Keyhole into a Lost World: The First Purely Freshwater Species of the Ponto-Caspian Genus Clathrocaspia (Caenogastropoda: Hydrobiidae)

Round 1

Reviewer 1 Report

In their study, Anistratenko and colleagues study the enigmatic malacofauna of the Caspian Sea, with a particular focus of a potential refuge in Dagestan and describe a new Clathrocaspia species from this area. To do so, they used a comprehensive dataset of >1000 specimens and an integrative taxonomic approach that includes conchological, anatomical, histological and genetic features, which I acknowledge very much.

The analytical part is very detailed and satisfactory and I agree with the authors that the population from Dagestan may represent a new species of Clathrocaspia. However, although the genetic distance to C. knipowitschii is considerably high for COI, the authors should make clear that genetic information is only available for these two species. As no other genetic resources are available for the remaining Clathrocaspia species, it remains unclear whether the specimens from Dagestan represent a new species or belong to one of the already described taxa.

Finally, I started with editing the language, but did not go beyond the abstract, except for some sporadic changes in the main text. I stronly recommend that the authors have a native speaker look over the manuscript.

I made some few edits and comments in the attached PDF. The authors should also modify the Discussion, because it includes information that should go into the Results section and information that should be introduced in the first part of the manuscript (i.e. commensalistic interactions with Dreissena).

Comments for author File: Comments.pdf

Author Response

We thank the anonymous reviewer for his/her positive evaluation of our manuscript and for critical comments that are very useful. We added a phrase that the status of the new species can be disputed as only two species of the genus have been studied genetically, and that there is a possiblity that the newly found snails can belong to an earlier described nominal species of Clathrocaspia.
We carefully followed all your linguistic suggestions and most of the suggestions concerning the relocation of parts of the text (e.g. from ‘Discussion’ to ‘Introduction’). In a few cases, however, we have felt it to be better to leave parts of the text on their original places. For example, we prefer to discuss the relationships between Clathrocaspia snails and dreissenid mussels only in ‘Discussion’, not mentioning them in the ‘Introduction’ (in our opinion, the Introduction must be rather concise and focused on the most important topics of the study). Please see attached the detailed responses to reviewer 1.

Author Response File: Author Response.pdf

Reviewer 2 Report

Congratulations to the excellent paper of an interesting subject. I have no major suggestions, just maybe the design of the Tab1 is a bit weird with large locality description in a narrow column. I would recommend to consider its rearrangement e.g. as on the suggestion I attached. Of course it does not influence the high quality of the paper and the final decision to follow my recommendation is fully upon you.

Wish you all the best and an uninterrupted continuation of your nice work

Comments for author File: Comments.pdf

Author Response

Thank you for your kind words and high estimation of our work! We made some changes into table 1 to make it more easy-to-read 

Reviewer 3 Report

The manuscript is overall very well written and reports on a finding of a new species in an unexpected habitat, which is obviously worthy of publication

Some notes and minor suggestions:

Table 2 is very lengthy and (at least about the BLAST result) carries no significant information: it is clear that C, knipowitschii and the new species are really different, in terms of COI distance it is 6.5-7%. But not such a large table is necessary to provide this information instead of a short sentence.

Possibly, a phylogenetic tree might be more informative...

When the case of C. milae is discussed (line 569-579), please keep in mind that Szekeres et al. (2022) makes strong arguments that C. milae is the junior synonym of C. knipowitschii and in the whole Danube section C. knipowitschii is found as an alien species.  It would be nice to refer to this paper, and also at the point when C. knipowitschii COI sequences are cited/used (e.g. Table 2, but see my note above):

Szekeres J, Beermann A, Neubauer TA, Očadlik M, Paunović M, Raković M, Csányi B, Varga A, Weigand A, Wilke T, Fehér Z. Rapid spread of a new alien and potentially invasive species, Clathrocaspia knipowitschii (Makarov, 1938)
(Gastropoda: Hydrobiidae), in the Danube River. Arch Biol Sci. 2022; https://
doi.org/10.2298/ABS220211006S.   (this is currently online-first)

 

Author Response

We thank you for the kind words and high estimate of our manuscript. 

As concerns your specific comments,

Table 2 will be moved to Supplementary Info.

We added the reference to Szekeres et al. (2022) and changed the original text accordingly

We agree that it would be nice to add a phylogenetic tree, but we will publish it a bit later, in a special molecular study of the living Clathrocaspia. The aim of this paper is to provide the formal description of the new species with a detailed account on its morphology and variability