Placoneis asymmetricus Glushchenko, Kezlya, Kulikovskiy & Kociolek, 2022

Kezlya, Elena, Glushchenko, Anton, Kociolek, John Patrick, Maltsev, Yevhen, Genkal, Sergey & Kulikovskiy, Maxim, 2022, A new species of Placoneis Mereschkowsky (Bacillariophyceae: Cymbellales) from wet soils in southern Vietnam, Cryptogamie, Algologie 20 (11), pp. 177-188 : 180-181

publication ID	https://doi.org/ 10.5252/cryptogamie-algologie2022v43a11
DOI	https://doi.org/10.5281/zenodo.7819448
persistent identifier	https://treatment.plazi.org/id/052A8797-FFCE-F34D-61E7-F999A0F3F976
treatment provided by	Felipe
scientific name	Placoneis asymmetricus Glushchenko, Kezlya, Kulikovskiy & Kociolek
status	sp. nov.

Treatment

Placoneis asymmetricus Glushchenko, Kezlya, Kulikovskiy & Kociolek , sp. nov.

( Figs 2-4 View FIG View FIG View FIG )

HOLOTYPE. — Vietnam. Đồng Nai Province , Cát Tiên National Park , from soil sampled at Đồng Nai riverside, 11°26’05.6”N, 107°25’44.8”E, 03.VI.2019, E.S. Gusev & E.M. Kezlya, slide no. 06728 (oxidized material of cultured strain VP57 ). Deposited in the collection of Maxim Kulikovskiy at the Herbarium of the Institute of Plant Physiology, Russian Academy of Science, Moscow, Russia ( Fig. 2P View FIG ). GoogleMaps

ISOTYPE. — Same data as holotype, slide no. 06728a. Deposited in the collection of the Main Botanical Garden of the Russian Academy of Science, Moscow, Russia ( MHA).

TYPE LOCALITY. — Vietnam. Đồng Nai Province, Cát Tiên National Park, Đồng Nai riverside, 11°26’05.6”N, 107°25’44.8”E.

ETYMOLOGY. — The specific epithet refers to the typical asymmetry of the valves of this species.

SEQUENCE DATA. — Nuclear-encoded SSU rDNA partial sequence (GenBank accession: MW 979509 View Materials ), plastid gene rbc L partial sequence (GenBank accession: MW 987572 View Materials ).

DISTRIBUTION. — So far only known from the type locality.

DESCRIPTION

LM ( Fig. 2 View FIG )

Cells solitary, rectangular in girdle view, with a single chloroplast with medially positioned centre and lobes beneath both valves ( Fig. 2 View FIG A-I). Chloroplasts share the characteristic organization typical for the genus ( Mereschkowsky 1903; Cox 1987, 2003). The chloroplast is single, large, and extends along the inner surface of the cell. The central column (isthmus) is offset to one side from the central axis and forms a slight bend. Libroplast is missing or represented by only one granule ( Fig. 2A, F View FIG ). The chloroplast has four irregular outgrowths (similar to petals) extending from the isthmus. Valve are linear-elliptical, slightly asymmetric along the longitudinal axis ( Fig. 2 View FIG J-Z). Apices are bluntly rostrate, often asymmetric, breadth 1.3-2.0 µm. Valve length 10.3- 15.4 µm, valve width 6.0-6.8 µm. Axial area narrow, almost linear, very slightly wided towards the valve middle. Central area is absent. Raphe filiform, straight, central pores are small. The structure of distal raphe ends not discernible in the LM. Striae radiate, 17-21 in 10 µm, in the valve middle 2-3 irregularly shortened striae are present on each side. Areolae not resolvable in LM.

SEM external views ( Fig. 3 View FIG )

Valve face is flat. Raphe narrow, linear ( Fig. 3A View FIG ). Proximal raphe ends straight, small, slightly expanded ( Fig. 3B View FIG ). Distal raphe ends hook-shaped, extending to the valve mantle and unilaterally bent ( Fig. 3A, C View FIG ). Striae composed of 3-11 rounded or weakly elongated areolae, continuing onto the valve mantle. Areolae 45-50 in 10 µm. Stigma is absent.

SEM internal views ( Fig. 4 View FIG )

The raphe is straight ( Fig. 4A View FIG ). Proximal raphe ends are hooked-shaped and deflected to one side ( Fig. 4B View FIG ). Distal ends terminating on small helictoglossae and may be slightly deflected to opposite sides ( Fig. 4A, C View FIG ). The striae are bordered by broad interstriae (virgae) ( Fig. 4C View FIG ). Areolae small, square or round.Two isolated areolae are present at the apices ( Fig. 4C View FIG ). Volate occlusions were not preserved during the material treatment.