Discovery of a Cryptic Lineage of <em>Oligonychus </em>(Acari: Tetranychidae) Associated with Cassava in the Republic of Congo Through Barcoding: Pilot Study and Perspective

Pest mites (Tetranychidae) are major cassava pests in tropical Africa, where this crop is crucial for food security. In the Republic of Congo (RC), specific pest mite diversity remains poorly documented and is mainly based on morphological identification using non-African taxonomic keys, which cannot effectively distinguish closely related or cryptic species. This study aimed to clarify the status of cassava-associated Tetranychidae in the RC using multi-locus molecular barcoding on 12 mite samples collected from two plots in Brazzaville. The obtained sequences were processed using Genious to generate consensus sequences for everyone, which were then compared with data from GenBank and BOLD databases. The cytochrome c oxidase I marker showed a 25% amplification rate, yielding three new sequences that exhibited low divergence and clustered with a related Oligonychus sequence. The genetic divergence observed with O. biharensis suggests a distinct, potentially undescribed lineage. Phylogenetic analysis supported this result, highlighting a subclade originating from the RC that was strongly supported by the corresponding node. Contrastingly, ITS marker amplification yielded no results, which prevented validation of the multi-locus approach and illustrated the challenges encountered with this marker in Tetranychidae. These initial molecular data on cassava-associated Tetranychidae in the RC revealed a previously unreported Oligonychus lineage, justifying further research to improve the overall characterisation of these bio-aggressors in understudied regions.