Branchiomma Bairdi Research Articles

New records of introduced species in the Mediterranean Sea (April 2023)

This Collective article reports 17 introduced species and 22 new locations for these species in the Mediterranean Sea. The reports are from three different Marine Strategy Framework Directive (MSFD) subregions (Aegean-Levantine Sea, Adriatic Sea and Western Mediterranean Sea) and the Sea of Marmara and cover ten different countries. The goal of consistent and detailed reporting of introduced species is to complement the existing species inventories and serve as a basis for establishing monitoring strategies and other conservation measures. Some of the reports from this article are the first species records for the Mediterranean Sea, namely the green alga Udotea flabellum from the Aegean Sea (Turkey) and the deepbody boarfish Antigonia capros from the Balearic Sea (Spain). In addition, new records of introduced species are included for different seas, namely the moon crab Matuta victor for the Aegean Sea (Greece), the whale shark Rhincodon typus and the lionfish Pterois miles for the Alboran Sea (Spain), the almaco jack Seriola rivoliana for the Tyrrhenian Sea (Italy), and the hound needlefish Tylosurus crocodilus for the Adriatic Sea (Italy). Furthermore, reports on first country records are included: the red alga Colaconema codicola from Slovenia, the nudibranch Melibe viridis from Bosnia and Herzegovina, the lionfish Pterois miles from Montenegro, and the goldstripe sardinella Sardinella gibbosa from Syria, which also represents a second record for the Mediterranean Sea. Furthermore, the occurrence of the scleractinian coral Oculina patagonica was noted in Gulf of Lion (France). Four polychaete species, namely Leodice antennata, Timarete punctata and Branchiomma bairdi, are reported from the vermetid reef habitat and two of them (L. antennata and B. bairdi) are also recorded for the first time in Lebanon. Evidence for established populations of the Asian date mussel Arcuatula senhousia in the Sea of Marmara (Turkey) and the rayed pearl oyster Pinctada radiata around the island of Sardinia (Italy) is provided.

Relationships between plastic litter and chemical pollutants on benthic biodiversity

Five Descriptors (D) of Marine Strategy Framework Directive (MSFD): marine litter (D10), non-indigenous species (D2) and organic and inorganic pollutants (D8), were estimated in a coastal area of GSA 16 (Augusta harbour, Central Mediterranean Sea) in order to study their effects on the biodiversity (D1) of the benthic community D6) and to improve data for the MSFD. Investigation of plastic debris had led to the identification of 38 fragments divided into four categories, among which microplastics resulted as the most abundant. Six non-indigenous species, belonging to Polychaeta (Kirkegaardia dorsobranchialis, Notomastus aberans, Pista unibranchia, Pseudonereis anomala, Branchiomma bairdi) and Mollusca (Brachidontes pharaonis) were found. Biodiversity and benthic indices suggested a generalised, slightly disturbed ecological status. Anthracene, Zinc and Chrome were the most abundant chemical compounds in analysed sediments. Significant correlations were found between the abundance of trace elements vs biotic indices and between plastic debris vs biodiversity and benthic indices. This study represents the first report about the abundance of plastic debris and its relationship to contaminants and infauna in Augusta harbour. Our results can provide useful information for national and international laws and directives.

Clarifying the taxonomic status of the alien species Branchiomma bairdi and Branchiomma boholense (Annelida: Sabellidae) using molecular and morphological evidence.

This study was performed to analyse the genetic and morphological diversity of the sabellid annelid genus Branchiomma, with special emphasis on a taxon so far identified as Branchiomma bairdi. This species, originally described from Bermuda, has frequently been reported as an invader in the Mediterranean, the Atlantic and the Eastern Pacific, but recent observations have raised some taxonomic questions. Samples of this taxon were collected from five sites in the Mediterranean Sea, two sites in the original distribution area of B. bairdi in the Gulf of Mexico and four localities in the east Pacific and Atlantic Oceans where B. bairdi has been reported as invasive. The molecular results revealed a conspicuous genetic divergence (18.5% K2P) between the sampled Mediterranean populations and all the other ones that led to a re-evaluation of their morphological characters. The latter showed that the Mediterranean and extra-Mediterranean populations also differ in some discrete morphological and reproductive features. Consequently, the Mediterranean samples were re-designated as B. boholense, another non-indigenous species originally described from Philippines. Branchiomma bairdi and B. boholense differ in body size, development and shape of micro and macrostylodes, size of radiolar eyes and body pigmentation. Genetic diversity was high in B. boholense from the Mediterranean as well as in B. bairdi from the Gulf of Mexico, but low in B. bairdi populations outside their native range. The phylogenetic analysis revealed the presence of connections between the Mediterranean localities as well as between native and introduced B. bairdi populations that focus the attention on the Panama Canal as important passage for the introduction of the species from the Gulf of Mexico to the north-east Pacific Ocean.

Citizen science: a successful tool for monitoring invasive alien species (IAS) in Marine Protected Areas. The case study of the Egadi Islands MPA (Tyrrhenian Sea, Italy)

The chief purpose of Marine Protected Areas (MPAs) is biodiversity conservation. The effects that invasive alien species (IAS) have on MPAs, and vice versa, are not yet fully known, even though assessing them is crucial for MPA planning. Management plans require sound knowledge of the pathways of introduction, the impact and current distribution of IAS. Monitoring plans are essential for preventing and reducing the risk of IAS introduction. In this respect, the involvement of citizen scientists in gathering data (validated by taxonomic experts) on the occurrence of IAS, that would otherwise be impossible to collect, may be crucial. We report on our experience of citizen science in the Egadi Islands MPA with the project ‘Caulerpa cylindracea – Egadi Islands’, aimed at monitoring the spread dynamics of the ‘sea grape’ C. cylindracea. The project registered 156 sightings and also allowed collection of records and information concerning other non-indigenous and cryptogenic species, e.g. the spotted sea hare (Aplysia dactylomela), the harpoon weed (Asparagopsis armata), the red sea plume (Asparagopsis taxiformis), the tube-building sabellid (Branchiomma bairdi), the blue spotted cornet fish (Fistularia commersoni) and the nomad jellyfish (Rhopilema nomadica).

First record of the invasive worm Branchiomma bairdi (Annelida: Sabellidae) in the Balearic Sea (Western Mediterranean)

The invasive sabellid Branchiomma bairdi (McIntosh, 1885) was collected in the Estany des Peix lagoon (Formentera Island, Balearic Sea, Western Mediterranean). This species is native to Bermuda (Western Atlantic Ocean), being widely distributed through the Caribbean Sea. However, it has been described as invasive worldwide, being also present in the Indo-Pacific region, the Eastern Atlantic Ocean and the Mediterranean Sea. We here provide the first record of the species for the Balearic Sea, together with a comparison to other morphologically similar alien species, Branchiomma boholense (Grube, 1878), which is supposed to have also been introduced in the Mediterranean basin. We also include comprehensive taxonomic descriptions of both taxa based on the type material, a dichotomous key for the Mediterranean species of Branchiomma and hypothesize the most likely way of introduction of B. bairdi in the Balearic region.

Larval development and post‐larval growth of Branchiomma bairdi (Annelida: Sabellidae) from a Mediterranean population

AbstractBranchiomma bairdi is a Caribbean fan worm introduced in several localities worldwide, including the Mediterranean Sea, where the species’ range has rapidly expanded. Reproduction in B. bairdi was previously investigated in both extra‐Mediterranean and Mediterranean areas, but no information is available on larval development and post‐larval growth. In the present article, we examined these features for a population from the Mar Grande of Taranto (Ionian Sea). The species is hermaphrodite, and fertilization occurs in situ. Mucus seems to play an important role in fertilization, and also in preserving eggs before fertilization. The trochophore stage develops within the mucus and after hatching, larvae swim for about 3 d before settlement. The trochophore showed a distinct prototroch and two red dorsolateral larval eyes. The pelagic stage takes only 96 h even though prototroch is maintained after settlement, disappearing at 5 d, when larvae showed three chaetigers and branchial crown consisted of four radioles. Some interesting observations concerning changes in the morphology of chaetae and in the number of uncini during growth are also reported, together with discussion of the development of stylodes, an important diagnostic feature in Branchiomma species identification.

First report of the invasive species Branchiomma bairdi McIntosh, 1885 (Annelida: Sabellidae) along the Tunisian coast (Mediterranean Sea)

The invasive sabellid polychaete Branchiomma bairdi McIntosh, 1885 was collected in the Boughrara Lagoon (southern Tunisian coast) between 2012 and 2013. This species was originally described from Bermuda and has been widely reported in the Caribbean Sea. It has been considered as non-indigenous species on the Pacific coast of Panama and the California Gulf. Recently, B. bairdi was recorded along the Italian and Turkish coasts, Australia, Canary and Madeira Islands. It was suggested that the commercial shipping is the most likely vector for the introduction of the species to Mediterranean Sea. A description of the species along with a discussion of its systematic position and ecology are provided.

New Mediterranean Biodiversity Records (November, 2016)

In the present Collective Article information on 26 taxa belonging to 8 Phyla and extended from the western Mediterranean to the Levantine Sea are presented. The new records were found in 9 countries as follows: Spain: first record for the Mediterranean of the crab Cancer bellianus; Algeria: further records of the alien fish Lagocephalus sceleratus to the west Algerian waters; Italy: first report on the presence and establishment of the ctenophore Mnemiopsis leidyi in Lessina and Varano Lagoons (W. Adriatic) and of Penaeus aztecus in Corigliano Gulf (Italian Ionian). Moreover, the extension of the distribution range of the polychaete Branchiomma bairdi to W. Sicily as well as that of the crab Ocypode cursor and the bryozoan Catenicella paradoxa to E. Sicily are cited. Slovenia: the record of the rare saccoglossan gastropod Placida cremoniana from Piran (Gulf of Trieste) is the first for the Adriatic; Greece: the native sea slug Eubranchus farrani is the first from the Eastern Mediterranean; many sightings of the bamboo corals Isididae distributed along all the E. Ionian Sea and the establishment of P. aztecus in all Greek waters are also reported for first time; the westernmost extension of the alien urchin Diadema setosum in Cretan waters is cited and new sights of the alien species Goniobranchus annulatus and Pterois miles are shown. Turkey: the alien fish Champsodon capensis is reported for first time from the Aegean Sea and the native acari Agauopsis microrhyncha from the Levantine Sea; a new observation of the alien crab Atergatis roseus in Güllük Bay-Aegean is also mentioned; Cyprus: first records of the alien urchin D. setosum and Lobotes surinamensis in Cypriot waters; Lebanon: several sightings of Monachus monachus from the Lebanese waters indicate a potential better status of the species in the area, Egypt: first records of the alien crab Dorippe quadridens and the alien gastropods Nerita sanguinolenta and Conomurex persicus from the Mediterranean Egyptian waters; extension of the distribution range of Diodora funiculata and Diodora rueppellii and a second record of the alien Nerita sanguinolenta in the same area.

Registros nuevos de poliquetos (Annelida) de la zona costera de isla del Carmen, Campeche, México

A taxonomic list of new records of polychaete worms collected off the coasts of the state of Campeche, Mexico, is reported. Distinctive taxonomic characters are included for each species, as well as information on their geographical distribution. The following species were reported for the first time in the study area: Mediomastus ambiseta (Hartman, 1947), Rasghua lobatus (Hartman, 1947), Eunice stigmatura (Verrill, 1900), Eunice unifrons (Verrill, 1900), Marphysa brevitentaculata Treadwell, 1921, Marphysa orensanzi Carrera-Parra and Salazar-Vallejo, 1998, Notaulax midoculi (Hoagland, 1919), Glycera pacifica Kinberg, 1865, Lumbrineris erecta Moore, 1904, Perinereis mochimaensis Liñero, 1983, Platynereis dumerilii (Audouin and Milne-Edwars, 1834), Naineris dendritica (Kinberg, 1867), Pectinaria gouldii (Verrill, 1874). Branchiomma bairdi (McIntosh, 1885) and Ficopomatus miamiensis (Treadwell, 1934) are reported as alien species, while Pseudopolydora floridensis Delgado-Blas, 2008 is recorded for the first time in Mexico.

New records of sabellids and serpulids (Polychaeta: Sabellidae, Serpulidae) from the Tropical Eastern Pacific.

Sabellids and serpulids are two well represented families in the polychaete fauna of the Tropical Eastern Pacific, with 31 and 34 species respectively; however, most records come from the Gulf of California or the western coast of Baja California Peninsula. Only a few records are from localities in the large expanse of the central and southern Mexican Pacific. Thus, sabellids and serpulids were collected from several shallow water habitats along the coast of Mexican Pacific, such as coastal lagoons, coral reefs, rocky shores and from man-made structures as marinas, piers and ships of several harbors; additionally, specimens from national collections were revised. More than 8,400 specimens of sabellids and serpulids from the states of Baja California, Baja California Sur, Sonora, Sinaloa, Michoacán, Guerrero, Oaxaca and Chiapas, and some specimens from Panamá and Perú were examined. In the present work we record new localities of four sabellids and 24 serpulids. One sabellid, Branchiomma bairdi, is an exotic/invasive species in Oaxaca, Sinaloa and Baja California Sur, while four species of serpulids are exotic and/or cryptogenic species: Ficopomatus uschakovi, Hydroides dirampha, H. elegans and H. sanctaecrucis. Additionally, the geographical range has been extended for five species: the sabellids Pseudobranchiomma punctata from Oahu, Hawaii to La Paz Bay, and Parasabella pallida from California to Puerto Escondido, Baja California Sur; and for three serpulids, Hydroides inermis from the Galápagos Islands to Agua Blanca, Oaxaca, H. gairacensis from Panamá to Puerto Ángel, Oaxaca, and H. panamensis from Panamá to Huatulco, Oaxaca and Faro de Bucerías, Michoacán. Hydroides cf. amri, previously recorded as H. brachyacantha from Oahu, Hawaii, is more similar to H. amri from Australia. The number of sabellids recorded for the Tropical Eastern Pacific increased to 33, the serpulid species to 35.

Settlement and population dynamics of the alien invasive Branchiomma bairdi (Annelida: Sabellidae) in the Mediterranean Sea: two years of observations in the Gulf of Taranto (Italy)

ABSTRACTSince the first discovery along the Italian coasts in 2004 of the polychaete Branchiomma bairdi, it has spread very quickly, reaching some localities in very high densities. In order to monitor its colonization, recruitment was investigated by means of PVC panels immersed in the Mar Grande of Taranto (Ionian Sea). Panels were monitored every three months from April 2013 to January 2015. The species showed the ability to settle on bare panels as well as on panels with a developed fouling community. Two years of monitoring identified two different cohorts, with recruits appearing in both years on panels submersed from July to October. Based on these observations B. bairdi is a short-lived species (no more than one year), reproducing at a temperature ranging from 20 to 29°C and reaching sexual maturity three months after recruitment. Oocytes were found in the coelom only in the warmest months and oogenesis was not synchronous either within each individual or within the population. Total annual secondary production was estimated at 43.42 g m−2 year−1. Annual mean biomass was 20.03 g m−2. The corresponding P/B ratio was 2.1678. This study may explain the invasiveness of B. bairdi; indeed, a rapid generation turnover coupled with a short lifespan, rapid growth and early maturity are common traits in most invasive species.

First record of Branchiomma bairdi McIntosh, 1885 (Annelida: Sabellidae) from Madeira Island, Portugal (northeastern Atlantic Ocean)

During a field survey to monitor marine non-indigenous species in several marinas of the Archipelago of Madeira (Portugal), the invasive sabellid polychaete Branchiomma bairdi McIntosh, 1885 was detected for the first time on Madeira Island, reaching densities of 238–516 ind.m -2 . B. bairdi was originally described from the western Atlantic (from Bermuda to Caribbean Sea) but the origin of this species is still unknown. This species has been recorded as an invasive species for the Pacific coast of Panama, Gulf of California, Mediterranean Sea, Canary Islands, and Australia. Hull fouling is the most likely vector for the introduction of the species.

Microbiological accumulation by the Mediterranean invasive alien species Branchiomma bairdi (Annelida, Sabellidae): Potential tool for bioremediation

We examined the bacterial accumulation and digestion in the alien polychaete Branchiomma bairdi. Microbiological analyses were performed on worm homogenates from “unstarved” and “starved” individuals and on seawater from the same sampling site (Ionian Sea, Italy). Densities of culturable heterotrophic bacteria (22°C), total culturable bacteria (37°C) and vibrios were measured on Marine Agar 2216, Plate Count Agar and TCBS Agar, respectively. Microbial pollution indicators were determined by the most probable number method. B. bairdi was able to accumulate all the six considered microbiological groups which, however, differ in their resistance to digestion. B. bairdi results more efficient than the other two co-occurring sabellids in removing bacteria suggesting that it may counteract the effects of microbial pollution playing a potential role for in situ bioremediation. Thus a potential risk, such as the invasion of an alien species, could be transformed into a benefit with high potential commercial gain and economic feasibility.

Chemical and structural defensive external strategies in six sabellid worms (Annelida)

AbstractIn the marine environment, sessile invertebrates have developed an impressive array of mechanisms to avoid predation, bacterial exploitation, and epibiotic overgrowth. In the present study we investigated several defensive strategies adopted by six sabellids: the hard bottom species Sabella spallanzanii (Gmelin, 1791), Branchiomma luctuosum Grube, 1869, Branchiomma bairdi (McIntosh, 1885), and Sabellastarte spectabilis (Grube, 1878), and the soft bottom species Myxicola infundibulum (Renier, 1804), and Megalomma lanigera (Grube, 1846), which have different morphological characteristics and geographical distribution. We examined and compared some defensive features such as branchial crown toughness, tube structure and strength, amount of released mucus, and antibacterial lysozyme‐activity in the mucus. The investigated species utilize a combination of defence and deterrence strategies that seems to be related to the colonized habitat. Tube strength was, higher in the hard bottom species compared with the soft bottom ones, where the tubes are generally buried and protected within the sediment. Branchial crown appeared stronger and resistant in hard bottom species, except for S. spallanzanii, which is the species showing the strongest tube. Sabella spallanzanii, M. infundibulum and S. spectabilis secreted high amount of mucus with high lysozyme‐like activity. By contrast, B. luctuosum, B. bairdi, and M. lanigera produced low amounts of mucus exerting lower antibacterial activity.

Biology and new records of the invasive species Branchiomma bairdi (Annelida: Sabellidae) in the Mediterranean Sea

First observations on the reproductive biology of the alien polychaete Branchiomma bairdi (McIntosh, 1885) (Sabellidae) in the Mediterranean Sea are provided as well as additional Mediterranean records of the species which can help to understand its introduction and spreading. Re-examination of the specimens from Miseno harbour (Tyrrhenian Sea, Italy) revealed the presence of B. bairdi in the central-Mediterranean since September 2004. The histological study of individuals collected in Malta revealed that the species is a simultaneous hermaphrodite, developing male and female gametes in the same body segments; embryos are brooded inside the parent tube. However, there is evidence also for asexual reproduction. The species shows a different reproductive pattern from the previously reported population from the eastern-Pacific; this demonstrates its great plasticity and adaptability. Branchiomma bairdi has an invasive behaviour, colonizing large areas in relatively short-time, and reaching relatively high densities (c.a. 50 individuals/m2). Its expansion throughout several Mediterranean localities is largely a consequence of the high capacity of this species to colonize extremely different habitats and substrates, to the occurrence of sexual and asexual reproductive strategies, and the combination of both. Further, B. bairdi appears to be particularly abundant in confined and anthropogenic degraded areas. Finally, our findings strongly suggest that the pathway of introduction in the Mediterranean, previously hypothesized as the Suez Canal (Lessepsian migration), is most likely via the Gibraltar Strait.

Biology and new records of the invasive species Branchiomma bairdi (Annelida: Sabellidae) in the Mediterranean Sea

First observations on the reproductive biology of the alien polychaete Branchiomma bairdi (McIntosh, 1885) (Sabellidae) in the Mediterranean Sea are provided as well as additional Mediterranean records of the species which can help to understand its introduction and spreading. Re-examination of the specimens from Miseno harbour (Tyrrhenian Sea, Italy) revealed the presence of B. bairdi in the central-Mediterranean since September 2004. The histological study of individuals collected in Malta revealed that the species is a simultaneous hermaphrodite, developing male and female gametes in the same body segments; embryos are brooded inside the parent tube. However, there is evidence also for asexual reproduction. The species shows a different reproductive pattern from the previously reported population from the eastern-Pacific; this demonstrates its great plasticity and adaptability. Branchiomma bairdi has an invasive behaviour, colonizing large areas in relatively short-time, and reaching relatively high densities (c.a. 50 individuals/m2). Its expansion throughout several Mediterranean localities is largely a consequence of the high capacity of this species to colonize extremely different habitats and substrates, to the occurrence of sexual and asexual reproductive strategies, and the combination of both. Further, B. bairdi appears to be particularly abundant in confined and anthropogenic degraded areas. Finally, our findings strongly suggest that the pathway of introduction in the Mediterranean, previously hypothesized as the Suez Canal (Lessepsian migration), is most likely via the Gibraltar Strait.

Sabellidae (Annelida) from the Faro coastal lake (Messina, Ionian Sea), with the first record of the invasive species Branchiomma bairdi along the Italian coast

In the present paper, morphological and ecological observations on 4 sabellid taxa, Branchiomma bairdi, B. luctuosum,Megalomma lanigera and Myxicola sp., collected from the coastal lake of Faro (Messina, Ionian Sea) (26-36 psu), are reported. Megalomma lanigera, Myxicola sp. and B. luctuosum were collected from the soft bottom in shallow water and B. bairdi from the hard bottom of an internal channel. The presence of the latter is remarkable, as there is no previous record of this species along the Italian coast, and it confirms the lake of Faro as a very favourable environment for the introduction of alien species, which has occurred frequently as a result of aquaculture. High intraspecific variation was observed for M. lanigera, whilst more extensive analysis is required to ascertain the taxonomic status of the Myxicola specimens, including a review of all Mediterranean data currently attributed to M. infundibulum.

Reproduction of the invasive fan worm Branchiomma bairdi (Polychaeta: Sabellidae)

The fan worm Branchiomma bairdi has been introduced to the Gulf of California from its original distribution in the Caribbean Sea, and is now a conspicuous component of most benthic communities. Study of reproductive features is essential to understand the dispersion capability of B. bairdi and its invasive potential. Sampling was carried out monthly in the port of Mazatlán during 2009 (23°12′13′′N, 106°24′31.4′′W). Abundance and biomass were measured. Sex and maturity were determined. Gametogenesis and observations on the spawning, fertilization, larval development and brooding are presented. The highest values of abundance (>2500 worms m−2) and biomass (175 g m−2) occurred during August and September. Mature simultaneous hermaphrodite worms were found continuously throughout the annual cycle as well as asexual forms. In B. bairdi gametogenesis is extra-ovarian. Three posterior thoracic segments and all abdominal segments are involved in the production of gametes. Sperm are ect-aquasperm type (free spawners with external fertilization). Spermatids are grouped in tetrads. Ovules are retained for intra-tubular fertilization. Larval development is lecithotrophic. Embryos are brooded on the collar and branchial crown.

Alien polychaete species (Annelida: Polychaeta) on the southern coast of Turkey (Levantine Sea, eastern Mediterranean), with 13 new records for the Mediterranean Sea

The examination of benthic material collected from different depths and habitats along the southern coast of Turkey (Levantine Sea, eastern Mediterranean) in September and October 2005 revealed 30 alien polychaete species belonging to 15 families. Thirteen species (Pisione guanche, Linopherus canariensis, Onuphis eremita oculata, Lumbrineris perkinsi, Dorvillea similis, Timarete caribous, Pherusa parmata, Pherusa saldanha, Streblosoma comatus, Polycirrus twisti, Laonome triangularis, Branchiomma bairdi and Janua steueri) are new to the Mediterranean fauna, 24 species are new to the Turkish fauna and 27 species are new to the Levantine coast of Turkey. The specimens collected from the Levantine coast of Turkey and northern Cyprus that were previously identified as Linopherus acarunculata and Branchiomma boholense are reidentified as L. canariensis and B. bairdi, respectively. In the light of present knowledge, the previous reports of Lumbrineris inflata and Streblosoma hesslei from the Mediterranean (Italian coast) could refer to the species L. perkinsi and S. comatus, respectively. The species new to the Mediterranean Sea are redescribed and discussed.

Fouling polychaete worms from the Southern Gulf of California: Sabellidae and Serpulidae

Members of the tubicolous polychaete families, Sabellidae and Serpulidae, constitute two of the most important groups in the marine fouling biota. This paper describes three fouling sabellids and six serpulids from the southern Gulf of California and provides information about the reproductive biology of these species. The invasive species, Branchiomma bairdi and Ficopomatus miamiensis, are established in the southern Gulf of California as self‐sustaining populations outside of their native range of the Caribbean Sea. Hull fouling is considered the most probable vector for the translocation of B. bairdi to the eastern Pacific, while the presence of F. miamiensis is most likely due to shrimp aquacultural activities. Hydroides elegans is probably an invasive species in the study area and is common as fouling on ships and piers in the Caribbean, Gulf of Mexico, the Turkish Levantine coast, Hawaii and California. Hydroides brachyacanthus has been widely recorded in the Mexican Pacific. Demonax pallidus and Megalomma coloratum constitute new records for México. Hydroides elegans, H. recurvispina and Vermiliopsis multiannulata are new records for the Mazatlán port. Hydroides cruciger, H. brachyacanthus, H. elegans, H. recurvispina and Megalomma coloratum have separate sexes without sexual dimorphism. Branchiomma bairdi and D. pallidus are simultaneous hermaphrodites, although asexual reproduction via scissiparity is documented in B. bairdi. Sperm morphology (spherical nucleus, rounded or subtriangular cap‐like acrosome and a long flagellum) suggests that the species recorded here are free‐spawners with external fertilisation or ect‐aquasperm type. This taxonomic effort is greatly enhanced by the integration of synonymies, characterisations and image collections with annotations archived in Morphbank.