Diving into Diversity: Haslea berepwari (Bacillariophyceae, Naviculaceae), a new species of marine diatom from New Caledonia

The current article introduces and describes <i>Hasleaberepwari</i> <b>sp. nov.</b>, a new species of diatom discovered in the vicinity of Boulouparis, New Caledonia. Under light microscopy, <i>H.berepwari</i> <b>sp. nov.</b> strongly resembles <i>Hasleapseudostrearia</i>, but preliminary molecular barcoding conducted using partial 18S and <i>rbcL</i> genes suggested that it was a distinct species. This was confirmed first by scanning electron microscopy which showed the differences in stria densities between both species. A short-reads genome-skimming protocol applied on <i>H.berepwari</i> <b>sp. nov.</b> led us to obtain its complete mitochondrial and plastid genomes. The mitogenome is 36,572 bp in length and as already observed among other species of <i>Haslea</i> spp., the <i>nad6</i> and <i>nad2</i> genes are fused within a single open-reading frame. The plastome is 131,897 bp length, and unlike the mitogenome, it is not colinear with those of <i>H.pseudostrearia</i>. The results derived from the sequencing of the plastome allowed to perform a 123-gene multigene maximum likelihood phylogeny that associates <i>H.berepwari</i> <b>sp. nov.</b> to <i>H.pseudostrearia</i> with maximum support at the nodes but also strictly distinguishes them, suggesting a greater genetic distance between these species than what has been previously observed between other marennine-producing species.