← Back to algae index

Plagioselmis nannoplanctica (Skuja) Novarino et al. 1994

Previous name used

Rhodomonas minuta var. nannoplanctica Skuja 1948

Phylum
Cryptista
Class
Cryptophyceae
Order
Cryptomonadales
Habitat
plankton, pelagic/littoral Distinctive featureses: heavily grazed by zooplankton, contains phycoerythrine (like cyanobacteria) – fluorecses orange when stained with DAPI. Always present in the water column. Distinctively smaller size than Cryptomonas. Probably mixotrophic.
Organization
flagellated single cells
Color
reddish to dark brown
Cell shape
drop-like
Cell diameter (D)
3 – 6 μm, median: 4.5 μm (N=477).
Cell length (L)
6 – 10 μm, median: 7.8 μm (N=390).
Cell biovolume
40 – 150 μm3, median: 82 μm3.
Biovolume equation
V=1.841D2.5264 (regression eqn. between D and V based on 390 measurements of both D and L with V computed for a Half sphere + cone; R2=0.93).

Morphological features

A small drop-shaped monad with two slightly unequal (Plate 1), this is the smaller cryptophyte of Lake Kinneret. A single red (contains phycoerythrin) chloroplast is with margins. A central large surrounded by a thick startch sheath of 2 hemispherical halves. The nucleus is . Its chloroplast fluoresces orange (auatofluorescence) when observed under an epifluorescent microscope.
Plagioselmis nannoplanctica (Skuja) Novarino et al. 1994 — plate 1 (from source)
Plate 1. Plagioselmis nannoplanctonica (previously named Rhodomonas minuta va. nannooplanctonica). Showing typical drop shape, and unequal flagella emerging from a groove at the top, rounded part of the cell. Left drawing shows also the periferal chloroplast (black), central pyrenoid surrounded by a thick starch sheath of two hemispheral halves. Right drawing shows details of cell surface seen by scanning electron microscopy. Drawing taken from Novarino (2002).

Ecology

Plagioselmis nannoplanctonica is present in the Kinneret water column, in the pelagial and littoral, at all times of year, and has been present continuously since 1970 (Fig. 1). It has a distinct annual cycle of peak abundance during winter holomixis (Dec. to Mar.), lowest in summer (Jun. to Oct.; Fig. 2). Indifferent to increasing salinity (or chloride conc.; Fig. 3). Like Cryptomnonas, it is present in both the pelagic and littoral zones and is highly grazed by zooplankton.

Environmental conditions

Present at the full range observed in Lake Kinneret of the following environmental variables: Zeu (euphotic zone depth), Secchi depth, pH, NH4, DO, SO4, Total suspended solids, Turbidity. Abundance increases with increasing and nitrate, and with declining water temperature, DON, Organic N, total dissolved P (Fig. 3).

Additional figures

Figure 1. Figure 1. Time series of Plagioselmis nannoplanctonica abundance (cells mL-1), Lake Kinneret, 1970-2020.
Figure 2. The annual pattern of water column cell abundance of Plagioselmis nannoplanctonica in Lake Kinneret, based on data for 1970-2020. Statistics shown are: median – middle line; 25th to 75th percentiles – box content; 90th and 10th percentiles - top and bottom bars, respectively.
Figure 3. Plagioselmis nannoplanctonica abundance (cells mL-1) vs. environmental parameters recorded at the site and time of sampling.

Cite this record as: Dr. Tamar Zohary, Dr. Alla Alster. 16 June 2026. Electronic publication. Israel Oceanographic & Limnological Research. https://kinneret-algae-atlas.org/ Searched on —.

Further reading

  1. Lund JWG 1962. A rarely recorded but very common British alga, Rhodomonas minuta Skuja. British Phycological Bulletin, 2: 133-139.
  2. Novarino G 2002. Cryptophyta (Cryptomonads). In: The freshwater algal flora of the British Isles. An identification guide to freshwater and terrestrial algae. Eds: John DM, Whitton BA, Brook AJ. pp. 240-249. Cambridge: Cambridge University Press.
  3. B-Beres V 2024. Az egybarazdas moszatok [cryptophyceae] kishatarozoja. Hun-REN OK VOI, Funkcionalis Algologgiai Kutatocsoport.

← Back to algae index