Morimotobathynella sp.

Morimotobathynella sp.

Material examined.

Pocheon-si (38°6'56.21"N, 127°15'46.38"E), South Korea. Collected by S.-J. Ji and C.-W. Lee on 31 May 2020 GoogleMaps .

Remarks.

This specimen was included in the phylogenetic analysis to mitigate potential long-branch attraction issues that could affect the phylogenetic placement of M. koreana sp. nov. The inclusion of this closely related species provides a more robust phylogenetic framework for the genus Morimotobathynella in East Asia. Although a detailed morphological examination suggests that this specimen represents another potentially new species, a formal description requires additional material.

CO 1 and 18 S rRNA gene sequencing

In this study, 597 bp of CO 1 (PQ 790059 – PQ 790061) and 1,713 bp of 18 S sequences (PQ 789943, PQ 789944) were obtained from M. koreana sp. nov. The three CO 1 and two 18 S sequences obtained from M. koreana sp. nov. showed no intraspecific variation. Additionally, 597 bp of CO 1 (PQ 790062) and 1,210 bp of 18 S sequences (PQ 789945) were obtained from Morimotobathynella sp. collected in Pocheon, South Korea. Genetic divergence analysis revealed that the two Korean Morimotobathynella species had p - distances of 10.4 % for CO 1 and 1.2 % for 18 S sequences.

Phylogenetic analysis

ML and BI analyses were performed using a concatenated 1,002 bp dataset comprising CO 1 (615 bp) and 18 S rRNA (387 bp) sequences from the new species and 18 other Bathynellidae species available in GenBank (Fig. 7 View Figure 7 , Suppl. material 2: table S 2). Allobathynella danyangensis Ji & Min, 2023 from South Korea (Family Parabathynellidae ) was used as outgroup, and the analysis confirmed the monophyly of Bathynellidae . Both the ML and BI analyses produced congruent tree topologies. Our results also support the separation of three distinct subfamilies within Bathynellidae , corroborating previous studies ( Camacho et al. 2013, 2020). Phylogenetic trees revealed that M. koreana sp. nov. and Morimotobathynella sp. from South Korea formed a distinct monophyletic lineage within the subfamily Bathynellinae , with strong support (bootstrap support: 100 %, posterior probability: 1.0). They showed a close relationship with species of the genus Altainella from Mongolia and Russia (bootstrap support: 68 %, posterior probability: 0.95). This phylogenetic relationship may suggest a historical biogeographic connection among bathynellid taxa in Northeast Asia.