New insights into the diversity of cryptobenthic Cirripectes blennies in the Mascarene Archipelago sampled using Autonomous Reef Monitoring Structures (ARMS).

Autonomous Reef Monitoring Structures (ARMS) are artificial mini-reefs designed for standardized sampling of sessile and small motile cryptobenthic organisms. ARMS are also effective for collecting small cryptobenthic fishes, such as the combtooth blennies of the genus Cirripectes . Recent studies discovered several Cirripectes species endemic to islands or archipelagos, in spite of the generally broad distributions of tropical and subtropical blennies. Thus, to evaluate the diversity and distribution of Cirripectes species in the Mascarene Archipelago, a little-studied region but an important biodiversity hotspot, complete mitochondrial genomes, and nuclear rhodopsin genes were sequenced for 39 specimens collected with ARMS deployed on outer reef slopes at Reunion and Rodrigues islands. Mitochondrial COI sequences were analyzed to integrate these specimens within the largest dataset of publicly available sequences. Three species were found in the Mascarene Archipelago, Cirripectes castaneus, Cirripectes randalli , and Cirripectes stigmaticus . C. castaneus and C. stigmaticus both have an Indo-Pacific distribution with several haplotypes shared among distant localities. In agreement with the literature, C. randalli shows a small-range endemism restricted to the Mascarenes. We confirmed the presence of C. castaneus, C. randalli , and C. stigmaticus in Rodrigues, and the presence of C. stigmaticus in Reunion. This study contributes to filling the gaps in taxonomic and molecular knowledge of the reef cryptobiome in the South-West Indian Ocean, and provides the first complete mitogenomes for the genus, a crucial step for future molecular-based inventories (e.g., eDNA).