This is an early access version, the complete PDF, HTML, and XML versions will be available soon.
Integrative Morphological and Molecular Diagnostics for Euseius nicholsi and Euseius oolong (Acari: Phytoseiidae)
Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute of Zoology, Guangdong Academy of Sciences, Guangzhou 510260, China
*
Author to whom correspondence should be addressed.
Insects 2025, 16(9), 950; https://doi.org/10.3390/insects16090950
Submission received: 21 July 2025
/
Revised: 31 August 2025
/
Accepted: 6 September 2025
/
Published: 10 September 2025
(This article belongs to the Special Issue Revival of a Prominent Taxonomy of Insects)
Simple Summary
Specimens of a phytoseiid mite were collected from Bajiaozhai National Forest Park, Guilin, China, and showed close resemblance to Euseius nicholsi and Euseius oolong. Despite similarities, some morphological traits, such as body dimensions, number of dorsal solenostomes, spermathecal shape, and setae length differed. To determine whether these variations indicated distinct species or fell within natural variation, we performed molecular analysis using mitochondrial COI, 12S rRNA, and nuclear ITS markers. The genetic divergence among the unidentified specimens, E. nicholsi, and E. oolong was minimal, and all samples clustered together in a single clade in the phylogenetic tree. This suggested that they were not separate species. We therefore concluded that the unidentified specimens are E. nicholsi, and E. oolong should be considered its junior synonym. These findings underscore the value of integrating morphological and molecular tools for accurate mite identification.
Abstract
In a survey of Bajiaozhai National Forest Park (Guilin, China), several specimens of an Euseius sp. were collected. These specimens were very similar to Euseius nicholsi and Euseius oolong, based on morphological observations. However, some morphological characters, such as the body size, number of solenostomes on the dorsal plate, calyx shape of the spermatheca, the shape and number of metapodal platelet, teeth number on the fixed digit, length of setae j3, and macroseta Seg IV, Sti IV, and St IV were different between these specimens and E. nicholsi and E. oolong. To ascertain whether these morphological differences were interspecific or intraspecific variations, molecular analyses were conducted using mitochondrial DNA COI, 12S rRNA, and nuclear ITS markers. Based on the three molecular markers, minimal genetic distances were observed (COI 0–4%, 12S rRNA 0–2%, and ITS 0%) among the putative Euseius sp., E. nicholsi (collected from Bauhinia purpurea in IZGAS and from Eurya macartneyi and Ficus hispida in Shaoguan City), and E. oolong (collected from B. purpurea in IZGAS). Amblyseius swirskii was used as the outgroup. Using the maximum likelihood method, the phylogenetic tree showed that these specimens of Euseius sp., E. nicholsi, and E. oolong clustered in a single clade. Therefore, we propose that this putative Euseius sp. is E. nicholsi, and E. oolong is a junior synonym of E. nicholsi. This study demonstrates the importance of integrative taxonomy for the proper identification of phytoseiid mites.
Keywords:
Phytoseiidae; taxonomy; morphology; molecular marker; integrative approach
