Unveiling host plant associations and cryptic genetic diversity of <i>Miyalachnus sorini</i> (Aphididae: Lachninae) on cherry trees in South Korea

This study presents the first record of <i>Miyalachnus sorini</i> Kanturski & Lee, 2024 (Aphididae: Lachninae) in South Korea, thereby extending its known distribution beyond Japan and identifying a new host plant, <i>Prunus sargentii</i> (Rosaceae). We describe diagnostic morphological traits across multiple life stages and compare them with those of Japanese populations. Comparative analyses with Japanese populations demonstrated consistent morphological differentiation, notably elevated ratios of the ultimate rostral segment to antennal segments across multiple morphs in the Korean population, indicating potential ecological adaptation. DNA barcoding using the mitochondrial cytochrome c oxidase I gene revealed low intraspecific divergence (average 0.2%) and interspecific divergence (average 10.5%) between <i>Miyalachnus</i> sp. and <i>M. sorini</i>. Haplotype analysis was performed to investigate the relationship between host plants and cryptic genetic diversity. These findings enhance our understanding of the morphological and genetic diversity of <i>M. sorini</i> and underscore the importance of monitoring its spread for informed pest management strategies.