ABSTRACT Aims Fine‐scale floristic heterogeneity is a hallmark of mature tropical forests. Restoring such patterns in degraded habitats should produce more resilient and biodiverse systems, yet these end‐goals are rarely compared across multiple restoration scenarios. We analyzed fine‐scale spatial tree recruitment patterns in a long‐term tropical forest restoration experiment. Location Coto Brus County in southern Costa Rica, 1100–1430 m above sea level. Methods We censused seedlings and saplings in 26 experimental restoration plots (0.25 ha) after 16–18 years and six reference forests. Restoration treatments included the following: (1) plantation—four tree species planted in rows; (2) applied nucleation—six tree nuclei of varying sizes planted with the same four species; and (3) natural regeneration—no trees planted. In 2022, we censused all tree stems ≥ 20 cm and mapped each to 3 × 3 m grid cells. Results Mean local species density of seedlings (per 6 × 6 m quadrat) was significantly greater in plantation (10.9; 95% CI = 10.0–11.9) and applied nucleation (8.4; 95% CI = 7.7–9.3) than in natural regeneration subplots (5.0; 95% CI = 4.5–5.5), as the latter commonly had quadrats with no recruits. Within‐plot Bray–Curtis dissimilarity was highest in natural regeneration, intermediate in applied nucleation, and lowest in plantations. Differences arose primarily from variation in seedling abundance, rather than from species turnover, but did not differ in sapling communities. Recruits of large‐seeded, later‐successional species were significantly less clustered and established more frequently in plot interiors of planted treatments than of natural regeneration. Conclusions After nearly two decades, the extent of initially planted trees did not substantially influence the fine‐scale heterogeneity of recruit community composition beyond spatial variation in seedling density. However, both applied nucleation and plantation restoration approaches resulted in a more even spatial distribution of large‐seeded recruits, highlighting the importance of tree planting for facilitating the recovery of dispersal‐limited species.

The genus Monstera is a diverse group of nomadic vines endemic to the Neotropics, with its greatest diversity concentrated in the montane forests of southern Central America. The Cordillera de Talamanca, spanning southern Costa Rica and western Panama, has emerged as a hotspot for pachycaul Monstera species which exhibit large leaf and inflorescence sizes. This study presents the discovery and description of two new giant Monstera species from Panama: M. corana and M. colossica. Both species occur relatively close to M. gigas in the cloud forests of the southern Talamanca range, an area characterised by high humidity, persistent cloud cover and heterogeneous volcanic soils. We provide detailed morphological descriptions, field observations, distribution maps and comparisons with morphologically related taxa.

ABSTRACTA first instance of parental care by a male‐plumaged hummingbird from a sexually dimorphic species contributes important natural history understanding and helps illuminate the possibility of interesting female‐limited polymorphisms across hummingbird species. Using photos and 2.5 min of video taken at close proximity, we documented a Veraguan mango (Anthracothorax veraguensis) with male plumage both incubating eggs and later feeding nestlings in the town of Palmar Norte in southern Costa Rica. Based on plumage characteristics and range, we rule out the similar green‐breasted mango (A. prevostii) that occurs in close geographic proximity. On‐ground exploration and Google Earth imagery revealed the landscape surrounding the nest as a heterogeneous mix of urban, residential, and agricultural land. Given our assumptions about the bird's sex and age, we speculated on potential mechanisms for male‐like plumage in adult female Veraguan mango (and related species in the Anthracothorax genus), including age‐related plumage ontogeny and the interaction of social and ecological selection pressures. Our observation contributes valuable information to the natural history of the Veraguan mango and opens the possibility of a female‐limited polymorphism in the species.

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.

Abstract Recovery of tree community composition in restored tropical forests relies on successful recruitment of later‐successional species. However, the long‐term effects of different restoration interventions on establishment success of arriving seeds are poorly understood. We evaluated the effects of three restoration treatments on the seed‐to‐seedling transition for later‐successional tree species in a fragmented agricultural landscape in southern Costa Rica. Restoration plots (0.25 ha) were established in a block design nearly two decades prior and spanned a gradient of intervention intensity: natural regeneration (not planted), applied nucleation (planted tree clusters) and plantation (fully planted). We conducted seed addition experiments from 2021 to 2023 using eight species at seven replicate restoration sites and in four nearby remnant forests. We defined the seed‐to‐seedling transition as two stages: seedling emergence and post‐emergence survival. Seedling emergence was highest in natural regeneration (48%), intermediate in applied nucleation (37%) and lowest in plantation (25%) and remnant forests (27%), with high variability across species. First‐year survival of emerged seedlings was greater in applied nucleation than in plantation and was lower in remnant forest than in all restoration treatments. On average, seedlings grew slightly taller in natural regeneration compared to the other treatments. Despite seed mass spanning four orders of magnitude among the eight species, this trait did not explain variation in seedling emergence or survival. Synthesis and applications: Taken together, results suggest that after ~15 years, applied nucleation and natural regeneration plots may provide more favourable conditions for establishment of later‐successional trees than do plantation plots. When the seed‐to‐seedling transition is not a major barrier for the recruitment of later‐successional tree species in restoration plots, practitioners should focus on increasing seed arrival for these species. Seed addition could be a viable strategy to introduce later‐successional species that fail to colonize restoration sites, particularly in restoration sites with low intensity interventions (i.e. natural regeneration or applied nucleation).

Abstract At the Osa Peninsula in southern Costa Rica, magnitude >7 earthquakes have been generated along the Middle American trench in 1904, 1941, and 1983 following a ∼40‐year recurrence interval, suggesting a rupture may be impending. However, regional interseismic coupling remains poorly constrained, largely due to sparse observations that are likely contaminated by aliasing effects of repeating shallow slow slip events (SSEs) that occur roughly every 4 years, but were only discovered recently. These SSEs, while likely reducing megathrust coupling near the trench, may load or trigger the next rupture of the 1983 asperity. Using new continuous Global Navigation Satellite System (GNSS) data from an updated and densified regional network, we derive inter‐SSE rates of deformation and invert for slip deficit and megathrust coupling along the Middle American Trench, implementing block modeling to correct for the motion of the Panama microplate. We invert for slow slip and remove a time‐averaged estimate of cumulative slow slip from our models. Our results indicate that the region of highest inter‐SSE coupling (>0.8) corresponds with the spatial extent of SSE slip. We also find that SSEs are sufficient to release nearly all the elastic strain accumulated over their 4‐year recurrence interval in localized regions. Accounting for this, in the region immediately downdip of the slow slip patch—the same region thought to have ruptured in the 1983 Mw 7.4 event—we estimate an interseismic coupling ratio of ∼0.5–0.7 corresponding to ∼1.75–2 m of accumulated slip deficit since 1983, sufficient to generate a similar magnitude rupture in the future.

Dung beetle communities change quickly following tropical forest restoration: A case study from southern Costa Rica

Recent vertebrate fossil collections in southern Costa Rica have uncovered fragmentary remains of five fossil turtle taxa. These remains were recovered from deltaic sedimentary deposits of the Upper Miocene San Gerardo unit, which unconformably overlies the Early–Middle Miocene Térraba Formation. Most of these remains belong to the highly aquatic living turtle genera Dermatemys and Apalone. Other taxa, which are less frequently found, include Bairdemys and Pseudemys, as well as the extinct terrestrial tortoise Hesperotestudo. Except for the marine-tolerant Bairdemys, all genera exhibit North American affinities, suggesting that this assemblage likely predates the formation of the Central American land bridge and the subsequent biotic interchange with South America.

Three dorsal vertebrae of boid snakes from the Upper Miocene deposits of southern Costa Rica are documented and tentatively assigned to Boa constrictor. These fossils represent the first described snake remains from Costa Rica and their earliest record from Central America north of Panama. Their presence supports the possibility of bidirectional snake dispersal between South and North America during the Late Miocene.

Restoration plantations accelerate recovery of fungal communities of coarse woody debris in southern Costa Rica

Land use change and deforestation drive both biodiversity loss and zoonotic disease transmission in tropical countrysides. For mosquito communities that can include disease vectors, forest loss has been linked to reduced biodiversity and increased vector presence. The spatial scales at which land use and tree cover shape mosquito communities present a knowledge gap relevant to both biodiversity and public health. We investigated the responses of mosquito species richness and Aedes albopictus disease vector presence to land use and to tree cover surrounding survey sites at different spatial scales. We also investigated species compositional turnover across land uses and along environmental gradients. We paired a field survey of mosquito communities in agricultural, residential, and forested lands in rural southern Costa Rica with remotely sensed tree cover data. We compared mosquito richness and vector presence responses to tree cover measured across scales from 30m to 1000m, and across land uses. We analyzed compositional turnover between land uses and along environmental gradients of tree cover, temperature, elevation, and geographic distance. Tree cover was both positively correlated with mosquito species richness and negatively correlated with the presence of the common invasive dengue vector Ae. albopictus at small spatial scales of 90 - 250m. Land use predicted community composition and Ae. albopictus presence. The results suggest that local tree cover preservation and expansion can support mosquito species richness and reduce disease vector presence. The identified spatial range at which tree cover shapes mosquito communities can inform the development of land management practices to protect both ecosystem and public health.

ContextLand use change and deforestation drive both biodiversity loss and zoonotic disease transmission in tropical countrysides. For mosquito communities that can include disease vectors, forest loss has been linked to reduced biodiversity and increased vector presence. The spatial scales at which land use and tree cover shape mosquito communities present a knowledge gap relevant to both biodiversity and public health.ObjectivesWe investigated the responses of mosquito species richness and Aedes albopictus disease vector presence to land use and to tree cover surrounding survey sites at different spatial scales. We also investigated species compositional turnover across land uses and along environmental gradients.MethodsWe paired a field survey of mosquito communities in agricultural, residential, and forested lands in rural southern Costa Rica with remotely sensed tree cover data. We compared mosquito richness and vector presence responses to tree cover measured across scales from 30 to 1000 m, and across land uses. We analyzed mosquito community compositional turnover between land uses and along environmental gradients of tree cover, temperature, elevation, and geographic distance.ResultsTree cover was both positively correlated with mosquito species richness and negatively correlated with the presence of the common invasive dengue vector Ae. albopictus at small spatial scales of 90–250 m. Land use predicted community composition and Ae. albopictus presence.ConclusionsThe results suggest that local tree cover preservation and expansion can support mosquito species richness and reduce disease vector presence. The identified spatial range at which tree cover shapes mosquito communities can inform the development of land management practices to protect both ecosystem and public health.

Tropical forest restoration presents a potential lifeline to mitigate climate change and biodiversity crises in the Anthropocene. Yet, the extent to which human interventions, such as tree planting, accelerate the recovery of mature functioning ecosystems or redirect successional trajectories toward novel states remains uncertain due to a lack of long-term experiments. In 2004-2006, we established three 0.25-ha plots at 10 sites in southern Costa Rica to test three forest restoration approaches: natural regeneration (no planting), applied nucleation (planting in patches), and plantation (full planting). In a comprehensive survey after 16-18 years of recovery, we censused >80,000 seedlings, saplings, and trees from at least 255 species across 26 restoration plots (nine natural regeneration, nine applied nucleation, eight plantation) and six adjacent reference forests to evaluate treatment effects on recruitment patterns and community composition. Both applied nucleation and plantation treatments resulted in significantly elevated seedling and sapling establishment and more predictable community composition compared with natural regeneration. Similarity of vegetation composition to reference forest tended to scale positively with treatment planting intensity. Later-successional species with seeds ≥5 mm had significantly greater seedling and sapling abundance in the two planted treatments, and plantation showed similar recruitment densities of large-seeded (≥10 mm) species to reference forest. Plantation tended toward a lower abundance of early-successional recruits than applied nucleation. Trees (≥5 cm dbh) in all restoration treatments continued to be dominated by a few early-successional species and originally transplanted individuals. Seedling recruits of planted taxa were more abundant in applied nucleation than the other treatments though few transitioned into the sapling layer. Overall, our findings show that active tree planting accelerates the establishment of later-successional trees compared with natural regeneration after nearly two decades. While the apparent advantages of higher density tree planting on dispersal and understory establishment of larger seeded, later-successional species recruitment is notable, more time is needed to assess whether these differences will persist and transition to the more rapid development of a mature later-successional canopy. Our results underscore the need for ecological restoration planning and monitoring that targets biodiversity recovery over multiple decades.

SummaryDuring the preparation of Clusiaceae for the Manual de Plantas de Costa Rica, several new species of Clusia L. were identified but left with lettered informal names. Here, we formally describe two of those. Clusia dotana Hammel can be distinguished most assuredly from morphologically related species by its pistillate flowers with 24 – 26 (– 42) staminodes and the unusual large mass of yellow arillate tissue covering the seeds. Clusia osaensis Hammel is similar to C. dotana but distinct by having relatively longer inflorescences (5 – 15 cm vs 4.5 cm), pistillate flowers with 16 staminodes, and seeds covered in an orange aril. These two new species are known from a limited number of localities and are endemic to mountain and lowland forests on the Pacific slopes in central and southern Costa Rica.

BackgroundThe tropical gar (Atractosteus tropicus), a member of the Lepisosteidae family, is native to regions extending from southeastern Mexico to southern Costa Rica. This species serves as a unique bridge between tetrapods and teleosts due to its phylogenetic position, slow evolutionary rate, dense genetic map, gene similarities with humans, and ease of laboratory cultivation. As a taxonomic sister group to teleosts like the zebrafish (Danio rerio), known for its high regenerative capacity, it remains unclear whether the tropical gar shares a similar ability for regeneration.ResultsThis study aims to elucidate the caudal fin regeneration process in tropical gar through skeletal and histological staining methods. Juvenile specimens were observed over a two-month period, during which they were fed brine shrimp, and anesthetized with 1% eugenol for caudal fin amputation. Samples were collected at various days post-amputation (dpa). Alcian blue and alizarin red staining were used to highlight skeletal regeneration, particularly the formation of new cartilage, while histological staining with hematoxylin and eosin was performed to observe tissue regeneration at the amputation site.ConclusionsThe findings reveal a remarkable ability for caudal fin regeneration in juvenile tropical gar. Given the Garfish evolutionary relationship with teleosts, this opens new avenues for research into tissue regeneration across different groups of Actinopterygii.

Abstract The effects of vertebrate seed predation on the regeneration of restored forests are not well understood because most past studies have focused on seed predation within the first few years after restoration and have measured seed removal without quantifying subsequent seedling establishment of seeds that avoid predation. Quantifying the establishment of seeds that escape predation in restored forests at later stages of regrowth is crucial for anticipating longer‐term recovery trajectories. Here, we evaluated the potential role of vertebrate seed predators in limiting recruitment of later‐successional tree species in nine forests actively restored ≥15 years prior and in four paired remnant forest fragments embedded in an agricultural landscape in southern Costa Rica. We conducted seed addition experiments with four tree species inside and outside vertebrate exclosures and used camera trapping to detect seed predators. To determine the fate of seeds that avoided predation, we also measured seedling establishment after 1 year, given that other mortality factors may compensate in the absence of vertebrate seed predation. We detected two species of birds and five species of granivorous mammals removing seeds. Seed tagging indicated that most removal resulted in predation. For three of the four tree species tested, vertebrate seed predation reduced seedling establishment. The magnitude of this effect depended on species' susceptibility to other causes of mortality during the seed‐to‐seedling transition. Our study demonstrates that vertebrate seed predators can substantially reduce later‐successional seedling recruitment in restored forests and should be considered alongside dispersal limitation and microsite conditions as factors slowing forest recovery.Abstract in Spanish is available with online material.

Land use change drives both biodiversity loss and zoonotic disease transmission in tropical countryside landscapes. Developing solutions for protecting countryside biodiversity, public health, and livelihoods requires understanding the scales at which habitat characteristics such as land cover shape biodiversity, especially for arthropods that transmit pathogens. Evidence increasingly shows that species richness for many taxa correlates with local tree cover. We investigated whether mosquito species richness, community composition, and presence of disease vector species responded to land use and tree cover - and if so, whether at spatial scales similar to other taxa. We paired a field survey of mosquito communities in agricultural, residential, and forested lands in rural southern Costa Rica with remotely sensed tree cover data. We compared mosquito community responses to tree cover surrounding survey sites measured across scales, and analyzed community responses to land use and environmental gradients. Tree cover was positively correlated with mosquito species richness, and negatively correlated with the presence of the common invasive dengue vector Aedes albopictus, particularly at small spatial scales of 80 - 200m. Land use predicted community composition and Ae. albopictus presence. Environmental gradients of tree cover, temperature, and elevation explained 7% of species turnover among survey sites. The results suggest that preservation and expansion of tree cover at local scales can protect biodiversity for a wide range of taxa, including arthropods, and also confer protection against disease vector occurrence. The identified spatial range of tree cover benefits can inform land management for conservation and public health protection.

Golfo Dulce is a fjord-like embayment on the southern Pacific coast of Costa Rica, which encompasses the marine protected area of Piedras Blancas National Park. The gulf is surrounded by mangroves, rocky shores, and sandy beaches that are home to migratory and resident bird species. Here, we provide a checklist of 73 marine birds, including records of six years of annual counts and incidental observations in Golfo Dulce. This paper represents an updated bird list, based on the 1998 Basic Information Units from Instituto Nacional de Biodiversidad. We added 16 species to the list, showing the importance of maintaining a monitoring program of marine birds in the Golfo Dulce area. We have also demonstrated the valuable contributions of citizen science for obtaining scientific information.

Introduction: Worldwide, false killer whales (Pseudorca crassidens) are infrequently encountered, yet long-term studies have shown strong site fidelity as well as long-term associations among individuals in several locations. Detailed studies of this species have primarily been conducted around tropical oceanic islands or in the subtropical southern hemisphere. Objectives: We assess movements and association patterns among false killer whales along the Pacific coasts of the USA, Mexico, Guatemala, Nicaragua, Costa Rica including Isla del Coco, and Panama, representing one of the longest-running (albeit non-continuous) studies of this species. We also examine photos for evidence of interactions with fisheries, a known source of mortality to false killer whales. Methods: From Central America, we selected 212 individuals (50 encounter groups) out of 244 individuals (56 encounters) for inclusion in analyses based on photo quality and distinctiveness. Photos were collected on dedicated surveys from 1991-1994 and dedicated and opportunistic surveys from 1998-2022. Other than the effort off the oceanic Isla del Coco (1993-1994), surveys were undertaken in continental shelf waters. Additionally, we selected by photo quality and distinctiveness 124 (33 encounter groups) out of 189 individuals from southern California and Mexico for inclusion in these analyses. Association patterns were analyzed in SOCPROG and movements were analyzed in R. Results: Of the 328 total individuals, 158 (48.2 %) were encountered more than once, and 114 (34.8 %) were re-sighted after a year or more. The longest individual sighting history spanned 26.2 years with six re-sightings over that period between southern Costa Rica and Panama. Association and movement analyses revealed that individuals identified off southern Costa Rica and Panama linked into a single social network, with extensive movements between the two countries. Three individuals encountered off northern Costa Rica were re-sighted off northern Nicaragua, and individuals encountered off Nicaragua were encountered off Guatemala and central mainland Mexico. Nine matches were found among false killer whales between central mainland Mexico and Central America. There were no matches between the mainland coastal waters and the 33 individuals encountered around Isla del Coco. Dorsal fin disfigurements consistent with interactions with line fisheries ranged from 0 to 21 % for individuals within social clusters identified by community division. Conclusions: The infrequency of sightings combined with a high re-sighting rate of individuals and groups from the same area, suggests multiple small populations with large home ranges that include coastal waters. Small populations are sensitive to environmental changes, and as the human population grows, so do the demands on fisheries and ecotourism, which could directly impact the different populations. Additional effort in offshore areas is needed to determine the population status of false killer whales in pelagic waters, how often false killer whales using coastal waters move into pelagic waters, and the relationship between whales in the two habitats.

Five events observed off the Osa Peninsula shed new light on the role that these small, slow earthquakes can play in strain accumulation and tsunami hazards along subduction zones.