Exploring the Intricate Web of Biodiversity: Notocomplana (Rhabditophora: Polycladida: Notocomplanidae) Species Networks in the North Pacific Ocean

The study concentrated on the <i>Notocomplana</i> Faubel, 1983 species that exist in the northern regions of the Pacific Ocean. The research utilized a comprehensive methodology that combined molecular (mitochondrial COI and nuclear 28S rRNA genes) and anatomical approaches. The primary objective of this study was to gain a thorough understanding of the diversity of the genus <i>Notocomplana</i> in this region. This includes all possible species and their populations. The study used various analysis tools to establish the boundaries and relationships within and between species. Bayesian inference and maximum likelihood were used for kinship analysis, while bPTP, mPTP, and ABGD were used for species delimitation. Haplotype studies were conducted using TCS and MSN. The study focused on <i>Notocomplana hagiyai</i> Oya and Kajihara, 2017, a well-known species of the genus from Asia found along the coasts of Vladivostok in Russia, as well as <i>Notocomplana</i> species from the North Pacific coast of Asia and North America. The analysis revealed the degree of diversity in <i>Notocomplana</i> and the relationships between different species and populations, both within and between them. The diversity of species and haplotypes found on the North Pacific coasts was very motivating, particularly concerning the relationships between the Asian and American populations. Although the 28S analysis indicated that <i>N</i>. <i>septentrionalis</i> (Kato, 1937) was a sister group to the Asian species, the COI analyses did not provide any definitive resolution regarding the kinship relationships between <i>N</i>. <i>septentrionalis</i> and the other groups.