Species Delimitation Methods Facilitate the Identification of Cryptic Species Within the Broadly Distributed Species in Homoeocerus (Tliponius) (Insecta: Hemiptera: Coreidae)^†

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear respected Editor and Authors

This manuscript aims to delimit species boundaries within the subgenus Tliponius of Homoeocerus, combining molecular and morphological evidence and ultimately describing a new species. While this is a valuable integrative approach, several major concerns, both scientific and taxonomic, undermine the manuscript’s current impact and clarity. These are summarized below.

1. Lack of clarity regarding comparison with all described specie. 

The new species proposed in this manuscript is only discussed in relation to H. unipunctatus, to which it is morphologically similar. However, the subgenus Tliponius currently includes at least 44 described species worldwide (Coreoidea online catalogue), and it remains unclear whether the authors have considered and compared the focal specimens with the full global diversity of the group. The apparent omission of other species, based solely on morphological similarity to H. unipunctatus, represents a highly limited and potentially problematic taxonomic scope.

 

2. Insufficient consideration of synonymized species

H. unipunctatus was originally described from Japan and has a complex taxonomic history, including several species from China, Hong Kong, and Japan that have since been synonymized with it. If the population proposed here as a new species corresponds to any of these synonyms, the proper taxonomic act would be resurrection of a previously synonymized name, not a new species description. However, there is no evidence in the manuscript that the authors examined the types, reviewed original descriptions, or otherwise considered the possibility of synonymy, which is essential for any rigorous taxonomic work.

 

3. Lack of basic taxonomic background expected in a species description

Despite aiming to describe a new species, the manuscript provides almost no taxonomic background on the subgenus Tliponius, such as the number of known species, diagnostic morphological characters, or a brief taxonomic history. At minimum, this context is necessary to inform readers and future researchers, and to place the proposed taxonomic changes in an appropriate systematic framework. If this paper will be an original description of a certain species, then those information should be provided.

 

4. Lack of scientific interpretation despite extensive analyses

The authors employed a wide range of analytical tools, including COI distance matrices, ddRAD phylogeny, ML trees, haplotype networks, STRUCTURE analysis, mitogenomic phylogeny, and BEAST-based molecular dating. While these analyses are robust and complementary in principle, the manuscript does not clearly explain their purpose, scientific rationale, or how the results contribute to the study’s objectives. In particular, molecular dating has the potential to illuminate the timing of cryptic divergence and correlate with geological or climatic events, yet its significance is not addressed. Many of these results appear to serve only as redundant support for the authors’ proposed a new species, rather than as tools to explore deeper evolutionary or biogeographic questions.

 

 

In its current form, the manuscript lacks sufficient context to clarify why this particular taxon was chosen as the focus of the study. To address this issue, the following alternative narrative may be considered.

As previously mentioned, whether the focal population represents a truly new species is a central question directly tied to the significance of the manuscript. This is not merely a matter of nomenclature, but a key point at which traditional taxonomy and modern molecular systematics should be integrated. If, for various reasons (e.g. lack of access to type material), the authors are unable to conduct the detailed taxonomic investigations necessary to justify the description of a new species, it may be more appropriate to treat these specimens as H. unipunctatus and restructure the manuscript to emphasize the presence of cryptic diversity within this complex.

Given the historical synonymy and broad morphological variation associated with H. unipunctatus, such an approach would still constitute a valuable scientific contribution. Moreover, it would help clarify the rationale for choosing this taxonomic group and demonstrate the authors’ awareness of its taxonomic complexity.

 

Other comments and suggestions are in the attached file. 

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper focuses on species delimitation within the subgenus Tliponius of Homoeocerus, using integrative methods combining morphology, mitochondrial genes, and SNP data. The study is of great significance for understanding the cryptic species diversity and phylogenetic relationships within widely distributed species. However, there are still some issues that need to be addressed in this study, as follows:

 

Please provide email for each author in the title page.

 

In the introduction, the description of the genus Tliponius currently only provides geographical distribution information for three widely distributed species. It is suggested to add descriptions of other relevant species.

 

The introduction mentions that “Only mitochondrial sequences from partial species within the genus Homoeocerus have been documented.” However, these data do not appear to be utilized in this manuscript.

 

The text mentions the use of integrated morphological data, but no morphological methods are described in the materials and methods section.

 

The first sentence in the discussion states, “Although some slight morphological differences between Hupt_YNML samples and other H. unipunctatus samples were observed (e.g. the depth of the abdominal punctures and the intensity of the antennal color), they were not initially solid enough to be direct evidence of species delimitation. Intraspecific morphological variation is common in many species, especially widely distributed ones, making further molecular evidence necessary to confirm species validity.” This content has not been mentioned in the previous sections. It would be more logical to provide relevant background information in the introduction before discussing it.

 

The citation style of figures used in the original text is inconsistent. Please check and unify the consistency throughout the text.

 

The format of the entire text needs to be unified. Better using the latest submission template (Insects 2025).

 

The Taxonomy section should be incorporated with the Results section. BTW, the new taxa and publication should be registered in ZooBank once this MS is accepted. And please provide the urn:lsid after the new taxa. Otherwise, it will be nomen nudum. Sample ID should be given for the Holotype and Paratypes.

“Liang & Bu sp.nov.” change to “Liang & Bu sp. nov.”

For the measurements, why not combine the data of holotype and paratypes for male and females?

 

Authors should also improve the quality of figures. For example, it’s hard to read the words of figures 1-4. Please note that Nine-dash line is incomplete in figure 1.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

I am delighted to see that my suggestions have been thoughtfully incorporated.

Thank you for considering my input.