Eastern Ecuador Research Articles

Ceratostema loucianae and Disterigma chriscanadayi (Ericaceae: Vaccinieae)—new epiphytic species from eastern Ecuador

Ceratostema loucianae and Disterigma chriscanadayi (Ericaceae: Vaccinieae), species of pendulous epiphytic shrubs, from eastern Ecuador and of ornamental potential are described and illustrated.

CFD simulation of the surface pumping of heavy crude oil in eastern Ecuador

The research addresses the study of heat exchange between heavy crude oil and the environment during surface pumping, specifically of a crude oil with an API gravity of 17.5, under the particular atmospheric conditions of Eastern Ecuador. The main objective of the study is to evaluate the temperature loss in a 50-meter segment of SCH-80 pipe, with a diameter of 4 inches, used for the transportation of heavy crude. This aims to understand how heavy crude loses temperature and to determine the convective coefficient, knowing that the heat loss from the fluid to the environment occurs mainly by convection. This is to determine what the temperature losses will be in longer pipe sections. For this purpose, a methodology using computational fluid dynamics (CFD) simulation was employed, a key tool for predicting the thermal behavior of crude in interaction with the environment. It was determined that the convective coefficient is 52 W/m2.K, and there is a temperature loss of 3.2 K in the 50-meter section. With this data, future research could evaluate potential heating technologies that facilitate the transport of heavy crude oil. This approach would allow for exploring innovative solutions to improve efficiency and effectiveness in managing heavy crude, facing one of the main challenges in its transport: managing its high viscosity

Sharp declines in observation and capture rates of Amazon birds in absence of human disturbance

Across the globe, unprecedented declines have been reported across a range of taxa. Among the most well documented are declines in bird populations, with most declines attributable to human activities such as deforestation and other alterations to habitats. There is increasing evidence that bird populations also have declined at sites within large expanses of relatively undisturbed lowland tropical forest, such as in Amazonia. Causes of such declines likely are varied and may be related to direct or indirect effects of climate change. Here, we use mist-net data and direct observations to examine changes in bird numbers over a 22-yr period on two 100-ha study plots in an Amazonian lowland forest of eastern Ecuador. As previously reported, capture rates experienced large declines from 2009 on; observation rates also showed large declines through 2013 but subsequently have shown no consistent trend up or down. Overall capture rates and observation rates are now approximately half the rates during the first decade. Most foraging guilds also declined over time, with declines particularly pronounced among insectivorous groups. With few exceptions, patterns of change were similar between plots suggesting a more general response rather than responses to local factors on each plot. Capture rates and observation rates of ∼90% of the most common species in both understory and canopy were lower during the latter part of the study, with only a few species (∼10%) showing increases. Similarly, large declines were seen in both canopy and understory mixed-species flocks. Large declines in bird numbers have been noted in other tropical sites that have conducted long-term population studies, including Panama and Brazil, suggesting a response to large-scale factors, such as climate change. While not yet documented, the consequences of losing approximately 50% of population abundance are likely substantial and could result in local extinction of rare species, altered species interactions and social organization, as well as declining ecological function and biotic integrity of these tropical forest ecosystems.

NEW SPECIES OF FROGS (ELEUTHERODACTYLUS: LEPTODACTYLIDAE) FROM THE CORDILLERA ORIENTAL OF NORTE DE SANTANDER AND SANTANDER, COLOMBIA

Three additional species of Eleutherodactylus are described from the Andean forests of the northern Cordillera Oriental. One belongs to the E. conspicillatus species group and appears to be related to the widespread E. wiligrum. Another resembles E. tubernasus in appearance but is related to other frogs found in the Central and Occidental cordilleras. The E. tubernasus species group is re-evaluated, reducing the four once-recognized species to two, which are not closely related. The third new species seems to have a connection to E. ga110110/us (Andean forests of eastern Ecuador) and E. viridis (northern part of the Cordillera Occidental).

Epipleoneura parmula sp. nov. (Odonata: Coenagrionidae: Protoneurinae) from Amazonian Ecuador.

Epipleoneura parmula sp. nov. is described and illustrated based on males from eastern Ecuador (holotype: , ECUADOR, Orellana Province, Primavera, Laguna Taracoa {0.4652S, 76.7638W}, 247 m, 27 July 1977, Dennis R. Paulson & Susan Hills leg., in FSCA). Using the most recent synopsis of the genus (Pessacq 2014), the new species keys to the couplet separating E. pallida Rcenis and E. ocuene De Marmels, but unlike in those species, the epiproct branches are longer, fused nearly their entire length and their tips are accentuated. Adults were collected at a lake and several ponds, indicating that the habitat is lentic, although the nymph is unknown.

Seasonality of reproduction in an ever-wet lowland tropical forest in Amazonian Ecuador.

Flowering and fruiting phenology have been little studied in the ever-wet hyperdiverse lowland forests of northwestern equatorial Amazonia. These Neotropical forests are typically called aseasonal with reference to climate because they are ever-wet, and it is often assumed they are also aseasonal with respect to phenology. The physiological limits to plant reproduction imposed by water and light availability are difficult to disentangle in seasonal forests because these variables are often temporally correlated, and both are rarely studied together, challenging our understanding of their relative importance as drivers of reproduction. Here we report on the first long-term study (18 years) of flowering and fruiting phenology in a diverse equatorial forest, Yasuní in eastern Ecuador, and the first to include a full suite of on-site monthly climate data. Using twice monthly censuses of 200 traps and > 1000 species, we determined whether reproduction at Yasuní is seasonal at the community- and species-levels and analyzed the relationships of environmental variables to phenology. We also tested the hypothesis that seasonality in phenology, if present, is driven primarily by irradiance. Both the community- and species-level measures demonstrated strong reproductive seasonality at Yasuní. Flowering peaked in September-November and fruiting peaked in March-April, with a strong annual signal for both phenophases. Irradiance and rainfall were also highly seasonal, even though no month on average experienced drought (a month with < 100 mm rainfall). Flowering was positively correlated with current or near-current irradiance, supporting our hypothesis that the extra energy available during the period of peak irradiance drives seasonality of flowering at Yasuní. As Yasuní is representative of lowland ever-wet equatorial forests of northwestern Amazonia, we expect that reproductive phenology will be strongly seasonal throughout this region. This article is protected by copyright. All rights reserved.

Elevation and cation exchange capacity determine diversity of ferns in a low-montane tropical rainforest in Ecuador

AbstractFerns (Polypodiophyta) are an abundant floral element of the tropics with high sensitivity to environmental conditions and good indicators of overall biodiversity. Here, we set out to identify which geochemical factors determine fern diversity in a low-montane tropical rainforest in Eastern Ecuador. We conducted a field survey of high-spatial resolution completing a comprehensive fern inventory across two elevational ranges, combined with biochemical characterisation of the underlying soils. While α-diversity was negatively correlated with cation exchange capacity (CEC) and with elevation, β-diversity increased with elevation and with geographic distance, as predicted. Our results confirm that ferns have a high sensitivity to both elevational and environmental gradients, where the latter in this study was derived from enhanced aluminium, iron and calcium contents in some of the studied soils. Further monitoring of fern communities could therefore help to better understand and predict how environmental change may impact biodiversity, with a particular focus on threats potentially arising from toxic elements being released in tropical soils through modified soil CEC.

Notes on the nesting of six species of birds in eastern Ecuador

I present new information on the breeding biology of six bird species found in the Ecuadorian Amazon. I describe, for the first time, the nests of Oleaginous Hemispingus Sphenopsis frontalis and Black-eared Hemispingus S. melanotis, as well as providing the first descriptions of the eggs of Black-eared Hemispingus, Streak-headed Antbird Drymophila striaticeps, Mottle-backed Elaenia Elaenia gigas and Casqued Cacique Cacicus oseryi. I also provide the first detailed nest description for Black-banded Crake Anurolimnas fasciatus, and correct previous descriptions of its eggs.

Observations of golden-mantled tamarins (&lt;i&gt;Leontocebus tripartitus&lt;/i&gt;) in Amazonian Ecuador

&#x0D; &#x0D; &#x0D; Golden-mantled tamarins (Leontocebus tripartitus) are an understudied callitrichid primate whose geographic range extends from the Río Napo and Río Curaray in Perú into eastern Ecuador. Only one behavioral study of this species has been published to date, which focused on the population overlapping the Tiputini Biodiversity Station in Amazonian Ecuador over two decades ago. We reevaluated this same population via a two-month preliminary assessment of demography, ranging patterns, and behavior. We located five groups within a roughly 1 km radius of the station, with group sizes ranging from approximately 5 to 11 individuals. Most groups were unhabituated to human presence, but for one group that was well habituated we collected ranging and behavioral data over approximately 101 follow-hours. The group had a mean daily path length of 1,483 m and home range estimates of 25.9 to 39.9 ha, depending on the method used. Intergroup encounters occurred at a rate of 0.08 per follow hour. Group members exhibited substantial variation in cohesion, with individuals routinely traveling, foraging, and sleeping up to 40 m apart. We observed repeated use of several sleep sites as well as the use of a tree hole as a sleep site (the first recorded use for this species) and documented rapid-avoidance and mobbing anti-predator behaviors. These data suggest substantial changes to the Tiputini golden-mantled tamarin population and provide much needed information on callitrichids from the western Amazon, furthering our understanding of variation in socioecology across the callitrichid radiation overall.&#x0D; &#x0D; &#x0D;

Kleptoparasites of social spider colonies do not track hosts' subdivided population structure.

Organisms with lower dispersal abilities tend to have more genetically dissimilar populations. The same is true for parasites, whose transmission frequency may depend on the population structure of the host. This should be especially true when hosts and parasites face similar barriers to dispersal. Here, we considered the similarities between host and parasite population structure in a social spider system. In this system, host colonies are typified by rapid growth via internal recruitment followed by budding or fission events when colonies grow too large, with each colony representing a distinct population. Host colonies provide habitat for kleptoparasitic spiders, which steal prey from and may also feed directly on host individuals. We asked whether kleptoparasites exhibit a similar degree of population subdivision as their host. Under the free-mixing hypothesis (i.e., horizontal transmission), kleptoparasites would have well-mixed populations across broader regions than a single host nest, whereas host populations would be strongly genetically structured. Under the host-tracking hypothesis (i.e., vertical transmission), kleptoparasites would have a population structure that parallels that of the host. We conducted a genotype-by-sequencing study to assess the population structure of both hosts and kleptoparasites within three nearby regions in eastern Ecuador. We found strong signatures of population differentiation and bottlenecks in the host species, which is congruent with past studies. However, we found that kleptoparasite populations were well mixed across host nests, with no evidence of recent bottlenecks. These results support our free-mixing hypothesis, suggesting that kleptoparasites follow patterns of horizontal transmission in this social spider system.

A new Masdevallia (Orchidaceae: Pleurothallidinae) from the Ecuadorian Amazon foothills of the Llanganates mountains

A new Masdevallia species from eastern Ecuador, is described, illustrated and compared with similar species. The species is most similar to Masdevallia aphanes; both species are small plants for the genus with weak inflorescences that bear striped flowers with acaudate sepals. The horizontal inflorescences with yellow flowers striped with red-brown and the convex, subpandurate lip of Masdevallia rubileoixchelorum immediately distinguishes it from the similar M. aphanes by the abaxially deep sandal-shaped lip and for the ovary with undulate-dentate ribs which are almost keeled.

A new species of Mindomys (Rodentia, Cricetidae) with remarks on external traits as indicators of arboreality in sigmodontine rodents

The diversity of the oryzomyine rat Mindomys (Cricetidae, Sigmodontinae, Oryzomyini), is doubled here with the description of a new species from the remote Cordillera de Kutukú (Ecuador). The novel form can be easily differentiated from Mindomys hammondi –type species of the genus– by a large set of anatomical traits including, among others, larger jugals, parietal “wings” extending to zygomatic roots, larger otic capsules, well-exposed petrosals, narrow zygomatic plates almost without upper free borders, foramen magnum caudally oriented, larger molars, and accessory root of first upper molar present. Until now, the records of Mindomys were restricted to western Andean foothills. The material from Kutukú highlights an Amazonian species and reinforces the valuable biological significance of isolated mountain ranges in eastern Ecuador. Since Mindomys shows some external traits classically related to arboreal life, here we present a brief reappraisal of this poorly explored topic. A partially neglected anatomical system in sigmodontine studies, the fore feet, encloses crucial information reflecting arboreality.

Inter- and intracontinental migration by the Eastern Kingbird (Tyrannus tyrannus)

We recovered 12 archival geolocators deployed on Eastern Kingbirds (Tyrannus tyrannus) breeding in New York (NY; n = 3, 2 with 2 years of data), Nebraska (NE; n = 6, 1 with 2 years of data), and Oregon (OR; n = 3) to describe migratory routes, timing and rates of migration, nonbreeding season distributions, and migratory connectedness. NY fall migrants migrated along the Atlantic coast to Florida, flew either nonstop across the Gulf of Mexico (GoM; 2 of 3 birds) or stopped once along the way (Cuba and Cayman Islands in different years) to land in Yucatan/Central America. Fall birds from NE and OR arrived at the GoM in the region of the border between Texas and Louisiana, and most likely took a land route to Central America. In spring, all NY birds flew nonstop across the GoM, and once in North America, took a more inland route than in fall. Trans-GoM flights were more common among NE and OR birds in spring than fall. Birds migrated faster in spring than fall, and in both seasons, late departure was associated with more rapid migration. Migratory connectivity was low, and all birds from OR, and one bird from NE and NY each, occupied a single region in northwestern Amazonia (southern Colombia, northern Peru, and eastern Ecuador) while in South America. Most kingbirds from NE and NY were intratropical migrants, occupying 2 regions for periods of ≥30 d. The latter birds migrated farther south to western Brazil and northern Bolivia, but then moved north to later use the same area in northwestern Amazonia where other birds remained throughout the overwinter period. Northwestern Amazonia thus appears to be a critical area for all Eastern Kingbirds during the nonbreeding season, possibly because a prolonged wet season supports abundant fruit resources.

Three New Species of Neocalyptrocalyx (Capparaceae) for South America

Abstract— Neocalyptrocalyx (Capparaceae) is a Neotropical genus that comprises eleven species that occur in the lowlands of Brazil, Guyana, French Guyana, Suriname, Venezuela, and Ecuador. The study of collections deposited in herbaria added to field observations allowed the recognition of three species as new to science, and those are formally presented here: Neocalyptrocalyx aequatoriensis, known only from eastern Ecuador, Neocalyptrocalyx atlanticum from the Atlantic Forest, and Neocalyptrocalyx polycataphyllus from the Brazilian Amazonia. Neocalyptrocalyx aequatoriensis represents the new westernmost boundary for the genus and the first generic record for Ecuador. We present diagnoses, descriptions, ink illustrations, field photos, distribution maps, notes on ecology, habitat, morphology, phenology, conservation status, and a key to distinguish the new species from related species.

Spatial and Temporal Patterns of Pelagic Catfish Larvae Drifting in Lowland Rivers of Eastern Ecuador (Pisces: Siluriformes)

This study investigated larval catfish abundance and diversity in various fluvial habitats in the Amazon lowlands of eastern Ecuador. It assessed the relationship between spawning behavior and the hydrological cycle, identified a potential spawning site, and elucidated community assemblages based on larval diversity among river tributaries with differing water chemistry profiles. Sampling sites included the mainstreams of the Napo and Aguarico Rivers and lower reaches of three tributaries. Drift samples were taken before, during, and after strong, rain-induced flooding occurred. Results suggest a strong peak of larval abundances in April, coinciding with the start of the flood period. In the Napo mainstream, samples were dominated by larvae of large migratory pimelodid catfishes, Pseudoplatystoma spp., which were caught between the upriver site in the foothills (254 m a.s.l.) and the downstream Peruvian frontier (175 m a.s.l.). Back-calculations based on water velocity and larval growth rate suggest that most of these larvae originated in the lowlands between those two locations, where the riverbed transitions from rocky to sandy/silty substrate. Thus, it appears that most spawning occurred over sandy substrates rather than the rocky substrates that were dominant above the upriver site. Comparisons of samples taken by day and night at the same sites revealed significantly higher larval abundances at night; thus, larvae must either preferentially drift at night, actively avoid the nets by day, or may do diel vertical migrations (e.g., related to predation pressure or pursuit of prey items). Dominant larval taxa in the whitewater mainstreams differed from those dominating samples from a blackwater mainstream system, and catfish larval assemblages in each of those habitats were distinct from those drifting in small, blackwater tributaries. These results provide key life-history information for catfish species in the Napo River, including for important commercial species, such as Pseudoplatystoma spp. Identification and protection of discrete spawning sites, such as those identified here, are critical to conservation efforts for these species.

Jurassic to Early Paleogene sedimentation in the Amazon region of Ecuador: Implications for the paleogeographic evolution of northwestern South America

The retroarc Amazon region of Ecuador recorded distinct events that are preserved in the Mesozoic-Cenozoic sedimentary record of the Subandean Zone and Oriente Basin. In this contribution, we review the Jurassic to Paleocene geologic and paleogeographic evolution of the Ecuadorian foreland using stratigraphic, sedimentologic, provenance, and geochronological data. Our results provide new insights into the sedimentary systems, stratigraphic framework, depositional ages, and sediment dispersal patterns of retroarc basin fill. During the Early Jurassic, marine deposits of the Santiago Formation formed a carbonate platform in eastern Ecuador. At ~180 Ma, an eastward-prograding deltaic system transported volcaniclastic material from a western volcanic arc. Nonmarine conditions prevailed during most of the Middle to Late Jurassic, characterized by deposition of red beds and intercalated volcanic and volcaniclastic deposits of the Chapiza Formation. Clastic and volcanic deposition dated from ~160 to 130 Ma was coeval with regional extension, as suggested by sedimentologic and seismic data from the Oriente Basin. Provenance results show that a ~ 120 Ma fluvial system at the base of the Hollín Formation was initially sourced from the west and progressively evolved to a mixed source with contributions from the Amazonian Craton and incipient Andean topography. Deposition of the Hollín Formation occurred in a northwest-flowing fluvial system that evolved into an estuary system confined by the Andes to the west and the Amazonian Craton to the east. Coastal to shallow marine deposits of the Napo Formation accumulated during regional sea-level variations throughout the Late Cretaceous. The geometry of coastal deposits and supporting provenance data suggest a drainage system characterized by west-flowing rivers derived chiefly from the Amazonian Craton. The latest Cretaceous (~70 Ma) onset of shortening in the Northern Andes coincided with collision of the Caribbean Plateau. This tectonic episode induced a continental-scale drainage reorganization documented in provenance data showing an Andean origin of the east-directed fluvial deposits of the Maastrichtian–Paleocene Tena Formation.

Rediscovery of Hemigrammus unilineatus (Gill, 1858) (Characiformes, Characidae) in Ecuador after more than three decades

Hemigrammus unilineatus (Gill, 1858) (Characidae) is rediscovered in Yasun&amp;iacute; National Park, eastern Ecuador, where it has not been reported since 1987. We present a detailed taxonomic description, including measurements and photographs, as well as a distribution map of this species in Ecuador. Based on our new evidence, we confirm the presence of H. unilineatus in the Ecuadorian Amazon.

Paleoenvironmental significance of trace fossils from mixed tide- and river-influenced marginal-marine settings, Cretaceous U and M2 Sandstone members, Napo Formation, Oriente Basin of Ecuador

The Upper Cretaceous M2 and U Sandstone members of the Napo Formation are prolific hydrocarbon producers in the Oriente Basin of eastern Ecuador. To understand the depositional origin of these reservoirs, an integrated sedimentologic, sequence-stratigraphic, and ichnologic study, using 490 ft (~149 m) of conventional core from six wells of oil fields located in the eastern part of the basin, was performed. Sedimentary facies, stratal stacking pattern, discontinuity surfaces, and trace fossils were documented. Nine lithofacies and two depositional sequences in each member were identified. Three main broad environments, fluvial, estuarine and deltaic, have been interpreted. Trace fossils are very rare in the fluvial deposits and comprise facies-crossing ichnotaxa. The trace-fossil association of estuarine deposits is of low diversity containing ichnotaxa indicative of marine influence (e.g. Asterosoma, Teichichnus). In comparison, deltaic deposits display higher ichnodiversity, and are more intensely bioturbated, locally including some ichnotaxa (e.g. Zoophycos) that suggest the system may have experienced fully marine conditions sporadically. Controlling factors are typically expressed differently in the various subenvironments as a result of the interplay of tides and river discharge. The most important stress factors were substrate type and consistency, episodic sedimentation, high energy, water turbidity, and changes in salinity. Our integrated approach may prompt similar studies in other hydrocarbon-bearing units in Ecuador.

Geothermal Gradients in the Upper Amazon Basin derived from BHT data

The Upper Amazon Basin (UAB), present foredeep of the sub Andean retro-foreland basin. It comprises Putumayo area (southeastern part of Colombia), Oriente area (eastern Ecuador) and Marañón area (northeastern part of Peru). Bottom Hole Temperature (BHT) from a regional well log database (1076 wells and 2957 logs) were analyzed and data discriminated according to drilling operations (i.e., log acquisition operations, cementing, formation test, tools misreading values), topography and shallow subsurface weathering conditions (i.e., temperature data from wells with depths below 305 m. were avoided). A new normalized database has been setup (1021 wells and 1399 logs). Analysis of this data set has allowed better understanding of the regional distribution of geothermal gradient variations within the study area. The results indicate mean uncorrected geothermal gradient (UCGG) for the UAB of 20.4 °C/km. The UCGG is a first approach based on well data with sufficient information and is useful for comparison purposes with other basin where corrected data is limited. In addition, a new computer-generated contour Geothermal Gradient Map (GGM) has been created, using 56 locations (for which number of BHT at different depths ≥ 3, and temperatures in the range 23.4 to 44.4 °C). As for the locations 2 are in Colombia, 28 in Ecuador and 26 in Peru. This map is useful in analysis data of UCGG due to its wide distribution along the basin. Finally, correction based on Horner´s method was applied to these datasets (where number of BHT ≥3 at the same depth; time since circulation - TSC incremental), obtaining a Corrected Geothermal Gradient (HCGG) of 22.9 °C/km (46 wells and 153 logs). We recommend the use of this gradient for comparative reference purposes.

Cambios en patrones de precipitación y temperatura en el Ecuador: regiones sierra y oriente.

En esta investigación se analizaron series de 40 años de precipitaciones y temperatura de las estaciones meteorológicas de la sierra y el oriente del Ecuador desde 1980 a 2019. Al considerar la variabilidad en las estaciones, fue posible establecer tendencias hacia el aumento o disminución de temperatura a lo largo del tiempo. Las fluctuaciones de las series de datos comparativos mostraron una variabilidad en el comportamiento; por ello, las mismas estuvieron sometidas a una prueba estadística no paramétrica de Mann Kendall para el análisis y estudio correspondiente.