Members of the Order Mastogloiales Sensu Cox Belong to the Different Evolutionary Lineages of Diatoms: Phylogenetic Resolutions and Descriptions of New Types of Pore Occlusions
, Anton Glushchenko 1, Sergey Genkal 3, Elena Kezlya 1, Yevhen Maltsev 1, Soninkhishig Nergui 4 and Maxim Kulikovskiy 1
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsRegarding the “breakup” of Mastogloia, Simonsen (1990 — invalidly) proposed a Section Marginulatae, which Lobban (2025) recently validated. As long as Mastogloia is defined by the presence of partecta, most of the anticipated breakup should take place within the genus, but it may eventually prove that a cluster of genera is necessary, unified under Mastogloiaceae by their synapomorphy (parteceta), with the other genera in the family at present then related within the order in one or several other families.
Indeed, maybe this is the time to propose this hierarchy and redefine not only Mastogloiales but also Mastogloiaceae, where the family would include all the taxa with partecta, i.e. Mastogloia and Stigmogloia (and Marginulatae??) and the Order would include Aneumastus and the other taxa right around Mastogloia (can they be within the Order without erecting additional families?).
Diagnosis of the Order: I recommend that the Order be defined only as far as necessary to exclude the other groups, rather than this detailed description where there are already exceptions that need to be allowed for. In particular:
lines 953-955, I would qualify the statements about plastids with “generally” because the number of species of Mastogloia for which plastids have been observed is fairly low and there are some, such as M. fimbriata, that have multiple plastids or other arrangements (see Lobban 2025: Nova Hedwigia). Anyway, to the extent that plastids are similar in Achnanthaceae, plastids do not define the Mastogloiales.
Similarly, line 956, isopolar: there are some heteropolar species in Mastogloia Section Marginulatae, and in line 966 some species have hyaline girdle bands (again, see Lobban 2025).
Comments on the Quality of English Language
Needs one last round of copyediting for typos and small grammatical errors (does the journal do this or are authors expected to?), for examples:
lines 42–43: lacunae
line 48: sinuous
line 63: hymenes
line 838: ? remove the sentence fragment “among different taxa is discussed below.”
Author Response
Reviewer 1
Regarding the “breakup” of Mastogloia, Simonsen (1990 — invalidly) proposed a Section Marginulatae, which Lobban (2025) recently validated. As long as Mastogloia is defined by the presence of partecta, most of the anticipated breakup should take place within the genus, but it may eventually prove that a cluster of genera is necessary, unified under Mastogloiaceae by their synapomorphy (parteceta), with the other genera in the family at present then related within the order in one or several other families. Indeed, maybe this is the time to propose this hierarchy and redefine not only Mastogloiales but also Mastogloiaceae, where the family would include all the taxa with partecta, i.e. Mastogloia and Stigmogloia (and Marginulatae??) and the Order would include Aneumastus and the other taxa right around Mastogloia (can they be within the Order without erecting additional families?).
We appreciate the ideas proposed by the Reviewer. We truly agree that the phylogenetic importance of partectae should be furtherly investigated in order to propose a correct classification for the order Mastogloiales. For now (based on the currently available genetic and morphological data), we are unable to clearly differentiate partecta-bearing and apartectal taxa of the order at the family level. Thus, we believe that it is insufficient to propose an emended diagnosis of Mastogloiaceae with two genera – Mastogloia and Stigmagloia. Similarly, we are yet unable to propose another family within the order, to comprise Aneumastus and Decussiphycus.
Diagnosis of the Order: I recommend that the Order be defined only as far as necessary to exclude the other groups, rather than this detailed description where there are already exceptions that need to be allowed for. In particular: lines 953-955, I would qualify the statements about plastids with “generally” because the number of species of Mastogloia for which plastids have been observed is fairly low and there are some, such as M. fimbriata, that have multiple plastids or other arrangements (see Lobban 2025: Nova Hedwigia). Anyway, to the extent that plastids are similar in Achnanthaceae, plastids do not define the Mastogloiales. Similarly, line 956, isopolar: there are some heteropolar species in Mastogloia Section Marginulatae, and in line 966 some species have hyaline girdle bands (again, see Lobban 2025).
The mentioned sentences were corrected. In the new version, the protoplasts are characterized as “typically with two chloroplasts, separated by the transapical cytoplasmic bridge…”, (line 962) as this type of plastid arrangement is indeed usual for the representatives of the order and the exceptions, such as Mastogloia fimbriata, are rare. Likewise, we mentioned that the girdle bands are “generally perforated” (line 975).
Comments on the Quality of English Language
Needs one last round of copyediting for typos and small grammatical errors (does the journal do this or are authors expected to?), for examples:
lines 42–43: lacunae
line 48: sinuous
line 63: hymens
line 838: ? remove the sentence fragment “among different taxa is discussed below.”
The typos mentioned above were corrected. We also checked through the text for typos and grammatic mistakes.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript is carefully prepared and presents a solid scientific level. The data are well organized, and the results are clearly presented.
However, some issues require clarification and minor improvements. The authors mention the use of three microscopy techniques (LM, SEM, and TEM), but only two are listed in the abstract and described in the methodology. The TEM technique is not described at all — this section should be completed to ensure methodological transparency.
In the description of the new species, it would be highly recommended to add a comparative table summarizing the diagnostic features of the new taxon and morphologically similar species. This would significantly improve the clarity and taxonomic value of the paper.
Finally, the manuscript should include a statement regarding compliance with the Nagoya Protocol (Access and Benefit-Sharing), specifying whether Prior Informed Consent (PIC) and Mutually Agreed Terms (MAT) were obtained for the use of genetic resources. This information is essential for transparency and legal compliance.
Author Response
Reviewer 2
The manuscript is carefully prepared and presents a solid scientific level. The data are well organized, and the results are clearly presented.
However, some issues require clarification and minor improvements. The authors mention the use of three microscopy techniques (LM, SEM, and TEM), but only two are listed in the abstract and described in the methodology. The TEM technique is not described at all — this section should be completed to ensure methodological transparency.
The description of TEM methodology was added (lines 200-205).
In the description of the new species, it would be highly recommended to add a comparative table summarizing the diagnostic features of the new taxon and morphologically similar species. This would significantly improve the clarity and taxonomic value of the paper.
The requested data was added in the form of a comparative table (Table 3; lines 662-666).
Finally, the manuscript should include a statement regarding compliance with the Nagoya Protocol (Access and Benefit-Sharing), specifying whether Prior Informed Consent (PIC) and Mutually Agreed Terms (MAT) were obtained for the use of genetic resources. This information is essential for transparency and legal compliance.
Our manuscript data does not contradict the Nagoya Protocol, as the study is conducted within the framework of the joint Russian-Mongolian scientific project “Molecular diversity and barcoding of diatoms and cyanobacteria from waterbodies of Mongolia” (project №24-44-03001, https://rscf.ru/project/24-44-03001/). To obtain and transport the samples and genetic resources to Russia, a formal permission from Mongolian National Chamber of Commerce and Industry. The permission number (MNRU42085–A0134549) is included in the Data availability statement. A PDF copy of the document can be provided to the Editor upon request.
Reviewer 3 Report
Comments and Suggestions for AuthorsManuscript ID: phycology-3921283
Title: Members of the order Mastogloiales sensu Cox belong to the different evolutionary lineages of diatoms: phylogenetic resolutions and descriptions of new types of pore occlusions
The authors used both molecular and morphological analyses to re-assess the phylogenetic and taxonomic composition of the order Mastogloiales (Bacillariophyta). They resolved the structure of pore occlusions among the genera in the order Mastogloiales and established the new species Aneumastus khovsgolensis sp. nov. The experimental work was performed in a very good way. The Results and data interpretation were clearly presented. I support the manuscript acceptance in its current shape.
Author Response
Reviewer 3
The authors used both molecular and morphological analyses to re-assess the phylogenetic and taxonomic composition of the order Mastogloiales (Bacillariophyta). They resolved the structure of pore occlusions among the genera in the order Mastogloiales and established the new species Aneumastus khovsgolensis sp. nov. The experimental work was performed in a very good way. The Results and data interpretation were clearly presented. I support the manuscript acceptance in its current shape.
No corrections were requested by Reviewer 3. We greatly appreciate the positive feedback on our work!
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsI appreciate the revisions and additions made to the manuscript, which have notably improved its overall quality. However, I find the authors’ response regarding the necessary permits and reference to the Nagoya Protocol to be rather evasive. While they clarified and provided evidence for the legal origin of samples from Mongolia, the study also includes material from Indonesia, China, and Vietnam, for which no explanation has been given. This continues to raise my concerns and suspicion of potential bioprospecting or biopoaching.
Author Response
Apart from the newly collected material from Mongolia we conducted this study on the basis of materials from publicly available sources.
Material from China (slide 09153 for strain Ca68) was already published in Mironov et al. 2025 (Mironov, A., Glushchenko, A., Kezlya, E., Maltsev, Y., Iurmanov, A., Liu, Y., & Kulikovskiy, M. (2025). Decussiphycus sinensis sp. nov. (Bacillariophyceae, Mastogloiales)–a new species described from China, with comments on phylogenetic position of the genus. PhytoKeys, 254, 1. https://doi. org/10.3897/phytokeys.254.142654). Genetic resources for this material are publicly available in GenBank (PV021297, PV016799). The use of this material is available according to the jurisdiction of China-Russia Center for Innovative Algae Research.
Material from Viet Nam (slide 09255 for strain SVN638) was already published in Kezlya et al. 2024 (Kezlya, E., Glushchenko, A., Kapustin, D., Maltsev, Y., Doan-Nhu, H., & Kulikovskiy, M. (2024). Stigmagloia lobbanii gen. et sp. nov.(Bacillariophyceae, Mastogloiales), a new stigma-bearing diatom genus separated from Mastogloia. Phytotaxa, 677(1), 49-65. https://doi.org/10.11646/phytotaxa.677.1.2). Genetic resources for this material are publicly available in GenBank (PQ571200, PQ589835). The use of this material is available according to the jurisdiction of Joint Vietnam-Russia Tropical Science and Technology Research Center (VRTC).
Material from Indonesia (slide 04185 for strain Ind427) was already published in Maltsev et al. 2016 (Maltsev, Y., Kulikovskiy, M., Andreeva, S. & Podunai, Y. (2016) Molecular phylogeny of the diatom genus Aneumastus D.G. Mann & A.J. Stickle (Bacillariophyceae, Mastogloiales). PROCEEDINGS OF 9TH INTERNATIONAL CHRYSOPHYTE SYMPOSIUM, Vol. 1 (1): 15-15). Sample origin information was acquired from GenBank (https://www.ncbi.nlm.nih.gov/nuccore/KY274427.1). Genetic resources for this material are publicly available in GenBank (KY274427, KY274426).
We would like to state that no live material of described origins was utilized for the current study – only cleaned siliceous valves were analyzed and illustrated. All permanent slides utilized for our study are available in publicly registered repository Diatom Herbarium (https://sweetgum.nybg.org/science/ih/herbarium-details/?irn=267855).
Round 3
Reviewer 2 Report
Comments and Suggestions for AuthorsAfter clarifying legality issues, the article may be accepted for publication
