Morphology and molecular phylogeny of Pleurosigma pacificum sp. nov. (Pleurosigmataceae), a new tropical pelagic species from the Western Pacific Ocean

By

Du, Feichao
Li, Yuhang
Xu, Kuidong

Type

Article

Date of Publication

2023

Original Publication

PhytoKeys

Volume

227

Pages

99--108

Subjects

marine diatoms , Morphology , new species , Phylogeny , Pleurosigma , Western Pacific Ocean

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers [2010]-

Identifiers

DOI: https://doi.org/10.3897/phytokeys.227.103890

 

Abstract

A new species of pelagic diatom, Pleurosigma pacificumsp. nov., is described from the tropical Western Pacific Ocean. It has the typical features of Pleurosigma, including a slightly sigmoid raphe, intersected transverse and oblique striae, and loculate areolae with external opening slits and internal poroids. Morphologically, P. pacificum belongs to a species group of Pleurosigma with lanceolate valves, including P. atlanticum Heiden & Kolbe, P. nubecula W. Smith, P. indicum Simonsen, and P. simonsenii Hasle. However, P. pacificum differs by its smaller lanceolate valve and smaller intersection angle as well as elliptical areolae without a silica bar. The SSU rDNA and rbcL sequence data place P. pacificum in a basal position relative to other species of Pleurosigma. Our molecular phylogenetic analyses did not support the monophyly of lanceolate and slightly sigmoid species. Thus, the sigmoidality of valve outline cannot be considered as a criterion to define the species group.