Deciphering Morphological Variability: Addressing Taxonomic Ambiguities in Contemporary Species Delimitation (Hymenoptera, Figitidae)

TL;DR

This paper uses a combination of physical traits and DNA data to better define species boundaries in tiny wasps called Charipinae, improving their classification.

Contribution

The study introduces an integrative taxonomic framework combining morphology and molecular data to resolve species delimitation in Charipinae wasps.

Findings

Morphological and molecular data largely agree, confirming traditional species in Charipinae.

DNA evidence refined species boundaries and revealed potential hidden diversity.

Morphology remains reliable, but combining it with molecular data improves accuracy and stability in classification.

Abstract

Charipinae (Hymenoptera, Figitidae) are a small group of important aphid hyperparasitoids known for their tiny size and minimal visible variation, making them challenging to identify. Traditional morphological characters sometimes vary within species, making species delimitation unstable. We used an integrative taxonomic approach that combines morphology and molecular data to clarify species limits in two genera, Alloxysta and Phaenoglyphis. By analyzing 53 morphological characters and three genetic markers (COI, ITS2, and 16S rRNA), we found that molecular and morphological data largely agree, confirming the traditionally recognized species in this group. Furthermore, DNA evidence also helped refine some species boundaries and revealed possible hidden diversity. Our results show that morphology remains a reliable foundation for Charipinae taxonomy, but combining it with molecular data leads to more accurate and stable identification. This integrative framework will largely support future ecological and evolutionary studies of these hyperparasitoids.

Species delimitation in Charipinae hyperparasitoids (Hymenoptera: Figitidae) is notoriously difficult due to their minute size and limited morphological variability. Traditional diagnostic characters sometimes show intraspecific variation, raising concerns about their reliability. Here, we applied an integrative taxonomic framework to evaluate species boundaries among six species of Alloxysta Förster and four species of Phaenoglyphis Förster. We combined a morphological dataset of 53 characters with data from three molecular markers (COI, ITS2, and 16S rRNA) and reconstructed phylogenies under maximum-likelihood criteria. Phylogenies consistently recovered morphologically defined taxa as well-supported clades, confirming the overall reliability of traditional characters (pronotal and propodeal carinae, radial cell shape, and flagellomere proportions). On the other hand, molecular evidence refined certain species limits and highlighted cases of potential cryptic variation. Our results demonstrate that morphology still provides a strong baseline for Charipinae taxonomy, but integration with molecular data yields more robust and stable classifications. This study underscores the value of multi-locus approaches for resolving taxonomic ambiguities and provides a framework for future ecological and evolutionary research on these hyperparasitoid wasps.

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