Ulva paschima
Endemic green seaweed of India's West Coast.
Ulva paschima is a green seaweed from the family Ulvaceae, found only along India’s West Coast. It was recognized as a distinct species in 2014 through molecular analysis of ITS sequences, which placed it in the “Paschima” clade.
The fronds are erect, filamentous, and grass-green, ranging from 5 to 40 cm in length. They are mostly unbranched and tubular, though some parts may be flattened like ribbons. The tufts attach to surfaces using rhizoids. Thalli growing in low-salinity water tend to be branched, while those in open ocean conditions are unbranched. The cells are roughly quadrilateral, sometimes arranged in lines, and each cell contains a parietal chloroplast with more than two pyrenoids.
This alga lives on intertidal rocks in both saline and estuarine environments, tolerating salinities from 35 down to 24 PSU.
Its life cycle involves sporangial and gametangial thalli that look identical. The diploid adult releases haploid zoospores through meiosis; these settle and grow into separate male and female haploid plants, which resemble the diploid form. When these haploid plants release gametes, they fuse to form a zygote that germinates into a new diploid plant.
Quick Facts
- Genus
- Ulva
- Species
- paschima
Facts from the source article.
Lore & Background
The fronds of Ulva paschima are erect, filamentous, and grass-green in color, ranging from 5 cm to 40 cm in length. They are mostly unbranched and tubular, with some parts of the thalli compressed like flat ribbons. The tufts of filamentous thalli attach to the substrate by rhizoids. Thalli from low-saline environments are branched, while those exposed to the ocean are non-branched. Cells are more or less quadrilateral; some have linear cell arrangement, and parietal chloroplasts contain more than two pyrenoids per cell.
The species is found on intertidal rocks in both saline and estuarine environments, tolerating seawater salinities from 35 to 24 PSU. Its distribution is strictly endemic to the Indian West Coast.
In its life history, the sporangial and gametangial thalli are morphologically alike. The diploid adult plant produces haploid zoospores by meiosis; these settle and grow to form haploid male and female plants similar to the diploid plants. When these haploid plants release gametes, they unite to produce the zygote, which germinates and grows to produce the diploid plant.
Reader's Guide
Ulva paschima is notable as a green seaweed endemic to the West Coast of India, identified in 2014 through molecular phylogenetics using ITS sequences. Its placement in the 'Paschima' clade distinguishes it from other Ulva species. The species exhibits morphological plasticity: thalli from low-saline environments are branched, while those from oceanic exposure are unbranched. This adaptation to varying salinities (35 to 24 PSU) allows it to occupy both intertidal rocks in saline and estuarine habitats. Its life history involves isomorphic alternation of generations, with diploid and haploid phases appearing similar. The species contributes to understanding of Ulva diversity along the Indian coast and highlights the role of molecular tools in resolving cryptic species. Its restricted distribution underscores the importance of conserving coastal habitats in the region.
Did You Know?
- Ulva paschima is endemic to the West Coast of India.
- The species was identified using ITS sequences in molecular phylogenetics.
- Parietal chloroplasts have more than two pyrenoids per cell.
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