Mallomonas foveata (Dürrschmidt) E.S. Gusev 2024

Gusev, Evgeniy S., Martynenko, Nikita A., Podunay, Yulia A. & Kuzmin, Denis V., 2024, Morphology, phylogenetic position and distribution of Mallomonas mangofera and Mallomonas foveata comb. et stat. nov. (Synurales, Chrysophyceae), Phytotaxa 662 (3), pp. 224-238 : 230

Mallomonas foveata (Dürrschmidt) E.S. Gusev comb. et stat. nov.

Basionym: Mallomonas mangofera f. foveata Dürrschmidt 1983 , Plant systematics and evolution 143: 182–185, Fig. 20 .

The cells are ellipsoidal, 10–13 × 6–7 μm, covered with overlapping scales and with a few bristles loosely associated with the apical scales. Three types of scales have been observed: apical domed collar scales, domeless body scales and small rear scales with spines. The body scales are wide-rhomboidal and 2.8–4.4 × 1.6–3.5 μm. The shield and anterior flanges are ornamented with numerous papillae and completely covered with the secondary siliceous layer. Anterior flanges are raised above the shield and usually have 2–3 rows of papillae along the edge. The shield is patterned with densely spaced papillae. The shield with or without internal reticulation in the form of polygonal mesh. There is a small pore in the distal part of the scale. The posterior submarginal rib is well developed. Several pits with rimmed pores inside are located along the posterior submarginal rib. The number of pits vary from one to six among scales from one strain, but usually from three to five. The posterior rim is wide and smooth. The posterior flange is narrow. At the distal end of each arm of the posterior submarginal rib, another parallel rib usually develops on the posterior flange. The collar scales are asymmetrical, elongate and 3.4–4.6 × 2.0–3.2 μm. Ornamentation on the shield and flanges is the same as that found on the body scales. The posterior submarginal rib on the “dorsal” side is well developed, connected with the dome. An additional submarginal rib (anterior) departs from the dome on the “ventral” side and connects with the posterior submarginal rib. There are several pits (usually 3–5) with rimmed pores inside the angle of the posterior submarginal rib. The dome on the collar scales is partially ornamented with papillae. The rear scales are 1.4–2.7 × 1.0–1.7 μm, similar in structure and outline to the body scales, and each scale bears a spine. Bristles are 6–8 μm long, curved and smooth.

Cysts were not observed.

Reference strain: Representative living and fixed strain 130Yu and DNA sample deposited at the Collection of the A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences.

Genbank accession numbers for reference strain (130Yu): PQ060085 (nuclear SSU rDNA), PQ064525 (rbc L cpDNA) and PQ060092 (nuclear ITS rDNA).

Genbank accession numbers for other strains. Strain 25Yu: PQ060084 (nuclear SSU rDNA), PQ064526 (rbc L cpDNA) and PQ060090 (nuclear ITS rDNA). Strain B2/25: PQ060091 (nuclear ITS rDNA).

Remarks: this organism was originally described from one locality in Chile ( Dürrschmidt 1983). In our studies, it was found in two provinces of Vietnam using molecular methods: Khanh Hoa and Hanoi administrative area ( Table 1).

Figures

FIGURES 15–24. Mallomonas foveata, strains 25Yu (Figures 15–16) and 130Yu (Figures 17–24). TEM and SEM. Figures 15–17. Body scales, TEM. Figure 18. Rear scale, TEM. Figure 19. Collar scale with bristle, TEM. Figure 20. Group of body, rear and collar scales, SEM. Figures 21–22. Body scales, SEM. Figures 23–24. Bristles, SEM. Scale bars: Figures 21–24: 1 μm; Figures 15–20: 2 μm.