Planothidium dyakonovii 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 : 277-278

Planothidium dyakonovii Tseplik, Glushchenko, Maltsev et Kulikovskiy sp. nov. ( Figs. 23–41 )

Holotype. Slide no. kam373 (08205), in collection of Maxim Kulikovskiy , Institute of Plant Physiology, Russian Academy of Sciences, Russia, represented here by Figure 24 .

Reference strain. kam373, isolated from sample 219.

Type locality. Russia, Dachnye hot springs, sample 219, detritus, sand and clay (N 52.530 .139 E 158.191.755), 18.07.2021.

Description. LM. Valves lanceolate, with rounded or slightly protracted ends. Length 12.0–14.0 μm, width 5.0– 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 elliptical or roundish, formed by 2–3 striae shortened on each side. Axial area on the rapheless valve narrow, linear. A large elongated cavum is present on one side of the valve; 2–3 striae are shortened on the other side and form a small semicircular central area. Striae on both valves almost parallel at the centre of the valve, radiate at the ends, 14–16 in 10 μm.

SEM. External central raphe ends straight, slightly 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 on both valves, consisting of 2–4 rows of areolae on the raphe valve and 3–4 rows on the rapheless valve. Areolae small, circular. The rapheless valve is ornamented with small round depressions along the axial area. Internally the interstriae are slightly raised. The cavum is large, elongated, with a relatively small opening.

Sequence data. Partial 18S rDNA gene sequence comprising V4 domain sequence (GenBank accession number PP965380) and partial rbc L sequence (GenBank accession number PP965731) for the strain kam373.

Etymology. This species is named after Pavel Nikolaevich Dyakonov, a renowned Russian expert in forestry and forest conservation. He authored the book Forests of Kamchatka and was known for his poetry and photographs of Kamchatkan landscapes. Dyakonov actively promoted nature conservation among the local population and was involved in the activities of the Soviet Geographical Society.

Distribution. As yet known only from type locality.

Figures

FIGURES 23–41. Planothidium dyakonovii sp. nov. Strain kam373, type material. 23–37. LM, DIC. 23–30. Raphe valves. 31–37. Rapheless valves. Holotype represented by fig. 24. 38–41. SEM. 38. Raphe valve, external view. 39. Rapheless valve, external view. 40. Raphe valve, internal view. 41. Rapheless valve, internal view. Scale bar 10 μm (figs. 23–37), 2 μm (figs. 38–39, 41), 1 μm (fig. 40).