The Reared Male Imago of Rhoenanthus sapa Nguyen et Bae, 2004 from China Showing Its Basal Position in the Genus (Ephemeroptera: Potamanthidae)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Overall, this manuscript is a good contribution that helps further our understanding of Indomalayan mayflies, in general, and the global systematics of the family Potamanthidae. I recommend publication after some relatively minor revisions. The biggest changes will involve additions to the Materials & Methods section, detailed below. The language needs significant improvement, but I limit my comments only to those areas where the language inhibits understanding.

SPECIFIC COMMENTS

Lines 46-47: What is meant by "deep abdomen"?

Line 48: What is being tested? The abdomen is either similar or it is not.

Line 58: How will rearing show functions of morphology? These observations come from behavior studies.

Line 61: don't mix tens and dozens. As written, it sounds like more were moved to the lab than were sampled in total.

Line 62: Avoid emotional statements in a scientific paper.

Line 64: You were able to hypothesize phylogenetic position.

Line 80: TAP water.

Line 83: Were nymph exuviae saved? Were subimagos reared to imagos?

Line 117: I suggest deleting "probably wrong" and replacing it with "possible misidentification, see discussion below"

Lines 133-134: I suggest a few figures to illustrate the variation in the shape of R1.

Line 158: Please indicate the meaning of each scale bar; currently only one is labeled, and none are mentioned in the caption.

Lines 162-163, 187-188: I suggest changing this to say "Descriptive data complement Nguyen et Bae (2004)" and delete "Main character including"

Line 165: delete their

Line 166: ...between COMPOUND eyes...

Line 170: delete that

Lines 171-173: How are they arranged by length? Shortest to longest? Why is this formulation used, rather than the ratios given for the foretarsi? Also, for the male, ratios were given for all legs.

Line 196: LEG (singular)

Lines 197-203: I think the "micropyle" really is just an area of the egg that is sunken due to the way it was preserved.

Line 201: Spindle usually describes something with a sharp point. This does not have a sharp point.

Line 205: Video techniques and other details about observation of living specimens are not described in the Materials & Methods section.

Line 206: Be more specific about which mouthparts are used in which ways.

Line 215: Burrowing behavior (in general?) was not observed? Or was burrowing observed, but not by them using their tusks?

Line 228: Give more detail about the comparisons of proportion and/or relative size.

Line 235: ...nymphs of R. SAPA have...

Line 241: see comments for lines 197-203.

Lines 242-243: I do not understand "farer to poles"

Lines 247-250: Give exact details about they are similar or close.

Line 258, 263: hyphen not n-dash

Line 264: tell exactly what the "normally running" condition is, rather than phrasing in this way

Line 272: again, tell exactly what the "deformed" condition is

Line 281: say "hypothesis" rather than "guess". Also, DNA methods also might help test this hypothesis in the future.

Line 292: The references require changes to ensure consistent formatting.

Comments on the Quality of English Language

The language needs significant improvement, but I limit my comments only to those areas where the language inhibits understanding.

Author Response

Reviewer1

Overall, this manuscript is a good contribution that helps further our understanding of Indomalayan mayflies, in general, and the global systematics of the family Potamanthidae. I recommend publication after some relatively minor revisions. The biggest changes will involve additions to the Materials & Methods section, detailed below. The language needs significant improvement, but I limit my comments only to those areas where the language inhibits understanding.

SPECIFIC COMMENTS

Lines 46-47: What is meant by "deep abdomen"?

Changed to “darkly pigmented abdomen”.

Line 48: What is being tested? The abdomen is either similar or it is not.

Rephrased and Changed, use a “which” to indicate the meaning.

Line 58: How will rearing show functions of morphology? These observations come from behavior studies.

Rephrased and Changed to “more observation on rearing potamanthids”

Line 61: don't mix tens and dozens. As written, it sounds like more were moved to the lab than were sampled in total.

Rephrased and Changed, provided the specific data. See the marked according place.

Line 62: Avoid emotional statements in a scientific paper.

Deleted, those words are deleted.

Line 64: You were able to hypothesize phylogenetic position.

Rephrased and Changed to as “discuss its phylogeny”.

Line 80: TAP water.

Improved to “tap water”.

Line 83: Were nymph exuviae saved? Were subimagos reared to imagos?

Rephrased and Changed, materials are presented clearly. See the marked according place.

Line 117: I suggest deleting "probably wrong" and replacing it with "possible misidentification, see discussion below"

Accepted accordingly, please see the marked according place.

Lines 133-134: I suggest a few figures to illustrate the variation in the shape of R1.

There is no place to add new figure in this plate, and this point is not very important, and change the “sometimes” to “some”.

Line 158: Please indicate the meaning of each scale bar; currently only one is labeled, and none are mentioned in the caption.

Improved, the figure 2 is totally checked and improved, all scale bars are added.

Lines 162-163, 187-188: I suggest changing this to say "Descriptive data complement Nguyen et Bae (2004)" and delete "Main character including"

Accepted your comment, see the marked according place.

Line 165: delete their

Accepted, their deleted.

Line 166: ...between COMPOUND eyes...

Accepted, the compound is added.

Line 170: delete that

Accepted, that is deleted.

Lines 171-173: How are they arranged by length? Shortest to longest? Why is this formulation used, rather than the ratios given for the foretarsi? Also, for the male, ratios were given for all legs.

Rephrased and Changed, the exact ratio of tarsal segments are provided.

Line 196: LEG (singular)

Rephrased and Changed, legs is changed to leg.

Lines 197-203: I think the "micropyle" really is just an area of the egg that is sunken due to the way it was preserved.

Figures are improved, notes are added, please check the new figure 5.

Line 201: Spindle usually describes something with a sharp point. This does not have a sharp point.

Rephrased and Changed, spindle is changed to olive.

Line 205: Video techniques and other details about observation of living specimens are not described in the Materials & Methods section.

Just cellphone video.

Line 206: Be more specific about which mouthparts are used in which ways.

This point is not clear in the cellphone video, all parts are moving. .

Line 215: Burrowing behavior (in general?) was not observed? Or was burrowing observed, but not by them using their tusks?

Rephrased and Changed to “the burrowing of them”

Line 228: Give more detail about the comparisons of proportion and/or relative size.

Rephrased and Changed, more structures are mentioned.

Line 235: ...nymphs of R. SAPA have...

Accepted, the “R. sapa” is added.

Line 241: see comments for lines 197-203.

Rephrased and Changed accordingly.

Lines 242-243: I do not understand "farer to poles"

Rephrased and Changed to “further”.

Lines 247-250: Give exact details about they are similar or close.

Rephrased and Changed to “in general shape and blunt apex of penes”.

Line 258, 263: hyphen not n-dash

Changed, all hyphen in the text is checked and changed.

Line 264: tell exactly what the "normally running" condition is, rather than phrasing in this way

Rephrased and Changed to “straightly running”

Line 272: again, tell exactly what the "deformed" condition is

Rephrased and Changed to “R1 veins of hindwings curved at base and MP forked asymmetrically”.

Line 281: say "hypothesis" rather than "guess". Also, DNA methods also might help test this hypothesis in the future.

Rephrased and Changed to “this issue”.

Line 292: The references require changes to ensure consistent formatting.

Improved and Changed according to guide.

Reviewer 2 Report

Comments and Suggestions for Authors

The study addresses a topic of potential interest. The following points require major revision:

1. Identifying the species from Yunnan and Vietnam as the same species carries risks, therefore, it is advisable that the paper should provide more taxonomic details (e.g., ventral posterior part of abdomen of male nymphs). Moreover, the authors could examine specimens from varying altitudes or localities within their available collection to assess morphological consistency, thereby substantiating whether the species exhibits a broad distribution.
2. Previous literature, including Nguyen and Bae (2006) and Han, Zhang, and Zhou (2021), have already documented key features of Rhoenanthus, such as its Potamanthodes–like venation, color, male genitalia and subequal length of caudal filaments. The basal position of R. sapa in the genus still retains the nymphal characteristics, which may create an impression that the data presented do not fully align with the implications of the title.
3. Other issues: the format of references is not unified, and some images lack a scale bar (e.g., Figure 2G).

Author Response

The study addresses a topic of potential interest. The following points require major revision:

1. Identifying the species from Yunnan and Vietnam as the same species carries risks, therefore, it is advisable that the paper should provide more taxonomic details (e.g., ventral posterior part of abdomen of male nymphs). Moreover, the authors could examine specimens from varying altitudes or localities within their available collection to assess morphological consistency, thereby substantiating whether the species exhibits a broad distribution.

The morphology of them are same, the locations of them are close. We believe they are same species.

1. Previous literature, including Nguyen and Bae (2006) and Han, Zhang, and Zhou (2021), have already documented key features of Rhoenanthus, such as its Potamanthodes–like venation, color, male genitalia and subequal length of caudal filaments. The basal position of R. sapa in the genus still retains the nymphal characteristics, which may create an impression that the data presented do not fully align with the implications of the title.

The male imago is more important than other materials, we think.

1. Other issues: the format of references is not unified, and some images lack a scale bar (e.g., Figure 2G).

Improved and Changed according to guide.

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript presents a valuable contribution to the taxonomy, phylogeny, and biology of the Oriental potamanthid mayfly Rhoenanthus sapa Nguyen & Bae, 2004. By successfully rearing mature nymphs in the laboratory, the authors have associated and described for the first time the male imago, a critical life stage previously missing for this species. The inclusion of egg micromorphology via SEM and direct behavioral observations of living nymphs adds significant functional and ecological value to the study of Potamanthidae.

The work is well-conceived, and the photographic plates are generally of high quality. However, several minor revisions are necessary prior to publication. These include resolving textual run-on sentences, removing informal language, enhancing figure annotations, clarifying ecological descriptions, and resolving discrepancies between in-text citations and the reference list. Specific comments line-by-line are below:

Summary, Abstract and keywords

Line 10–11: Change to past tense for grammatical consistency: "Previously, the differences  (...) were clear."

Line 12–13: Rephrase to improve academic fluency: "...narrowed the gaps between them." or "...blurred the distinctions among them."

Line 15: The word "parsimony should be changed to adjective form: "...show a more parsimonious evolutionary pattern..."

Line 18–19: There is a subject-verb agreement issue (plural "imagos" with singular "was"). Rephrase as: "The male imago of Rhoenanthus sapa Nguyen et Bae, 2004, which had not been previously reported, was reared for the first time from mature nymphs in China."

Line 24: In the keywords, I suppose you meant "imago," not "imagine". Correct the typo from "imagine" to "imago".

 

Introduction

Lines 31–32: "The genus Rhoenanthus Eaton, 1881 was divided into two subgenera with nine species [2–4]. The nymphs of them have diverse mandibular tusks." is very informal. I sugest to change to: "The genus Rhoenanthus Eaton, 1881 is divided into two subgenera comprising nine species [2–4], whose nymphs exhibit diverse mandibular tusk morphologies."

Lines 31–32: "The nymphs of them" is very informal for a scientific paper. I suggest changing to: " whose nymphs exhibit diverse mandibular tusk morphologies."

Lines 32–37: This sentence is currently very long and complex, reading more like a list of fragmented clauses rather than a grammatically complete sentence. Because it lacks a clear main verb to connect the species to their morphological descriptions, it becomes difficult for the reader to follow.  To improve readability and grammatical flow, please consider breaking this long passage into smaller, distinct sentences or using appropriate verbs (e.g., possesses, bears, has) for each species comparison. Also, please check the journal's formatting guidelines regarding author citations in the main text (e.g., using "&" or "and" instead of "et" when citing two authors).  

Lines 41–42: The phrase "But this point needs its male imago to confirm" uses a conversational tone and a sentence structure that feels overly informal for a scientific publication. Please rephrase this sentence using more formal academic language. Consider specifying what "this point" refers to (e.g., this hypothesis, this assumption, or this taxonomic position) and stating more clearly how the male imago serves to test or confirm it.  

Lines 43–46: This sentence contains a few grammatical inconsistencies and technical ambiguities that affect its clarity:  The introductory clause lacks a subordinating conjunction (e.g., "reported that the female..."), and there are shifting agreements throughout the list of characters (such as alternating between plural features and singular pronouns like "its abdomen"). 

The phrase "deep abdomen of others" is vague in a taxonomic context. It is unclear whether "deep" refers to body shape, depth, or dark cuticular pigmentation.  Please revise this sentence to ensure grammatical agreement and use more precise terminology (e.g., darkly pigmented, heavily sclerotized, or intensely colored) when contrasting the abdominal coloration of R. sapa with that of its congeners.  

Lines 46–48: The phrasing "This kind of body is somewhat similar to..." uses informal language that dilutes scientific precision. Additionally, the relative pronoun "which" at the end creates ambiguity regarding what exactly is being tested by the male genitalia. I recommend rephrasing using formal taxonomic vocabulary (e.g., "resembles", "morphological pattern") and clarifying that it is the proposed generic relationship/affinity being evaluated.

 Lines 49–51:This sentence presents a grammatical mismatch ("regarded ... is") and joins two independent clauses without proper punctuation or connecting conjunctions. I suggest correcting the verb construction (e.g., "regarded ... as...") and introducing a clear transition (such as "suggesting that...") to link Kluge’s hypothesis on mandibular tusks to the proposed relationship between the genera.

Lines 56–58: There is a citation inconsistency here. The text cites "Mayorga et al. (2023)", but Reference 16 in your literature list is dated 2024.

Lines 61–64: The expression "Joyfully surprised" introduces a subjective, narrative tone that is inappropriate for formal scientific writing. Furthermore, "most those nymphs became the adults" contains minor grammatical errors. My recommendation is to remove emotional descriptors and adopt an objective passive/declarative voice.

 Materials and Methods

Lines 67–74: There are formatting inconsistencies in dates and names. Roman numerals and dashes used for dates vary across entries (e.g., VII–2008, 15–IV–2001, 7– IV–2001 with extra space, and 14–16–IV–2026). Please standardize the date formatting across all examined material entries according to MDPI style.  Ensure author name formatting is consistent (e.g., "Changfa Zhou" vs. "Chang-Fa Zhou").

Lines 79–83: There are informal phrasing, minor typos, and mid-paragraph tense shift. For example, the phrase "tape water" (Line 80) looks like a typo for "tap water".  Line 82 shifts to present tense ("is employed"), whereas surrounding descriptions use past tense ("were gathered", "was covered", "were collected").  My recommendation is to maintain past tense consistently throughout the methodology and rephrase informal descriptions using standard technical language.

Line 101–103: Again, there is informal wording and redundancy. The phrasing "uploaded to GenBank to blast" and "totally five related sequences in same genus" is informal.I suggest rephrasing to formal academic English.

Line 109: I understand that the authors may be keeping the sequence private or awaiting paper acceptance before finalizing the release of the GenBank Accession Number for R. sapa. However, please remember that this number is required for reproducibility. The authors must deposit the sequence into the GenBank database and insert the official accession number into Table 1 and Section 2.3 prior to final acceptance and publication.

Results

Lines 115–117: There is a year mismatch in inline text vs. bibliography. Line 116 cites "Vasanth et al., 2024", but later in Discussion (Line 278) it is cited as "Vasanth et al. (2004)". Please standardize the year to 2024 across all sections to match Reference 18.

Line 171–172: the expression "length arrangement of four segments of tarsi= 4, 1, 2, 3" is informal. Rephrase to formal descriptive style (e.g., "relative tarsal segment lengths arranged as IV > I > II > III").

Lines 168: It is missing word in comparison here. Where you wrote "MP2 of hindwing more distinct and longer male (Fig. 3C)". You should add the missing word: "longer than in the male" or "longer than that of the male".

Line 194: There is a typographical error in figure legend. Correct the typo in the caption of Figure 4: change "Nymphal hatitus" to "Nymphal habitus".

Line 203: The  is a sentence that begins with a lowercase letter "surface decorated...". Change to "Surface..."

Lines 205–214: Please review the description of feeding behaviors to correct minor typographical errors and polish the phrasing for academic clarity:

     Line 208: Change "deliver those food" to "deliver this food" (or simply "deliver food").

     Line 210: Correct the typo "scape" to "scrape".

     Line 212: Change "wave inwards" to "wave them inwards" to ensure correct transitive verb usage.

Lines 214–216: In Section 3.2, the manuscript briefly notes that "The nymphs usually live in interstitial microhabitats." To enrich the ecological context of this species for aquatic entomologists and ecologists, it would be beneficial if the authors could expand slightly on the physical characteristics of the river at the collection site, if avaiable (e.g., current velocity, dominant substrate composition such as cobble/gravel, and presence of riparian or instream vegetation).

Line 225: change "the abdomen of this species have" to "has".  

Line 242: correct the comparative adjective "farer" to "further" 

Discussion

Line 254: change "shortened mandibular tusks is the evolutionary trend" to "are the evolutionary trend".

Lines 254–277: The hypothesis presented regarding the evolutionary sequence of mandibular tusks and forelegs within the Rhoenanthus–Potamanthodes lineage is well-reasoned. However, when discussing the nymphs' use of forelegs for food scraping, collecting, and pebble manipulation rather than burrowing, the authors maybe could strengthen the discussion by directly linking this behavior to the specific tusk morphology of R. sapa. Specifically, discussing how their relatively shorter and strongly incurved tusks (compared to the elongated tusks of other Rhoenanthus species) adaptively correlate with a non-burrowing, interstitial lifestyle would provide a clearer functional explanation for these observed behaviors.

Line 259, change "tusks may evolved" to "may have evolved".

Line 262: add the missing article in "common ancestor", it should be "the common ancestor". 

Line 274: There is a reference mismatch here. You wrote "Mayorga et al. (2023)", but Reference 16 is 2024. Please check.

Line 278 cites "Vasanth et al. (2004)", but Reference 18 is 2024.

Figures and Tables

Line 145 (Figure 1 Caption): Correct "Female sub imago" in 1D to "Female subimago".

Lines 157–160 (Figure 2 Caption & Panel 2K): Mention missing labels: Labels 2I (Foreclaw) and 2J (Midclaw) appear on the figure plate but are missing from the caption text.

References

The journal title formatting is inconsistent throughout the references. Ensure that all journal names follow the target journal’s specific style. Also, several references lack DOIs. It is strongly recommended to add active DOI links to all references where available.

Ref. 1 (Nguyen & Bae, 2004): Check the journal title and volume capitalization. Ensure author initials are spaced consistently with the rest of the bibliography (e.g., Nguyen, V.V.; Bae, Y.J.).

Ref. 2 and Ref. 3 (Bae & McCafferty publications): Verify consistent formatting for two-author citations in the references list. Ensure page ranges use full numbers (e.g., 1–18 instead of truncated ranges) and standard en-dashes (–) instead of hyphens (-).

Ref. 4 and Ref. 5: Check for missing volume/issue numbers or incorrect page number ranges. Ensure taxa names within article titles are properly italicized.

Ref. 14 (Kluge, 2004): Verify the exact monograph/book title representation: The Phylogenetic System of Ephemeroptera. Ensure publisher details (Kluwer Academic Publishers) and page numbers are accurately cited.

Ref. 16 (Mayorga et al.): Discrepancy in Text vs. References: In the main text (Lines 56 and 274), this paper is cited as Mayorga et al. (2023), whereas the reference list entries cite it as 2024.

Ref. 18 (Vasanth et al.): Discrepancy in Text vs. References: In Line 278 of the main text, this work is cited as 2004, while in Line 116 it is cited as 2024.

I would like to congratulate the authors on this detailed work and the high quality of the photographic plates. I wish you the best of luck with the revision process and look forward to seeing this paper published.

 

Comments on the Quality of English Language

The overall scientific quality of the manuscript is clear and the core ideas are easy to follow. However, the text requires careful language editing to meet the standards of a formal academic publication.

Several sections, particularly the Abstract and Introduction, contain run-on sentences, occasional informal phrasing (e.g., "Joyfully surprised", "This kind of body"), and minor grammatical inconsistencies in subject-verb agreement and citation formatting. Additionally, a few technical terms would benefit from greater precision 

I strongly recommend that the authors thoroughly proofread the manuscript or seek assistance from a native English speaker or a professional scientific editing service before resubmission. Addressing these minor language, syntax, and punctuation details will significantly enhance the overall clarity and readability of the paper.

Author Response

 

Reviewer3

This manuscript presents a valuable contribution to the taxonomy, phylogeny, and biology of the Oriental potamanthid mayfly Rhoenanthus sapa Nguyen & Bae, 2004. By successfully rearing mature nymphs in the laboratory, the authors have associated and described for the first time the male imago, a critical life stage previously missing for this species. The inclusion of egg micromorphology via SEM and direct behavioral observations of living nymphs adds significant functional and ecological value to the study of Potamanthidae.

The work is well-conceived, and the photographic plates are generally of high quality. However, several minor revisions are necessary prior to publication. These include resolving textual run-on sentences, removing informal language, enhancing figure annotations, clarifying ecological descriptions, and resolving discrepancies between in-text citations and the reference list. Specific comments line-by-line are below:

Summary, Abstract and keywords

Line 10–11: Change to past tense for grammatical consistency: "Previously, the differences  (...) were clear."

Improved and Changed, was is changed to were.

Line 12–13: Rephrase to improve academic fluency: "...narrowed the gaps between them." or "...blurred the distinctions among them."

Rephrased and Changed, a between is added.

Line 15: The word "parsimony should be changed to adjective form: "...show a more parsimonious evolutionary pattern..."

Rephrased and Changed to parsimonious evolutionary pattern.

Line 18–19: There is a subject-verb agreement issue (plural "imagos" with singular "was"). Rephrase as: "The male imago of Rhoenanthus sapa Nguyen et Bae, 2004, which had not been previously reported, was reared for the first time from mature nymphs in China."

Rephrased and Changed, were is changed to was.

Line 24: In the keywords, I suppose you meant "imago," not "imagine". Correct the typo from "imagine" to "imago".

Improved and Changed to imago.

 

Introduction

Lines 31–32: "The genus Rhoenanthus Eaton, 1881 was divided into two subgenera with nine species [2–4]. The nymphs of them have diverse mandibular tusks." is very informal. I sugest to change to: "The genus Rhoenanthus Eaton, 1881 is divided into two subgenera comprising nine species [2–4], whose nymphs exhibit diverse mandibular tusk morphologies."

Rephrased and Changed accordingly.

Lines 31–32: "The nymphs of them" is very informal for a scientific paper. I suggest changing to: " whose nymphs exhibit diverse mandibular tusk morphologies."

Rephrased and Changed to “whose nymphs exhibit diverse mandibular tusk morphologies".

Lines 32–37: This sentence is currently very long and complex, reading more like a list of fragmented clauses rather than a grammatically complete sentence. Because it lacks a clear main verb to connect the species to their morphological descriptions, it becomes difficult for the reader to follow.  To improve readability and grammatical flow, please consider breaking this long passage into smaller, distinct sentences or using appropriate verbs (e.g., possesses, bears, has) for each species comparison. Also, please check the journal's formatting guidelines regarding author citations in the main text (e.g., using "&" or "and" instead of "et" when citing two authors).  

Rephrased and Changed, a “for instances” is added.

Lines 41–42: The phrase "But this point needs its male imago to confirm" uses a conversational tone and a sentence structure that feels overly informal for a scientific publication. Please rephrase this sentence using more formal academic language. Consider specifying what "this point" refers to (e.g., this hypothesis, this assumption, or this taxonomic position) and stating more clearly how the male imago serves to test or confirm it.  

Rephrased and Changed, point is changed to “assumption”.

Lines 43–46: This sentence contains a few grammatical inconsistencies and technical ambiguities that affect its clarity:  The introductory clause lacks a subordinating conjunction (e.g., "reported that the female..."), and there are shifting agreements throughout the list of characters (such as alternating between plural features and singular pronouns like "its abdomen"). 

Rephrased and Changed, gramma is checked.

The phrase "deep abdomen of others" is vague in a taxonomic context. It is unclear whether "deep" refers to body shape, depth, or dark cuticular pigmentation.  Please revise this sentence to ensure grammatical agreement and use more precise terminology (e.g., darkly pigmented, heavily sclerotized, or intensely colored) when contrasting the abdominal coloration of R. sapa with that of its congeners.  

Rephrased and Changed to “darkly pigmented abdomen”.

Lines 46–48: The phrasing "This kind of body is somewhat similar to..." uses informal language that dilutes scientific precision. Additionally, the relative pronoun "which" at the end creates ambiguity regarding what exactly is being tested by the male genitalia. I recommend rephrasing using formal taxonomic vocabulary (e.g., "resembles", "morphological pattern") and clarifying that it is the proposed generic relationship/affinity being evaluated.

Rephrased and Changed to “this kind of body color pattern”.

 Lines 49–51:This sentence presents a grammatical mismatch ("regarded ... is") and joins two independent clauses without proper punctuation or connecting conjunctions. I suggest correcting the verb construction (e.g., "regarded ... as...") and introducing a clear transition (such as "suggesting that...") to link Kluge’s hypothesis on mandibular tusks to the proposed relationship between the genera.

Rephrased and Changed to past tense.  

Lines 56–58: There is a citation inconsistency here. The text cites "Mayorga et al. (2023)", but Reference 16 in your literature list is dated 2024.

Checked and changed to “2024”.

Lines 61–64: The expression "Joyfully surprised" introduces a subjective, narrative tone that is inappropriate for formal scientific writing. Furthermore, "most those nymphs became the adults" contains minor grammatical errors. My recommendation is to remove emotional descriptors and adopt an objective passive/declarative voice.

Rephrased and Changed, this two words are deleted.

 Materials and Methods

Lines 67–74: There are formatting inconsistencies in dates and names. Roman numerals and dashes used for dates vary across entries (e.g., VII–2008, 15–IV–2001, 7– IV–2001 with extra space, and 14–16–IV–2026). Please standardize the date formatting across all examined material entries according to MDPI style.  Ensure author name formatting is consistent (e.g., "Changfa Zhou" vs. "Chang-Fa Zhou").

Improved and Changed, hyphens in the text are changed in one format.

Lines 79–83: There are informal phrasing, minor typos, and mid-paragraph tense shift. For example, the phrase "tape water" (Line 80) looks like a typo for "tap water".  Line 82 shifts to present tense ("is employed"), whereas surrounding descriptions use past tense ("were gathered", "was covered", "were collected").  My recommendation is to maintain past tense consistently throughout the methodology and rephrase informal descriptions using standard technical language.

Improved and Changed to past tense.

Line 101–103: Again, there is informal wording and redundancy. The phrasing "uploaded to GenBank to blast" and "totally five related sequences in same genus" is informal.I suggest rephrasing to formal academic English.

Improved and Changed, see marked according sentences.

Line 109: I understand that the authors may be keeping the sequence private or awaiting paper acceptance before finalizing the release of the GenBank Accession Number for R. sapa. However, please remember that this number is required for reproducibility. The authors must deposit the sequence into the GenBank database and insert the official accession number into Table 1 and Section 2.3 prior to final acceptance and publication.

The COI Id is provided.

 

Results

Lines 115–117: There is a year mismatch in inline text vs. bibliography. Line 116 cites "Vasanth et al., 2024", but later in Discussion (Line 278) it is cited as "Vasanth et al. (2004)". Please standardize the year to 2024 across all sections to match Reference 18.

Improved and Changed to 2024.

 

Line 171–172: the expression "length arrangement of four segments of tarsi= 4, 1, 2, 3" is informal. Rephrase to formal descriptive style (e.g., "relative tarsal segment lengths arranged as IV > I > II > III").

Improved and Changed to exact data and ratio.

Lines 168: It is missing word in comparison here. Where you wrote "MP2 of hindwing more distinct and longer male (Fig. 3C)". You should add the missing word: "longer than in the male" or "longer than that of the male".

Improved and Changed to “than that of male”.

Line 194: There is a typographical error in figure legend. Correct the typo in the caption of Figure 4: change "Nymphal hatitus" to "Nymphal habitus".

Improved and Changed to “habitus”.

Line 203: The  is a sentence that begins with a lowercase letter "surface decorated...". Change to "Surface..."

Improved and Changed, surface is deleted.

Lines 205–214: Please review the description of feeding behaviors to correct minor typographical errors and polish the phrasing for academic clarity:

     Line 208: Change "deliver those food" to "deliver this food" (or simply "deliver food").

Improved and Changed to “deliver food”.

     Line 210: Correct the typo "scape" to "scrape".

Improved and Changed to “scrape”.

     Line 212: Change "wave inwards" to "wave them inwards" to ensure correct transitive verb usage.

Rephrased and Changed to “swing them inwards”.

Lines 214–216: In Section 3.2, the manuscript briefly notes that "The nymphs usually live in interstitial microhabitats." To enrich the ecological context of this species for aquatic entomologists and ecologists, it would be beneficial if the authors could expand slightly on the physical characteristics of the river at the collection site, if avaiable (e.g., current velocity, dominant substrate composition such as cobble/gravel, and presence of riparian or instream vegetation).

A habitat photo is added (figure 6).

Line 225: change "the abdomen of this species have" to "has".  

Rephrased and Changed to “has”.

Line 242: correct the comparative adjective "farer" to "further" 

Changed to “further”.

 

Discussion

Line 254: change "shortened mandibular tusks is the evolutionary trend" to "are the evolutionary trend".

Changed to “are”.

Lines 254–277: The hypothesis presented regarding the evolutionary sequence of mandibular tusks and forelegs within the Rhoenanthus–Potamanthodes lineage is well-reasoned. However, when discussing the nymphs' use of forelegs for food scraping, collecting, and pebble manipulation rather than burrowing, the authors maybe could strengthen the discussion by directly linking this behavior to the specific tusk morphology of R. sapa. Specifically, discussing how their relatively shorter and strongly incurved tusks (compared to the elongated tusks of other Rhoenanthus species) adaptively correlate with a non-burrowing, interstitial lifestyle would provide a clearer functional explanation for these observed behaviors.

This point can not be said clearly or specifically.

Line 259, change "tusks may evolved" to "may have evolved".

Rephrased and Changed to “may have evolved”,

Line 262: add the missing article in "common ancestor", it should be "the common ancestor". 

A “the” is added.

Line 274: There is a reference mismatch here. You wrote "Mayorga et al. (2023)", but Reference 16 is 2024. Please check.

Checked and changed to 2024.

Line 278 cites "Vasanth et al. (2004)", but Reference 18 is 2024.

Checked and changed to 2024.


Figures and Tables

Line 145 (Figure 1 Caption): Correct "Female sub imago" in 1D to "Female subimago".

Checked and changed to “subimago”.

Lines 157–160 (Figure 2 Caption & Panel 2K): Mention missing labels: Labels 2I (Foreclaw) and 2J (Midclaw) appear on the figure plate but are missing from the caption text.

The figure is changed to a new one.

References

The journal title formatting is inconsistent throughout the references. Ensure that all journal names follow the target journal’s specific style. Also, several references lack DOIs. It is strongly recommended to add active DOI links to all references where available.

Checked and changed.
Ref. 1 (Nguyen & Bae, 2004): Check the journal title and volume capitalization. Ensure author initials are spaced consistently with the rest of the bibliography (e.g., Nguyen, V.V.; Bae, Y.J.).

Checked and changed.

Ref. 2 and Ref. 3 (Bae & McCafferty publications): Verify consistent formatting for two-author citations in the references list. Ensure page ranges use full numbers (e.g., 1–18 instead of truncated ranges) and standard en-dashes (–) instead of hyphens (-).

Checked and changed.

Ref. 4 and Ref. 5: Check for missing volume/issue numbers or incorrect page number ranges. Ensure taxa names within article titles are properly italicized.

Checked and changed.

Ref. 14 (Kluge, 2004): Verify the exact monograph/book title representation: The Phylogenetic System of Ephemeroptera. Ensure publisher details (Kluwer Academic Publishers) and page numbers are accurately cited.

Checked and changed.

Ref. 16 (Mayorga et al.): Discrepancy in Text vs. References: In the main text (Lines 56 and 274), this paper is cited as Mayorga et al. (2023), whereas the reference list entries cite it as 2024.

Checked and changed.

Ref. 18 (Vasanth et al.): Discrepancy in Text vs. References: In Line 278 of the main text, this work is cited as 2004, while in Line 116 it is cited as 2024.

Checked and changed.


I would like to congratulate the authors on this detailed work and the high quality of the photographic plates. I wish you the best of luck with the revision process and look forward to seeing this paper published.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Identifying the species from Yunnan and Vietnam as the same species carries risks. Therefore, it is very necessary to provide more nymphal pictures of Rhoenanthus sapa in Yunnan, China.

Author Response

Identifying the species from Yunnan and Vietnam as the same species carries risks. Therefore, it is very necessary to provide more nymphal pictures of Rhoenanthus sapa in Yunnan, China.

Reply: (1)  the morphology of our spacimens match perfectly the description of Vietnam paper; (2) the locations of them are close. (3) the key character figures are provided in our figures (mandibles and legs); (4) the key characters of our specimens are same as the pictures of Vietnam materails. (5) females of them are same too.

We believe they are same.