Mallomonas sibirica Bessudova & Firsova & Tomberg & Bayramova & Hilkhanova & Bedoshvili & Bashenkhaeva & Zakharova & Likhoshway 2023, sp. nov.

<i>Mallomonas sibirica sp. nov.</i> Bessudova (Figs. 5–11) <p> <b>Description:</b> Scales are 4.1–5.5 × 2.0–2.9 μm, oval, with lateral incurvings. The dome is subcircular, its ornamentation appears to vary between samples: smooth surface or with struts or rounded depressions (up to 0.15 μm in diameter) or reticulum variants were noted. The shield is covered with a thick secondary siliceous layer, marked with 8–12 regularly spaced transverse ribs with rounded depressions between them. Rounded depressions (up to 0.15 μm in diameter) are evenly distributed between the transverse ribs (Fig. 5, 6, 9). There is a pore on the basal plate inside each depression. A group of 8–10 pores is located in the angle of the V-rib in the posterior part of the shield (Fig. 5). This area is lacking the secondary siliceous layer. Anterior flanges are well-developed, with 2–8 (14) struts on each side (Figs. 7, 8). The V-rib on the scales is acutely angled, slightly hooded, and continues on the anterior flanges. The posterior rim is wide and smooth, bears numerous internal struts (Fig. 5). The posterior flange contains approximately 14–20 struts and scattered rounded depressions between them, that are not evenly spaced (Fig. 5). Bristles are 3.3–8.7 μm in length, slightly curved (Fig. 11). 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. Cysts were not observed.</p> <p> <b>Holotype</b> (here designated): Portion of a single gathering of cells on SEM stubs No. 18075 deposited at the herbarium of the Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk (LIN). Y.R. Zakharova, Y.D. Bedoshvili and L.I. Kopyrina collected material from Ulu Lake, in the Republic of Yakutia, Russia, on April 24, 2021. Figure 6 illustrates illustrates the characteristic scales from the holotype.</p> <p> <b>Type locality:</b> Ulu Lake, Republic of Yakutia, Russia. Latitude/Longitude: N63º20ʹ9ʺ E141º3ʹ54ʺ.</p> <p> <b>Etymology:</b> The new species is named after the region of its origin, Siberia.</p> <p> <b>Distribution:</b> Up-to-date, <i>M. sibirica</i> have been recorded in the type locality and in other water bodies of Eastern Siberia: мixing zone of Yenisei River and Kara Sea waters; Vorota and Labynkyr lakes, Lake Baikal. <i>M. sibirica</i> was found at wide ranges of environmental parameters: pH from 6.97 to 9.34, specific conductance from 5.17 to 6560 μS̛ сm−1, and temperature of 0.4–10.2°C, salinity from 0.4 to 3.8 ‰ (see Table 1).</p>Published as part of <i>Bessudova, Anna, Firsova, Alena D., Tomberg, Irina V., Bayramova, Elvira, Hilkhanova, Diana, Bedoshvili, Yekaterina D., Bashenkhaeva, Maria, Zakharova, Lyubov I. Kopyrina Yulia R. & Likhoshway, Yelena V., 2023, Two new species of silica-scaled chrysophytes (Chrysophyceae, Synurales) Mallomonas kicherica and M. sibirica water bodies of Eastern Siberia, Russia, pp. 59-69 in Phytotaxa 620 (1)</i> on pages 64-65, DOI: 10.11646/phytotaxa.620.1.5, <a href="http://zenodo.org/record/10015521">http://zenodo.org/record/10015521</a&gt

Mallomonas kicherica Bessudova & Firsova & Tomberg & Bayramova & Hilkhanova & Bedoshvili & Bashenkhaeva & Zakharova & Likhoshway 2023, sp. nov.

<i>Mallomonas kicherica sp. nov.</i> Bessudova (Figs. 2–4). <p> <b>Description:</b> Scales are 3.4–4.5 × 1.8–2.4 μm, oval with lateral incurvings. The dome is subcircular with labyrinth-like reticulation. Small ribs extending to the first transverse rib extend from the dome towards the shield. The shield is patterned with of 8–11 regularly spaced transverse ribs. The transverse ribs, except for the area between the first and second (closest to the dome), are connected in random order by short ribs-jumpers (Figs. 2–4). The anterior flanges with 8–11 closely spaced struts on each side (Figs. 2–4). The anterior submarginal ribs are well-developed. The V-rib on the scales is acutely angled, hooded. The posterior rim is wide and smooth. The posterior flange contains approximately 20–23 struts (Figs. 2–4). Bristles are 6.5–9.2 μm in length, slightly curved (Fig. 2). The tip of the bristle 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. Cysts were not observed.</p> <p> <b>Holotype</b> (here designated): Portion of a single gathering of cells on SEM stub No. 18422 deposited at the herbarium of the Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk (LIN). Material from the Angara-Kichera estuary, a tributary of the northern part of Lake Baikal, was collected in June 2022. Figures 2–4 illustrates the characteristic scales from the holotype.</p> <p> <b>Type locality:</b> Mouth of the Kichera River, a tributary of the northern part of Lake Baikal, Republic of Buryatia, Russia. Latitude/Longitude: 55°43′55′′N, 109°32′24′′E.</p> <p> <b>Etymology:</b> The new species name is derived from the type locality, the Kichera River.</p> <p> <b>Distribution:</b> Up-to-date, <i>M. kicherica</i> has been only observed in its type locality. At the time of collection, pH = 8.04, T = 16.9°C, and EC = 112 μS̛ сm−1 (see Table 1).</p>Published as part of <i>Bessudova, Anna, Firsova, Alena D., Tomberg, Irina V., Bayramova, Elvira, Hilkhanova, Diana, Bedoshvili, Yekaterina D., Bashenkhaeva, Maria, Zakharova, Lyubov I. Kopyrina Yulia R. & Likhoshway, Yelena V., 2023, Two new species of silica-scaled chrysophytes (Chrysophyceae, Synurales) Mallomonas kicherica and M. sibirica water bodies of Eastern Siberia, Russia, pp. 59-69 in Phytotaxa 620 (1)</i> on pages 62-63, DOI: 10.11646/phytotaxa.620.1.5, <a href="http://zenodo.org/record/10015521">http://zenodo.org/record/10015521</a&gt