Novel molecular resources for single-specimen barcoding of enigmatic crustacean y-larvae.

Despite discovery more than 100years ago and documented global occurrence from shallow waters to the deep sea, the life cycle of the enigmatic crustacean y-larvae isincompletely understood and adult forms remain unknown. To date, only 2 of the 17 formally described species, all based on larval stages, have been investigated using an integrative taxonomic approach. This approach provided descriptions of the morphology of the naupliar and cyprid stages, and made use of exuvial voucher material and DNA barcodes. To improve our knowledge about the evolutionary history and ecological importance of y-larvae, we developed a novel protocol that maximises the amount of morpho-ecological and molecular data that can be harvested from single larval specimens. This includes single-specimen DNA barcoding and daily imaging of y-nauplii reared in culture dishes, mounting of the last naupliar exuviae on a slide as a reference voucher, live imaging of the y-cyprid instar that follows, and fixation, DNA extraction, amplification and sequencing of the y-cyprid specimen. Through development and testing of a suite of new primers for both nuclear and mitochondrial protein-coding and ribosomal genes, we showcase how new sequence data can be used to estimate the phylogeny of Facetotecta. We expect that our novel procedure will help to unravel the complex systematics of y-larvae and show how these fascinating larval forms have evolved. Moreover, we posit that our protocols should work on larval specimens from a diverse array of moulting marine invertebrate taxa.

Potential PCR amplification bias in identifying complex ecological patterns: Higher species compositional homogeneity revealed in smaller-size coral reef zooplankton by metatranscriptomics.

PCR-based high-throughput sequencing has permitted comprehensive resolution analyses of zooplankton diversity dynamics. However, significant methodological issues still surround analyses of complex bulk community samples, not least as in prevailing PCR-based approaches. Marine drifting animals-zooplankton-play essential ecological roles in the pelagic ecosystem, transferring energy and elements to higher trophic levels, such as fishes, cetaceans and others. In the present study, we collected 48 size-fractionated zooplankton samples in the vicinity of a coral reef island with environmental gradients. To investigate the spatiotemporal dynamics of zooplankton diversity patterns and the effect of PCR amplification biases across these complex communities, we first took metatranscriptomics approach. Comprehensive computational analyses revealed a clear pattern of higher/lower homogeneity in smaller/larger zooplankton compositions across samples respectively. Our study thus suggests changes in the role of dispersal across the sizes. Next, we applied in silico PCR to the metatranscriptomics datasets, in order to estimate the extent of PCR amplification bias. Irrespective of stringency criteria, we observed clear separations of size fraction sample clusters in both metatranscriptomics and in silico datasets. In contrast, the pattern-smaller-fractioned communities had higher compositional homogeneity than larger ones-was observed in the metatranscriptomics data but not in the in silico datasets. To investigate this discrepancy further, we analysed the mismatches of widely used mitochondrial CO1 primers and identified priming site mismatches likely driving PCR-based biases. Our results suggest the use of metatranscriptomics or, although less ideal, redesigning the CO1 primers is necessary to circumvent these issues.

Comparative genomics reveals the dynamic evolutionary history of cement protein genes of barnacles from intertidal to deep-sea hydrothermal vents.

Thoracican barnacles are a diverse group of marine organisms for which the availability of genome assemblies is currently limited. In this study, we sequenced the genomes of two neolepadoid species (Ashinkailepas kermadecensis, Imbricaverruca yamaguchii) from hydrothermal vents, in addition to two intertidal species. Genome sizes ranged from 481 to 1054 Mb, with repetitive sequence contents of 21.2% to 50.7%. Concordance rates of orthologs and heterozygosity rates were between 82.4% and 91.7% and between 1.0% and 2.1%, respectively, indicating high genetic diversity and heterozygosity. Based on phylogenomic analyses, we revised the nomenclature of cement genes encoding cement proteins that are not homologous to any known proteins. The major cement gene, CP100A, was found in all thoracican species, including vent-associated neolepadoids, and was hypothesised to be essential for thoracican settlement. Duplicated genes, CP100B and CP100C, were found only in balanids, suggesting potential functional redundancy or acquisition of new functions associated with the calcareous base. An ancestor of CP52 genes was duplicated dynamically among lepadids, pollicipedids with multiple copies on a single scaffold, and balanids with multiple sequential repeats of the conserved regions, but no CP52 genes were found in neolepadoids, providing insights into cement gene evolution among thoracican lineages. This study enhances our understanding of the adhesion mechanisms of thoracicans in underwater environments. The newly sequenced genomes provide opportunities for studying their evolution and ecology, shedding light on their adaptation to diverse marine environments, and contributing to our knowledge of barnacle biology with valuable genomic resources for further studies in this field.

Gene co-option, duplication and divergence of cement proteins underpin the evolution of bioadhesives across barnacle life histories.

Acquisition of new genes often results in the emergence of novel functions and is a key step in lineage-specific adaptation. As a group of sessile crustaceans, barnacles establish permanent attachment through initial cement secretion at the larval phase followed by continuous cement secretion in juveniles and adults. However, the origins and evolution of barnacle larval and adult cement proteins remain poorly understood. By performing microdissection of larval cement glands, transcriptome and shotgun proteomics and immunohistochemistry validation, we identified 30 larval and 27 adult cement proteins of the epibiotic turtle barnacle Chelonibia testudinaria, of which the majority are stage- and barnacle-specific. While only two proteins, SIPC and CP100K, were expressed in both larvae and adults, detection of protease inhibitors and the cross-linking enzyme lysyl oxidase paralogs in larvae and adult cement. Other barnacle-specific cement proteins such as CP100k and CP52k likely share a common origin dating back at least to the divergence of Rhizocephala and Thoracica. Different CP52k paralogues could be detected in larval and adult cement, suggesting stage-specific cement proteins may arise from duplication followed by changes in expression timing of the duplicates. Interestingly, the biochemical properties of larval- and adult-specific CP52k paralogues exhibited remarkable differences. We conclude that barnacle larval and adult cement systems evolved independently, and both emerged from co-option of existing genes and de novo formation, duplication and functional divergence of lineage-specific cement protein genes. Our findings provide important insights into the evolutionary mechanisms of bioadhesives in sessile marine invertebrates.

A draft genome assembly of reef-building octocoral Heliopora coerulea.

Coral reefs are under existential threat from climate change and anthropogenic impacts. Genomic studies have enhanced our knowledge of resilience and responses of some coral species to environmental stress, but reference genomes are lacking for many coral species. The blue coral Heliopora is the only reef-building octocoral genus and exhibits optimal growth at a temperature close to the bleaching threshold of scleractinian corals. Local and high-latitude expansions of Heliopora coerulea were reported in the last decade, but little is known about the molecular mechanisms underlying its thermal resistance. We generated a draft genome of H. coerulea with an assembled size of 429.9 Mb, scaffold N50 of 1.42 Mb and BUSCO completeness of 94.9%. The genome contains 239.1 Mb repetitive sequences, 27,108 protein coding genes, 6,225 lncRNAs, and 79 miRNAs. This reference genome provides a valuable resource for in-depth studies on the adaptive mechanisms of corals under climate change and the evolution of skeleton in cnidarian.

Host specificity and adaptive evolution in settlement behaviour of coral-associated barnacle larvae (Cirripedia: Pyrgomatidae).

Coral-associated organisms often exhibit a continuum of host specificities. We do not know whether the variation in host specificity is related to the settlement organs or preferential settlement behaviours of the larvae. We examined the morphology of attachment discs, the settlement and metamorphosis of coral barnacles-Pyrgoma cancellatum (lives in a single coral species), Nobia grandis (two families of corals), and Armatobalanus allium (six families of corals). Our results revealed that the attachment organ of all three species are spear-shaped with sparse villi, indicating that the morphology of the attachment organs does not vary among species with different host specificities. Larvae of P. cancellatum and N. grandis only settle on their specific hosts, suggesting that chemical cues are involved in the settlement. Cyprids of N. grandis display close searching behaviour before settlement. Cyprids of P. cancellatum settle immediately on their specific host corals, without any exploratory behaviour. The host specificity and exploratory behaviours of coral barnacle cyprids are results of adaptive evolution. We argue that there is a trade-off between exploration and energy conservation for metamorphosis processes. Coral barnacle metamorphosis is longer when compared to free-living species, likely because it involves the development of a tube-shaped base on the coral surface.

Single-specimen systematics resolves the phylogeny and diversity conundrum of enigmatic crustacean y-larvae.

Resolving the evolutionary history of organisms is a major goal in biology. Yet for some taxa the diversity, phylogeny, and even adult stages remain unknown. The enigmatic crustacean "y-larvae" (Facetotecta) are one particularly striking example. Here, we use extensive video-imaging and single-specimen molecular sequencing of >200 y-larval specimens to comprehensively explore for the first time their evolutionary history and diversity. This integrative approach revealed five major clades of Facetotecta, four of which encompass a considerable larval diversity. Whereas morphological analyses recognized 35 y-naupliar "morphospecies", molecular species-delimitation analyses suggested the existence of between 88 and 127 species. The phenotypic and genetic diversity between the morphospecies suggests that a more elaborate classification than the current one-genus approach is needed. Morphology and molecular data were highly congruent at shallower phylogenetic levels, but no morphological synapomorphies could be unambiguously identified for major clades, which mostly comprise both planktotrophic and lecithotrophic y-nauplii. We argue that lecithotrophy arose several times independently whereas planktotrophic y-nauplii, which are structurally more similar across clades, most likely display the ancestral feeding mode of Facetotecta. We document a remarkably complex and highly diverse phylogenetic backbone for a taxon of larval marine crustaceans, the full life cycle of which remains a mystery.

Systematics and Biogeography of Fiddler Crabs -A Special Issue in Zoological Studies.

Fiddler crabs are a fantastic group of intertidal brachyuran crabs, and the research fields focused on their biodiversity, phylogeography, phylogenomics, and larval biology are still in developing stages. In this special issue, seven articles are included focusing on the diversity, phylogeography, mitogenome phylogeny and larval morphology of fiddler crabs, covering the regions of the Indo-West Pacific and Americas. Results from this special issue open up further opportunities to study new species identification based on an integrative taxonomy approach, genomic-level phylogeny and larval morphology, especially in regards to the mitogenomes in the genera Cranuca, Gelasimus, Paraleptuca, and Uca for filling up the knowledge gap of fiddler crabs in the world.

A synthesis of the external morphology of cypridiform larvae of Facetotecta (crustacea: Thecostraca) and the limits of the genus Hansenocaris.

Although the naupliar and cypridiform stages of the enigmatic y-larvae of Facetotecta have been found in the marine plankton worldwide, they still represent the last significant group of crustaceans for which the adult forms are still unknown. From a number of y-cyprids representing different taxa from different locations, we employ scanning electron microscopy to describe fine morphological details of all external structures of this unique larval form. We document different segmentation patterns of the abdomen and presence/absence of the labrum and structural differences in the antennules, labrum, paraocular process, thoracopods, and telson lend support for the erection of several new genera as opposed to the single Hansenocaris. The data presented here emphasize the morphological limits of the genus Hansenocaris and the "bauplan" of cyprydiform larvae of Facetotecta. Although the optimum pathway is a joint analysis of both molecular and morphological characters, we use the morphological characters of y-cyprids to align them cladistically and determine the limits of the genus Hansenocaris s.s. and describe common characters for all y-cyprids including six pairs of the lattice organs instead five pairs considered as a ground pattern for all Thecostraca. We also determine plesiomorphic and apomorphic characters of all known y-cyprids and separate them from other thecostracan cypridiform larvae.

Living on fire: Deactivating fire coral polyps for larval settlement and symbiosis in the fire coral-associated barnacle Wanella milleporae (Thoracicalcarea: Wanellinae).

Symbiosis is increasingly recognized as being an important component in marine systems, and many such relationships are initiated when free-swimming larvae of one partner settle and become sedentary on a host partner. Therefore, several crucial questions emerge such as the larva's mechanism of locating a host, selection of substratum and finally settlement on the surface of its future partner. Here, we investigated these mechanisms by studying how larvae of the fire coral-associated barnacle Wanella milleporae move, settle and establish symbiosis with their host, Millepora tenera. Cyprids of W. milleporae possess a pair of specialized antennules with bell-shaped attachment discs that enable them to explore and settle superficially on the hostile surface of the fire coral. Intriguingly, the stinging polyps of the fire coral remain in their respective pores when the cyprids explore the fire coral surface. Even when cyprids come into contact with the nematocysts on the extended stinging polyps during the exploratory phase, no immobilization effects against the cyprids were observed. The exploratory phase of Wanella cyprids can be divided into a sequence of wide searching (large step length and high walking speed), close searching (small step length and low speed) and inspection behavior, eventually resulting in permanent settlement and metamorphosis. After settlement, xenogeneic interactions occur between the fire coral and the newly metamorphosed juvenile barnacle. This involved tissue necrosis and regeneration in the fire coral host, leading to a callus ring structure around the juvenile barnacle, enhancing survival rate after settlement. The complex exploratory and settlement patterns and interactions documented here represent a breakthrough in coral reef symbiosis studies to show how invertebrates start symbiosis with fire corals.

Utilisation of Oxford Nanopore sequencing to generate six complete gastropod mitochondrial genomes as part of a biodiversity curriculum.

High-throughput sequencing has enabled genome skimming approaches to produce complete mitochondrial genomes (mitogenomes) for species identification and phylogenomics purposes. In particular, the portable sequencing device from Oxford Nanopore Technologies (ONT) has the potential to facilitate hands-on training from sampling to sequencing and interpretation of mitogenomes. In this study, we present the results from sampling and sequencing of six gastropod mitogenomes (Aplysia argus, Cellana orientalis, Cellana toreuma, Conus ebraeus, Conus miles and Tylothais aculeata) from a graduate level biodiversity course. The students were able to produce mitogenomes from sampling to annotation using existing protocols and programs. Approximately 4 Gb of sequence was produced from 16 Flongle and one MinION flow cells, averaging 235 Mb and N50 = 4.4 kb per flow cell. Five of the six 14.1-18 kb mitogenomes were circlised containing all 13 core protein coding genes. Additional Illumina sequencing revealed that the ONT assemblies spanned over highly AT rich sequences in the control region that were otherwise missing in Illumina-assembled mitogenomes, but still contained a base error of one every 70.8-346.7 bp under the fast mode basecalling with the majority occurring at homopolymer regions. Our findings suggest that the portable MinION device can be used to rapidly produce low-cost mitogenomes onsite and tailored to genomics-based training in biodiversity research.

Autochthony and isotopic niches of benthic fauna at shallow-water hydrothermal vents.

The food webs of shallow-water hydrothermal vents are supported by chemosynthetic and photosynthetic autotrophs. However, the relative importance of these two basal resources for benthic consumers and its changes along the physicochemical gradient caused by vent plumes are unknown. We used stable carbon and nitrogen isotopes (i.e., δ13C and δ15N) and Bayesian mixing models to quantify the dietary contribution of basal resources to the benthic fauna at the shallow-water vents around Kueishan Island, Taiwan. Our results indicated that the food chains and consumer production at the shallow-water vents were mainly driven by photoautotrophs (total algal contribution: 26-54%) and zooplankton (19-34%) rather than by chemosynthetic production (total contribution: 14-26%). Intraspecific differences in the trophic support and isotopic niche of the benthic consumers along the physicochemical gradient were also evident. For instance, sea anemone Anthopleura sp. exhibited the greatest reliance on chemosynthetic bacteria (26%) and photoautotrophs (66%) near the vent openings, but zooplankton was its main diet in regions 150-300 m (32-49%) and 300-700 m (32-78%) away from the vent mouths. The vent-induced physicochemical gradient structures not only the community but also the trophic support and isotopic niche of vent consumers.

Phylogeny and shell form evolution of the hydrothermal vent asymmetrical barnacles (Cirripedia, Thoracicalcarea, Neoverrucidae).

Imbricaverruca and Neoverruca are two genera of hydrothermal vent asymmetrical barnacles in Neoverrucidae, but found in vents of the Southwest Pacific and Northwest Pacific Oceans, respectively. Imbricaverruca has a flattened operculum and the shell base with multiple whorls of imbricating plates, while Neoverruca has an inclined operculum and the shell base with fewer developed imbricating plates. It has been hypothesized that Imbricaverruca has apomorphic shell characters in Neoverrucidae. Although the monophyletic relationship of the vent barnacle members in the superfamily Neolepadoidea were confirmed based on molecular phylogeny, the relationships between Neobrachylepadidae and Neoverrucidae, and between Neoverruca and Imbricaverruca have not been determined because there are no molecular data on Imbricaverruca. In this study, we sequenced three nuclear (18S rDNA, 28S rDNA, histone 3) and one mitochondrial (CO1) genes of I. yamaguchii from the Southwest Pacific. Our phylogenetic results showed that Neobrahchylepadidae is the sister taxon to Neoverrucidae (Imbricaverruca + Neoverruca), and Imbricaverruca and Neoverruca are monophyletic sister taxa each other, which not supporting the previous hypothesis that Neoverruca is sister to the clade containing Neobrahchylepadidae and Neolepadidae. These implied that the differences in shell forms between Neoverruca and Imbricaverruca are a result of independent divergent evolution in different deep-sea basins.

Independent and adaptive evolution of phenotypic novelties driven by coral symbiosis in barnacle larvae.

The invasion of novel habitats is recognized as a major promotor of adaptive trait evolution in animals. We tested whether similar ecological niches entail independent and adaptive evolution of key phenotypic structures related to larval host invasion in distantly related taxa. We use disparately related clades of coral barnacles as our model system (Acrothoracica: Berndtia and Thoracicalcarea: Pyrgomatidae). We analyze the larval antennular phenotypes and functional morphologies facilitating host invasion. Extensive video recordings show that coral host invasion is carried out exclusively by cypris larvae with spear-shaped antennules. These first exercise a series of complex probing behaviors followed by repeated antennular penetration of the soft host tissues, which subsequently facilitates permanent invasion. Phylogenetic mapping of larval form and function related to niche invasion in 99 species of barnacles (Thecostraca) compellingly shows that the spear phenotype is uniquely associated with corals and penetrative behaviors. These features evolved independently in the two coral barnacle clades and from ancestors with fundamentally different antennular phenotypes. The larval host invasion system in coral barnacles likely evolved adaptively across millions of years for overcoming challenges associated with invading and entering demanding coral hosts.

Diversity and Distribution of Fiddler Crabs (Crustacea: Brachyura: Ocypodidae) in Vietnam.

Based on recently collected material and records in the literature, 14 species of fiddler crabs (Crustacea: Ocypodidae: Gelasiminae) are reported from Vietnam. DNA barcoding analyses using the mitochondrial gene COI (cytochrome c oxidase subunit I) was performed to identify examined materials and their precise distributional range. Thirteen species-level taxa are identified and, with the exception of Galsimus borealis and G. vocans, have minimum interspcific divergences of at least 7.27%. The identified species include seven species of Tubuca Bott, 1973, three of Austruca Bott, 1973 and three of Gelasimus Latreille, 1817, and one Paraleptuca Bott, 1973. Two new records of Vietnam are herein reported: Tubuca rhizophorae and T. dussumieri. The southernmost distribution limits of East Asian G. borealis, T. acuta and T. arcuata are in northern Vietnam, A. lactea in central Vietnam, whereas northernmost limit of Southeast Asian T. rhizophorae and T. forcipata in southern Vietnam. A dichotomous key to identify the 14 Vietnamese species is provided.

Five hundred million years to mobility: directed locomotion and its ecological function in a turtle barnacle.

Movement is a fundamental characteristic of life, yet some invertebrate taxa, such as barnacles, permanently affix to a substratum as adults. Adult barnacles became 'sessile' over 500 Ma; however, we confirm that the epizoic sea turtle barnacle, Chelonibia testudinaria, has evolved the capacity for self-directed locomotion as adults. We also assess how these movements are affected by water currents and the distance between conspecifics. Finally, we microscopically examine the barnacle cement. Chelonibia testudinaria moved distances up to 78.6 mm yr-1 on loggerhead and green sea turtle hosts. Movements on live hosts and on acrylic panels occasionally involved abrupt course alterations of up to 90°. Our findings showed that barnacles tended to move directly against water flow and independent of nearby conspecifics. This suggests that these movements are not passively driven by external forces and instead are behaviourally directed. In addition, it indicates that these movements function primarily to facilitate feeding, not reproduction. While the mechanism enabling movement remained elusive, we observed that trails of cement bore signs of multi-layered, episodic secretion. We speculate that proximal causes of movement involve one or a combination of rapid shell growth, cement secretion coordinated with basal membrane lifting, and directed contraction of basal perimeter muscles.

Genomic insights into the sessile life and biofouling of barnacles (Crustacea: Cirripedia).

Members of the infraclass Cirripedia, commonly called barnacles, are unique among the subphylum Crustacea in that they exhibit a biphasic life cycle with a planktonic larval stage and a sessile adult stage. Understanding their unique sessile life and mechanisms of attachment are hampered by the lack of genomic resources. Here, we present a 746 Mb genome assembly of Lepas anserifera - the first sequenced stalked barnacle genome. We estimate that Cirripedia first arose ~495 million years ago (MYA) and further diversified since Mesozoic. A demographic analysis revealed remarkable population changes of the barnacle in relation to sea-level fluctuations in the last 2 MYA. Comparative genomic analyses revealed the expansion of a number of developmental related genes families in barnacle genomes, such as Br-C, PCP20 and Lola, which are potentially important for the evolution of metamorphosis, cuticle development and central nervous system. Phylogenetic analysis and tissue expression profiling showed the possible roles of gene duplication, functional diversification and co-option in shaping the genomic evolution of barnacles. Overall, our study provides not only a valuable draft genome for comparative genomic analysis of crustacean evolution, but also facilitates studies of biofouling control.

DNA-based diversity assessment reveals a new coral barnacle, Cantellius alveoporae sp. nov. (Balanomorpha: Pyrgomatidae) exclusively associated with the high latitude coral Alveopora japonica in the waters of southern Korea.

In the present study, the Indo-Pacific coral associated barnacle Cantellius euspinulosum (Broch, 1931) was found to have cryptic species in Korea, Taiwan and other regions based on molecular studies. However, the original specimens of C. euspinulosum from Broch have not been previously described or illustrated, making it difficult to assign which cryptic species to the original C. euspinulosum. The original specimen of C. euspinulosum was examined and illustrated here, and the species identity of C. cf. euspinulosum collected from Jejudo Island in the present study and other cryptic species (based on literature illustrations) in the Indo-Pacific were evaluated.C. euspinulosum from Singapore, Java, Mergui Archipelago in Andaman Sea and Nha Trang represented the C. euspinulosum identified by Broch (1931). It is a generalist on Acropora, Favia, Favites, Leptoria, Montipora, Pachyseris and Pocillipora corals and distributed in the Indo-Pacific region. Morphological examination and DNA sequencing (COI, 12S DNA sequences) in the present study showed that C. cf. euspinulosum from Jejudo Island, Korea represents a distinct species, herein named C. alveoporae sp. nov. Cantellius alveroporae sp. nov. is a specialist species that only grows on Alveopora and also present in Palau, and Ogasawara Island in Japan. Cantellius cf. euspinuloum in Taiwan, the Moscos Island, and Australia belong to several other distinct species awaiting further morphological and molecular studies. At least five cryptic species of C. euspinulosum were identified in the present study, including both specialist and generalists.

The mitochondrial genome of hydrothermal vent barnacle Eochionelasmus coreana (Cirripedia: Thoracica) from the Indian Ocean.

Balanomorph Eochionelasmus species are hydrothermal vent endemic barnacles. In the genus Eochionelasmus, three species are known to date and they distribute at three different vent fields in Pacific and Indian Oceans, E. ohtai in the Southwest Pacific Ocean, E. paquensis in the East Pacific Ocean, and E. coreana in the Indian Ocean. Therefore, Eochionelasmus species are considered to be a meaningful model taxon to elucidate the evolutionary history of vent organism in relation to geotectonic events. Here, we characterized the partial mitogenome of a newly described vent barnacle Eochionelasmus coreana Chan et al., 2020 from the Solitaire vent field in the Indian Ocean. The length of mitogenome was 16,804 bp with 64.0% AT content. Its gene content and organization was identical to those of E. ohtai. There was one significant part in the mitogenome of E. coreana, which was a long intergenic region over 2 kb found between tRNAPro and tRNAThr. The phylogenetic tree suggested the monophyly of E. ohtai and E. coreana with high supporting values. In the future, additional mitogenome analysis of the last Eochionelasmus species, E. paquensis, could expand our understanding about the speciation and global distribution of Eochionelasmus species.

Diversity of intertidal, epibiotic, and fouling barnacles (Cirripedia, Thoracica) from Gujarat, northwest India.

The present work studied the diversity of intertidal, epibiotic, and fouling barnacles in the state of Gujarat, northwest India. In total, eleven species belonging to eight genera and five families were recorded in the present study. The Arabian intertidal species Tetraclita ehsani Shahdadi, Chan & Sari, 2011 and Chthamalus barnesi Achituv & Safriel, 1980 are common in the high- and mid-intertidal rocky shores of Gujarat suggesting that the Gujarat barnacle assemblages are similar to the assemblages in the Gulf of Oman Ecoregion. The biogeographical boundary between the Gulf of Oman and Western Indian ecoregions for barnacles should probably extend southward towards the waters adjacent to Mumbai, where Indo-Pacific species of intertidal barnacles dominate. This study provides the first reports of the common widely distributed balanomorph barnacles Striatobalanus tenuis (Hoek, 1883), Tetraclitella karandei Ross, 1971, Amphibalanus reticulatus (Utinomi, 1967), and lepadid barnacle Lepas anatifera Linnaeus, 1758 in Gujarat, as well as of the chthamalid barnacle Chthamalus barnesi in India.