Spurilla braziliana MacFarland 1909 is a morphologically diverse nudibranch found in the Pacific and Western Atlantic. The complete mitochondrial genome of S. braziliana has been constructed using next-generation sequencing technology. The mitochondrial genome is 14,291 bp and contains 13 protein-coding genes, 2 rRNA genes, and 23 tRNA genes. Molecular phylogenetic analysis using the maximum likelihood method revealed that S. braziliana is included in the superfamily Aeolidioidea and forms a monophyletic group with Berghia stephanieae , a nudibranch of the family Aeolidiidae. This study reinforces existing taxonomic insights and provides a basis for further molecular phylogenetic analysis.

The intricate coexistence of Symbiodiniacean algae with a diverse range of marine invertebrates underpins the flourishing biodiversity observed within coral reef ecosystems. However, the phenomenon of coral bleaching—precipitated by the dissolution of symbiotic relationships with Symbiodiniaceae—poses a significant threat to these ecosystems, thereby necessitating an urgent investigation into the underlying symbiotic mechanisms. The symbiosis between nudibranchs and Symbiodiniaceae has been identified as an efficacious model for examining these mechanisms, yet a comprehensive understanding of their histological structures and cellular processes remains elusive. In this study, we concentrate on the nudibranch hostPteraeolidia semperi, renowned for its exceptional symbiotic capabilities, and we elucidate its sophisticated symbiotic architecture. Furthermore, we delineate the bleaching process within the nudibranch, uncovering the associated cellular processes. Collectively, these findings furnish invaluable insights into the intricate relationship between nudibranchs and Symbiodiniaceae, thereby contributing to our understanding of the symbiosis that sustains these critical marine ecosystems.

Spurilla brazilianaMacFarland 1909 is a morphologically diverse nudibranch found in the Pacific and Western Atlantic. The complete mitochondrial genome of S. braziliana has been constructed using next-generation sequencing technology. The mitochondrial genome is 14,291 bp and contains 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. Molecular phylogenetic analysis using the maximum likelihood method revealed thatS. brazilianais included in the superfamily Aeolidioidea and forms a monophyletic group withBerghia stephanieae, a nudibranch of the family Aeolidiidae. This study reinforces existing taxonomic insights and provides a basis for further molecular phylogenetic analysis.

Existing fish species distribution databases have the following problems: the possibility of species identification errors due to plasticity of morphological characteristics, the impossibility of quantitative composition, and the difficulty of geographically and time-series integrated interpretation. To solve the above problems, we constructed MitoSearch database. It is a fish species distribution database using 2,160 samples of variable regions of 12S rRNA genes amplified by MiFish primers registered at NCBI/EBI/DDBJ, and visualizes the fish species composition data on a map. By integrating a large amount of data registered in public databases, MitoSearch was aimed to provide the comprehensive understanding of spatial and temporal distribution of organisms on a global scale.