Mallomonas voloshkoae, Gusev & Němcová & Kulikovskiy, 2022

Gusev, Evgeniy, Němcová, Yvonne & Kulikovskiy, Maxim, 2022, Mallomonas voloshkoae sp. nov. (Synurales, Chrysophyceae) and distribution of M. pechlaneri in mountain lakes of Siberia, Phytotaxa 530 (2), pp. 221-229 : 224-226

Mallomonas voloshkoae sp. nov. Gusev, Němcová & Kulikovskiy

( Figs. 2–18 )

Description: Scales are 3.4–4.5 × 1.7–2.4 μm (up to 2.6 μm with winged flanges), oval to obovate with lateral incurvings. Scales possess a posterior rim, a V-rib, anterior ribs and flanges, and a dome. The dome is subcircular and smooth. The shield is marked with four to six regularly spaced transverse ribs. A group of numerous pores, usually more than 20, is located at the angle of the V-rib in the posterior part of the shield. Anterior flanges are wide, in the form of wing-like extensions, with three to seven closely spaced struts. Anterior flanges surround the dome. The anterior submarginal ribs are well developed. The V-rib on the scales is acutely angled, slightly hooded, and continues on wing-like extensions. The posterior rim bears internal struts but is smooth on the surface. The posterior flange bears approximately 14–18 struts and scattered base-plate pores, sometimes organised to form a row ( Fig. 6 ). Bristles are 4.5–6.2 μm in length, slightly curved. The distal end of the bristle is widened. The tip is bifurcated with unequal diverging branches. One branch is short and sharp, whereas the other is wide with an acute tip and flat dorsal side ( Figs. 10–14 ). Cysts were not observed.

Holotype specimen: Portion of a single gathering of cells on SEM stub No. B137 deposited at the Herbarium, Papanin Institute for Biology of Inland Waters RAS, Borok ( IBIW). Material from an unnamed lake in the Barguzin Mountains, Republic of Buryatia, Russia, collected by E.S. Gusev and M.S. Kulikovskiy on 18 July 2014. Figure 2 illustrates a representative scale from the holotype specimen. Type Locality: Unnamed lake 1 in Barguzin Mountains , Republic of Buryatia, Russia. Latitude/Longitude: N55° 26.250’ E110° 16.363’ .

Epithet: The species is named in honour of Lyudmila Voloshko, a well-known specialist in chrysophyte algae.

Distribution: In addition to the type locality, this species was observed in other lakes of the Transbaikal area ( Table 1 ). Mallomonas voloshkoae was found in acidic to slightly acidic conditions (pH from 5.2 to 6.5) with a specific conductance ranging from 2 to 14 µS cm-1 and a temperature of 12–20°C ( Table 1 ).

Figures

FIGURES 2–14. Mallomonas voloshkoae sp. nov., scales from the type habitat. Figures 2–5. Body scales, SEM. Figure 6. Bottom surface of a scale. Note the base-plate pores covering the area in the angle of the V-rib and posterior flanges. Figures 7–9. Body scales, TEM. Figures 10–11. Body scales with bristles, TEM. Figures 12–13. Bristles, SEM. Figure 14. Tips of two bristles, SEM. Scale bars: Figs 7–11: 2 μm; Fig. 2, 4–6, 12–14: 1 μm Fig. 3: 0.5 μm.

FIGURES 15–20. Mallomonas voloshkoae and M. pechlaneri. TEM images. FIGURES 15–18. Mallomonas voloshkoae sp. nov. Body scales from different habitats. Figure 15. Unnamed lake 1. Figure 16. Unnamed lake 2. Figure 17. Unnamed lake 3. Figure 18. Lake Frolikha. FIGURES 19–20. Mallomonas pechlaneri. Figure 19. Scales with bristles from Teletskoe Lake. Figure 20. Scales with bristles from Ilchir Lake. Scale bars: Figs 15–20: 2 μm.