Rhabdomonas costata (Korshikov) Pringsheim, 1942

Bharti, Daizy & Kumar, Santosh, 2019, Two freshwater flagellates from the Mahananda Wildlife Sanctuary, West Bengal, Records of the Zoological Survey of India 119 (4), pp. 451-455 : 452

1. Rhabdomonas costata (Korshikov) Pringsheim, 1942

( Figure 1 A-E)

Diagnosis of the Indian population (Data based on 7 specimens): Size about 20 × 10 μm in stained preparations; shape elliptical to narrowly elliptical, longitudinally extended, abdominal side convex,dorsal slightly curved.Nucleus slightly posterior of body midline, about 6-11 μm from anterior body end with diameter about 4-5 μm, nucleolus globular visible in stained preparation with diameter about 3-4 μm. Paramylon bodies of 2-5 μm length present throughout the cell. A row (sometime two rows) of ejectosomes present posterior to the base of flagellum.Two flagella emerging out from a prominent small groove at the anterior body end, one flagellum slightly shorter than the other.

Material deposited: A slide including protargolimpregnated specimens have been deposited at the National Zoological Collections of the Zoological Survey of India, Kolkata, India with the following accession numbers Pt. 4506 (specimens marked with black ink circles on the slide).

Occurrence and ecology: The species Rhabdomonas costata is rather common in both freshwater ecosystems. It has a rather cosmopolitan distribution with reports from Europe, Poland, Asia, and North America. The present study reports its presence from a small pond near Helay Khola watch tower, Lower Ghoramara Block, Sevok Beat, North Range, Mahananda Wildlife Sanctuary, West Bengal (26°50'671"N 88°26'293"E). When the sample was collected the specimens were in high abundance and possibly responsible for the slightly greenish colour of the water due to its blooming.

Figures

Figure 1. Photomicrographs of Rhabdomonas costata from live (A-D) and silver stained preparations (E). A-D. Specimens showing the body shape, paramylon bodies (B), nucleus position (D) and ejectosomes (C, D), Arrows point to the flagellum. E. Four specimens showing the body size variation, flagella length, and nucleus position. The nucleolus is visible in the stained preparations. E, ejectosomes; F1,2, flagellum 1, 2; N, nucleus; Nu, nucleolus; PG, paramylon bodies. Scale bars, 10 μm.