Mallomonas loricata Gusev, Shkurina & Kulikovskiy, 2021

Gusev, Evgeniy, Shkurina, Nataliya & Kulikovskiy, Maxim, 2021, Mallomonas loricata sp. nov. (Synurales, Chrysophyceae), a new tropical species from section Planae, Phytotaxa 500 (3), pp. 225-233 : 229

Mallomonas loricata Gusev, Shkurina & Kulikovskiy sp. nov.

(figs 2–13)

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.

Holotype:—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.

Type locality: — VIETNAM: Binh Dinh Province, My Binh Reservoir, Latitude / Longitude : 14°33.869’ N, 108°59.427’ E .

Epithet:—The epithet refers to the thick scales, forming armor, surrounding the cell.

Distribution:—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 M. matvienkoae (Neustupa & Řezáčová 2007: 225, fig 7). Mallomonas loricata 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).

Figures

FIGURES 2–7. Mallomonas loricata sp. nov., SEM images. Figures 2–4. Scales from the type habitat, My Binh Reservoir in Binh Dinh Province; figure 2 is from the holotype specimen. Figure 5. Undersurface view of a scale. Note the base-plate pores, cover almost the entire scale surface. Figure 6. Undersurface view of two scales. Note the base-plate pores, cover about two-thirds of the proximal part of the scales, and fewer appear at the distal portion. Figure 7. Bristle. Scale bars: Figs. 5–7: 2 μm; Figs. 2–4: 1 μm.