Northwestern Andes Research Articles

Resolving the Drymoniakillipii (Gesneriaceae) complex results in a new species from the northwestern Andes of South America.

A new species, Drymoniaquadrangulata Clavijo & J.L.Clark, sp. nov. (Gesneriaceae, Columneinae), is described from the western Andean slopes of southern Colombia and northern Ecuador. The new species has been historically confused with D.killipii, an endemic species to Colombia, restricted to the lowlands of the Chocó biogeographic region in the departments of Cauca, Chocó, and Valle del Cauca. These two species have large foliaceous calyx lobes that cover at least half of the corolla tube, and tubular-infundibuliform corollas. The new species differs by strigose quadrangulate and sometimes winged stems, leaves reticulate abaxially with obtuse to subcordate bases, midveins green, corolla lobes white to yellow with margins incised to short laciniate, and indehiscent berry fruits. Digital photographs, detailed morphological comparisons with the similar species, and an IUCN preliminary risk extinction assessment are provided for the new species.

A new species of Centrozoros Kukalová-Peck & Peck, 1993 (Zoraptera: Spiralizoridae) from high elevations in the northwestern Andes of Colombia

This study aims to expand the knowledge of angel insects in Colombia. A new species of Centrozoros Kukalová-Peck & Peck, 1993 (Zoraptera: Spiralizoridae) from a high elevation area of Colombia is described. Centrozoros mesenia Lima, Oliveira & Rafael sp. nov. was collected from Andean cloud forest at the Mesenia-Paramillo Nature Reserve. The new species is described based on a male specimen and is characterized mainly by the presence of a leaf-like sclerotized projection at the base of the aedeagus. We present digital images of the new species and a distribution map of the species of Zoraptera registered for Colombia until now.

A New Species of Burmeistera (Campanulaceae, Lobelioideae) from the Pacific Slope of the Northwestern Andes of Colombia

A new species of Burmeistera (Campanulaceae, Lobelioideae) from the Pacific slope of the Northwestern Andes of Colombia, in the Antioquia and Chocó departments, is described. Burmeistera luciae is distinguished by being a hemiepiphytic herb with scandent and glabrous stems; ebracteate peduncle, obconic hypanthium, and its most particular feature, the filiform, ascending, and curved calyx lobes in anthesis; corolla lobes forming an obtuse angle in relation to the tube, falcate; ventral anthers barbate; ellipsoid berries that turn a striking fuchsia color when mature. These characters differentiate it from Burmeistera serraniaguae, B. succulenta, and B. crocodila, the three most morphologically similar species that also inhabit the humid Andean regions of the Chocó biogeographic region between Colombia and Ecuador. Additional comments related to its distribution, etymology, and conservation status are presented.

Synopsis of Lusius Tosquinet, 1903 (Hymenoptera: Ichneumonidae: Phaeogenini) from South America: a new species, new records, and key to Neotropical species.

A new species of Lusius Tosquinet, 1903 (Hymenoptera: Ichneumonidae: Phaeogenini) is described from the northwestern Andes of Colombia, and additionally, the geographic distribution of Lusius ferrugineus Graf, 2000 is expanded to Bahia and Rio Grande do Sul states, Brazil. New comparative diagnoses, distribution maps, and an illustrated key to Neotropical species are also provided.

Tectonic setting of the northwestern andes Constrained by a high-resolution earthquake catalog: Block Kinematics

A high-precision earthquake catalog was generated using source-specific station terms and waveform cross-correlation techniques. This detailed catalog serves to interpret the crustal structure and deformation related to the tectonic setting in Northwestern South America. The Panamá-Chocó Block (PCB) is in contact with the Northwestern Andes causing crustal deformation and hence, fault interaction in the brittle regime leading to a high earthquake production concentrated in the Murindó Seismic Cluster (MSC) which is located in the northeastern corner of the PCB. Slip on the Uramita Fault Zone (UFZ) is a response to the accommodation of the PCB against the North Andean block (NAB), splitting the fault into two segments, marked by an abrupt change in its strike. The north segment of the UFZ, a dextral transform fault (strike = S52°E and near vertical plane), which produced the Mutatá earthquake (2016-09-14, Mw = 6.2). The central segment of the UFZ strikes N12°E and exhibits mainly reverse slip with a subvertical fault plane which produced the 1987-03-19 Mw = 5.4 and 1987-11-11 Mw = 5.3 events. The Murindó sinistral strike-slip fault (strike = N9°W), which produced the great Murindó earthquake (1992-10-18, Mw = 7.1, epicentral intensity XI) is characterized by its wide zone of brittle deformation as a response to internal deformation of the PCB under a compressional NW-SE stress. Intermediate depth earthquakes are widely observed in the area, where we find evidence of the Caribbean slab subducting southwards beneath Panamá. The subduction of the Malpelo microplate to the south, shows high productivity within the Cauca Cluster and the presence of at least three finger-shaped mantle zones of seismicity.

Two new Darwin wasp species of Eiphosoma Cresson, 1865 (Ichneumonidae: Cremastinae) from the northwestern Andes of Colombia.

Two new Darwin wasp species of Eiphosoma Cresson, 1865 (E. nigroandinum Fernandes sp. nov. and E. merceae Fernandes sp. nov.) are described from the northwestern Andes of Colombia. Furthermore, we propose the establishment of a new species-group, E. nigroandinum species-group, to encompass these newly described species. Additionally, we expand the geographical distribution of Eiphosoma vitticolle Cresson, 1865, and complement the findings with a map and digital images.

Distribution of the northern pampas cat, Leopardus garleppi, in northern South America, confirmation of its presence in Colombia and genetic analysis of a controversial record from the country

Abstract The common name of pampas cat includes a complex of small Neotropical felid species found in various habitats of South America. Recently several species of this complex were proposed, but there are few records in the northernmost distribution of the continent, and reports of the pampas cat’s presence in Colombia have been ambiguous. Current northern limits of Leopardus garleppi are limited to the Andes of Ecuador. Here we present the northernmost record of the species, validating its presence in Colombia and review previous controversial records from the country. The new record is based on a road-killed specimen in a dry tropical forest ecosystem in the municipality of Mercaderes, Department of Cauca. Our morphological and genetic comparisons also shown that a previous record from Colombia supported by a single skin recently used to described a new species named Leopardus narinensis belong to Leopardus tigrinus. With the information compiled from new localities in Colombia and Ecuador, the known distribution range for L. garleppi is increased towards the northern part of South America into areas of Tropical Dry Forest. The distribution now includes 14 ecoregions from Colombia to Bolivia, and four in Colombia (Eastern Cordillera real montane forests, Northwestern Andean montane forests, Northern Andean paramo, and the Patía Valley dry forests), which correspond to similar ecosystems inhabited by the species in other Andean landscapes. The potential distribution hypothesis showed that the species has high suitability in large areas of southwestern Colombia (Nariño). With the recording of L. garleppi in Colombia, the number of extant felid species in the country has increased to seven.

Fossil leaves, woods, gastropods, and a crocodile tooth: Is the Amagá Formation worth exploring?

We have generated a spatial framework for macrofossil searching based on the current knowledge of fossil localities and fossil beds reported for the Amagá Formation in the northwestern Andes in Colombia. Our results show that twenty-three fossil localities and ninety-five fossil beds are distributed along this sedimentary succession. Preservation potential is higher in the Lower Member, given the high accommodation space and the dominance of a meandering fluvial system, compared with the Upper Member, where there was less accommodation space with a braided fluvial system controlling it. Our findings show that even though paleontological studies are null in this area, there are several options to find terrestrial macrofossil assemblages that will allow us to investigate the possible biological role of global climatic changes and regional tectonics in the Neotropical biomes based on the Amagá Formation.

Caribbean–South America interactions since the Late Cretaceous: Insights from zircon U–Pb and Lu–Hf isotopic data in sedimentary sequences of the northwestern Andes

The Northern Andes in Colombia developed along an active, convergent margin with a complex subduction-accretion/collision history since Triassic times. Sedimentary basins that developed within, or close to, the evolving margin provide an important record for the tectonic history. Here we present U–Pb and Hf isotopic data of detrital zircons from Late Cretaceous and Miocene sedimentary strata. Two sedimentary sequences deposited in an active margin setting are analyzed in this study along two roughly E–W trending transects. Targeted sedimentary sequences are the Late Cretaceous-Paleocene siliciclastic member of the Penderisco Formation outcropping in the Western Cordillera and the hemipelagic Miocene Beibaviejo Formation overlying the suture zone between the Western Cordillera and the Panama-Chocó Block (PCB). Provenance and Hf isotopic signatures for sediments and volcaniclastic sandstones associated with the Penderisco Formation indicate a maximum depositional age of ca. 57 Ma with input of detrital material from mixed sources from two major domains: an eastern ancient continental domain, and a western Cretaceous oceanic domain that defines the present Western Cordillera. The record from continental sources suggests a para-autochthonous to autochthonous syn-tectonic history. For the Beibaviejo Formation provenance and Hf isotopic data suggest the Penderisco Formation and Eocene rocks with oceanic affinity within the PCB as the main sources and define a middle Miocene maximum depositional age (∼16 Ma). Our results provide a new insight into the evolution of volcaniclastic sequences at the northwestern margin of South America and provide a new constraint on the timing of collision between the PCB and the Andean margin during the middle Miocene.

Taxonomy and Biogeography of Andinia-Complex (Orchidaceae)

The results of a revision of the orchid genus Andinia are presented. The proposed classification is based on outcomes of morphological and molecular studies. Additionally, the similarity of the climatic niches occupied by representatives of the Andinia-complex was calculated and visualized. The highest number of Andinia representatives is found in the Eastern Cordillera real montane forests, while Neooreophilus species are found in two ecoregions—the Eastern Cordillera real montane forests, and the Northwestern Andes. According to the level of endemism, a very unique orchid flora was noted in the Guajira–Barranquilla xeric scrub ecoregion, as well as in the Isthmian-Pacific and the Ucayali moist forests, where single endemic species occur. In the proposed classification, nine genera are recognized within the Andinia-complex, three of which (Xenosiella, Chicalia, and Minuscula) are described in this paper. A key to the identification of all genera is provided. Additionally, sections Amplectentes and Bilamellatae of Neooreophilus are elevated to the subgeneric rank, and subgenus Aenigma is here considered as a separate genus. A complete list of representatives of each taxon is provided, and new combinations are proposed accordingly. A new species of Neooreophilus from Colombia is described.

Insights into Moho depth beneath the northwestern Andean region from gravity data inversion

SUMMARYThe complex Moho topography beneath the northwestern Andes is the result of multiple geodynamic processes during the Cenozoic. To contribute to our understanding of the Moho depth distribution beneath this region, we inverted gravity data from two widely used satellite-derived data sets (EGM2008 and EIGEN-6C4) and one regional airborne Bouguer gravity anomaly map (ANH2010). Their inversion allowed choosing the ANH2010, based on lower residual gravity and a higher agreement with seismic estimations, as the most suitable data set to gain insights into the Moho depth beneath the northwestern Andes and its relationship with previously identified tectonic features. The inverted Moho argues for a 40–50 km depth beneath the Central and Eastern cordilleras, reaching depths beyond 50 km below the Eastern Cordillera, and shallower depths between 30 and 40 km mainly along the foreland region to the east, the Western Cordillera and the coastal plains. Three main thickened crust features of regional extent were identified: (1) a deep Moho expression with a crustal thickness greater than 40 km in the northwesternmost foreland region, which we consider a direct consequence of the adjacent thickened Eastern Cordillera involving the fold and thrust deformation migration from the range towards the foreland, and the flexural deformation proposed for the eastern foothills; (2) a regional deep Moho expression (50–60 km) along the axis of the Eastern Cordillera, related to its shortening history including multiple phases of Cenozoic thick-skinned deformation and magmatic underplating; and (3) a Moho deeper than 60 km in a southern latitude (1°S–1°N) beneath the modern magmatic arc, whose interpretation is more complex, likely a combined result of mafic addition to the base of the crust, foundering tectonics, and lateral displacement of the lower crust prompted by the subducting Carnegie ridge.

A new species of Pristimantis (Anura: Strabomantidae) with a colourful venter from the cloud forests of Colombian western Andes.

The Terrarana frogs of the genus Pristimantis are acknowledged for their direct development into froglets and for their astonishing species richness, which renders it the anuran genus with the highest number of species. We describe a new species of Pristimantis from the northwestern Andes of Colombia. The species is distributed from an area between 2750-2900 m.a.s.l. in the Mesenia-Paramillo Nature Reserve. Pristimantis postducheminorum sp. nov. differs from other, phylogenetically related, or similar resembling Pristimantis taxa by a striking yellow coloration in the ventral area, dark grey coloration in the concealed surfaces of the thighs and groin, absence of nuptial pads, presence of lateral fringes on fingers, presence of vomerine odontophores triangular in shape from the ventral view, and absence of dorsolateral folds. Molecular phylogenetics place this new species close to P. satagius and therefore within the P. ridens species group. The new species is also phylogenetically close and sympatric with the recently described P. ferwerdai, which further indicates that the Pristimantis fauna has been notoriously underestimated in the Colombian western cloud forests, a fact that should be considered in assessments of environmental impact.

Caribbean–South America Interactions Since the Late Cretaceous: Insights from Zircon U-Pb and Lu-Hf Isotopic Data in Sedimentary Sequences of the Northwestern Andes

Caribbean–South America Interactions Since the Late Cretaceous: Insights from Zircon U-Pb and Lu-Hf Isotopic Data in Sedimentary Sequences of the Northwestern Andes

A new species of Cypriconcha Sars (Crustacea: Ostracoda) from high mountain<br>wetlands of Argentina

Cypriconcha hypsophila n. sp. is described and illustrated from high-altitude freshwater bodies within the Argentine province of Catamarca, which represents the first record of this genus in South America. This paper also presents a taxonomical key for identification of all species within the genus. Some comments concerning how this particular species could have spread from the high mountains from the Nearctic region to those of the northwestern Andes are provided.

Plant Trait Assembly in Species-Rich Forests at Varying Elevations in the Northwest Andes of Colombia

Andean forests are home to a strikingly high diversity of plants, making it difficult to understand the main drivers of species assembly. Trait-based approaches, however, help overcome some challenges associated with high taxonomic complexity, providing insights into the main drivers of species coexistence. Here, we evaluated the roles of climate, soil fertility, and symbiotic root associations on shaping the assembly of six plant functional traits (leaf area, specific leaf area, dry leaf matter content, leaf thickness, leaf toughness, and wood density) along an elevational gradient in the species-rich northwestern Andean forests of Colombia. The two main axes of the correspondence RLQ analysis explained 95.75% of the variability. The first axis was associated with the leaf economic spectrum, while the second axis with the tradeoff between growth and survival. Furthermore, the fourth corner method showed that both regional (climatic variables) and local factors (soil fertility, symbiotic root associations, and light distribution) played a key role in determining plant trait assembly. In summary, our study emphasizes the importance of considering both individual size and local factors to better understand drivers of plant trait assembly along environmental gradients.

Synopsis of EcuadorianPterichis(Orchidaceae)

A taxonomic synopsis of the orchid genus Pterichis in Ecuador is presented. All national representatives of this genus are characterized and their floral segments are illustrated. Four new species and two new varieties are described. An updated key to Ecuadorian Pterichis is provided. Plants of the genus are growing mostly as terrestrial herbs at the altitude of 2,300–4,110 m. Often two or more species co-occur in the area of 25 × 25 km. Their occurrence was reported from three ecoregions—the Eastern Cordillera real montane forests, the Northern Andean páramo and the Northwestern Andean montane forests. Seven Ecuadorian Pterichis are endemic.

Earthquake distribution and lithospheric rheology beneath the Northwestern Andes, Colombia

The rheological behavior of the lithosphere beneath the Northwestern (NW) Andes (Colombian) remains uncertain under a complex geological setting. Here, we analyze the earthquake distribution and the stress drop on the western and the eastern of the transition area between the Upper Magdalena Valley (UMV) and the Middle Magdalena Valley (MMV), a zone related to a plate tectonic transition from steeper to flatter subduction style slabs (Nazca and Caribbean plates). Our results consistently explain the tectonic and geodynamic context of the study area supported in two rheological profiles, which reveal the brittle/ductile transition of the lithospheric crust and mantle and allow to constrain the lithospheric rheological thickness. The subduction phenomenon of the Nazca Plate under the South American Plate is observed in the western zone. In the eastern region, we find a remarkable aseismic zone under the Eastern Cordillera below 20-km-deep, which made more difficultan accurate estimation of the crust/mantle boundary. This seismic particularity leads us to support the hypothesis of a delamination process due to the tectonic overload generated by the Eastern Cordillera, and that promotes thermal anomalies. Our results also suggest that the earthquake dataset correlated with rheological estimations may offer a consistent interpretation of the mechanical behavior of the lithosphere.

Knowledge status of predators of the freshwater prawn Cryphiops caementarius (Decapoda: Palaemonidae) in river systems along the North Western Andean region from Perú and Chile

Introduction: Cryphiops caementarius, is an endemic prawn from river ecosystems in Southern Perú and Northern Chile. In these watersheds, natural populations are threatened by multiple anthropic interventions such as mining activities and fishing pressure, but also, by increasing impacts of invasive exotic predators. Information related with predation on C. caementarius is scarce representing a major knowledge gap to ensure suitable management and conservation practices. Accordingly, the further deepening in relevant aspects such as the estimation of populations losses due to predators has been indicated as critical by relevant agencies as FAO. Objective: To conduct a complete registry and classification of C. caementarius predators, updating the knowledge for the Andean region. Methods: A thorough bibliographic review on existing information on C. caementarius' predators from Perú and Chile was carried out calculating percentage of occurrence, relative frequency of species, zoogeographic origin, trophic structure, phenotypic attributes, river zone that inhabits and life stage of incidence. The registry was complemented using semi-structured interviews from prawn´s fishers in central-Northern Chile. Results: C. caementarius is predated along the entire fluvial network (estuary, potamon and rhithron) by 21 species of opportunists, carnivores, omnivores and herbivores, mostly aquatic vertebrates. In turn, these belong to 15 families and six guilds of native, exotic and cosmopolitan species. Approximately 86 % predate on adult prawns, whilst, 71 % on juveniles and 24 % on larvae. More than 40 % of the predation pressure seems to be exerted by native waterfowls and 24 % by exotic fish. Conclusions: The results emphasize the relevance for conservation of native species of predators in the Andean region and the need of control measures on exotic species in a latitudinal basis. Accordingly, this review may serve as an initial decision-making tool for future conservation efforts both on prawns and native biota, but also supporting restocking actions, fisheries management plans and risk assessment for C. caementariuspopulations across the Andean region.

Contemporaneous Paleogene arc-magmatism within continental and accreted oceanic arc complexes in the northwestern Andes and Panama

The basement rocks of the northwestern Andes are composed of accreted, fault bound, slivers of the Cretaceous Caribbean Large Igneous Province (CLIP). Previous geologic mapping, geochronological and geochemical data show that Paleogene arc-like units make up part of the accreted CLIP in SW Colombia (Timbiquí Complex), NW Colombia (Santa Cecilila La Equis Complex), and at the boundary between Colombia and Panama (Acandí Region). Similar Paleogene igneous units have been reported in Ecuador (Silante and Macuchí arc), and Panama (Chagres-Bayano Arc). These arc-like rocks are commonly interpreted to have formed as part of an intra-oceanic arc before accretion to the continental margin. Alternative explanations suggest that the Paleogene igneous rocks in Ecuador were formed within a continental magmatic arc. We compare Paleogene igneous rocks in the San Blas Complex (Chagres-Bayano Arc and Acandí Region), Santa Cecilia la Equis Complex, and the SW Complex (Timbiquí Complex, Silante and Macuchí arcs) using geochemical (major and trace elements), geochronological (zircon U-Pb) and isotopic (zircon Hf, and whole rock Pb, Sr, Nd isotopes) data. Zircon U-Pb analyses yield ages of 46–42 Ma for the Acandí Region, 59–51 Ma for the Santa Cecilia La Equis Complex, and 44–42 Ma for the Timbiquí Complex. Major and trace element data show low-K to calc-alkaline compositions with negative Nb anomaly and LREE/HREE enrichment typically attributed to arc-like signatures, for the three complexes. Pb, Sr, and Nd whole rock and zircon Lu-Hf isotopic data for the Santa Cecilia La Equis and the San Blas complexes, are consistent with a depleted mantle source mixed with Pacific sediments. However, the presence of inherited Proterozoic zircons, elevated 207Pb/204Pb ratios in some evolved igneous rocks, and crystallization under low pressure conditions, suggest assimilation of continental-derived sediments. These data indicate that the Santa Cecilia La Equis and the San Blas complexes likely originated in an intra-oceanic island arc setting, in a close proximity to the South American margin before accretion to the Andean margin. In the case of the SW Complex, the absence of Eu anomaly, slightly depleted HREE, as well as increased Sr/Y values with fractionation, indicate that these magmas formed in a moderately mature arc within a mid-shallow crust level. Moreover, radiogenic Pb and Sr isotopic values for the less evolved igneous rocks of the SW Complex evolving to less radiogenic values suggest involvement of continental sediments in the parental magma source, and assimilation of the mafic basement crust. This indicates that the Paleogene magmatic rocks of the SW Complex originated in a continental arc-like setting within previously accreted slivers of the CLIP.

A new species of Pristimantis (Anura: Craugastoridae) from the cloud forests ofColombian western Andes.

The frogs of the genus Pristimantis are recognized for their characteristic reproductive mode and for their incredible diversity of species, becoming the genus with the highest number of species within tetrapod vertebrates. We describe here a new species of Pristimantis from the northwestern Andes of Colombia. The species was found between 2000-2500 m.a.s.l., mostly within moss hanging of tree branches in a tropical cloud forest. It can be easily distinguished from other Pristimantis species of the western Andes by the unique black and white patterning in the ventral surface and the flanks, the hourglass-shaped dorsal folds, and the prominent conical tubercles on eyelids, heels, and outer edge of tarsus. A phylogenetic analysis further supports its status of a lineage reciprocally monophyletic to P. satagius and separated by a genetic distance of 0.03; the latter species bear whitish rather than predominantly black ventral coloration. To the best of our knowledge, this species is only known from the 2,500 ha nature reserve Mesenia-Paramillo, despite other research on this area of the country. Therefore, the species is declared vulnerable while new evidence on its distribution range is accumulated.