Lesser Antilles Research Articles

Atmospheric contribution to cations cycling in highly weathered catchment, Guadeloupe (Lesser Antilles)

The important fertilizing role of atmospheric dust, and particularly African dust, in tropical rainforests is increasingly recognized but still poorly quantified. To better evaluate dust input into the Caribbean basin, we sampled critical zone compartments of a small forested volcanic catchment in Guadeloupe (soils, parent rock, atmospheric dust, plants, soil solutions, stream and rain waters). The aims of this study are to track sources of cation nutrients (Ca, Mg, K, Sr) developed on highly weathered soil in the rainforest of Guadeloupe, to quantify plant recycling of these nutrients, and to identify constraints on regolith development and its associated nutrient pool.In the Quiock Creek catchment, a large isotopic range of 87Sr/86Sr and εNd values was observed despite the small scale of observation. Sr isotopic composition of the dissolved load varied from 0.7084 in rainfall to 0.7110 in soil solution, whereas it ranges between 0.7068 and 0.7153 for soil samples and between 0.7096 and 0.7102 for plants. The Nd isotopic composition varied between -8.39 in near-surface soil samples to 2.71 in deeper soil. All samples had an intermediate signature between that of the bedrock endmember (87Sr/86Sr=0.7038; εNd=4.8) and the atmospheric endmember (sea salt: 87Sr/86Sr=0.7092 and Saharan dust: 87Sr/86Sr=0.7187, εNd=-11.5).The regolith was built on pyroclastic deposits, but, because of extreme leaching, the regolith has lost its original bedrock signature and inherited an exogenous atmospheric signature. Our results show that only the chemical weathering of the fresh near-surface minerals can provide nutrients to the ecosystem (first 30cm). However, this dust weathering is too low to sustain the tropical forest ecosystem on its own. The cationic mass balance at the catchment scale, as well as the Sr isotopic signature, show that cation and Sr fluxes are of atmospheric origin only and that original bedrock no longer participates in nutrient cycles. The vegetation reflects the 87Sr/86Sr of the dissolved pool of atmospheric Sr.At the soil-plant scale, the cation-nutrient fluxes provided by vegetation (litter fall+leaf excretion) are major compared to input and output fluxes. The annual Ca, K, Sr and Mg fluxes within the vegetation are, respectively, 31, 28, 20 and 3 times greater than the exported fluxes at the outlet of the basin. The residence time of nutrients in the vegetation is 16 years for K and close to 45 years for Sr, Ca and Mg. These results emphasize the highly efficient vegetative turnover that dominates the nutrient cycle in the Quiock Creek catchment.This first characterization of biogeochemical cycles in the Guadeloupean rainforest suggests that the forest community of Quiock Creek is sustained by a small near-surface nutrient pool disconnected from the deep volcanic bedrock. We also demonstrated that, even with efficient nutrient recycling, Saharan dust plays a significant role in maintaining ecosystem productivity in Guadeloupe over long-time scales.

Volcanological context of the Bouillante high temperature geothermal system, Guadeloupe, Lesser Antilles

The hydrothermal manifestations of Bouillante area (Guadeloupe, Lesser Antilles) motivated a geothermal survey in the sixties. Nevertheless, the heat source of the Bouillante hydrothermal system is still debated: (i) local magma body, (ii) magmatic source beneath the centre of the island or (iii) result from the deep circulation.Several arguments support the first hypothesis and the definition of a specific volcanic series, the « Bouillante chain », according to the following characteristics:➢ location: small monogenic volcanoes are scattered along the Caribbean coastline, on- and off-shore;➢ structural control: volcanic centres have developed at the junction of two regional tectonic systems, the NNW-SSE trending Montserrat - Les Saintes fault and the sub-E-W trending Marie-Galante’s grabens system;➢ dynamics: their products often result from a magma - water interaction between, either in an external or internal hydromagmatism;➢ petrology: specific magmatic trend reached an extreme (rhyolitic) level by crystal fractionation.The links between the Bouillante chain and contemporary / neighbouring other Guadeloupe volcanic formations (Les Mamelles domes, Axial chain, Caraïbes mountains, Grande Découverte volcano) are discussed but partly remain to be specified.

3‐D Modeling of Vertical Gravity Gradients and the Delimitation of Tectonic Boundaries: The Caribbean Oceanic Domain as a Case Study

AbstractGeophysical data acquisition in oceanic domains is challenging, implying measurements with low and/or nonhomogeneous spatial resolution. The evolution of satellite gravimetry and altimetry techniques allows testing 3‐D density models of the lithosphere, taking advantage of the high spatial resolution and homogeneous coverage of satellites. However, it is not trivial to discretise the source of the gravity field at different depths. Here, we propose a new method for inferring tectonic boundaries at the crustal level. As a novelty, instead of modeling the gravity anomalies and assuming a flat Earth approximation, we model the vertical gravity gradients (VGG) in spherical coordinates, which are especially sensitive to density contrasts in the upper layers of the Earth. To validate the methodology, the complex oceanic domain of the Caribbean region is studied, which includes different crustal domains with a tectonic history since Late Jurassic time. After defining a lithospheric starting model constrained by up‐to‐date geophysical data sets, we tested several a‐priory density distributions and selected the model with the minimum misfits with respect to the VGG calculated from the EIGEN‐6C4 data set. Additionally, the density of the crystalline crust was inferred by inverting the VGG field. Our methodology enabled us not only to refine, confirm, and/or propose tectonic boundaries in the study area but also to identify a new anomalous buoyant body, located in the South Lesser Antilles subduction zone, and high‐density bodies along the Greater, Lesser, and Leeward Antilles forearcs.

The polygenetic Kahouanne Seamounts in the northern Lesser Antilles island arc: Evidence for large-scale volcanic island subsidence

Remotely operated vehicle (ROV) explorations of the Kahouanne Seamounts, located 25 km SE of Montserrat in the northern Lesser Antilles island arc, have discovered the occurrence of honeycomb-scalloped erosional features on volcanic and limestone outcrops at depths of up to 600 m below sea level (mbsl). These features, combined with the flat-topped morphology of the seamounts, the occurrence of shallow-water carbonates (rhodoliths, benthic foraminifera), and the presence of oxidized, highly-vesicular volcanic fragments, suggest that the seamounts were once subaerial islands and have subsequently subsided to their present depth. The subsidence is likely to have been in response to a combination of 1) graben development southeast of the island of Montserrat where faulting and extension are driven by the accommodation of slip convergence associated with oblique subduction along the Lesser Antilles volcanic arc and 2) regional subsidence inferred from studies of nearby carbonate platforms. 40Ar/39Ar dating of basalt/andesite lavas from the central seamount indicates active volcanism around 5.4 Ma. Shallow-water carbonates recovered from an apparent wave-cut terrace at ~600 mbsl in the same area, were deposited approximately 3 Ma, based on Sr-isotope stratigraphy, indicating significant subsidence of the complex since that time. The total subsidence is in line with displacements in the Kahouanne valley graben and regional subsidence rates inferred from carbonate platform depths around the islands of Guadeloupe and Martinique, implying that intra-arc subsidence has been a significant process shaping the present bathymetry and topography of this island arc.

Reclaiming history: dehumanization and the failure of decolonization

PurposeThe purpose of this paper is to show, with reference to the writings of important decolonization theorists and liberationists, how Nazism in Europe and the establishment of the UN had a significant impetus in awakening the sense of injustice in colonised peoples in Africa and the Lesser Antilles. Colonized peoples were denied human rights through a process of dehumanization, which involved seizing “native” histories and representing them as backward, depraved and savage, awaiting the arrival of European civilization. Marxism, further supported this narrative by denying that “primitive” peoples had histories, and being unable to account for race and racism because of its emphasis on class. Colonization evolved, not into decolonization, but neo-colonialism because of the complicity of “native” bourgeois elites.Design/methodology/approachThe methodology combines historical narrative with theoretical insight from the point of view of the colonised, such as Fanon, Cabral, Mimmi, Ceasare, Nkrumah, etc. It is hermeneutic in its methodology.FindingsPeoples of the Lesser Antilles and Africans were dehumanized; denied human rights; and dehistoricized. Prominent liberation theorists develop these themes and reject elements of Marxism in order to reflect the unique experiences of the colonised. Colonization gets under the skin of the colonised and persists in contemporary societies. Colonization was replaced by neo-colonialism, not decolonization.Research limitations/implicationsThe implications are to bring to the fore the importance of colonialism in relation to western practises of anti-Fascism and the promotion of human rights, while perpetrating Fascist modes of behaviour and denying human rights in colonised countries. Far from being simply an historical phenomenon the insidious implications persist.Social implicationsThe demonstration of how deep the roots of colonialism go, and how difficult the task of decolonization has become as a consequence of systematic western “penetration”.Originality/valueIt looks at colonialism and its widespread injustices through the activists who suffered at the hands of a system of rule based exploitation and dehumanization effected not only by seizing their land, but also their history language and culture, ensuring that decolonization became transformed into neo-colonialism.

Description of a new species of the genus Schizonampa discovered in Martinique (Chilopoda, Geophilidae)

A new species of geophilomorph centipede of the genus Schizonampa Chamberlin, 1914, collected in Martinique Island (Lesser Antilles) is described: S. barberi n. sp. It is distinguished from other species of Schizonampa by a number of morphological characters, particularly its 47 to 51 pairs of legs, its larger size, number of coxal pores and the intermediate part of its labrum. With this discovery and other unpublished data, a provisional list of eight species for the order Geophilomorpha of Martinique is provided, with also a ninth unpublished species of the family Geophilidae.

Is the local seismicity in western Hispaniola (Haiti) capable of imaging northern Caribbean subduction?

Abstract The boundary between the Caribbean and North American plates in the Hispaniola region is the northwestern termination of the North American plate subduction evolving from westward subduction in the Lesser Antilles to southward subduction in the Greater Antilles and oblique collision against the Bahamas platform in Cuba. We analyze P waveforms recorded by 27 broadband seismic temporary stations deployed during the Trans-Haiti project. Seismicity recorded by the temporary network from June 2013 to June 2014 is used to locate the earthquakes. A total of 514 events were identified with magnitudes ranging from 1 to 4.5. Twenty-six moment tensors were calculated by full waveform inversion using the ISOLA software. The analysis of the new moment tensors for the Haiti upper lithosphere indicates that normal, thrust and strike-slip faulting are present but with a majority of thrust faulting. The mean P and T axes for the moment tensors indicated that the current compressional deformation is mainly N-S to NNE-SSW. Moreover, a dozen intermediate-depth earthquakes (>70 km) are located under Haiti, with one event in the south of the island reaching 260 km depth. The seismic data of the Haiti network, over a one-year time period, tend to confirm the existence of a lithospheric slab inherited from southward subduction under the Greater Antilles. The scarcity of the intermediate-depth seismic events in this area may be the effect of the lack of a dense seismic network or may indicate that we image the western slab edge.

First stranding record of Kogia sima (Owen, 1866) in the Colombian Caribbean

The dwarf sperm whale, Kogia sima, is one of the lesser known Odontoceti species, in spite of its worldwide distribution, and is considered rare due to the difficult identification in the field. Detailed information is scarce and mostly comes from stranding events or bycatch animals, just a few sightings correspond to live specimens. In the Caribbean Basin, the species has been reported in the Lesser Antilles, Mexico, Honduras, Costa Rica and Venezuela. We present the first stranding record of Kogia sima in the Colombian Caribbean coast from a pregnant female in Mendihuaca region, Magdalena Department. The specimen showed no fishing or entanglement lines whatsoever, and the overall condition was good. Morphological measurements were taken and the confirmation of the species was made from the following features: body length, height and position of dorsal fin, position of blowhole, and number of teeth in the lower jaw. The record of the adult specimen is documented in the System of Information of Marine Biodiversity of Colombia –SIBM and the fetus is deposited in the Mammal collection of the Museum of Marine Natural History of Colombia –MAKURIWA under the catalogue number INV-MAM004.

The Bunce Fault and Strain Partitioning in the Northern Lesser Antilles

AbstractStrain partitioning related to oblique plate convergence has long been debated in Northern Lesser Antilles. Geophysical data acquired during the ANTITHESIS cruises highlight that the sinistral strike‐slip Bunce Fault develops along the vertical, long, and linear discontinuity between the sedimentary wedge and a more rigid backstop. The narrowness of the 20‐ to 30‐km‐wide accretionary wedge and its continuity over ~850 km is remarkable. The Bunce Fault extends as far south as 18.5°N where it anastomoses within the accretionary prism where the sharp increase in convergence obliquity possibly acts as a mechanical threshold. Surface traces related to subducting seamounts suggest that 80% of the lateral component of the convergent motion is taken up by internal deformation within the accretionary prism and by the Bunce Fault. The absence of crustal‐scale, long‐term tectonic system south of the Anegada Passage casts doubt upon the degree of strain partitioning in the Northern Lesser Antilles.

Impact of hurricanes Irma and Maria on the Pacific Tsunami Warning Center initial tsunami warning capability for the Caribbean region

Abstract. In September 2017, hurricanes Irma and Maria wreaked havoc across the Caribbean region. While obliterating the infrastructure in the Caribbean nations found along their path, both hurricanes gradually destroyed the existing seismic networks. We quantified the impact of the hurricanes on the Pacific Tsunami Warning Center (PTWC) initial tsunami warning capability for the Caribbean region relying on the computation of theoretical earthquake detection and response times after accounting for hurricane-related station outages. The results show that the hurricanes rendered 38 % of the 146 stations available in the Caribbean inoperative. Within the eastern Caribbean region monitored by PTWC the hurricanes exacerbated outages to an astonishing 82 % of the available 76 seismic stations. Puerto Rico, the Virgin Islands, and the Lesser Antilles suffered the brunt of both hurricanes, and their seismic networks nearly disappeared. The double punch delivered by two successive category 5 hurricanes added up to 02:43 and 04:33 min to the earthquake detection and response times, effectively knocking out PTWC's local tsunami warning capabilities in the region. Emergency adjustments, including the temporary reduction of the number of stations required for earthquake detection and ML magnitude release, enabled a faster response to earthquakes in the region than otherwise possible in the aftermath of hurricanes Irma and Maria.

Detection of full and limited amphidromous migratory dynamics of fish in Caribbean rivers

AbstractAll native fishes living in the Caribbean island rivers are considered diadromous but few species have been validated as diadromous. In Guadeloupe (Lesser Antilles) as well as in the other tropical islands, the riverine habitats are subject to strong anthropogenic pressure due to resource modifications or dams. The management of fish biodiversity requires knowledge concerning their life history traits and behaviour that are still unknown for most species at a local scale and at the whole distribution area of the species. In a Guadeloupe river, we inferred the migratory patterns of four freshwater fishes common to Caribbean rivers by the analysis of otolith microchemistry. We found two species Eleotris perniger (Eleotridae) and Sicydium plumieri (Gobiidae) to be completely amphidromous with a marine larval phase and a freshwater adult phase. Agonostomus monticola (Mugilidae) was also found to be amphidromous in this system. The fourth species Gobiesox cephalus (Gobiesocidae) showed elemental ratios suggesting an estuarine larval phase and was defined as “limited amphidromous”. The identification of such life history traits, with limited dispersion abilities, argues for specific management measures in tropical island rivers at a basin scale for the conservation of biodiversity.

Petrological and experimental constraints on magma storage for large pumiceous eruptions in Dominica island (Lesser Antilles)

The general question of the generation of large-volume silicic eruptions is here addressed through the experimental determination of the storage conditions of the primary magmas that generated ignimbritic eruptions at Dominica Island (Lesser Antilles) during the 24–51 ka period of time. The basal plinian fallouts and pumice pyroclastic flows from the large-volume (~ 5 km3 DRE) events of Layou, Roseau and Grand Fond were investigated, together with the smaller ignimbritic eruptions of Grand Bay and Grande Savane. All samples are dacitic (63–66 wt% SiO2) and contain ~ 30 vol% phenocrysts of plagioclase (~ 21 vol%), orthopyroxene (~ 5 vol%) and Fe-Ti oxides (< 1 vol%), in a rhyolitic matrix glass. The most differentiated samples contain additional amphibole (up to 5 vol%) and quartz. Crystallization experiments were performed starting from Layou and Roseau pumice samples at 800 to 900 °C, 200 to 400 MPa, ~ ΔNNO + 1 and for H2O-saturated and H2O-undersaturated conditions. The main phase contents, assemblages and compositions of both natural samples were reproduced experimentally at ~ 850 °C, ΔNNO + 0.6, 7–8 wt% melt H2O and ~ 400 MPa (~ 16 km depth) consistent with magma ponding at the mid-crustal discontinuity. There is also evidence of more differentiated magma batches that may reflect a plumbing system with a significant vertical extension. The relationships between the chamber depth, width and volume argue for eruptions that do not form collapse calderas, in agreement with field evidence. The erupted magma volumes in Dominica are more than five times larger than those emitted in the neighbouring islands (Martinique, Guadeloupe, Montserrat; < 1 km3), which may be explained by a locally extensional tectonic context that favoured assembly of large magma bodies, but also by the rarity of frequently draining upper crustal reservoirs (as evidenced on the neighbouring volcanic systems) that favoured deep accumulation of large volumes of magma during this period and time for differentiation to dacitic compositions.

The role of arc migration in the development of the Lesser Antilles: A new tectonic model for the Cenozoic evolution of the eastern Caribbean

Abstract Continental arc systems often show evidence of large-scale migration both toward and away from the incoming plate. In oceanic arc systems, however, while slab roll-back and the associated processes of backarc spreading and arc migration toward the incoming plate are commonplace, arc migration away from the incoming plate is rarely observed. We present a new compilation of marine magnetic anomaly and seismic data in order to propose a new tectonic model for the eastern Caribbean region that includes arc migration in both directions. We synthesized new evidence to show two phases of backarc spreading and eastward arc migration toward the incoming Atlantic. A third and final phase of arc migration to the west subdivided the earlier backarc basin on either side of the present-day Lesser Antilles arc. This is the first example of regional multidirectional arc migration in an intra-oceanic setting, and it has implications for along-arc structural and geochemical variations. The back and forth arc migrations were probably due to the constraints imposed by the neighboring American plates on this isolated subduction system, rather than variations in subducting slab buoyancy.

Volatile behaviour in the 1995-2010 eruption of the Soufrière Hills Volcano, Montserrat recorded by U-series disequilibria in mafic enclaves and andesite host

Mafic enclaves brought to the surface in volcanic eruptions offer insight into the deeper sections of a volcanic plumbing system, where the degree of interaction between deeper, mafic magma and the magma reservoir directly feeding a volcanic edifice is not well-constrained. At Soufrière Hills Volcano (SHV) on the island of Montserrat, Lesser Antilles, mafic enclaves have been a ubiquitous feature of the andesitic eruptions during the five phases of the 1995-2010 eruption. We use the short-lived isotopes 210Pb and 226Ra within the Uranium series decay chain, which are sensitive to volatile transfer and loss (due to the loss or gain of the intermediary daughter 222Rn), in both the enclaves and the host andesite to reveal significant time-related information. The sequentially erupted andesites are almost entirely in equilibrium or have deficits of 210Pb with the deficits becoming more pronounced over several eruptive phases. We model that the andesitic reservoirs involved were subject to continuous volatile loss both before and during the eruption. The majority of enclaves, however, have excesses of 210Pb, showing volatile enrichment that lasted over a decade. The highest (210Pb/226Ra)0 ratios are from enclaves in Phase II, indicating that the deeper mafic system was closed to fresh gas influx from Phase III onwards. Enclaves are modelled as being sporadically entrained in the andesite prior to eruption, suggesting that enclave formation is not a triggering mechanism for each eruptive phase.

Roles of land bridges in global biogeography and ecosystems

Roles of land bridges in global biogeography and ecosystems

Coastal Processes and Influence on Damage to Urban Structures during Hurricane Irma (St-Martin &amp; St-Barthélemy, French West Indies)

This study aims to better understand coastal processes associated with extreme cyclonic events through the study of the coastal changes, flooding and damage that resulted from the passage of a category 5 hurricane (Irma) on 6 September 2017 over the islands of Saint-Martin and Saint-Barthélemy in the Lesser Antilles. Hurricane Irma was contextualized from tropical cyclone track data and local weather observations collected by Météo-France, as well as high-resolution numerical modelling. Field work involved the study of accretion coasts through qualitative observations, topo-morphological and sedimentary surveys, as well as image acquisition with Unmanned Aerial Vehicle (UAV) surveys during two trips that were made 2 and 8 months after the catastrophe. Wave propagation and flood numerical models are presented and compared to field data. Our field analysis also reports on the devastating impacts of storm surges and waves, which reached 4 and 10 meters height, respectively, especially along east-facing shores. The approaches reveal a variety of morpho-sedimentary responses over both natural and highly urbanized coasts. The analysis shows the effects of coastal structures and streets on flow channeling, on the amplification of some erosion types, and on water level increase. Positive spatial correlation is found between damage intensity and marine flood depth. The signatures of ocean-induced damage are clear and tend to validate the relevance of the intensity scale used in this study.

Mapping geologic features onto subducted slabs

SUMMARY Estimating the location of geologic and tectonic features on a subducting plate is important for interpreting their spatial relationships with other observables including seismicity, seismic velocity and attenuation anomalies, and the location of ore deposits and arc volcanism in the over-riding plate. Here we present two methods for estimating the location of predictable features such as seamounts, ridges and fracture zones on the slab. One uses kinematic reconstructions of plate motions, and the other uses multidimensional scaling to flatten the slab onto the surface of the Earth. We demonstrate the methods using synthetic examples and also using the test case of fracture zones entering the Lesser Antilles subduction zone. The two methods produce results that are in good agreement with each other in both the synthetic and real examples. In the Lesser Antilles, the subducted fracture zones trend northwards of the surface projections. The two methods begin to diverge in regions where the multidimensional scaling method has its greatest likely error. Wider application of these methods may help to establish spatial correlations globally.

Sinkhole and brackish water nereidid polychaetes: Revision of Stenoninereis Wesenberg-Lund, 1958 (Annelida)

Stenoninereis species are nereidids with a small body (ca. 35 chaetigers), dorsal cirri with conspicuous cirrophores and cirrostyles, bare pharynx, and lack of neuropodial ventral ligules throughout the body. Currently, there are two valid species, S.martini Wesenberg-Lund, 1958 from the Lesser Antilles and S.tecolutlensis de León-González &amp;amp; Solís-Weiss, 1997 from Eastern Mexico. Niconlackeyi Hartman, 1958 has been regarded as a junior synonym of S.martini. The examination of type and topotype specimens indicated that N.lackeyi is a distinct species and both species are redescribed, S.martini is restricted to the Caribbean islands, and N.lackeyi is reinstated and transferred to Stenoninereis. Further, Puerto Rican specimens differ from these known species and a new species, S.elisae is also described, featured mainly by large cirrophores and short cirrostyles in anterior and middle chaetigers. Further discussions about their morphology and phylogenetic affinities and a key to identify all known Stenoninereis species are also included.

The Smugglers’ World. Illicit Trade and Atlantic Communities in Eighteenth-Century Venezuela. By Jesse Cromwell

The historiography of the southern coasts of the Caribbean is undergoing a renaissance. Important works focusing on contours and impact of the multiethnic and multinational interactions in this maritime and coastal region, as well as the revolutionary winds that swept Colombia and Venezuela towards independence, have recently emerged. Despite the importance of contraband to colonial Caribbean societies in this period, and the southern Caribbean in particular, works on illicit trade are few. For this reason, Jesse Cromwell’s The Smugglers’ World is a much welcome and needed entry into this collection of new works. Dealing mostly with the first two thirds of the 1700s, Cromwell’s argument is brilliant in its simplicity and persuasiveness. By the time the Bourbons came to power, inhabitants of Venezuela, experiencing commercial neglect from Spain, turned to engaging in an active contraband trade with their English, French and Dutch neighbors in the Lesser Antilles and Curaçao. Borrowing the term “moral economy” from E. P. Thompson, Cromwell describes how coastal Venezuelans saw illicit trade as an inherent right, normalizing contraband as substantively equal to legal commercial practices. Royal bureaucrats generally permitted illicit trade as a necessity, and at times they participated and benefitted themselves from it. Bourbon Spain’s desire to increase colonial revenue sources, however, brought tolerance for smuggling to an end. In order to maximize Venezuela’s revenue, the crown granted the Basque-led Caracas Company a monopoly on Venezuela’s growing cacao production, while entrusting it with policing and curbing the illicit trade in the region. Spain’s thrust to tighten its imperial control Venezuela led to increasing local hostility and dissatisfaction, and conflicts over contraband increased throughout the century.

Kinorhyncha from the Caribbean, with the description of two new species from Puerto Rico and Barbados

Two new kinorhynch species from Puerto Rico (Greater Antilles) and Barbados (Lesser Antilles) are described herein from Dr R. P. Higgins' unexamined Caribbean meiofaunal samples, which have been stored in the Smithsonian Institution collections. The species from Puerto Rico, Cristaphyes cornifrons sp. nov., belongs to the class Allomalorhagida, whereas the species from Barbados, Echinoderes barbadensis sp. nov., belongs to the class Cyclorhagida. C. cornifrons sp. nov. is easily distinguished from most of its congeners by the presence of lateral terminal spines and the absence of male, sexually dimorphic, ventromedial tubes on segment 2, as only other two species of the genus lack these features. Of these, C. cornifrons sp. nov. may be easily differentiated by its pattern of paradorsal, ventrolateral and ventromedial setae. E. barbadensis sp. nov. is unique among its congeners by the combined presence of middorsal spines on segments 4–8, lateroventral spines on segments 6–9, lateral accessory tubes on segment 8, lateroventral tubes on segment 5, ventrolateral tubes on segment 2 and type 2 glandular cell outlets in subdorsal position on segment 2 and in midlateral position on segment 4.