Publications
Active Plume, Abandoned Ridge, or Ancient Slab? olivine‐Hosted Melt Inclusions Record the Mantle Melting Conditions Below the East Pacific Revillagigedo Archipelago, Mexico
New research on the Revillagigedo Archipelago reveals that the volcanic activity, previously attributed to hotspot geochemistry, is likely driven by a deep mantle plume rising around a mid-mantle slab remnant. Analysis of olivine-hosted melt inclusions shows melting conditions hotter and deeper than typical mid-ocean ridge basalts (MORBs), suggesting active mantle upwelling confirmed by seismic data indicating a deeper 410 km discontinuity and shallower 660 km discontinuity, implying the presence of hot material below the mantle transition zone. The study finds no evidence of fossil subduction wedge signatures in enriched melts, ruling out an ancient slab influence and supporting the hypothesis of plume-derived melts diluted by a depleted ridge component.
Beyond a simple wet-to-dry transition: Staged eruptive evolution during growth of the alkaline Bárcena volcano, Isla San Benedicto, México
Research on the Bárcena volcano in Mexico's Revillagigedo Archipelago reveals that its 1952–1953 eruption did not follow a simple wet-to-dry transition but instead involved staged changes in eruptive conditions and magma supply. The study analyzed stratigraphy, grain-size distributions, petrography, SEM observations of juvenile clasts, and whole-rock geochemistry to demonstrate that the volcano's growth was marked by distinct phases: initial pyroclastic cone construction, intra-crater dome extrusion, and a lateral lava breakout. These stages were characterized by varying degrees of magma-water interaction, with Package 2 showing the strongest evidence for such interactions, including structured ash beds and black-glassy juvenile clasts. Geochemical data further indicated that the late lava was less siliceous and more crystalline than the pyroclastic pumice, suggesting a transition from an evolved alkaline suite to a related but less evolved magma domain.
Borradas del mapa nacional. La invisibilización de las islas mexicanas frente a la supremacía continental en la cartografía
Mexican islands, particularly those in the Archipiélago de Revillagigedo and other strategic locations, are often omitted or marginalized in national cartography due to a 'continental supremacy' bias. This study reveals how such omissions contribute to their invisibility in public imagination, despite their geopolitical significance as maritime border nodes. Through archipelagic thought and cartographic analysis, the research identifies cases where islands were either underrepresented, inaccurately depicted (e.g., non-existent islands), or erased entirely due to geopolitical pressures—such as the Archipiélago del Norte and Clipperton. The findings underscore the need for more inclusive map representation, advocating for the integration of island toponyms in both political and thematic cartography to highlight their relevance in physical, human, and economic geography.
Mixed-Stock Composition Analyses Suggest Michoacán and Revillagigedo as the Principal Sources of Green Sea Turtle (Chelonia mydas) Foraging Grounds Populations in the Baja California Peninsula
Green sea turtles (Chelonia mydas) foraging populations in the Baja California peninsula, Mexico, primarily originate from nesting sites in the Eastern Pacific, specifically the Revillagigedo Islands and Michoacán coast. A two-year study analyzed mitochondrial DNA from turtles at Bahía de Los Ángeles (BLA) and Complejo Lagunar Ojo de Liebre (CLOL), revealing that both source populations contribute equally to these foraging grounds (Bayes Factor <1.9). This finding highlights the importance of protecting critical nesting areas in Revillagigedo to safeguard these endangered turtles' migratory pathways.
Shark movements between islands in the Revillagigedo Archipelago and connectivity to other islands in the Eastern Tropical Pacific
Long-distance shark movements spanning multiple Marine Protected Areas (MPAs) in the Eastern Tropical Pacific highlight critical gaps in conservation efforts. The study tracked 92 Galapagos sharks and silky sharks, revealing that while some sharks remained resident within a single island or MPA, others traveled extensively—including a record-breaking 3,160 km journey by a Galapagos shark from Socorro Island to Clipperton Atoll and Darwin Island. Notably, three sharks crossed between MPAs, including one silky shark that migrated between the Revillagigedo Archipelago (RA) and Clipperton Atoll (CA), then returned. These findings underscore the need for international collaboration to implement effective protection measures, such as swimways or MigraVías, to safeguard shark populations across the region.
Unraveling the Volcanic Structure of Oceanic Islands—Gravity Survey of Socorro Island, Revillagigedo Archipelago, Mathematician Ridge, Pacific Plate
A gravity survey of Socorro Island, part of the UNESCO-listed Revillagigedo Archipelago, reveals the volcanic structure beneath one of the most active oceanic islands in the Eastern Pacific. The study identifies a subsidence depth of approximately 100 meters within the island's caldera, correlating with an erupted volume of around 2 cubic kilometers and a caldera size of roughly 4.5 by 3.8 kilometers. This finding sheds light on the post-caldera volcanic activity and stratigraphy, including basaltic and pyroclastic sequences that form the shield edifice. The research employs Bouguer anomaly analysis, upward and downward analytical continuations, vertical derivatives, and 2.5-D forward modeling to constrain subsurface structures and density contrasts, providing a detailed understanding of Socorro Island's volcanic evolution.
Análisis de la diversidad y nuevos registros de equinodermos (Echinodermata) para el Parque Nacional Revillagigedo, México
A comprehensive analysis of echinoderm diversity in the UNESCO-listed Revillagigedo Archipelago, Mexico, reveals 94 species, including five new records: two starfish (Heliaster kubiniji and Astrometis sertulifera) and three brittle stars (Ophiolepis variegata, Ophiopsila californica, and Ophiothela mirabilis). The study, conducted across four volcanic islands, found Ophiuroidea to be the most species-rich class with 31 species, followed by Asteroidea, Echinoidea, and Holothuroidea, each with 21 species. Clarión and Socorro Islands exhibited the highest species richness (60 and 58 species, respectively), while San Benedicto and Roca Partida may have underreported diversity due to limited sampling efforts. The research employed ecological analyses, including species richness, similarity, and taxonomic distinctiveness, to assess biodiversity patterns in this pristine tropical ecosystem.
Identification and Distribution of the Brown and Cocos Boobies and Their Subspecies
Research identifies five distinct taxa within the Brown–Cocos Booby complex, distinguishing them through key morphological traits such as head color, underwing covert patterns, iris darkness, culmen concavity, and bill color. These differences vary by sex and subspecies, with male Cocos Boobies exhibiting unique white neck markings that help identify subspecies in the Revillagigedo Islands. The study analyzed 50 museum specimens and 754 living birds from 47 locations, providing critical insights for field identification and tracking population movements under environmental changes.
Nuevos registros de babosas marinas (Gastropoda: Heterobranchia) para isla Clarión, archipiélago Revillagigedo, México
A recent study on the island of Clarión, part of Mexico's Revillagigedo Archipelago, has documented 14 species of sea slugs (Gastropoda: Heterobranchia), including 13 new records for the island and five for the entire archipelago. This significant contribution to marine biodiversity knowledge was achieved through continuous sampling at Clarión's southern beaches, intertidal pools, and shallow reef zones between January 2023 and March 2024. The archipelago's unique position at the convergence of cold California Current waters and warm North Equatorial Current waters creates a high-biodiversity environment, though Clarión's remote, rugged terrain poses challenges for research. This study expands our understanding of heterobranch sea slug diversity in the tropical Pacific, highlighting the ecological importance of this UNESCO World Heritage Site.
Primer registro morfométrico y de salud de tortuga carey (Eretmochelys imbricata) en el Parque Nacional Archipiélago de Revillagigedo, México
A juvenile hawksbill sea turtle (Eretmochelys imbricata), a critically endangered species, was recorded for the first time in the Revillagigedo Archipelago National Park, Mexico. The discovery underscores Socorro Island as a vital refuge and feeding habitat for this species, which has experienced significant population decline in the Eastern Pacific. Researchers captured, measured, tagged, and conducted a comprehensive health assessment of the turtle, including hematological analysis, blood biometry, clinical biochemistry, and clinicopathological evaluation. Results confirmed the turtle's healthy condition, providing critical insights into its distribution and conservation status. This study highlights the importance of Socorro Island for the preservation of hawksbill sea turtles in the region.
Complementary description of Peltidium nayarit (Copepoda, Harpaticoida, Peltidiidae) and a new record at Revillagigedo Archipelago, Mexico
Researchers have documented the first occurrence of Peltidium nayarit, a rare harpacticoid copepod, in the Revillagigedo Archipelago, Mexico. This discovery extends its known range to the southwesternmost record of the genus in the Americas and marks the second confirmed location for this species in Mexico. The study provides an enhanced morphological description using scanning electron microscopy (SEM), detailing previously unrecorded features such as antennules, caudal rami, legs 1 and 5, and cuticular ornamentation. P. nayarit is notable for its reddish-pink coloration, which may serve as mimicry against macroalgae, though the specimens were collected from sea surface zooplankton net tows rather than their presumed benthic/epiphytic habitat.
Evidencia de Comportamiento Reproductivo de Tortuga Verde del Pacífico Oriental (Chelonia mydas) en el Parque Nacional Archipiélago de Revillagigedo, México
Researchers document the first photographic evidence of mating behavior in Eastern Pacific green sea turtles (Chelonia mydas) at two sites within Mexico's Revillagigedo Archipelago, Bahía Azufre on Clarión Island and Bahía Vargas Lozano on Socorro Island. This discovery suggests an extended breeding season beyond previously documented nesting peaks. The study, part of a broader effort to establish baseline data for turtle conservation in the region, combines monitoring efforts with health assessments to better understand reproductive patterns and inform protection strategies for this endangered species.
Halichoeres sanchezi n. sp., a new wrasse from the Revillagigedo Archipelago of Mexico, tropical eastern Pacific Ocean (Teleostei: Labridae)
Researchers have identified a new species of wrasse, Halichoeres sanchezi n. sp., in the Revillagigedo Archipelago, Mexico, adding to the region's endemic fish diversity. This discovery highlights unique genetic distinctions within the Halichoeres melanotis species complex, with H. sanchezi differing by 2.4% in mitochondrial DNA from its closest relative and exhibiting distinct color patterns—including a vermilion-orangish terminal-phase male with dark scale outlines and a black caudal band—not found in related species. The study employed an innovative approach during a 2022 expedition, combining underwater photography to document specimens in situ, tissue sampling, and museum vouchering, setting a precedent for collaborative ichthyofauna inventory in isolated archipelagos.
Insular and mainland interconnectivity in the movements of oceanic manta rays (Mobula birostris) off Mexico in the Eastern Tropical Pacific
Research reveals significant connectivity between oceanic manta ray (Mobula birostris) populations around the Revillagigedo Archipelago and mainland Mexico, suggesting a metapopulation structure. Over 21 years, 22 individuals were tracked using unique color markings and acoustic beacons, showing movements between the archipelago and sites such as Bahia de Banderas, Bahía de Navidad, and the Gulf of California. Some rays traveled over 560 km, with transit times ranging from months to over a decade, indicating strong interconnections. The study highlights the importance of these regions for manta ray conservation, particularly in areas like the Revillagigedo Archipelago and Gulf of California, where research has been historically limited.
Mexico
A critical shift from arid to tropical environmental conditions occurs along the Mexican mainland coastal region, with the Archipiélago de Revillagigedo wetlands serving as a unique transition zone. This study highlights the ecological significance of nine coastal wetland ecosystems in Colima, Michoacán, and Guerrero, emphasizing their role as vital habitats for diverse terrestrial and aquatic species, as well as indigenous communities. The research underscores the importance of these wetlands in supporting biodiversity and cultural heritage, offering insights into the complex interplay between environmental gradients and ecological systems.
Primer registro del colibrí barba negra (Archilochus alexandri) en Isla Socorro, Archipiélago de Revillagigedo, México
A groundbreaking discovery has been made on Socorro Island, part of Mexico's Revillagigedo Archipelago: the first recorded presence of the Black-chinned Hummingbird (Archilochus alexandri). This finding significantly enriches the island's biodiversity and expands the known distribution range of this species. Researchers identified three hummingbirds during a November 2017 expedition, distinguishing them from smaller migratory species by their body structure and long beaks. One individual was observed feeding on amole flower nectar (Ipomoea triloba) in mixed scrub vegetation, confirming its presence. This record marks the first hummingbird sighting in the archipelago and the first for the Black-chinned Hummingbird on Socorro Island.
Revisiting the biogeographical regionalization of the Pacific Lowlands biogeographical province using bird distributional data
A new biogeographical regionalization of the Pacific Lowlands province, part of the Mesoamerican dominion, was established using distributional data from 47 endemic bird species. The study reclassified six existing districts into two subprovinces: the Coastal Lowlands of Nayarit-Sinaloa subprovince (stat. nov.), encompassing the Sinaloan, Tres Marías Islands, Revillagigedo Islands, and Guerreran districts; and the Coastal Lowlands of Southwestern Mexico subprovince (stat. nov.), including the Tehuanan and Tapachultecan districts. This refinement improves the understanding of biogeographical patterns in the region, with bird species listed to support the recognized subprovinces and districts.
Acoustic recording of false killer whale (Pseudorca crassidens) from Mexico (L)
A study of false killer whales (Pseudorca crassidens) near Roca Partida Island, Mexico, revealed that their acoustic signals are more varied than previously thought. Researchers recorded 321 whistles from a group of at least ten individuals and found that ascending contour types, particularly upsweeps, accounted for nearly 43% of the signals—contradicting the assumption that these whales predominantly produce constant whistles. The findings highlight inconsistencies in whistle type categorization across studies, suggesting a need for standardized reproducibility criteria. This research contributes to the limited knowledge base on false killer whale acoustics and calls for further ecological and acoustic investigations to clarify signal modulation patterns.
Evolutionary biogeography of the Revillagigedo Archipelago, Mexico
The Revillagigedo Archipelago, Mexico, serves as a critical biogeographic node where Nearctic and Neotropical species overlap, suggesting it functions as a distinct province or district within the Pacific Lowlands. Researchers identified two ancient cenocrons—one originating from Baja California and another from the Pacific coast—that colonized the archipelago during the Pliocene–Pleistocene, likely after volcanic activity shaped the islands. Using parsimony analysis of endemicity and cladistic biogeographic methods, the study reconstructed the evolutionary pathways of 194 species, revealing a complex geobiotic history tied to the Mathematician Ridge's volcanism. This work provides new insights into the archipelago's role in shaping biodiversity and its geological origins.
Vascular Plant Species Inventory of Mexico’s Revillagigedo National Park: Awareness of Alien Invaders as a Sine Qua Non Prerequisite for Island Conservation
Nearly 40% of the vascular plant species in Mexico's Revillagigedo National Park are alien, with a significant portion posing invasion risks. The study presents the most comprehensive inventory to date, identifying 272 species, including 106 aliens (39.3%), of which 67 are naturalized and 25 persist under cultivation. The research, based on extensive reviews of plant collections and other sources, reveals a stark increase in introduced species since human habitation began, with most naturalized aliens originating from North America. Annual and perennial herbs dominate the alien flora, highlighting their potential to disrupt island ecosystems. This inventory underscores the urgent need for awareness and control measures to mitigate the threat posed by invasive alien plants.
First report of signature whistles in an oceanic common bottlenose dolphin (Tursiops truncatus) population from Revillagigedo Archipelago, Mexico
Researchers have identified signature whistles (SWs) in an oceanic population of common bottlenose dolphins (Tursiops truncatus) from the Revillagigedo Archipelago, Mexico, marking the first such report for a pelagic population. Analyzing 233 recorded whistles, they found that 85% were stereotyped and categorized into five SW types, with 42% of the repertoire consisting of these signature calls. Principal component analysis revealed that shape/contour variables explained 77% of the variance in SWs, suggesting distinct acoustic characteristics between oceanic and coastal dolphin populations. The study also noted higher mean acoustic parameters in Revillagigedo's dolphins compared to coastal regions, hinting at potential ecological or behavioral differences. This groundbreaking finding calls for further research to expand understanding, identify individual dolphins through photo ID and SW catalogs, and investigate similar patterns across other oceanic islands.
Holothuria (Lessonothuria) coronata sp. nov. (Echinodermata, Holothuroidea), a new species of sea cucumber from Socorro Island, México
A new species of sea cucumber, Holothuria (Lessonothuria) coronata sp. nov., has been discovered off Socorro Island in the Revillagigedo Archipelago, Mexico. This species is distinguished by unique morphological features, including circular disc tables with large peripheral holes—sometimes accompanied by a second series—and a spiny or smooth rim on its disc. Additionally, it exhibits a spire crossed by a single cross-beam and ventral tube feet with curved supporting rods bearing spiny edges. The discovery was made through detailed morphological analysis of specimens collected at depths of 5–10 meters, highlighting the biodiversity of this UNESCO-listed marine protected area.
Humpback whales ( Megaptera novaeangliae ) attend both Mexico and Hawaii breeding grounds in the same winter: mixing in the northeast Pacific
Definitive evidence shows that humpback whales (Megaptera novaeangliae) can attend both Mexico and Hawaii breeding grounds within the same winter season, challenging the presumed seasonal isolation of these populations. Two whales were photo-identified at both locations: one traveling from Maui, Hawaii to the Revillagigedo Archipelago in 53 days (2006), and another moving from Guerrero, Mexico to Maui in 49 days (2018). These findings, combined with additional data on individual interchange, song similarity, and mid-ocean detections, suggest that these populations may not be as distinct as previously classified. The study relies on long-term photo-identification records and genetic sampling to track whale movements across the northeast Pacific.
La investigación bioacústica de las aves del Archipiélago de Revillagigedo: un reporte de avance
Bioacoustic research on birds from the Revillagigedo Archipelago reveals distinct vocalization patterns among 12 species, highlighting geographic variations at deme, subspecies, or species levels. The study compares island vocalizations with continental counterparts, documenting significant acoustic events such as female vocalizations in certain species and duets in the Socorro mockingbird. It also explores the potential of bird songs for conservation tasks, including population censuses and sex identification. Spectral analyses were used to characterize these vocalizations, offering insights into behavioral ecology and sexual selection while proposing future research directions for this understudied insular region.
Mixed‐stock aging analysis reveals variable sea turtle maturity rates in a recovering population
Green turtles (Chelonia mydas) in the eastern Pacific Ocean exhibit variable maturity rates, with females from Michoacán, Mexico, reaching sexual maturity at a younger age (~17 years) and smaller size compared to those from the Revillagigedo Islands (~30 years). This divergence suggests that anthropogenic pressures, such as historical harvesting, may have accelerated maturation in some subpopulations. Researchers used skeletochronology to analyze growth rates and life-history traits in 65 turtles, revealing that smaller body sizes correlate with earlier maturity. The study also highlights the importance of protecting nearshore habitats where young turtles (4–6 years old) transition from oceanic to neritic environments, emphasizing the need for variable maturation time in population recovery assessments.
Población de langosta centroamericana (Schistocerca piceifrons) en la isla Socorro y su impacto sobre la vegetación
A recent study on Socorro Island, part of Mexico's Revillagigedo Archipelago, reveals that the abundance of the Central American grasshopper (Schistocerca piceifrons) is linked to moderate temperatures and high atmospheric humidity. Unlike previous reports of significant outbreaks, current populations are not posing a threat to native vegetation, with herbivory levels remaining below 7%. The research, conducted during both rainy and dry seasons in 2018, sampled grasshopper populations across 25 sites with varying vegetation types and assessed plant damage. While no swarms were observed, the study suggests that periodic monitoring is advisable due to historical population fluctuations, though immediate control measures are not deemed necessary.
Políticas locales para la preservación de un patrimonio global. El Archipiélago de Revillagigedo, Patrimonio Mundial
The Revillagigedo Archipelago, inscribed as a UNESCO World Heritage Site in 2016, faces systemic challenges in its conservation despite ongoing efforts by institutions and governments. The study highlights the critical need for stronger collaboration among public management bodies, academic institutions, and civil society organizations to meet global preservation standards. While local policies and scientific knowledge development aim to protect this unique natural heritage, their effectiveness is hindered by underlying weaknesses in governance and coordination. This research underscores the importance of integrated strategies to address these gaps and ensure the long-term sustainability of the archipelago's biodiversity.
Butterfly Biodiversity on Isla Socorro, Mexico, with Comments on the Taxonomic Status of the Endemic Hairstreak Strymon istapa socorroica (Lycaenidae)
A recent survey of butterfly biodiversity on Isla Socorro, Mexico—a volcanic island in the UNESCO-listed Revillagigedo Archipelago—reveals that five of the eight previously recorded species remain present, while a new species, Pyrisitia lisa centralis, has established itself since the last study over 30 years ago. The research, conducted in November 2019, also used DNA barcoding to support the taxonomic status of the endemic hairstreak Strymon istapa socorroica. Meanwhile, the island's habitat recovery post-feral sheep eradication in 2012 may have benefited butterfly populations, though further sampling is needed to confirm whether three previously recorded species are now extinct. The study highlights both the resilience and vulnerability of this unique ecosystem.
Echinoderms (Echinodermata) from the Central Mexican Pacific
A comprehensive study of echinoderms (Echinodermata) in the Central Mexican Pacific, including the UNESCO-listed Archipiélago de Revillagigedo, reveals a rich biodiversity of 187 species, with Ophiuroidea being the most diverse group. The research corrects 52 invalid and five doubtful records from previous literature, while adding 16 new records for Ophiuroidea, four of which are first-time sightings in the region. Jalisco and the Revillagigedo archipelago exhibit the highest species richness, reflecting their significant biogeographical importance. The study highlights the influence of sampling effort and environmental factors on biodiversity patterns, emphasizing the Central Mexican Pacific's unique oceanographic conditions that blend northern and southern Pacific influences.
Metabolic response to water shortage in an isolated feral sheep population
Feral sheep on Socorro Island, Revillagigedo Archipelago, exhibit significant metabolic adaptations to water scarcity. Research found that biochemical analytes such as total cholesterol (COL-T), triglycerides (TAG), urea, albumin (ALB), and others showed marked changes under restricted water intake, peaking at 14 days of limitation. These changes were linked to physiological responses like increased arginine vasopressin (AVP) and aldosterone (Aldo) levels, indicating dehydration coping mechanisms. Negative correlations between ALB with COL-T and TAG, alongside positive correlations among multiple analytes, suggest intricate metabolic adjustments. The study, analyzing 376 blood samples over three weeks, provides a foundation for developing accurate dehydration indicators in feral sheep populations.
Population-level morphological variation of Anisotremus interruptus (Gill, 1862) (Perciformes: Haemulidae) in the Tropical Eastern Pacific, with the description of two new species
Research reveals significant morphological variation within the species Anisotremus interruptus (Perciformes: Haemulidae) in the Tropical Eastern Pacific, leading to the identification of two new species: A. perezponcedeleoni from the Revillagigedo Archipelago and A. espinozai from the Galapagos Archipelago-Cocos Island. This discovery aligns with prior genetic studies indicating a species complex within A. interruptus, suggesting its taxonomic diversity was previously underestimated. The study employed comparative analysis of meristic and morphometric traits to assess population-level differences, providing concrete evidence for these new species distinctions.
Challenges and Priorities for Seabird Conservation in Northwestern Mexico
A comprehensive analysis identifies ten islands or archipelagos in Northwestern Mexico as high-priority sites for seabird conservation, including the Revillagigedo and San Benito archipelagos. The study ranked 91 sites based on breeding seabird communities (35 species across 11 families), using criteria such as conservation category, preferred habitat, and foraging guilds. Highlighting the urgency, it notes that many species migrate internationally, escalating conservation challenges beyond national borders. The research, synthesizing 119 reports from 1922–2018, emphasizes the need for advanced monitoring tools to establish population baselines and track trends effectively.
Ensamblajes de peces en la zona mesofótica del Pacífico: una comparación entre islas continentales y oceánicas de México
A comparison of mesophotic reef fish assemblages between continental and oceanic islands off Mexico reveals that habitat type is the primary driver of diversity, with rocky reefs in oceanic islands exhibiting higher functional diversity. This study used a remotely operated vehicle to explore depths receiving 1–10% surface light, an understudied region due to traditional diving limitations. Researchers analyzed 78 video transects, identifying species and calculating both traditional (species richness, taxonomic differentiation) and functional indices (functional entities, functional volume). Findings suggest oceanic mesophotic reefs may be in better conservation status than continental ones, potentially serving as refuges for commercially important transpacific species amid increasing disturbance in shallow reefs. However, further exploration is needed to confirm these patterns over time.
Evolutionary history of the reef fishAnisotremus interruptus(Perciformes: Haemulidae) throughout the Tropical Eastern Pacific
Research reveals that the reef fish Anisotremus interruptus exhibits distinct genetic groups across the Tropical Eastern Pacific (TEP), with populations from the Galapagos and Revillagigedo archipelagos showing significant divergence. The study, using mitochondrial and nuclear markers, found that continental TEP individuals lack genetic structure but experienced population expansion during the Pleistocene. Notably, the open sea gap between oceanic islands and the mainland acts as a barrier to gene flow, unlike sandy gaps in the TEP. This suggests that oceanic isolation plays a critical role in shaping the species' evolutionary history.
First detection of an ocellate octopus in the Revillagigedos ecoregion, a biodiversity hotspot located in the Tropical East Pacific Province
Scientists have made a significant discovery in the Revillagigedos ecoregion, a biodiversity hotspot in the Tropical East Pacific Province: the first detection of an ocellate octopus, Octopus oculifer. Traditionally considered endemic to the Galapagos Archipelago, this species was identified using morphological criteria and molecular data from two mitochondrial genes (COIII and COI). The study also suggests that O. mimus, O. hubbsorum, and O. oculifer may form a closely related species complex with three distinct morphotypes, challenging previous assumptions about their evolutionary relationships. Researchers found that the presence of ocelli does not determine these octopuses' evolutionary connections, revealing a new clade comprised of both ocellate and non-ocellate species. This finding marks a milestone in understanding cephalopod biodiversity in the region.
Fishes of Archipelago of Revillagigedo Islands: A Systematic and Biogeographic Update
A comprehensive update of the ichthyofauna of the Revillagigedo Archipelago reveals 366 fish species across four islands, highlighting significant biogeographic and taxonomic diversity. Socorro Island exhibits the highest species richness (220), followed by Clarion (179), San Benedicto (128), and Roca Partida (62). The study identifies Carangidae, Serranidae, and Muraenidae as the most species-rich families, while endemic species account for 7.1% of the total. Biogeographic analysis shows strong affinities with the Panamic province (42.3%) and Cortes (41.5%), with a notable proportion of circumglobal (21%) and amphipacific (22.4%) species. The findings underscore the archipelago's unique ichthyofaunal composition, influenced by island surface area and geographic proximity.
Floral Trait Evolution of Angiosperms on Pacific Islands
Contrary to expectations, flowers on Pacific islands are not universally smaller than those on the mainland. However, a closer look at specific archipelagos reveals that island taxa, including those of the UNESCO-listed Archipiélago de Revillagigedo, do evolve smaller flowers compared to their mainland counterparts. This divergence in flower size is not consistent across all plant families; some exhibit no change, while others show an increase in flower size on islands. The study analyzed 556 plant species and 136 phylogenetic contrasts, suggesting that ecological filtering rather than evolutionary divergence may explain the prevalence of small-flowered species on islands. This research challenges the notion of a general 'island syndrome' for floral traits, highlighting the complexity and context-dependency of floral evolution.
Reference values for biochemical analytes in feral sheep from Socorro Island, Revillagigedo Archipelago, Mexico
Feral sheep on Socorro Island, part of Mexico's Revillagigedo Archipelago, exhibit distinct seasonal variations in biochemical analytes linked to freshwater adaptation. Key findings include elevated levels of total cholesterol, triglycerides, urea, albumin, and sodium ions compared to domestic sheep, with some values aligning with those of goats. Seasonal differences were significant (P<0.05), with peak concentrations observed during winter and the lowest during spring. These insights provide critical reference values for assessing dehydration in these animals and shed light on their physiological adaptations to limited freshwater availability.
Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae)
A comprehensive taxonomic revision of the hesionid annelid genera Leocrates and Leocratides reveals significant morphological diversity, leading to the reclassification of species into five distinct genera. The study identifies three new genus-group names—Paradalhousia, Paralamprophaea, and Paraleocrates—and reinstates Dalhousia and Lamprophaea as separate genera, correcting previous synonymizations proposed by Marian Pettibone. Key morphological features such as nuchal organs lobes, pharyngeal armature, and neurochaetal blades were standardized to distinguish species. The revision describes 18 new species from various World localities, including the Revillagigedo Islands, and provides identification keys for all hesioninae genera and species. This work challenges long-standing taxonomic assumptions and enhances our understanding of annelid biodiversity.
Spatial and temporal characteristics of tropical cyclone strikes in the northeastern Pacific Basin between San Diego, California and Las Peñitas, Nicaragua
A study analyzing 52 years of tropical cyclone (TC) data in the northeastern Pacific Basin reveals distinct hot spots for TC strikes, with regions around Manzanillo, Colima, and Isla Socorro experiencing return periods of 2 years or less. Conversely, areas like Sonora, Central America, San Diego, and northern Baja California face much longer return periods, exceeding 52 years. The research utilized track data from the National Hurricane Center's HURDAT2 and a TC size model to construct time series and calculate strike frequencies, highlighting significant spatial and temporal variations in TC activity. These findings underscore varying coastal risks across the region, providing critical insights for planners, governments, tourism agencies, and investors.
Dieta y ámbito hogareño del gato feral, Felis catus (Carnivora: Felidae) en la Isla Socorro, Archipiélago de Revillagigedo, México
Research on feral cats (Felis catus) in Isla Socorro, part of the UNESCO-listed Revillagigedo Archipelago, reveals critical insights for their eradication to protect local biodiversity. Analysis of stomach contents from 79 cats showed their diet primarily consisted of domestic mice (22.16%), endemic lizards (Urosaurus auriculatus, 15.09%), anthropogenic waste (15.09%), and insects (Orthoptera, 13.20%). Telemetry tracking of four cats using GPS/VHF collars further uncovered significant differences in home range sizes: males averaged 219.10 hectares, while females averaged 118.86 hectares. These findings are pivotal for planning effective eradication efforts, as they inform the required trapping density and bait distribution to minimize environmental impact during ongoing conservation actions.
First record of the dinoflagellate Prorocentrum panamense (Prorocentrales, dinophyceae) in the Mexican Pacific from the Archipiélago de Revillagigedo
Scientists document the first occurrence of the toxic dinoflagellate Prorocentrum panamense in Mexican Pacific waters, specifically within the UNESCO-listed Revillagigedo Archipelago. During March 2017 sampling across three islands (at depths of 60–70 m and surface temperatures of 21–23 °C), ten cells were identified via plankton net sampling—a notable finding given the species’ association with harmful algal blooms in other regions. This discovery extends its known range northward along the Pacific coast, raising potential implications for marine ecosystems and coastal communities in the area.
Presencia de la paloma turca (Streptopelia decaocto) en el archipiélago de Revillagigedo, México
A notable finding of the Turkish turtle dove (Streptopelia decaocto) in the Revillagigedo Archipelago, Mexico, was documented for the first time at two islands: Clarión and Socorro. Observations between March and July 2015 revealed adult birds associated with human activity, specifically around a naval base and its vessels. This discovery highlights the species' presence in remote, pristine environments influenced by anthropogenic factors. The study underscores the need for further research to assess the distribution, abundance, and ecological impacts of this invasive species on the archipelago's biodiversity.
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