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The Ostracoda (Crustacea; Class Ostracoda) is a diverse, frequently abundant, and ecologically important component of the marine zooplankton assemblage. There are more than 200 described species of marine planktonic ostracods, many of which (especially conspecific species) can be identified only by microscopic examination and dissection of fragile morphological characters. Given the complexity of species identification and increasing lack of expert taxonomists, DNA barcodes (short DNA sequences for species discrimination and identification) are particularly useful and necessary. Results are reported from analysis of 210 specimens of 78 species of marine planktonic ostracods, including two novel species, and 51 species for which barcodes have not been previously published. Specimens were collected during 2006 to 2008 from the Atlantic, Indian, and Southern Oceans, Greenland Sea and Gulf of Alaska. Samples were collected from surface to 5,000 m using various collection devices. DNA sequence variation was analyzed for a 598 base-pair region of the mitochondrial cytochrome oxidase subunit I (COI) gene. Kimura-2-Parameter (K2P) genetic distances within described species (mean = 0.010 ± 0.017 SD) were significantly smaller than between species (0.260 + 0.080), excluding eight taxa hypothesized to comprise cryptic species due to morphological variation (especially different size forms) and/or collection from different geographic regions. These taxa showed similar K2P distance values within (0.014 + 0.026) and between (0.221 ± 0.068) species. All K2P distances > 0.1 resulted from comparisons between identified or cryptic species, with no overlap between intra- and interspecific genetic distances. A Neighbor Joining tree resolved nearly all described species analyzed, with multiple sequences forming monophyletic clusters with high bootstrap values (typically 99%). Based on taxonomically and geographically extensive sampling and analysis (albeit with small sample sizes), the COI barcode region was shown to be a valuable character for discrimination, recognition, identification, and discovery of species of marine planktonic ostracods.

The Indonesian-Australian Archipelago is the center of the world's marine biodiversity. Although many biogeographers have suggested that this region is a "center of origin," criticism of this theory has focused on the absence of processes promoting lineage diversification in the center. In this study we compare patterns of phylogeographic structure and gene flow in three codistributed, ecologically similar Indo-West Pacific stomatopod (mantis shrimp) species. All three taxa show evidence for limited gene flow across the Maluku Sea with deep genetic breaks between populations from Papua and Northern Indonesia, suggesting that limited water transport across the Maluku Sea may limit larval dispersal and gene flow across this region. All three taxa also show moderate to strong genetic structure between populations from Northern and Southern Indonesia, indicating limited gene flow across the Flores and Java Seas. Despite the similarities in phylogeographic structure, results indicate varied ages of the genetic discontinuities, ranging from the middle Pleistocene to the Pliocene. Concordance of genetic structure across multiple taxa combined with temporal discordance suggests that regional genetic structures have arisen from the action of common physical processes operating over extended time periods. The presence in all three species of both intraspecific genetic structure as well as deeply divergent lineages that likely represent cryptic species suggests that these processes may promote lineage diversification within the Indonesian-Australian Archipelago, providing a potential mechanism for the center of origin. Efforts to conserve biodiversity in the Coral Triangle should work to preserve both existing biodiversity as well as the processes creating the biodiversity.

There is a push to fully document the biodiversity of the world within 25 years. However, the magnitude of this challenge, particularly in marine environments, is not well known. In this study, we apply DNA barcoding to explore the biodiversity of gonodactylid stomatopods (mantis shrimp) in both the Coral Triangle and the Red Sea. Comparison of sequences from 189 unknown stomatopod larvae to 327 known adults representing 67 taxa in the superfamily Gonodactyloidea revealed 22 distinct larval operational taxonomic units (OTUs). In the Western Pacific, 10 larval OTUs were members of the Gonodactylidae and Protosquillidae where success of positive identification was expected to be 96.5%. However, only five OTUs could be identified to species and at least three OTUs represent new species unknown in their adult form. In the Red Sea where the identification rate was expected to be 75% in the Gonodactylidae, none of four larval OTUs could be identified to species; at least two represent new species unknown in their adult forms. Results indicate that the biodiversity in this well-studied group in the Coral Triangle and Red Sea may be underestimated by a minimum of 50% to more than 150%, suggesting a much greater challenge in lesser-studied groups. Although the DNA barcoding methodology was effective, its overall success was limited due to the newly discovered taxonomic limitations of the reference sequence database, highlighting the importance of synergy between molecular geneticists and taxonomists in understanding and documenting our world's biodiversity, both in marine and terrestrial environments.

Three new species of Dermoergasilus are described from six species of grey mullet hosts. Dermoergasilus longiabdominalis n. sp. was found on Valamugil engeli (Bleeker) from the Philippines and Madagascar and on V. cunnesius (Valenciennes) from the Philippines and Mangalore, India. D. semiamplectens n. sp. occurred on Sicamugil hamiltoni (Day) from the Sittang River, Burma, on Liza subviridis (Valenciennes) and L. parsia (Hamilton Buchanan) from Calcutta, India, and on V. cunnesius (Valenciennes) from China. D. curtus n. sp. parasitised Rhinomugil squamipinnis (Swainson) from Alahabad, India. A key to the ten currently accepted species of Dermoergasilus is given. The biogeographical distribution of Dermoergasilus species is analysed and levels of host-specificity are surveyed within the genus. The phylogenetic relationships between the species of Dermoergasilus are also analysed.