﻿Checklist of Orchidaceae from Caquetá, Colombia

﻿Abstract A checklist of Orchidaceae from Caquetá, Colombia is presented here. We recorded 98 genera and 418 species, exceeding a previous inventory by 276 species. The checklist is conservative in the number of genera and species by including only taxa that were fully and reliably identified and that are either linked to a corresponding herbarium voucher, a living collection specimen or a photo taken in the field and published in iNaturalist by one of the authors or a collaborator. The documented species diversity in the region could dramatically increase in the next few years with additional collecting efforts in the eastern slopes of the Andes nested in Caquetá. About 9% (418/4600) of all Orchidaceae species recorded for Colombia are reported for this area, showing the important contribution to orchid diversity of Andean-Amazonian foothills of Caquetá.


Introduction
Orchidaceae are one of the most diverse and widely distributed flowering plant families including 25,000-27,000 species and 880 genera (Chase et al. 2015). Colombia has the largest diversity of orchid species in the American tropics (Pérez-Escobar et al. 2022a), hosting ~ 4,600 species that represent ~18% of the known species diversity in the family. The highest level of species richness arises in the northern Andes region of the country (Pérez-Escobar et al. 2022a), where a large number of endemic species occur, accounting for 36.8% of the total species reported for Colombia. With new orchid novelties published annually (Ortiz Valdivieso et al. 2009;Hágsater et al. 2013;Pérez-Escobar et al. 2021, 2022b; Vieira-Uribe and Moreno 2022), Colombia is a hotspot for biodiversity conservation (Betancur et al. 2015).
Caquetá, one of Colombia's 32 Departments, is a largely unexplored region with an extraordinary ecosystem diversity, geographically presenting a variety of landscapes, topographic forms and different types of associated vegetation and water sources, including the Amazon plains, valleys, hills, foothills and mountain ranges (Fig. 1). The Department contains four national natural parks, covers part of the Chiribiquete World Heritage Park and 35 recognised civil society reserves (RUNAP 2022, webpage checked June 2023. Caquetá is placed in the eastern slopes of the Andean foothills, a confluence zone of mountainous and lowland Amazonian landscapes with different communities' composition. The Andean foothills of Caquetá range between 200 and 1000 m a.s.l. The Colombian Eastern Andean Mountain range transitions along an environmental gradient from foothills to either the Guyana Shield (Meta and Caquetá), the Amazon Basin (Caquetá, Putumayo and Amazonas) or the Orinoco Basin (Arauca, Casanare and Meta) (Hoorn et al. 2010). These ecotones are hyperdiverse because of the evolutionary, biogeographical and ecological processes that operate in a rich array of landscapes (Ruiz et al. 2007;Instituto Geográfico Agustín Codazzi 2010). It is perhaps in the confluence of lowland and mountainous landscapes where the greatest wealth of plant species diversity and endemism occurs in the country (Ruiz et al. 2007;Pérez-Escobar et al. 2022a), but the limited existing orchid inventories underestimate the region's species diversity.
Although Orchidaceae are diverse within Caquetá, few checklists and taxonomic studies focusing on this group are available. For example, the Catalogue of Plants and Lichens of Colombia (Bernal et al. 2016), reported a total of 104 orchid species, whereas "The National Orchid Conservation Plan" presented a count of 142 species (Betancur et al. 2015). Currently, Caquetá is severely affected by deforestation driven by anthropogenic transformations of the natural ecosystems (Jaramillo-Castelblanco 2016; IDEAM 2020). Biological diversity inventories of the Andean-Amazonian Region are, thus, crucial to provide information for habitat conservation strategies in the region.
In this study, we generated a detailed species list of Orchidaceae for the Department of Caquetá, one of the most unexplored areas in Colombia, due to, amongst other factors, difficulties such as security risks and lack of easy access routes to some of its regions and municipalities. This is a collective work developed by more than twelve Colombian botanists during 2019-2023, under the umbrella project "Orquídeas para la Paz" (Orchids for Peace). This programme aims to explore, reproduce and support orchid species recovery, while developing sustainable strategies for business, based on horticulture for vulnerable communities around Colombia. Data obtained here come from living collections, photographs taken from field and an extensive review of herbarium collections around the world.

Study area
Caquetá is located in south-western Colombia, between latitudes 0.7°S-2.9°N and longitudes 71°-76°W. It comprises 16 municipalities including Florencia, Belén de los Andaquíes, El Paujil, Doncello and La Montañita, amongst others (Table 1). This region contains a variety of landscapes and ecosystems ranging from the Eastern Cordillera of the Andes to the Amazonian plains, with elevations ranging from 0-3200 m a.s.l. The mean annual rainfall is about 2179 mm. The mean annual temperature ranges from 27-29 °C (Instituto Geográfico Agustín Codazzi 2010) (Fig. 1).

Field expeditions
To expand the checklist of Orchidaceae that occur in Caquetá, we carried out a total of 12 field expeditions between 2019 and 2023 for the project "Orquídeas para la Paz." Two expeditions explored part of the Alto Fragua Indi Wasi National Natural Park in collaboration with the Park and ten expeditions explored montane, premontane forests and lowland Amazonian Forest of the Department. Fertile specimens were collected and prepared for herbaria according to techniques used for orchid collections, that includes the preservation of flowers in spirit collections, photographs and tissue collections for ongoing DNA analyses. The specimens were deposited at either the Universidad de la Amazonía (HUAZ) or the Universidad del Valle (CUCV) Herbaria (acronyms according to Thiers 2020). Duplicate collections were made for other herbaria when possible. Living specimens, collected when flowers were not found, were taken to local nurseries at El Caraño, Florencia, located at 950 m a.s.l. for cold weather orchids, or El Manantial, Florencia, located at 300 m a.s.l. for warm weather orchids. Once they flowered, they were photographed, identified and herbarium specimens were made. All collections were deposited under the collection permit of the Universidad de la Amazonia (permit number 01691 October 2020; Indi Wasi National Park memorandum No. 20182200004943) by Alexis Calderón, Marco Correa and Edwin Trujillo.

Resources used
Databases and herbaria were used to find herbarium specimens that were examined to back-up observations without vouchers. Available literature, as well as local, regional and national catalogues were used to find herbarium specimens collected in the region. Only records with a herbarium specimen were considered for this checklist; living specimens and iNaturalist records by one of the authors or collaborators and with a specialist identification were considered in the list, but only as "tentative" until the herbarium collection is available.
To carry out online consultations in herbaria, search criteria were considered using the keywords: "Caquetá", "Orchidaceae", "tropical humid forest", "botanical expeditions", "Amazon region" and "Caquetá River." The "advanced search" option was used for most of the herbaria consulted, since it allows for a more direct search for information. International herbaria consulted, either in person or online, included: Harvard University Oak Ames Herbarium (

Name validation and data curation
Correct scientific names of species were assigned, based on the World Flora Online (WFO 2022), except for the genus Tubella (Luer) Archila, which was accepted as valid following Bogarín et al. (2018). All names were supported by herbarium specimens, photographs uploaded on iNaturalist (www.inaturalist. com) or living collections in one of the local nurseries that supported their presence in Caquetá with reliable taxonomic determination.
All records obtained from herbaria, databases and literature were carefully curated regarding their scientific name, locality, collector and collection number. For localities, names of municipalities were verified and updated. To assign a name to duplicates with different identification, the provenance of each assigned name was investigated, paying particular attention to plants identified by experts, curators and recognised taxonomists, besides using the date of determination and its citation in a publication. Lastly, using photographs and a list of taxonomic groups within orchids, we reached out to as many specialists as possible for their species expertise (see Acknowledgements). This final dataset was used for analyses.

Data analysis
Collection records were georeferenced as precisely as the information allowed, since in many records, the location is not clearly specified, a frequent situation in orchids, old collections and those made by amateurs. Due to the lack of standardised geographical coordinates, only the number of species in municipalities is reported for this study. Georeferenced records and species distribution maps were constructed for the 16 municipalities and are available upon request.

Results
A total number of 228 fertile specimens were collected in the field (collections made by Arias T., Chaux-Varela J., Perdomo O., Trujillo E. and Correa M.), 692 herbarium specimens were reviewed in different herbaria, 100 photographs and two living collections accessed for specimen identifications. The most abundant species in the field were Epidendrum nocturnum Jacq., E. lacustre Lindl., Maxillaria discolor (G. Lodd. ex Lindl.) Rchb. f. and Scaphyglottis stellata Lodd. ex Lindl. Some of the rarest ones only observed in the field once were Cyrtochilum caquetanum P. Ortiz, L. E. Álvarez & A. J. Carrillo, Masdevallia ensata Rchb. f. and Paphinia cristata (Lindl.) Lindl. In "Orquídeas para la Paz" expeditions, 98 species (collections made by Arias T. and Chaux-Varela J.) representing 29 genera were collected. Living individuals that were not flowering in the field were brought to El Manantial (300 m a.s.l.) and El Caraño (950 m a.s.l.) both located in the Municipality of Florencia. Herbaria collections are actively being made once orchids start flowering. A total of 55 species are available at El Manantial and 60 at El Caraño.
We report 418 species belonging to 98 genera represented in 744 herbarium collections including duplicates. Eighty-two species are new reports for Caquetá since they have not been vouchered until this study (Table 1, (Table 1,  . Most genera found in Caquetá (75) have one to three species (Fig. 5). We found two introduced species around urban areas of Florencia, Arundina graminifolia (D. Don) Hochr. and Dendrobium nobile Lindl.; these were not included in the species list.
Eighty-one species are included as "tentative" because they have been accurately identified, but lack a herbarium voucher. Fifty-three out of these 81 were included as potentially distributed in the Caquetá because records produced by the authors and collaborators in the field through photographs were not documented with herbarium vouchers. Such photographic records were submitted to iNaturalist (see https://www.inaturalist.org/projects/orquideas-del-caqueta). Twenty-seven species including 15 in El Manantial and 12 in El Caraño, are part of our living collections. They were collected fertile in the field and identified, but have not been photographed or documented with herbarium vouchers to date.
For the Municipality of Florencia, 192 species were recorded, followed by Solano with 108 and Belén de los Andaquíes with 77 (Fig. 4). Five municipalities including Albania, Morelia, Valparaíso, Milán and La Montañita have three or less records and there are no orchid botanical collections for Curillo and Solita (Table 1)

Discussion
A total of 276 new species records of Orchidaceae were added to the previous orchid report of Betancur et al. (2015), who cited 142 species. The great diversity of Orchidaceae species in Caquetá might be explained by spatial heterogeneity and phytophysiognomies in this region (Etter et al. 2006). The significant diversity of Epidendrum (68/1000) and Maxillaria (59/570) was expected because these are some of largest Neotropical Orchidaceae genera with regards to species number (Fig. 5, Suppl. material 1: table S1). The four most species-rich genera account for 40% of the total species, but they represent 4.12% of the total genera. Forty-three genera included only one species for the region, which corresponds to 19% of the total species and 42% of the total genera. Species in genera, such Encyclia Hook. and Stelis Sw., were challenging to identify and additional taxonomic work is required. One widely distributed and unpublished hybrid Epidendrum × communis Hágsater Ined. was added to the list after specialist advice (Hágsater, pers. comm.) During the construction of this list, we left out collections made by Werner Hopp (Schlechter 1924) since they were collected in Putumayo in 1921 and 1922 when Putumayo was part of the Caquetá intendancy. In 1991, Putumayo was politically recognised as a Department and, as such, it is no longer part of Caquetá. Additionally, some species collected by Hopp were deposited in the Berlin Herbarium (B) and destroyed during Second World War (Suppl. material 1. table S2).
Most orchid species documented in Caquetá are found in the Florencia Municipality (192 spp.). This could be explained by the convenience of collecting around cities and the wide altitudinal gradient in this municipality. We present collections numbers by municipality because conservation strategies might differ between political boundaries in Colombia. Regional Autonomous Corporations (CAR) are the main environmental authority. They are responsible for im- plementing policies and plans from the Ministry of Environment and are granted administrative and financial autonomy. Entities responsible for the formulation of such conservation strategies might benefit more from having such information presented following Departmental divisions. By depositing 140 herbarium specimens at HUAZ (duplicates will be sent to other herbaria) in the framework of this study, we substantially increased its orchid collection to 210 species, positioning HUAZ as the first local herbarium with more herbarium collections from Caquetá than any other herbaria (Fig. 6, Suppl. material 1: table S1). Five of the municipalities of Caquetá, representing ~ 20% of the total geographical area of the Department, had zero to three herbarium collections or species reported (Fig. 4). The areas in the north-eastern part of the eastern Andean Mountain range still need extensive exploration. These areas include the National Natural Park Cordillera de Los Picachos, where landmines were planted by rebel groups during the long armed conflict that lasted for decades and these have not been removed to date. Orchid diversity could significantly increase with the development of intensive exploration in these mountainous ecosystems and a thorough exploration of the Amazonian Forest canopy. For instance, Departments like Antioquia and Huila have been catalogued as having the largest orchid diversity (Betancur et al. 2015); however, these areas of Colombia have not been extensively explored for decades. During our expeditions, two species Cattleya violacea (Kunth) Lindl. and Trichocentrum lanceanum (Lindl.) M. W. Chase & N. H. Williams have been found only in La Laguna del Chaira in the Cartagena del Chaira Municipality. We doubt these species have a natural distribution there. Rather, we suspect they were introduced during the massive effort to bring orchids to La Laguna del Chaira during the 1980s, during which "uninformed" reintroductions of non-native species could have taken place.
This checklist places Caquetá as the eighth Department in Colombia in terms of genera diversity (98 genera) from its original position in the National Plan of Orchid Conservation (15 th place, 62 genera). As for the ranking in species number for Colombia, Caquetá goes from position 17 th (142 spp.) to position 9 th (418 spp.) (Betancur et al. 2015). Caquetá has many orchid genera (98/258 in Colombia) with few species each, 76% of genera having around 1-3 species. Each of these genera include a unique clade distributed in a relatively small area of Colombia. This could be of particular interest in conservation, prioritising evolutionary history over species diversity (Arponen 2012). Caquetá would be one of the regions of Colombia where there are more different genera represented in clades than in other Colombian regions. This work supplies valuable evidence to promote conservation efforts and politics for habitat preservation of the Colombia Andean Piedmont.
Caquetá has lost approximately 30% of its original area due to human impacts, such as cattle ranching. National parks in Caquetá make up 65% of the protected remnants. In the last 50 years, expansion of the agricultural frontier for the establishment of grazing lands, wood extraction and illegal coca crops have destroyed many ecosystems, greatly impacting all national parks. Florencia, for example, is currently undergoing consistent expansion of farming lands ultimately leading to the decimation of natural ecosystems (IDEAM 2020).

Conclusion
Our floristic study is a needed contribution towards a better understanding of the diversity of Colombian orchids. The checklist provides a set of freely-available data on orchid diversity in Caquetá. Furthermore, our study is a baseline panorama of orchid species diversity in the Department, identifying groups of interest for further taxonomic work, especially those which have not been monographed. Lastly, the information provided could enhance local conservation strategies for endangered floristic elements in the Department by adding to a more complete overview of the high orchid diversity in the region. members of different municipalities and regions around Caquetá who guided us, helped us in the field and hosted us in their houses during expeditions for this work. The curators and staff from all herbaria consulted here. Additionally, Eric Hágsater from Herbario AMO; Gerardo Salazar from Universidad Nacional de Mexico (UNAM); Mark Wilson from Colorado College; Adam Karremans and Gustavo Rojas from Lankester Botanical Garden; Stig Dalstrom, Sebastian Vieira, Eugenio Restrepo and Sebastian Moreno for their help in the identification and curation of the specimens. Alvaro Duque from Universidad Nacional sede Medellín provided a list of orchids from Chiribiquete and William Vargas from Corporación Paisajes Rurales provided a list of orchids from field trips he has made around Caquetá.