Disentangling the Taxonomic History of the Widespread and Overlooked Centric Diatom Stephanodiscus makarovae and Its Transfer to Cyclostephanos

Round 1

Reviewer 1 Report

I do not have any special recommendations for improving the manuscript, except the advice to change in line 19. The correct name of the country is Russia or Russian Federation, but not Russian in this meaning.

The authors provided evidence for taxonomic transfer of the common centric taxon Stephanodiscus makarovae to Cyclostephanos genera. The research is relevant and interesting. Moreover, the authors presented original findings of the common “Russian” species not only from Russian territory. The topic is original and needs to be published as soon as possible.

The idea of such taxonomic transformation was raised by the authors working with centrics, but never been proved by molecular data. The authors made all efforts to become this theory real.

The paper is well written, scientifically proven and has a strong background. The text is easy to read.

The conclusions are consistent with the presented evidence and arguments. The posed main question is addressed in the conclusions.

Author Response

Thank you for your suggestion for improvement of our manuscript! We have modified it as follows: 

In line 19 our formulation was misleading - we changed it to “Russian language” in the revised manuscript.

Reviewer 2 Report

At stated in the introduction, Theriot et al. 1987 [5] then highlighted the significance of the external opening of the rimoportula to distinguish between both genera, which  is inconspicuous in Cyclostephanos and spine-like in Stephanodiscus. It their article, Theriot et al.(1987) highlighted not only the importance of the rimoportula external opening but also its position in Cyclostephanos - below spines, and this should be included in the text of this sentence. Since these  are important differential characteristics for the genus Cyclostephanos, it would be desirable for the authors to provide SEM images of external and internal view of the rimoportula of C.makarovae.

The Introduction section also stated that S.makarovae is morphologically quite similar to the aforementioned taxa. It has, however, not been transferred to the genus Cyclostephanos and has had little to no recognition in taxonomic publications outside of Russia, possibly due to the fact that the original publication [9] was written in Russian. However, in the reference list, references to this work are incomplete - the volume and pages are missing (Vol.63, N9, p.1309-1312 + 4 pls respectively). I suggest that the authors remove this work from the text and the list of references, since it lacks information on S.makarovae, and provides description of other new to sciences: S,tenuis var. tener Genkal, S.triporus Genkal et Kuzmin, S.perforatus Genkal et Kuzmin, S.incognitus Kuzmin et Genkal.

    For the new combination Cyclostephanos makarovae (Genkal) Schultz comb.nov. in Basionym there is a reference to the work: Novosti Sistematiki Nizshykh Rasteniy 15: 11-14, 2 pls,......The reference gives pages of the entire article (11-14), and the Latin diagnosis of S.makarovae is found on pages 13 and 14.    

Author Response

“Theriot et al.(1987) highlighted not only the importance of the rimoportula external opening but also its position in Cyclostephanos - below spines, and this should be included in the text of this sentence.”

Thank you for this valuable addition, which we added in the lines 46-48.

-----

“Since these are important differential characteristics for the genus Cyclostephanos, it would be desirable for the authors to provide SEM images of external and internal view of the rimoportula of C.makarovae.”

This is a good point and we added two images of the external view and one image of a closer internal view of the openings of the Rimoportula to the manuscript (Figures 50-52).

-----

“…original publication [9] was written in Russian. However, in the reference list, references to this work are incomplete - the volume and pages are missing (Vol.63, N9, p.1309-1312 + 4 pls respectively). I suggest that the authors remove this work from the text and the list of references, since it lacks information on S.makarovae, and provides description of other new to sciences: S,tenuis var. tener Genkal, S.triporus Genkal et Kuzmin, S.perforatus Genkal et Kuzmin, S.incognitus Kuzmin et Genkal.”   In this case it seems we confused two publications by Genkal both from the same year (1978). We replaced the wrong reference with the correct one including volume and pages.

-----

“…and the Latin diagnosis of S.makarovae is found on pages 13 and 14…”                                           We added this information to the reference of the basionym.