Planothidium tyushovii Tseplik, Glushchenko, Maltsev et Kulikovskiy, 2024

Tseplik, Natalia, Maltsev, Yevhen, Glushchenko, Anton, Genkal, Sergey, Mironova, Elina & Kulikovskiy, Maxim, 2024, New cavum-bearing Planothidium (Achnanthidiaceae, Bacillariophyceae) species from the Kamchatka Peninsula, Russia, Phytotaxa 665 (3), pp. 271-281 : 276-277

Planothidium tyushovii Tseplik, Glushchenko, Maltsev et Kulikovskiy sp. nov. ( Figs. 4–22 )

Holotype. Slide no. kam288 (08120), in collection of Maxim Kulikovskiy , Institute of Plant Physiology, Russian Academy of Sciences, Russia, represented here by Figure 4 .

Reference strain. kam288, isolated from sample 116.

Type locality. Russia, Greshnaya river, sample 116, sand and detritus (N 55.923 .778 E 158.701.194), 15.07.2021.

Description. LM. Valves small, elliptic-lanceolate, with protracted and rounded ends. Length 11.0–13.5 μm, width 4.5–5.5 μm. Raphe straight, filiform, with expanded central ends and distal ends turned to one side. Axial area on the raphe valve narrow linear, central area rectangular, formed by 2–3 shortened striae on each side of the valve. Axial area on the rapheless valve narrow linear. A cavum is present on one side of the rapheless valve; 3–4 striae are shortened on the other side, forming a small semicircular central area. Striae on both valves almost parallel in the centre, becoming distinctly radiate on the ends of the valves. Striae density 15–19 in 10 μm on the raphe valve, 15–17 in 10 μm on the rapheless valve.

SEM. External central raphe ends straight, expanded, distal ends turned to one side and extended onto the mantle. Internal central raphe ends slightly turned to opposite sides, distal ends terminate in faint helictoglossae. Striae multiseriate, consisting of 3–4 rows of small round areolae on both valves. Rapheless valve is faintly ornamented with small round depressions along the axial area. Internally, the interstriae are distinctly raised. The cavum is elongated, with a moderately wide opening.

Sequence data. Partial 18S rDNA gene sequence comprising V4 domain sequence (GenBank accession number PP965379) and partial rbc L sequence (GenBank accession number PP965730) for the strain kam288.

Etymology. The name of this species is dedicated to Vladimir Nikolaevich Tyushov, a prominent Russian naturalist and researcher of Kamchatka nature. He was a doctor in the Petropavlovsk region and took part in an expedition organized by the Russian Geographical Society. His achievements include the study of glaciers in the Klyuchyevskaya volcanic group, the establishment of the first hospital in Petropavlovsk, and the publication of the book On the West Coast of Kamchatka.

Distribution. As yet known only from type locality.

Figures

FIGURES 4–22. Planothidium tyushovii sp. nov. Strain kam288, type material. 4–18. LM, DIC. 4–11. Raphe valves. 12–18. Rapheless valves. Holotype represented by fig. 4. 19–22. SEM. 19. Raphe valve, external view. 20. Rapheless valve, external view. 21. Raphe valve, internal view. 22. Rapheless valve, internal view. Scale bar 10 μm (figs. 4–18), 2 μm (fig. 22), 1 μm (figs. 19–21).