Original paper
Gomphadelpha (Bacillariophyceae) – a new genus name for taxa formerly subsumed in the Gomphoneis herculeana-group
Abarca, Nélida; Stancheva, Rosalina; Skibbe, Oliver; Schimani, Katherina; Kusber, Wolf-Henning; Zimmermann, Jonas; Jahn, Regine
Nova Hedwigia Band 117 Heft 1-4 (2023), p. 213 - 254
63 references
published: Dec 12, 2023
published online: Oct 16, 2023
manuscript accepted: Aug 11, 2023
final revised version received: Jul 6, 2023
manuscript revision requested: Jun 20, 2023
manuscript received: Mar 31, 2023
DOI: 10.1127/nova_hedwigia/2023/0859
ArtNo. ESP050011700014, Price: 29.00 €
Abstract
Within the project “German Barcode of Life – Diatoms” diatoms of German waters were isolated and cultivated for integrative taxonomical research. In one of these studies, it was discovered that the genus Gomphoneis was not monophyletic. In terms of their molecular data some taxa – such as Gomphoneis herculeana var. minuta – clustered next to taxa of the Gomphonema core group within the family Gomphonemataceae as expected. Other taxa, such as Gomphonella olivacea and G. tegelensis, which have been shown to be morphologically close to the generitype of Gomphoneis – G. elegans – clustered outside this family but within the order Cymbellales. Since G. herculeanum had been described from North American waters by Ehrenberg 1845, its original material was studied in detail morphometrically and with high-resolution SEM. It was compared to strains and populations of a gomphonemoid taxon isolated from a mountain creek in northern California. The molecular data (rbcL and 18SV4) place this species within the taxa clustering next to the Gomphonema core group. Since the genus name Gomphoneis was tied to the G. elegans-group that clustered outside the Gomphonemataceae, we separated this group of taxa into a new genus described herein, Gomphadelpha, based on the new taxon G. kociolekii. Besides molecular data, Gomphadelpha can be separated morphologically from Gomphoneis and Gomphonella by having areolae that are differentiated between the valve and the footpole as well as a single round stigma that is slit-like internally, in contrast to undifferentiated apical poles and no or several stigmoids. In addition, the longitudinal lines are produced by the mantle lamella in Gomphoneis, in contrast to longitudinal lines produced mainly by the axial plate in Gomphadelpha. The autapomorphies to Gomphonema are clear with well visible longitudinal lines produced by the internal axial plate as well as differently formed perforations covering the external areolae which sit in deep troughs.
Keywords
Cymbellales • Gomphonemataceae • Gomphonema • Gomphoneis • Gomphonella • integrative taxonomy