Mallomonas mangofera K. Harris & D.E. Bradley ex 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 : 228-230

Mallomonas mangofera K. Harris & D.E. Bradley ex E.S. Gusev sp. nov. ( Figs 1–14 )

Synonym: Mallomonas mangofera K. Harris & D.E. Bradley 1960 , Journal of General Microbiology 22: 772–773, Figs 41–44, Pl. 7, Figs 54, 56, 57, nom. inval. ( Turland et al., 2018: Art. 40), non Mallomonas mangofera f. mangofera apud Dürrschmidt (1983: 177–182).

Cells are ellipsoidal, 20–30 × 10–16 μm, covered with overlapping scales and with a few long curved 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 or oval, 3.7–5.0 × 2.1–3.3 μm. The shield and anterior flanges are ornamented with numerous papillae. Anterior flanges are raised above the shield and usually have 3–4 rows of papillae along the edge. The shield is patterned with densely spaced papillae except for an area at the base of the posterior submarginal rib that lacks a secondary siliceous layer. There are base plate pores on the shield. Scales from samples have numerous base plate pores on the shield ( Figures 11–14 ) while scales from cultures have fewer base plate pores on the shield ( Figures 8–10 ). The posterior submarginal rib is well developed. There is a rounded or triangular area in the angle of the posterior submarginal rib, lacking a secondary layer, which contains rows of pores on the base plate along the arms of the posterior submarginal rib. The posterior rim is narrow and smooth. The posterior flange has a distinct row of base plate pores on each side along the posterior rim. The collar scales are asymmetrical, elongate, 5.2–6.4 × 2.3–3.9 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. There is a large area adjacent to the posterior submarginal rib lacking a secondary siliceous layer with numerous base plate pores. An additional submarginal rib (anterior) departs from the dome on the “ventral“ side and connects with the posterior submarginal rib. The posterior flange has a distinct row of base plate pores along the posterior rim. The dome on the collar scales is partially ornamented with papillae. The rear scales are 1.5–3.3 × 1.1–2.0 μm, similar in structure and outline to the body scales, and each scale bears a spine. Bristles are 10–19 µm long, curved and smooth. Stomatocysts are wide ellipsoidal, 14–16 × 12–14 µm, with a collar and ornamented surface. The collar is obconical (apical diameter 2.6 µm, height 0.6–1.3 µm), located asymmetrically relative to the central axis of the stomatocyst. The apex of the collar has toothed projections. The pore is regular, 0.7 µm in diameter, surrounded by a swollen annulus. The stomatocyst surface is ornamented with verrucae, small acute conical spines or elongated spines bifurcating at the apex, depending on the stage of cyst maturity.

Holotype: — Portion of a single gathering of cells on SEM stub, deposited at the Herbarium , Komarov Botanical Institute RAS ( LE), Saint Petersburg, Russia ( LE A0006799 ). Material from a floodplain area adjacent to the Rybinsk Reservoir near Borok settlement (Yaroslavskaya oblast), Russia, collected by E.S. Gusev, 5 November 2015. Figure 1 is a representative scale from the specimen.

Type locality: — Russia, Yaroslavskaya oblast, floodplain area adjacent to the Rybinsk Reservoir. Latitude/ Longitude: 58°04.056’N 038°14.842’E.

Reference strain: Representative living and fixed strain R 092 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 ( R 092): PQ060087 (nuclear SSU rDNA), PQ064528 (rbc L cpDNA) and PQ060089 (nuclear ITS rDNA).

Genbank accession numbers for other strain ( R 079): PQ060086 (nuclear SSU rDNA), PQ064527 (rbc L cpDNA) and PQ060088 (nuclear ITS rDNA).

Remarks: the species was originally described from one locality (small pond on acid peat) near Hook, Nat. Grid 4721155 ( Harris & Bradley 1960) without indication of the type.

Figures

FIGURES 1–7. Mallomonas mangofera, strains R092 (scales and bristle) and R079 (stomatocysts). SEM. Figure 1. Body scale. Figure 2. Collar scale. Figure 3. Two rear scales. Figure 4. Group of body and collar scales. Figures 5–6. Stomatocysts. Figure 7. Bristle. Scale bars: Figures 1–4: 1 μm; Figures 5–7: 2 μm.

FIGURES 8–14. Mallomonas mangofera, strain R092 (Figures 8–10) and material from natural samples (Figures 11–14). TEM. Figures 8–9. Body scales. Figure 10. Collar scale. Figures 11–12. Body scales. Figure 13. Collar scale. Figure 14. Collar scale with bristle. Scale bars: Figures 8–13: 5 μm; Figure 14: 5 μm.