Strong Endemism of Bloom-Forming Tubular Ulva in Indian West Coast, with Description of Ulva paschima Sp. Nov. (Ulvales, Chlorophyta)

Felix Bast,Aijaz Ahmad John,Satej Bhushan,Ross Frederick Waller

doi:10.1371/journal.pone.0109295

Abstract

Ulva intestinalis and Ulva compressa are two bloom-forming morphologically-cryptic species of green seaweeds widely accepted as cosmopolitan in distribution. Previous studies have shown that these are two distinct species that exhibit great morphological plasticity with changing seawater salinity. Here we present a phylogeographic assessment of tubular Ulva that we considered belonging to this complex collected from various marine and estuarine green-tide occurrences in a ca. 600 km stretch of the Indian west coast. Maximum Likelihood and Bayesian Inference phylogenetic reconstructions using ITS nrDNA revealed strong endemism of Indian tubular Ulva, with none of the Indian isolates forming part of the already described phylogenetic clades of either U. compressa or U. intestinalis. Due to the straightforward conclusion that Indian isolates form a robust and distinct phylogenetic clade, a description of a new bloom-forming species, Ulva paschima Bast, is formally proposed. Our phylogenetic reconstructions using Neighbor-Joining method revealed evolutionary affinity of this new species with Ulva flexuosa. This is the first molecular assessment of Ulva from the Indian Subcontinent.

Highlights

Genus Ulva (Linnaeus), commonly known as ‘‘Sea Lettuce’’, encompasses some of the most ubiquitous green seaweeds distributed throughout the world, with habitats ranging from marine to freshwater
This algal genus is both beneficial and disadvantageous; beneficial as some species of this genus, including Ulva prolifera [1] and Ulva intestinalis [2], are commercially cultivated worldwide for its culinary use and disadvantageous as this genus is notorious for its ability to cause massive green-tides [3] and marine fouling [4]
In terms of cell arrangement, isolates KAR and KAN were similar, with more or less linear arrangement of cells

Summary

Introduction

Genus Ulva (Linnaeus), commonly known as ‘‘Sea Lettuce’’, encompasses some of the most ubiquitous green seaweeds distributed throughout the world, with habitats ranging from marine to freshwater This algal genus is both beneficial and disadvantageous; beneficial as some species of this genus, including Ulva prolifera [1] and Ulva intestinalis [2], are commercially cultivated worldwide for its culinary use and disadvantageous as this genus is notorious for its ability to cause massive green-tides [3] and marine fouling [4]. Due to taxonomic confusions in morphology-based species delineation, concept of Operational Taxonomic Units (OTUs) have been used in recent phylogeographic assessments of Ulva from Hawaii [10] and USA [11]

Methods

Results

Conclusion