Mallomonas loricata Gusev, Shkurina & Kulikovskiy 2021, sp. nov.

<i>Mallomonas loricata</i> Gusev, Shkurina & Kulikovskiy <i>sp. nov.</i> <p>(figs 2–13)</p> <p>Scales are obovate, 5.7–6.8 × 3.8–4.4 μm in size. A wide posterior rim encircles one-half to two-thirds of the scale perimeter (figs 2–4). Evenly spaced small base-plate pores cover the scale surface and are often more widely spaced across the distal part (figs 5–6). One large, rimmed pore is situated in the posterior region and is surrounded by a cluster of minute pores. A thick secondary siliceous layer with internal reticulation covers almost the entire surface of the scales, excluding a small, rounded area surrounding the large, rimmed pore (figs 2–4 and 8–10). Bristles are 12–14 μm long, smooth, slightly curved, and possess a serrated distal tip; the bristle shaft is tubular, with a longitudinal slit (figs 7, 12–13). Cysts unknown.</p> <p> <b>Holotype</b>:—Portion of a single gathering of cells on SEM stub no. BD25 (holotype designated here in fig. 2) deposited at the Herbarium, Papanin Institute for Biology of Inland Waters RAS, Borok (IBIW). Material from My Binh Reservoir, Binh Dinh Province, VIETNAM, collected by E.S. Gusev on the 23 d of May, 2018. Figure 2 illustrates a representative scale from the specimen.</p> <p> <b>Type locality:</b> — VIETNAM: Binh Dinh Province, My Binh Reservoir, Latitude / Longitude: 14°33.869’ N, 108°59.427’ E.</p> <p> <b>Epithet</b>:—The epithet refers to the thick scales, forming armor, surrounding the cell.</p> <p> <b>Distribution</b>:—In addition to the type locality, this species has been observed from the other regions of Vietnam: Binh Dinh, Binh Thuan, Dak Lak, Khanh Hoa, Phu Yen, Quang Tri, and Thua Thien Hue provinces, and in Hanoi (Table 1). Also, scales of this species were reported from Singapore and Malaysia under the name <i>M. matvienkoae</i> (Neustupa & Řezáčová 2007: 225, fig 7). <i>Mallomonas loricata</i> was found in a wide range of environmental parameters including pH (6.1–8.3), specific conductance (32–287 µS cm-1) and temperature (28–36 ºC) (Table 1).</p>Published as part of <i>Gusev, Evgeniy, Shkurina, Nataliya & Kulikovskiy, Maxim, 2021, Mallomonas loricata sp. nov. (Synurales, Chrysophyceae), a new tropical species from section Planae, pp. 225-233 in Phytotaxa 500 (3)</i> on page 229, DOI: 10.11646/phytotaxa.500.3.6, <a href="http://zenodo.org/record/5424594">http://zenodo.org/record/5424594</a&gt

Mallomonas acidophila Gusev & Shkurina & Huan 2023

<i>Mallomonas acidophila</i> Gusev & Shkurina (Figures 2–22) <p>Cell dimensions unknown. Scales are tripartite, oval, 4.3–5.6 × 2.4–3.5 μm, with a dome, a V-rib, anterior submarginal ribs, a shield, anterior and posterior flanges, and a posterior rim. The base plate is devoid of pores. The dome is recessed from the distal margin, shallow, elongated or narrowly elliptical, sometimes curved. The dome can be placed perpendicular to the longitudinal axis of the scale or at an angle to this axis. It is covered with papillae. The shield is ornamented with numerous unevenly distributed papillae. The V-rib is rounded, with a broad and U-shaped base, slightly hooded, with arms that are continuous with the anterior submarginal ribs. The anterior submarginal ribs are of equal length if the dome is perpendicular to the longitudinal axis or unequal if the dome is located at an angle to the longitudinal axis. The anterior flanges are narrow. The posterior rim is narrow and encircles one-third to one-half of the scale perimeter. The posterior flange is wide and smooth. It lacks a secondary siliceous layer in a narrow area along the posterior rim and is strongly thickened in the area adjacent to the V-rib. Bristles are 2.4–7.2 μm long, straight, with a hook-shaped flattened foot, turned at an angle of approximately 45 degrees or less relative to the shaft, gutter-shaped bristle shaft, and a flattened and bifurcated apical tip with a wide, rounded middle part. Cysts are unknown.</p> <p> <b>Holotype (</b> designated here <b>)</b>:— Portion of a single gathering of cells on SEM stub number TTH55 deposited at the Herbarium of the Papanin Institute for Biology of Inland Waters RAS, Borok (IBIW). Material from unnamed reservoir in Thua Thien Hue Province, Vietnam. Sample collected 28 October 2022 by E. Gusev. Figure 3 is a representative scale from the type specimen.</p> <p>Type locality:— Vietnam: unnamed swamp water body in Thua Thien Hue Province, Phong Điễn District, Latitude / Longitude: N16°39.777’ E107°21.905’.</p> <p> <b>Etymology</b>:—The epithet “acidophila” refers to the fact that this species is found at low pH values.</p> <p> <b>Distribution:</b> —To date, <i>M</i>. <i>acidophila</i> has been observed in two neighbouring localities in Vietnam. In addition to the type locality, it has been found in another unnamed water body (Latitude/Longitude: N16°39.694’ E107°21.746’).</p> <p> <b>Observations:</b> — <i>Mallomonas acidophila</i> was found in acidic conditions (pH 5.0–5.2), with low specific conductance values ranged from 17 to 18 μS cm-1, temperature 26 ºC, total phosphorus concentrations 68–133 μL-1, Kjeldahl nitrogen concentrations 406–508 μL-1.</p>Published as part of <i>Gusev, Evgeniy, Shkurina, Nataliya & Huan, Phan Trong, 2023, Mallomonas acidophila sp. nov. (Synurales, Chrysophyceae) - a new species from the tropics with morphological features of fossil taxa, pp. 157-166 in Phytotaxa 620 (2)</i> on page 159, DOI: 10.11646/phytotaxa.620.2.3, <a href="http://zenodo.org/record/10022374">http://zenodo.org/record/10022374</a&gt

Mallomonas pseudocorymbosa Gusev, Martynenko & Shkurina 2023, sp. nov.

<i>Mallomonas pseudocorymbosa</i> Gusev, Martynenko & Shkurina <i>sp. nov.</i> (Figure 2). <p> <b>Diagnosis:</b> Scales are oval, tripartite, 4.8–5.9 × 3.3–4.3 µm in size, with or without a dome. The dome is large, rounded, oval or asymmetrical. The V-rib is acute, slightly hooded and its arms continuous with the anterior submarginal ribs. Anterior submarginal ribs are well developed. The anterior flange is wide, especially on the domeless scales, with a row of base plate pores at each side. The posterior flange is wide, with numerous base plate pores distributed on the surface. The shield and posterior flange have a secondary siliceous layer forming circular or elongated oval meshes unevenly distributed on the surface often with areas without development of the secondary layer. Numerous pores are placed on the basal plate. The posterior upturned rim is narrow, with inner struts visible only on TEM images, encircles less than a half of the scale perimeter. Bristles are 13–25 μm long, curved and serrated at the distal half. Shorter bristles have a bifurcated tip with a long terminal spine, and longer bristles have a prolonged thread-like terminal part. Cysts unknown.</p> <p> <i>Holotype (here designated):</i> Portion of a single gathering of cells on SEM stub No. CD8 deposited at the Herbarium, Papanin Institute for Biology of Inland Waters RAS, Borok (IBIW). Material from Ahn Hai Lake, Côn SƠn Island, Bà Rịa-Vũng Tàu Province, Vietnam. Figure 2C illustrates a representative scale from the holotype specimen.</p> <p> <i>Type Locality:</i> Ahn Hai Lake, Côn SƠn Island, Bà Rịa-Vũng Tàu Province, Vietnam. Latitude / Longitude: 8° 40.645’ N 106° 35.867’ E. At the time of collection, the pH was 6.5, temperature 30 °C, and specific conductance 201 µS cm-1. Material was collected by E.S. Gusev and Nguyen-Ngoc Lam on 3 May 2015.</p> <p> <i>Etymology:</i> The species name is derived from the fact that its scales resemble, and could be confused with, those of <i>Mallomonas corymbosa</i>.</p> <p> <i>Distribution:</i> This species has been observed in 17 localities in 13 provinces of Vietnam (Table 1). Scales of this species were also observed in Bangladesh (Takahashi & Hayakawa 1979), China (Wei &Yuan 2001, 2013; Wei <i>et al</i>. 2014), Brazil (Franceschini & Couté 1991)and South Africa (Janse van Vuuren <i>et al</i>. 2022). <i>Mallomonas pseudocorymbosa</i> was found at wide ranges of environmental parameters: pH from 6.1 to 8.6, specific conductance from 62 to 2370 µS cm-1, chlorophyll <i>a</i> values from 5 to 76 µg l –1, and temperature 17–39 ºC (Table 1).</p>Published as part of <i>Gusev, Evgeniy, Martynenko, Nikita, Shkurina, Nataliya & Dien, Tran Duc, 2023, Description of a new species of the genus Mallomonas from section Mallomonas (Synurales, Chrysophyceae) in the tropics, pp. 59-68 in Phytotaxa 618 (1)</i> on page 62, DOI: 10.11646/phytotaxa.618.1.5, <a href="http://zenodo.org/record/8389917">http://zenodo.org/record/8389917</a&gt

An Annotated Checklist of Algae from the Order Synurales (Chrysophyceae) of Viet Nam

This paper presents an annotated list of the Mallomonas and Synura taxa (order Synurales, class Chrysophyceae) found in Viet Nam. This list is based on materials from long-term studies (from 2008 to 2020) of 371 freshwater localities in 18 provinces in the country. A total of 67 taxa (morphotypes) of the genus Mallomonas and 7 of the genus Synura were reported. For each species, the range of abiotic environmental parameters under which they were found is given, as well as comments on the distribution of these taxa within Viet Nam and the tropical region