Achnanthidium gladius Tseplik, Kulikovskiy, Glushchenko & Genkal, 2021

Tseplik, Natalia D., Maltsev, Yevhen I., Glushchenko, Anton M., Kuznetsova, Irina V., Genkal, Sergei I., Gusev, Evgeniy S. & Kulikovskiy, Maxim S., 2021, Achnanthidium gladius sp. nov. (Bacillariophyceae) - a new monoraphid diatom species from Indonesia, PhytoKeys 187, pp. 129-140 : 129

Achnanthidium gladius Tseplik, Kulikovskiy, Glushchenko & Genkal sp. nov.

Figures 2 , 3

Holotype.

Slide no 04123 in collection of MHA, Main Botanical Garden Russian Academy of Science, Moscow, Russia, represented here by Fig. 2G .

Reference strain.

Strain Ind391, isolated in sample no. I241.

Type locality.

Indonesia, Lake Matano, 02°31.985'S, 121°26.279'E.

Description.

LM (Fig. 2 ). Valves relatively big, linear to linear-lanceolate, with gradually narrowing, rounded apices. Length 27.7-30.4 µm, breadth 3.3-4.0 µm. Raphe straight, filiform. Striae on the raphe valve radiate, uniseriate, 27-28 in 10 µm, consist of round and narrow elongated areolae. On the rapheless valve the central and axial areas are absent. Striae are almost parallel, 26-27 in 10 µm, becoming noticeably more radiate near the valve apices. Areolae not resolved in LM.

SEM (Fig. 3 ). External proximal raphe ends simple, distal raphe ends straight. Internal proximal raphe ends slightly bent in opposite directions, distal raphe ends terminate is weakly developed helictoglossae. Raphe positioned in a narrow axial area that slightly widens near the centre of the valve. A distinct central area is absent, but 2 or 3 striae in the center of the valve are spaced wider than the majority of the striae. Areolae are mostly elongated.

Etymology.

The specific epithet " gladius " refers to the similarity in valve morphology contour with a sword.

Distribution.

As yet known only from the type locality.

Sequence data.

Partial 18S rDNA gene sequence comprising V4 domain sequence (GenBank accession number MW025231).

Figures

Figure 2. A-X Achnanthidium gladius Tseplik, Kulikovskiy, Glushchenko & Genkal, sp. nov. LM, DIC, size diminution series. Slide no 04123. A-L raphe valves M-X rapheless valves. Holotype (G). Scale bar: 10 μm.

Figure 3. A-H Achnanthidium gladius Tseplik, Kulikovskiy, Glushchenko & Genkal, sp. nov. SEM. Sample no 04123. A-F raphe valves G, H rapheless valves A-C, G, H external views D-F, H internal views. Scale bars: 2 μm (A, D, G, H), 1 μm (C, F), 0.5 μm (B, E).