters. Bootstrap supports from ML (constructed by RAxML) and posterior probabilities from BI (constructed by Beast) are presented on the nodes in order. Only BS and PP above 50 and 0.85 are shown. Strain numbers (if available) and GenBank numbers are indicated for all sequences.