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Etisine crabs are some of the most abundant cryptobionts in Indo-West Pacific coral reef systems. Despite their ecological importance and abundance in museum collections, several recent systematic studies have indicated family- to subspecies-level taxonomic problems. One such case involves the former chlorodielline genus Soliella Lasley, Klaus & Ng, 2015 (treated here as part of Etisinae), which currently comprises two valid species and three available names that have been in flux in recent literature. The validity of these taxa has only been cursorily discussed. To resolve species limits and distributions, a thorough morphological examination of hundreds of specimens was conducted, including scanning electron microscopy of male gonopods, along with analysis of sequence data of the mitochondrial marker cytochrome c oxidase subunit I (COI) from 84 exemplars across the distribution of the genus. The status of two species that have Indian Ocean versus Pacific Ocean distributions with overlap in the Indo-Australian Archipelago and adjacent regions is confirmed. While external morphology is not reliable for identification, a few discrete, although slight, differences in gonopod morphology were found, and these results are consistent with a “pseudocryptic species” designation. Speciation conforms to a previously published etisine model of allopatric differentiation followed by subsequent divergence of gonopod morphology upon secondary sympatry. This pattern, the biogeography of the two species, and the term “pseudocryptic species” are discussed.
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Biodiversity and biogeography of zooxanthellate soft corals across the Indo-Pacific
Documentation of biodiversity and its geographical distribution is necessary to understand the processes and drivers of evolutionary diversification as well as to guide conservation and management initiatives. Among the most emblematic patterns of biodiversity in the world’s oceans is the Coral Triangle (Indo-Australian Archipelago), widely recognized to be the center of species richness for a variety of marine life forms. The distribution of biodiversity remains incompletely documented, however, for a majority of reef-associated invertebrate taxa, including the zooxanthellate soft corals (Octocorallia) that dominate hard substrate on many Indo-Pacific reefs. We used a genetic approach to document the diversity of Indo-Pacific soft corals, sequencing two single-locus barcoding markers for > 4400 soft coral specimens and assigning individuals to molecular operational taxonomic units as proxies of species. We document two centers of species richness for zooxanthellate soft corals, one in the Indo-Australian Archipelago and a second, equally diverse center in the Western Indian Ocean. Centers of endemicity for soft corals are coincident with these centers of species richness, although the peripheral Red Sea and Hawaii also support high proportions of endemic taxa. The patterns documented here suggest that biogeographic distributions of soft coral families may be driven in part by larval dispersal potential: taxa with benthic larvae are absent from most oceanic islands of the central Pacific and are represented by higher proportions of endemic taxa in other geographic regions. Our findings demonstrate the distinct biogeographic patterns among reef taxa and underscore the need to document and analyze species distributions of more reef-associated invertebrate groups to derive a complete picture of reef biogeography.
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- PAR ID:
- 10639676
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Nature Portfolio
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1038/s41598-025-98790-7
