Two Species Delimitation of Pseudaulacaspis (Hemiptera: Diaspididae) Based on Morphology, Molecular Clustering, and Niche Differentiation

SIMPLE SUMMARY: Two species belonging to the genus Pseudaulacaspis MacGillivray, 1921 (Hemiptera: Diaspididae), Pseudaulacaspis pentagona (Targioni Tozzetti, 1886) and Pseudaulacaspis prunicola (Maskell, 1895) are well-known pests for a great variety of ornamental plants and fruit trees worldwide. Both are notorious pests and significantly similar in morphology characteristics, life cycle, and ecological conditions, making it quite challenging to distinguish between the two species. In this paper, we implemented an integrative approach combining morphological, molecular, and ecological niche analyses in order to species delimitation. Overall, our findings indicate that the results further underpin the notion that the two species are closely related but distinct. We show that the integration of multiple approaches is useful in identifying morphologically similar species of the genus Pseudaulacaspis, overcoming the difficulties encountered when using traditional taxonomy alone. ABSTRACT: Pseudaucalaspis pentagona and P. prunicola are notorious pests and commonly feed on various ornamental plants and fruit trees worldwide. The two species share many host-plant species, and are similar in morphological characteristics and life cycle, making it difficult to distinguish to distinguish between them. In this study, morphological characteristics, molecular evidence, and ecological niches were used to define these species. We performed PCA analysis on 22 morphological characteristics that allowed the delineation of the species. We then sequenced the COI gene of both species revealing five populations of P. pentagona and one population of P. prunicola, and the higher support rate could distinguish the two species. We also identified the potential distribution area of the two species based on the MaxEnt niche model, which showed that the degree of niche overlap was high, but that they occupied different niches. Ultimately, we combined three lines of evidence to show that the two species are distinctly different. This study supports species definition using combined morphology, genetics, and ecology and provides a theoretical basis for the effective control of these two pests in the future.