Albinism in a Yellow-bellied Earth Snake (Geophis godmani Boulenger, 1894) (Serpentes: Dipsadidae) from Central Costa Rica

The Central American anoles, Anolis frenatus, A. insignis and A. microtus belong to a series of eight giant species with standard lengths greater than 100 mm that form the latifrons group. These canopyinhabiting species were formerly rare in collections but have recently been frequently taken in areas of forest destruction. A. frenatus ranges in the lowlands from northeastern and southwestern Costa Rica to northern and central Colombia. A. insignis occurs at intermediate elevations along the slopes of the cordilleras of Costa Rica into eastern Panama. Diaphoranolis brooksi Barbour is an unquestioned juvenile of the latter species. A. microtus is found from 1300-1500 m from central Costa Rica into western Panama. A. frenatus is predominately green in life, has 4 postxiphisternal inscriptional ribs and is allied to the green forms A. latifrons, A. princeps, A. purpurescens and A. squamulatus of eastern Panama and northern South America. A. insignis and A. microtus are predominately brown in life and have 5 postxiphisternal inscriptional ribs and are distinct from the other members of the latifrons group. A. purpurescens of northwestern Colombia known only from the type has 5 postxiphisternal ribs and clearly belongs to the same stock as the other latifrons group giants.

A high-quality data set of 3790 earthquakes were simultaneously inverted for hypocentre locations and 3-D P-wave velocities in Costa Rica. Tests with synthetic data and resolution estimates derived from the resolution matrix indicate that the velocity model is well constrained in central Costa Rica to a depth of 70 km; northwestern and southeastern Costa Rica are less well resolved owing to a lack of seismic stations and seismicity. Maximum H2O content and seismic wave speeds of mid-ocean ridge basalt and harzburgite were calculated for metamorphic phase transformations relevant to subduction. Both the 3-D P-wave velocity structure and petrological modelling indicate the existence of low-velocity hydrous oceanic crust in the subducting Cocos Plate beneath central Costa Rica. Intermediate-depth seismicity correlates well with the predicted locations of hydrous metamorphic rocks, suggesting that dehydration plays a key role in generating intermediate-depth earthquakes beneath Costa Rica. Wadati–Benioff zone seismicity beneath central Costa Rica shows a remarkable decrease in maximum depth toward southeastern Costa Rica. The presence of asthenosphere beneath southeastern Costa Rica, which entered through a proposed slab window, may explain the shallowing of seismicity due to increased temperatures and associated shallowing of dehydration of the slab. Tomographic images further constrain the existence of deeply subducted seamounts beneath central Costa Rica. Large, low P-wave velocity areas within the lower crust are imaged beneath the southeasternmost volcanoes in central Costa Rica. These low velocities may represent anomalously hot material or even melt associated with active volcanism in central Costa Rica. Tomographic images and petrological modelling indicate the existence of a shallow, possibly hydrated mantle wedge beneath central Costa Rica.

Lepanthes is one of the most diverse genera in the Neotropics, representing a significant portion of Costa Rica’s orchid flora. However, the taxonomic identification and delimitation of Lepanthes species remain incomplete, particularly in the highly diverse regions of the Neotropics. While previous studies have recorded Lepanthes demissa in Costa Rica, some of these records actually correspond to an undescribed species that morphologically resembles Lepanthes mentosa. This study aims to clarify the taxonomic status of populations previously identified as L. demissa in Costa Rica. Our findings indicate that L. demissa is restricted to southern Costa Rica and western Panama along the Cordillera de Talamanca. In contrast, the populations from central Costa Rica previously assigned to this species represent a distinct, undescribed species, which we name here as L. gibbosa. The new species resembles L. mentosa but can be distinguished by its longer ramicauls, longer coflorescences, yellowish-white flowers with red veins, orange petals marked with a red spot, upper petal lobes that are convergent and longer than the lower lobes, the lip with oblong-ovate lobes, 1.0–1.3 mm long with an oblong, external, subquadrate, slightly reflexed appendix and a column that is concealed by the thick body when viewed from the front. Additionally, we provide detailed information on its distribution, habitat, phenology, and conservation status. Conservation efforts should prioritize ongoing fieldwork to confirm the presence of L. gibbosa within protected areas.

A tomographic study has been carried out in Costa Rica utilizing teleseismic events recorded by the national seismic network OVSICORI-UNA. The data consist of 130 earthquakes which occurred at epicentral distances of 23°–100° (P phases) and 110°–180° (PKP phases). 1378 IASP91 traveltime residuals were computed and inverted using an iterative linearized inversion procedure which incorporates 3-D minimum-traveltime ray tracing. The 3-D velocity structure of the upper mantle, as derived from teleseismic tomography, shows a northeastward-dipping high-velocity body beneath northern Costa Rica, interpreted as the subducting Cocos plate. Although less evident, a similar pattern of lateral heterogeneities characterizes the deep structure of central Costa Rica. There is no evidence for deep high-velocity bodies beneath southern Costa Rica. The 3-D reconstruction of the subducting Cocos Plate shows a steeply dipping slab (subvertical) beneath northern Costa Rica. Here the oceanic lithosphere is older and denser than in central Costa Rica, where the slab dips at about 60°. Southern Costa Rica does not show a dipping slab; this is in accordance with the subduction/collision of the thick and buoyant Cocos Ridge. The geometry of the slab, the maximum velocity anomalies and the sudden change in the local seismicity depth pattern suggest the existence of a tear in the subducted plate, located between the northern and central Costa Rican subduction zones. The strain field in the overriding plate indicates a strong structural control induced by the along-trench variations in subduction. Northern Costa Rica shows slight tensile deformation, while southern Costa Rica displays moderate to strong compressive deformation. The maximum horizontal gradient of the strain field is located in central Costa Rica where a sinistral transcurrent fault system crosses the country from the Pacific to the Atlantic coast. This system is likely to be generated by the along-trench variations in subduction.

Geophis downsi, a new species of colubrid snake, from southwestern Costa Rica, is most closely allied to G. ruthveni of central and northern Costa Rica, but the known ranges of the two are separated by a distance of 230 km. The former differs from the latter in lacking supraocular and postocular plates and in having a higher subcaudal count. The new form belongs to the championi group of the genus, which also includes G. championi of western Panama, G. godmani of Costa Rica and western Panama, as well as G. ruthveni.

The appearance of adakitic magmas with steep rare earth element (REE) patterns in southern Costa Rica and Panama at ∼4 Ma coincides with the collision of the Cocos Ridge and the inception of slab shallowing along the margin. Distinctly higher 206Pb/204Pb and 208Pb/204Pb ratios in these adakitic lavas than in older Miocene lavas suggest that components enriched in radiogenic Pb also entered the mantle magma source at ∼4 Ma. Published Pb‐isotopic data for Central American arc lavas show that a similar radiogenic component is not present in lavas farther north and that maxima in post‐Miocene 206Pb/204Pb and 208Pb/204Pb ratios occur in central Costa Rica and western Panama. Cretaceous and early Tertiary ophiolites in the forearc, whose origins have been linked to the Galápagos hot spot, show a similar spatial pattern in Pb isotopic ratios. The incorporation of ophiolitic forearc crust into the mantle wedge by forearc subduction erosion can explain the along‐arc spatial and temporal pattern of Pb‐isotopic ratios in southern Central American arc lavas. Partial melting of crust removed from the base of the forearc and subjected to high‐pressure metamorphism in the subduction channel provides an explanation for the steep adakitic REE patterns in some Costa Rican and Panamanian arc lavas.

On March 25, 1990 a large earthquake (Mw = 7.0, ML = 6.8) occurred at the entrance of the Nicoya Gulf, Costa Rica, at 1322:55.6 UTC, producing considerable damage in central Costa Rica and generating much interest about whether or not the Nicoya seismic gap (Nishenko, 1989) had broken. The local country‐wide seismographic network recorded 6 years of activity prior to this large earthquake, 16 hours of foreshocks, the mainshock, and its aftershocks. This network is operated jointly by the Costa Rica Volcanological and Seismological Observatory at the National University (OVSICORI‐UNA), and the Charles F. Richter Seismological Laboratory at the University of California, Santa Cruz (CFRSL‐UCSC). We obtained high resolution locations from this network and located the mainshock at 9°38.5′N, 84°55.6′W (depth is 20.0 km) and the largest foreshock (Mw = 6.0, March 25, 1990, at 1316:05.8 UTC) at 9°36.4′N, 84°57.1′W (depth is 22.4 km). We find that the aftershock zone abuts the southeast boundary of the Nicoya seismic gap, suggesting that the seismic gap did not rupture. Since the installation of the local network in April 1984 to March 24, 1990, nearly 1900 earthquakes with magnitudes from 1.7 to 4.8 (318 with magnitude 3.0 or larger) have been located at the entrance of the Nicoya Gulf, one of the most active regions in Costa Rica. The March 25 earthquake occurred at the northwest edge of this region, where a sequence of foreshocks began 16 hours prior to the mainshock. The spatial‐temporal distribution of aftershocks and directivity analysis of the mainshock rupture process using teleseismic records both indicate a southeast propagating rupture. The mainshock ruptured an asperity of approximately 600 km2 of area, with this area expanding to 4000 km2 after 7 days. We present evidence that suggests that the ruptured asperity is produced by the subduction of a seamount. Inversion of teleseismic broadband and long‐period P and SH waves yields a thrust faulting mechanism with the shallow plane striking 292°, dipping 26°, and with a rake of 88°, in agreement with the subduction of the Cocos plate under the Caribbean plate. Local first motions for the largest foreshock and the mainshock agree with this solution. We also present evidence suggesting that the March 25, 1990, earthquake triggered and reactivated several seismic swarms in central Costa Rica and temporally decreased the activity in the epicentral area of the July 3, 1983 (Ms = 6.2), Pérez Zeledón earthquake.

Boron geochemistry of the Central American Volcanic Arc: Constraints on the genesis of subduction-related magmas

An array of broadband seismometers transecting the Talamanca Range in southern Costa Rica was operated from 2005 until 2007. In combination with data from a short‐period network near Quepos in central Costa Rica, this data is analyzed by the receiver function method to image the crustal structure in south‐central Costa Rica. Two strong positive signals are seen in the migrated images, interpreted as the Moho (at around 35 km depth) and an intra‐crustal discontinuity (15 km depth). A relatively flat crustal and Moho interface underneath the north‐east flank of the Talamanca Range can be followed for a lateral distance of about 50 km parallel to the trench, with only slight changes in the overall geometry. Closer to the coast, the topography of the discontinuities shows several features, most notably a deeper Moho underneath the Talamanca Mountain Range and volcanic arc. Under the highest part of the mountain ranges, the Moho reaches a depth of about 50 km, which indicates that the mountain ranges are approximately isostatically compensated. Local deviations from the crustal thickness expected for isostatic equilibrium occur under the active volcanic arc and in south Costa Rica. In the transition region between the active volcanic arc and the Talamanca Range, both the Moho and intracrustal discontinuity appear distorted, possibly related to the southern edge of the active volcanic zone and deformation within the southern part of the Central Costa Rica Deformed Belt. Near the volcanoes Irazu and Turrialba, a shallow converter occurs, correlating with a low‐velocity, low‐density body seen in tomography and gravimetry. Applying a grid search for the crustal interface depth and vp/vs ratio cannot constrain vp/vs values well, but points to generally low values (<1.7) in the upper crust. This is consistent with quartz‐rich rocks forming the mountain range.

Geochronologic and geological data define a 600 ka age for the current volcanic front in Costa Rica. In Nicaragua, this age is less constrained but is likely within the range 600 ka to 330 ka. In Costa Rica, the new geochronologic data significantly improve estimates of the volumes of the volcanoes because they define the contact between the active volcanoes and the previous volcanic front, which is substantially older (2.2 to 1.0 Ma). In addition, the contrast in extrusive volcanic flux between western Nicaragua (1.3 × 1010 kg/m/Myr) and central Costa Rica (2.4 × 1010 kg/m/Myr) is greatly reduced from previous estimates and now within the range of error estimates. We estimate the subducted component of flux for Cs, Rb, Ba, Th, U, K, La, Pb, and Sr by subtracting estimated mantle‐derived contributions from the total element flux. An incompatible element‐rich OIB source for the Cordillera Central segment in Costa Rica makes the subducted element flux there highly sensitive to small changes in the modeled mantle‐derived contribution. For the other three segments studied, the estimated errors in concentrations of highly enriched, subduction‐derived elements (Cs, Ba, K, and Pb) are less than 26%. Averaged over the time of the current episode of volcanism, the subduction‐derived fluxes of Cs, Ba, K, Pb, and Sr are not significantly different among the four segments of the Central American volcanic front in Nicaragua and Costa Rica. The subduction‐derived fluxes of Th and La appear to increase to the SE across Nicaragua and Costa Rica, but the estimated errors in their subduction‐derived concentrations are very high, making this variation questionable. The lack of change in the fluxes of Cs, Ba, K, Pb, and Sr argues that the well‐defined regional variation in Ba/La is the result of changes in the mode or mechanics of fluid delivery into the mantle wedge, not the total amounts of fluids released from the slab. Concentrated or focused fluids in Nicaragua lead to high degrees of melting. Diffuse fluids in Costa Rica cause lower degrees of melting.

The ubiquitous Mexican and Central American stream frogs allied to Eleutherodactylus rugulosus form a confusing spectrum of distinctive to subtly different populations. The condition of the male secondary sexual features: presence or absence of vocal slits and presence or absence of nuptial pads on the thumb, combined with the geographically consistent color (white, pale yellow, gold, orange, red or chestnut) of the venter of adults in life, provide the key to untangling the species problem in this group. For purposes of analysis the populations were grouped by the male secondary sexual features and compared in detail on the basis of 15 other characters of morphology and coloration. Twelve species are recognized within the rugulosus group, and may be placed in four series based on the presence (+) or absence (-) of vocal slits and nuptial pads in adult males. + +: Eleutherodactylus milesi of northern Honduras; E. merendonensis of northwestern Honduras; E. punctariolus of southern Costa Rica and western Panama; E. fleischmanni of Costa Rica; and E. escoces (sp. nov.) a bright red-bellied new species from the slopes (1100-2100 m) of Volcan Barba, Volcan Irazu and Volcan Turrialba of Costa Rica; +-: E. vocalis of northwestern Mexico; a new species, E. azueroensis (sp. nov.) from the Peninsula Azuero of western Panama; and E. taurus of the Golfo Dulce lowlands of southwestern Costa Rica and adjacent Panama; +: E. matudai from the Pacific slopes of extreme southern Mexico and adjacent Guatemala; and a new species, E. angelicus, from the Cordillera de Tilaran and Volcan Poas in Costa Rica; --: E. brocchi of Alta and Baja Verapaz, Guatemala; and the wideranging lowland and slope species known from Mexico to western Panama, E. rugulosus. The Atlantic versant Mexican populations of this species are distinctive and have been variously recognized as a subspecies of E. rugulosus or as a separate species by previous authors. The earliest name for this population is Hylodes berkenbuschii Peters and E. natator Taylor and E. vulcani Shannon and Werler are strict synonyms. The seemingly allopatrically isolated southern populations of E. rugulosus in eastern and southwestern Nicaragua, Costa Rica and Panama are slightly distinct from the main population system of E. rugulosus. The earliest name for the southern stock is Lithodytes ranoides Cope with Liohyla pittieri Guinther a strict synonym. Neither of these populations is recognized as separate from E. rugulosus. E. chiquito Lynch placed by its describer in the rugulosus group is a synonym of E. greggi of extreme southern Pacific slope Mexico and Guatemala, which is a member of the distantly related mexicanus group. Members of the rugulosus group fall into four geographic and ecologic distribution patterns: a) lowland and slope species, centered on the distribution of the wide-ranging E. rugulosus population system, with the allopatric E. vocalis on the northwest Mexican periphery, E. azueroensis on the southwest Panama periphery, the small population of E. merendonensis in northwestern Honduras and E. taurus occupying the Golfo Dulce lowlands of Costa Rica and western Panama, where E. rugulosus occurs only along the Pacific slope (600-1200 m) of the Talamanca-Chiriqui massif; b) E. brocchi and E. matudai in the highlands of southern Mexico and Guatemala; c) E. milesi in the uplands of

Bovine cysticercosis (BCC) is a parasitic zoonotic disease of veterinary and sanitary importance affecting cattle production in Costa Rica. The causal agent is the larval form of Taenia saginata, which requires cattle to complete its life cycle. This study aims to determine the distribution of BCC cases in the country’s export slaughterhouses and to characterize T. saginata in suspicious samples molecularly. A cross-sectional study was conducted, analyzing reports of CCB retentions recorded by the National Animal Health Service (SENASA) between 2015 and 2019 in four export slaughterhouses in the country. The number and distribution of cases in the cantons of Costa Rica were identified from this data. Additionally, cysts suspected of BCC were collected for detection using polymerase chain reaction (PCR). Results showed that of the 852 cases reported, the majority came from Alajuela (33.5%), San José (21.1%), and Guanacaste (10.8%). The cantons of Alajuela (n=118) and San Carlos (n=90) in the province of Alajuela had the highest number of cases. Between June and August, 24 cysts were collected, with the majority originating from the province of Alajuela, specifically 58.3% found in the masseter muscles. PCR analysis identified T. saginata in 11 samples (45.8%), and sequencing revealed two distinct genotypes. One genotype exhibited 100% nucleotide similarity with isolates from South Korea, Brazil, Ecuador, and Belgium, while the other genotype showed similarity with an isolate from China. These findings highlight the prevalence and distribution of bovine cysticercosis in Costa Rica, as well as the importance of implementing effective control and prevention measures.

Oxynetra stangelandi Grishin & Burns, new species, from high elevations of Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica, is most similar to Oxynetra hopfferi Staudinger, known from mountains of central and southern Costa Rica and western Panama. These hesperiid species differ mainly in body color pattern and in DNA barcodes. We compare their barcodes, nucleotide by nucleotide, together with barcodes of a congener and a species of the related genus Olafia, and use the barcode data to show phylogenetic relationships. We describe the new species, its discovery, its male and female genitalia, and its life history as a cloud forest herbivore of Prunus annularis (Rosaceae). In ACG, no other skippers feed on this plant species, and no other skippers of the tribe Pyrrhopygini feed on plants in the family Rosaceae. Various stages of O. stangelandi belong to mimicry complexes. Although our adults, which are reared from wild-caught caterpillars, are split between the sexes (4 males, 6 females), there are scarcely any females of Oxynetra in the world's museums.

Individual preferences and farm-level decisions : experimental evidence from Costa Rica

The geometry of the Wadati-Benioff zone under southern Central America and its tectonic significance: results from a high-resolution local seismographic network