Prestauroneis genkalii Glushchenko, Kulikovskiy & Kociolek, 2019

Glushchenko, Anton, Kociolek, John Patrick, Kuznetsova, Irina, Kezlya, Elena & Kulikovskiy, Maxim, 2019, Prestauroneis genkalii-a new diatom species (Bacillariophyceae: Stauroneidaceae) from Southeast Asia, Phytotaxa 414 (4), pp. 156-164 : 157-160

Prestauroneis genkalii Glushchenko, Kulikovskiy & Kociolek , sp. nov. ( Figs 1–27 )

Description.

LM ( Figs 1–21 ). Valves lanceolate to lanceolate-elliptic with rounded ends. Length 27–62 μm, width 8.0–10.5 μm. Axial area is very narrow. Central area small, rounded, to ellipsoidal, sometimes asymmetrical. At the central area shortened striae sometimes occur. Raphe filiform, straight, proximal raphe ends inconspicuous. Striae uniseriate, finely punctate, radiate, becoming subparallel at the apices, more distantly spaced and sometimes shortened near the central area, 15–17 in 10 μm.

SEM, external view ( Figs 22–24 ). Striae uniseriate. Proximal raphe endings are slightly expanded, weakly unilaterally curved. Distal raphe fissures unilaterally curved in opposite way to proximal ends, extending onto the valve mantle. Openings of areolae are variable in shape and orientation, rounded to elliptic, 36–40 in 10 μm.

SEM, internal view ( Figs 25–27 ). Proximal raphe endings are indistinct and sometimes hook-like. Helictoglossae are small, positioned below the conspicuous pseudosepta. Raphe located on weakly pronounced sternum-like structure. Central nodule rounded, weakly developed. Openings of areolae round, occluded by hymens. Pseudosepta extend inward from the mantle of each valve apex.

Type: — VIETNAM. Cái River, Khánh Hòa Province, benthos, N12°15.983´E109°06.517´, leg. E.S. Gusev, 17.04.2010 (in collection of Maxim Kulikovskiy at the Herbarium of the Institute of Plant Physiology Russian Academy of Science, Moscow, Russia), holotype here designated, slide no. 04853 = Fig. 9 ).

Etymology: —Species epithet honors the famous Russian diatomist Dr. Sergei Ivanovich Genkal from Institute for Biology of Inland Waters Russian Academy of Science, Borok, Yaroslavl Region.

Figures

FIGURES 1–21: Prestauroneis genkalii Glushchenko, Kulikovskiy & Kociolek, sp. nov. LM, DIC. Slide no 04853. Size diminution series. Figure 9 is of the holotype. Scale bar = 10 μm.

FIGURES 22–27: Prestauroneis genkalii Glushchenko, Kulikovskiy & Kociolek, sp. nov. SEM. External view (Figs 22–24), internal view (Figs 25–27). Figs 22: Whole valve, raphe filiform, proximal raphe endings are slightly expanded, weakly unilaterally curved, distal raphe fissures unilaterally curved in opposite way to proximal ends. Fig. 23: Central area, proximal raphe ends, openings of areolae are variable in shape and orientation, rounded to elliptic. Fig. 24: Distal raphe fissure. Fig. 25. Raphe filiform, helictoglossae are small, the raphe located on weakly pronounced sternum-like structure, pseudoseptae are present on the mantle of each valve apex. Fig. 26: Central area, proximal raphe endings indistinct and sometimes hook-like, openings of areolae round, occluded by hymenes. Fig. 27: Pseudosepta present, openings of areolae round, occluded by hymenes. Scale bars = 5 μm (Figs 22, 25); 1 μm (Figs 23, 24, 26, 27).