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Article
Peer-Review Record

Rotifera of the Peruvian Andes: New Records and Insights

Diversity 2025, 17(3), 217; https://doi.org/10.3390/d17030217
by Maciej Karpowicz 1,*, Jolanta Ejsmont-Karabin 1, Elian Rojas-Baez 2, María José Pardo 3 and Carlos López 4,5
Reviewer 1:
Reviewer 2: Anonymous
Reviewer 3: Anonymous
Diversity 2025, 17(3), 217; https://doi.org/10.3390/d17030217
Submission received: 9 February 2025 / Revised: 12 March 2025 / Accepted: 16 March 2025 / Published: 18 March 2025
(This article belongs to the Special Issue Tropical Aquatic Biodiversity)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comments:

This is an interesting manuscript for Diversity readers, due to the new information it provides on Rotifera of the Neotropical Region, specifically, from previously unstudied areas of the Peruvian Andes. Another important aspect is the inclusion of samples from Lake Titicaca, which, with an area of ​​8370 km2 and an altitude of 3812 meters a.s.l., has few studies on zooplankton and, in particular, on rotifers. Besides the lake, several freshwater habitats were explored such as streams, springs, and groundwater. New occurrences of rotifer species are reported for the Andes region and for the Neotropical Region.

Suggestions:

Lines 147-148: Table 2 – In the methods, the authors explained that unidentified bdelloid species were segregated into three groups of individuals similar in size and general morphology. However, at Table 2 they listed Bdelloidae sp.1, Bdelloidae sp. 2 and Bdelloidae sp. 3. These three listed taxa probably correspond to the three groups of similar sizes and not to unidentified species. The denomination in the table should therefore be changed.

Line 162: The CCA showed that samples of the Lake Titicaca were distinguished from the others. As can be seen in the CCA plot, the authors could comment that this distinction was mainly due to the presence of truly planktonic species in the samples from this lake, such as Keratella quadrata and K. tropica.

Line 185: We cannot agree that Lake Titicaca has an extensive history of zooplankton research. Due to its importance, with peculiarities such as size and altitude, there are few reports about this community. We can see this among the scarce cited references, which include manuscripts from 1939 a master's dissertation (Moreno, 1983).

Line 245: In addition to its importance for the Peruvian region, the authors could highlight the significance of the study for the biogeography of rotifers in the Neotropical Region. The Andean region studied, located in the tropical belt (see latitude) of South America, presents taxa normally found in the subtropical-temperate belt of this continent, such as the genus Notholca.

Author Response

Comment: Lines 147-148: Table 2 – In the methods, the authors explained that unidentified bdelloid species were segregated into three groups of individuals similar in size and general morphology. However, at Table 2 they listed Bdelloidae sp.1, Bdelloidae sp. 2 and Bdelloidae sp. 3. These three listed taxa probably correspond to the three groups of similar sizes and not to unidentified species. The denomination in the table should therefore be changed.

Response: True. We have addressed this issue by removing the original groupings (Bdelloidae sp. 1, Bdelloidae sp. 2, and Bdelloidae sp. 3) and have instead used the designation Bdelloidae n. det. throughout the manuscript, including Table 2, Methods and Results.

 

Comment: Line 162: The CCA showed that samples of the Lake Titicaca were distinguished from the others. As can be seen in the CCA plot, the authors could comment that this distinction was mainly due to the presence of truly planktonic species in the samples from this lake, such as Keratella quadrata and K. tropica.

Response: We have added information “ This distinction was mainly due to the high abundance of truly planktonic species, such as Keratella quadrata and K. cochlearis (Table S1)”. Additionally, we have provided raw data on the total abundance of Rotifera in the entire sample in the Supplementary Materials (Table S1). However, Keratella tropica was represented by only a single individual, while the dominant species were Keratella quadrata and K. cochlearis.

 

Comment: Line 185: We cannot agree that Lake Titicaca has an extensive history of zooplankton research. Due to its importance, with peculiarities such as size and altitude, there are few reports about this community. We can see this among the scarce cited references, which include manuscripts from 1939 a master's dissertation (Moreno, 1983).

Response: This sentence referred to general zooplankton studies, including those in which Rotifera were analyzed as a component of the zooplankton community. In comparison, copepods have been studied in much greater detail. We want to point out a surprisingly low number of Rotifera species (only seven) reported from Lake Titicaca.

 

Comment: Line 245: In addition to its importance for the Peruvian region, the authors could highlight the significance of the study for the biogeography of rotifers in the Neotropical Region. The Andean region studied, located in the tropical belt (see latitude) of South America, presents taxa normally found in the subtropical-temperate belt of this continent, such as the genus Notholca.

Response: The Andean species that can be considered here typical of the Neotropics are rarely found, thus their biogeography is unknown. I am not sure we can generalize on this basis. Nevertheless, the second half of the discussion mostly focuses on presenting the identified species in the context of their occurrence in the Neotropics.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have done a great job. Their research really contributes to shaping the understanding of Rotifera fauna in a little-studied region.

I recommend adding a map with the sampling location.

Since the authors claim to have discovered 2 new 2 new species, could the authors provide photographs or drawings of them, as well as a detailed description of their morphology. Are there any differences from the typical diagnosis? Was the identification carried out only on the basis of morphological observations? Do the authors plan to use the methods of molecular genetic analysis in the future?

In the discussion, could the authors describe the species listed on page 8 in a little more detail?

Author Response

Comment: The authors have done a great job. Their research really contributes to shaping the understanding of Rotifera fauna in a little-studied region.

Response: Thank you!

 

Comment: I recommend adding a map with the sampling location.

Response: The map of Peru with locations of sampling sites was added to the main text as Figure 1.

 

Comment: Since the authors claim to have discovered 2 new 2 new species, could the authors provide photographs or drawings of them, as well as a detailed description of their morphology. Are there any differences from the typical diagnosis? Was the identification carried out only on the basis of morphological observations? Do the authors plan to use the methods of molecular genetic analysis in the future?

Response: This is a misunderstanding. In our manuscript we note the presence of two species new to the Neotropics. We did not find in our studies species new to science. Furthermore, the Rotifera identification was conducted by a recognized specialist in Rotifera taxonomy, who is also the author of several identification keys. The analysis was based on detailed morphological observations. While we did not use molecular genetic methods in this study, we acknowledge their value and consider them a potential approach for future research. We also emphasize the need for more comprehensive taxonomical studies using an integrative approach combining genetic and morphology (lines: 67-69).

 

Comment: In the discussion, could the authors describe the species listed on page 8 in a little more detail?

Response: We are unsure how we could further elaborate on these species. Our goal was to outline their biogeography in the Neotropics, using over 40 literature sources to provide a comprehensive context.

Reviewer 3 Report

Comments and Suggestions for Authors

Abstract:

L18/27: I am confused by the fact that you state 12 Monogononta and 3 species of Bdelloidea on L 18 and then 19 Monogononta and 4 Bdelloidea species on L27; both lines sate that these records are new to Peru. Therefore, please uniform the text and be more specific

 

Introduction

L67: “focusing” instead of “focused”

L67-69: please use a Rotifera paper for this statement

 

Material and Methods

General question: is the sampling effort the same between sampling sites so that it does make sense to count the samples and perform a multivariate ordination? Please provide a justification and details for this

L95: while I understand the authors enthusiasm about the studied region, I do not understand what these unique conditions are for studying rotifer diversity. I suggest deleting this sentence.

 

L98: “as much water as possible” is a little bit vague. Please give an estimate in time, be more specific. From where did you take the water (which depth did you sample, surface, whole water column?), how did you sample the water to filter the water? Please provide this information

L115: hauls from the surface to which depth? Please be more specific

L127: “according to” instead of “after”

L133: delete “map of” because it is obvious that you present results of the ordination in a figure

L132: please write: “The distribution of Rotifera  …. regions was visualized  ….”

L130-132: in this sentence you combine clustering with correlation but both analyses are independent; please provide a more clear description of what you did because generally both analyses are separate. Finally, after seeing figure 2, I understand but the description of the method is inappropriate and please state what were the input data (presence/absence or abundance? For abundance I am not positive about because of a supposed unbalanced sampling effort. Write something like this “The similarity between sampling sites was investigated by agglomerative hierarchical classification (AHC) using Jaccard as dissimilarity index based on presence/absence” or ”….. Bray-Curtis dissimilarity based on abundance data” -> which I do not recommend

 

 

Results

L136: “identified” instead of “have identified”

Please provide the criteria for distinguishing the three Bdelloidea types

Figure 2: is this done with presence/absence data (as I hope because of your assumed unbalanced sampling effort)? Please provide this detail in the method section and legend of the figure -> please change the analysis based on my comment for figure 2

Please provide an indication from which region the samples are, this help to see if there is a clustering according to region

 

L159: nothing is automatic, but I understand you trusted the software. Delete “automatic”

 

In the whole result section use past tense

L161: write “The CCA indicated …”

 

L172: this “relatively high numbers” is very unclear and needs clarification; what are high numbers? Since you did not tell anything about the sampling effort and I hypothesise an uneven sampling effort between sites, you could provide a classification for abundance based on personal judgement (e.g. low abundance +; medium abundance ++; high abundance +++) and you provide your thresholds for this semi quantitative levels; something similar to https://link.springer.com/article/10.1007/s10750-023-05391-4

 

Discussion

L201: “particularly abundant in these habitats” -> same comment as for L172

Author Response

Comment: L18/27: I am confused by the fact that you state 12 Monogononta and 3 species of Bdelloidea on L 18 and then 19 Monogononta and 4 Bdelloidea species on L27; both lines sate that these records are new to Peru. Therefore, please uniform the text and be more specific

Response: We have removed the total number of species found in the Cusco region (19 Monogononta and 4 Bdelloidea species) and we present only the number of new records for Peru (same as above in Lake Titicaca)

 

Comment: L67: “focusing” instead of “focused”

Response: Corrected

 

Comment: L67-69: please use a Rotifera paper for this statement

Response: We have changed it to a paper related to Rotifera from Peru (Sánchez-Dávila, P.P.A.; Sotil, G.; Adabache-Ortiz, A.; Cueva, D.; Silva-Briano, M. Integrative Taxonomy of Two Peruvian Strains of Brachionus plicatilis Complex with Potential in Aquaculture. Diversity 2021, 13, 671. https://doi.org/10.3390/d13120671)

 

General question: is the sampling effort the same between sampling sites so that it does make sense to count the samples and perform a multivariate ordination? Please provide a justification and details for this

Response: We believed that quality samples could also show the differences in community composition. Our approach allowed us to detect species occurring in very low abundances in highly specific groundwater-dependent ecosystems, such as springs and mountain streams. Additionally, we have provided raw data on the total abundance of Rotifera in the entire sample in the Supplementary Materials (Table S1). Furthermore, both analyses (CCA and AHC) clearly distinguished the studied habitats based on their Rotifera fauna.

 

Comment: L95: while I understand the authors enthusiasm about the studied region, I do not understand what these unique conditions are for studying rotifer diversity. I suggest deleting this sentence.

Response: We would like to keep this sentence as it highlights the uniqueness of the habitats we studied (groundwater-dependent ecosystems, such as springs and mountain streams). Additionally, in the discussion, we emphasize the limited knowledge about the fauna of South American groundwater ecosystems, making this aspect particularly relevant to our study.

 

Comment: L98: “as much water as possible” is a little bit vague. Please give an estimate in time, be more specific. From where did you take the water (which depth did you sample, surface, whole water column?), how did you sample the water to filter the water? Please provide this information

Response: We added some more information about our quality sampling: “We performed quality sampling at each station. In most cases, we placed the 50 µm plankton net in the main current of small streams, keeping it there long enough to filter as much water as possible, taking into account the amount of organic matter. This procedure was repeated 2–3 times per sample”.

 

Comment: L115: hauls from the surface to which depth? Please be more specific

Response: We have added the information “vertical hauls from surface to depth 2-3 meters”

 

Comment: L127: “according to” instead of “after”

Response: Corrected

 

Comment: L133: delete “map of” because it is obvious that you present results of the ordination in a figure

Response: Corrected

 

Comment: L132: please write: “The distribution of Rotifera  …. regions was visualized  ….”

Response: We improve this sentence – “The distribution of Rotifera species in geographic regions was visualized by canonical correspondence analysis (CCA)”

 

Comment: L130-132: in this sentence you combine clustering with correlation but both analyses are independent; please provide a more clear description of what you did because generally both analyses are separate. Finally, after seeing figure 2, I understand but the description of the method is inappropriate and please state what were the input data (presence/absence or abundance? For abundance I am not positive about because of a supposed unbalanced sampling effort. Write something like this “The similarity between sampling sites was investigated by agglomerative hierarchical classification (AHC) using Jaccard as dissimilarity index based on presence/absence” or ”….. Bray-Curtis dissimilarity based on abundance data” -> which I do not recommend

Response: We added information that “Raw data for these analyses are presented in Table S1.” The input data was a total abundance of each taxon in the sample. Our raw data indicated rather low abundance of each species, besides the pelagic samples from Lake Titicaca. We also provided information in Results why the Lake Titicaca distinguished from the others sampling sites on CCA – “This distinction was mainly due to the high abundance of truly planktonic species, such as Keratella quadrata and K. cochlearis (Table S1)”.

 

Comment: L136: “identified” instead of “have identified”

Response: Corrected

 

Comment: Please provide the criteria for distinguishing the three Bdelloidea types

Response: We have removed the three Bdelloidea groups and now use the designation Bdelloidae n. det. throughout the manuscript, including Table 2, Methods, and Results.

 

Comment: Figure 2: is this done with presence/absence data (as I hope because of your assumed unbalanced sampling effort)? Please provide this detail in the method section and legend of the figure -> please change the analysis based on my comment for figure 2

Response: We responded above.

 

Comment: Please provide an indication from which region the samples are, this help to see if there is a clustering according to region

Response: Detailed information about sampling sites (and region) is presented in Table 1. Furthermore, a map of the studied sampling sites was provided in response to the Reviewer's request. But generally: 1-6 Cusco; 7-15 Machu Picchu; 16-18 Titicaca.

 

Comment: L159: nothing is automatic, but I understand you trusted the software. Delete “automatic”

Response: Corrected

 

Comment: In the whole result section use past tense

Response: We have revised the Results section to ensure consistency in the past tense.

 

Comment: L161: write “The CCA indicated …”

Response: Corrected

 

Comment: L172: this “relatively high numbers” is very unclear and needs clarification; what are high numbers? Since you did not tell anything about the sampling effort and I hypothesise an uneven sampling effort between sites, you could provide a classification for abundance based on personal judgement (e.g. low abundance +; medium abundance ++; high abundance +++) and you provide your thresholds for this semi quantitative levels; something similar to https://link.springer.com/article/10.1007/s10750-023-05391-4

Response: We have provided raw data in the Supplementary Materials (Table S1) and added a reference to Table S1 in the Results section.

 

Comment: L201: “particularly abundant in these habitats” -> same comment as for L172

Response: We have added a reference to Table S1.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have made the necessary changes.​​

In Figure 2, the letter designations are poorly visible. Perhaps the authors should have placed the letters in white squares?​​​

On page 7, lines 162-168, it is enough to refer to Figure 3 once, in the first sentence of the paragraph.

​​

Author Response

Comment: In Figure 2, the letter designations are poorly visible. Perhaps the authors should have placed the letters in white squares?​​​

Response: We appreciate your suggestion regarding the visibility of the letter designations in Figure 2. We carefully evaluated this aspect and tested the use of white squares. However, we found that adding them negatively impacted the overall clarity and aesthetic of the figure. Given that the letters remain distinguishable in the current version, we have decided to maintain the original design.

 

Comment:  On page 7, lines 162-168, it is enough to refer to Figure 3 once, in the first sentence of the paragraph.

Response: Thank you for your suggestion. We have revised the paragraph by removing two (Figure 3) from the middle, keeping a single reference at the beginning and another at the end to maintain clarity and readability.

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