Entomoneis tenera sp. nov., a new marine planktonic diatom (Entomoneidaceae, Bacillariophyta) from the Adriatic Sea

Abstract

The genus Entomoneis Ehrenberg includes diatoms with structurally complex frustules having a bilobate keel elevated above the valve surface and numerous girdle bands. We describe here a new member of the genus, Entomoneis tenera sp. nov., a minute species found in the plankton of the south-eastern Adriatic Sea. The description and proposed taxonomic affiliation are based on both morphological observations and molecular analyses obtained from three cultivated strains. The cultures were established from plankton net samples taken during BIOTA (Bio-tracing Adriatic Water Masses) cruise conducted in February–March 2015. In addition to characteristic Entomoneis features such as panduriform cells, often twisted around the apical axis and a raphe with simple endings positioned on the sigmoid keel, morphological characteristics of E. tenera are: (1) very small cells, 16–21 μm long and 5–20 μm wide (2) very lightly silicified, delicate frustules without valve striation discernible in light microscopy, (3) broad lanceolate valves with scalpeliform apices (4) a straight to slightly arcuate junction line. Phylogenetic analyses using SSU, rbcL and psbC supported the position of E. tenera within the Entomoneis genus with a clear separation from the other described species.

Morphological diversity and phylogeny of the diatom genus Entomoneis (Bacillariophyta) in marine plankton: six new species from the Adriatic Sea

“…In Mejdandžić et al. () TEM micrographs published as figures 21, 22, 24, 26, and 31 and labeled as Entomoneis tenera actually depict specimens of E. pusilla .…”

“…Specific terminology for Entomoneis follows Paddock and Sims (), Osada and Kobayasi () and Mejdandžić et al. (). The “junction line” introduced by Cleve () has featured prominently in the taxonomy and classification of Entomoneis and related genera.…”

“… Correction of seven accession numbers belonging to sequences of each of three E. tenera strains published by Mejdandžić et al. (). …”

“…), and of these, the description of Entomoneis tenera pioneered the use of combined morphological and molecular evidence for species delimitation within the Entomoneis genus (Mejdandžić et al. ).…”

“…, Mejdandžić et al. ) and majority of species are understudied from a taxonomic and phylogenetic perspective. Understanding the phylogeny of Entomoneis has been hindered by the fact that the majority of available molecular sequences originate from strains that have not been identified to the species level (e.g., Damsté et al.…”