Haslea nusantara (Bacillariophyceae), a new blue diatom from the Java Sea, Indonesia: morphology, biometry and molecular characterization

Claude Lemieux,Romain Gastineau,Monique Turmel,Fiddy Semba Prasetiya,Vincent Leignel,Sulastri Arsad,Charlotte Falaise,Ikha Safitri,Jean-Luc Mouget,Yann Hardivillier,Ita Widowati,Toto Subroto,Agung Dhamar Syakti,Yenny Risjani,Iskandar Iskandar,Michel Poulin

doi:10.5091/plecevo.2019.1623

Abstract

Background and aims – The present study aims to describe a new species of pennate blue diatom from the genus Haslea, H. nusantara sp. nov., collected from Semak Daun Island, the Seribu Archipelago, in Indonesian marine waters. Methods – Assessment for species identification was conducted using light microscopy, Scanning Electron Microscopy and molecular techniques. The morphological characteristics of H. nusantara have been described, illustrated and compared to other morphologically similar blue Haslea taxa, distributed worldwide. Additionally, molecular characterization was achieved by sequencing plastidial and mitochondrial genomes. Key results – This new species, named Haslea nusantara, cannot be discriminated by its morphology (stria density) but it is characterized by its gene sequences (rbcL chloroplast gene and cox1 mitochondrial gene). Moreover, it differentiates from other blue Haslea species by the presence of a thin central bar, which has been previously reported in non-blue species like H. pseudostrearia. The complete mitochondrion (36,288 basepairs, bp) and plastid (120,448 bp) genomes of H. nusantara were sequenced and the gene arrangements were compared with other diatom genomes. Phylogeny analyses established using rbcL indicated that H. nusantara is included in the blue Haslea cluster and close to a blue Haslea sp. found in Canary Islands (H. silbo sp. ined.). Conclusions – All investigations carried out in this study show that H. nusantara is a new blue-pigmented species, which belongs to the blue Haslea clade, with an exceptional geographic distribution in the Southern Hemisphere.

Highlights

The pennate diatom Haslea ostrearia (Gaillon) Simonsen, has long been known as the only blue diatom ever described, and it is the type species of the genus Haslea Simonsen (Simonsen 1974, Poulin et al 2019)
Recent works on the blue Haslea using scanning electron microscopy (SEM) observation and molecular approaches have enlightened an unsuspected biodiversity of this genus, with two new species, H. karadagensis Davidovich et al (Gastineau et al 2012b) col
The present study aims to describe a new species of pennate blue diatom from the genus Haslea, H. nusantara sp. nov., collected from Semak Daun Island, the Seribu Archipelago, in Indonesian marine waters

Summary

Introduction

The pennate diatom Haslea ostrearia (Gaillon) Simonsen, has long been known as the only blue diatom ever described, and it is the type species of the genus Haslea Simonsen (Simonsen 1974, Poulin et al 2019) This microalga produces a water-soluble blue pigment, marennine (Lankester 1886), which accumulates at cell apices and is released into the seawater. This pigment is responsible for the greening of oyster’s gills in the Atlantic coast of France (Gaillon 1820) This phenomenon gives a significant economic added value to the French oyster industry, since green oysters, with specific flavour and emerald colour, are rarer and more expensive than ordinary oysters. Recent works on the blue Haslea using scanning electron microscopy (SEM) observation and molecular approaches have enlightened an unsuspected biodiversity of this genus, with two new species, H. karadagensis Davidovich et al (Gastineau et al 2012b) col-

Methods

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Conclusion