Subterranean amblypygids, or whip spiders, are important yet understudied components of cave ecosystems, playing key roles as apex predators in these fragile, nutrient-limited environments. Their restricted distributions make them particularly valuable for understanding cave ecosystem dynamics and conservation needs. However, the diversity and distribution of these arachnids in Colombian caves remain poorly documented. This study examines 53 specimens of amblypygids from 12 Colombian caves, and compiles all available literature records to provide an updated list of cave-associated species in Colombia. A new species of Charinus is described, based on females collected in a cave in Santander. The genus Heterophrynus is recorded from six Colombian caves; H. yarigui is newly recorded from Tolima, and for the first time to hypogean microhabitats from Cueva de Los Guácharos, Cunday, Tolima); H. cervinus is recorded from Boyacá, Las Cacas Cave, while H. batesii is newly recorded from Guaviare Caves in Serranía La Macarena/La Lindosa, Caquetá, and for the first time in hypogean microhabitats. The male gonopodes of H. guacharo are described from topotipic specimens from Natural National Park Los Guácharos in the Suaza River basin. Phrynus araya is recorded for two additional caves in Santander, and finally Paraphrynus laevifrons, is recorded for the first time from Providencia Island and for insular hypogean environments in Colombia from the cave (Cueva Bat Hole, Chay Hill, and Represa Freshwater Bay). These findings expand the distribution of amblypygids in Colombian caves, improve our understanding of their diversity, and provide important data for developing conservation strategies for subterranean ecosystems.

Biospeleology, checklist, hypogean fauna, Pedipalpi

Amblypygids, commonly known as whip spiders, are nocturnal arachnids that occupy various microhabitats, including crevices, beneath rocks, fallen logs, termite and ant nest, and even trunks of large trees where they forage at night (Armas and Selter 2013; Giupponi and Kury 2013). They inhabit a wide range of environments, such as tropical rainforests, dry forests, morichales (palm swamps dominated by Mauritia flexuosa, typically found in flooded or humid areas), plantations, and anthropogenic areas (Quintero 1981; Armas and Maes 2000; Bloch and Weiss 2002; Armas et al. 2012; Chiriví and Armas 2012; Armas and Selter 2013; Giupponi and Miranda 2016; Vasconcelos et al. 2016; Cubas-Rodríguez and Armas 2023). Notably, amblypygids are frequently associated with caves (Armas and Selter 2013; Torres-Contreras et al. 2019; Moreno-González et al. 2023). Cave-associated amblypygids, found in diverse biomes where caves exist, from tropical rainforest to arid regions, remain understudied, particularly in the context of their ecological and evolutionary adaptations. While many amblypygid species, especially those in the genus Charinus, are often short-range endemics, some species, such as those within the genera Heterophrynus, Phrynus, and Paraphrynus, can occupy broader geographic ranges.

The ongoing global decline in biodiversity (Cowie et al. 2022), along with shifts in species distributions driven by climate change and other human interventions (Chen et al. 2011; Lenoir et al. 2020), highlights the critical need to document contemporary species distributions as a baseline for future research and conservation. This is particularly relevant for amblypygids, as their ecological roles as top predators (Chapin 2019) and their sensitivity to environmental changes make them important indicators of ecosystem health. By studying these arachnids, especially in understudied habitats like caves, we can better understand their adaptations, distributions, and conservation needs in the context of ongoing environmental and climatic changes.

Caves are important ecosystems that harbor unique and often endemic species. Importantly, subterranean ecosystems are increasingly impacted by diverse human activities, including climate change (Vaccarelli et al. 2023), threatening this unique biodiversity (Mammola et al. 2019). Amblypygids are commonly reported in faunistic surveys of caves, playing important ecological roles as apical predators (Araújo et al. 2019; Chapin 2019). Some species exhibit troglomorphic traits, such as elongated appendages and depigmentation, reflecting strict adaptation to hypogean conditions (e.g. Delle-Cave et al. 2009; Souza et al. 2024). However, most information on cave-dwelling amblypygids comes from general inventories rather than in-depth studies on their ecology, behavior, or evolutionary significance.

In recent decades, research on amblypygids has advanced significantly, including in understudied countries such as Colombia. Taxonomic studies have led to the discovery and description of new genus and species in Colombia (e.g. Giupponi and Kury 2013; Chirivi-Joya et al. 2020; Seiter and Gredler 2020; Miranda et al. 2021; Moreno-González et al. 2023). Recent efforts have also proposed a homologous system and standardized nomenclature for male genital structures, providing critical tools for resolving taxonomic complexities within the group (Giupponi and Kury 2013; Löscher et al. 2022). Beyond taxonomy, amblypygids have been locally studied from various diverse perspectives, including intraspecific morphological variation in Colombian populations (Vásquez-Palacios and Chirivi-Joya 2023), ecological analyses of distribution and abundance patterns (e.g., Bloch and Weiss 2002), and predictive habitat modeling in Colombia (Vásquez-Palacios and Chirivi-Joya 2023).

Prior to this study, approximately 19 species of amblypygids were documented in Colombia, with seven reported from hypogean environments. Among these, the genera Heterophrynus Pocock, 1894a and Phrynus (family Phrynidae) are notable for their relatively wide distributions in subterranean ecosystems (e.g. Chapin 2019). Other cave-associated genera, as such Charinus and Jorottui, exhibit more restricted distributions, often limited to single localities. Despite this growing information, we still lack a comprehensive synthesis consolidating existing knowledge and providing updated records of amblypygids in Colombian caves. This synthesis is crucial, as amblypygids are top predators in caves, contributing to maintain ecological balance. Additionally, species with restricted distributions, such as Charinus and Jorottui, could be particularly sensitive to environmental changes due their narrow ecological niches and limited distribution, potentially serving as sentinels for conservation.

This study addresses this gap by synthesizing all available literature on amblypygids associated with caves in Colombia and presenting new records that extend the known distribution of these species. We examined 53 specimens from 17 collection events—each representing a group of individuals collected together at the same locality, date, and habitat—in 12 caves in karstic and pseudokarstic systems across 8 departments. Key findings include the description of a new species of Charinus Simon, 1892 from the department of Santander, description of males gonopods of Heterophrynus guacharo Armas, 2015, the first Colombian record of Paraphrynus laevifrons (Pocock, 1894b) in hypogean environments, and new records of Heterophrynus spp. in Colombia. These results contribute to the understanding of amblypygid diversity in Colombian cave systems and provide a foundation for future research on their ecology, evolution, and conservation.

We produced a list of Amblypygi species from caves in Colombia based on a comprehensive review of the literature and examination and collection of specimens. All examined specimens are deposited in the collection of the Alexander von Humboldt Institute (IAvH), Bogota, Colombia.

Plates of figures were made using Adobe Photoshop CS program, based on digital photographs taken with a Leica M205C stereoscope attached to a Leica DFC450 digital camera. The map was made using the software ArcGIS® 10.1 (ESRI 2024). Description of Charinus sp. nov. follows Miranda et al. (2021). The pedipalp morphology follows Harvey and West (1998) as explained in Miranda et al. (2021), and genital nomenclature follows Giupponi and Kury (2013) and Seiter and Gredler (2020). The abbreviations used in the text and figures are: LaM = lamina medialis; Fi = fistula; LoD = lobus dorsalis; LoL1 = lobus lateralis primus; LoL2 = lobus lateralis secundus; PI = processus internus.

Terminology for specimen records follow the Darwin Core (DWC) standard, allowing for interoperability with the Global Biodiversity Information Facility and other biodiversity resources. For literature-derived data, only locality, coordinates, elevation, and original reference(s) are provided to avoid redundancy, as full details remain accessible in the primary sources.

Our results provide new knowledge on cave-dwelling amblypygids in Colombia, including the description of a new species. The association of Amblypigi with caves in Colombia has been documented in three families and five genera. The monotypic Jorottui, the sole representative of the family Paracharontidae in the New World, may represent a faunal relict of this group (Moreno-González et al. 2023; Miranda et al. 2024). The family Charontidae is represented by the diverse genus Charinus, with species frequently associated with caves (Miranda et al. 2021), including some troglobitic representatives. Some species lack median eyes, a feature shared by the newly described species C. santandereanus sp. nov. and some geographically nearby cave-dwelling species such as C. rocamadre, C. tronchonii (Ravelo, 1975), and C. bordoni (Ravelo 1977) (Ravelo 1975; Ravelo 1977). Phrynidae being the family most widely represented and known, it is also the most abundant in the Colombian cave fauna, with three genera: Paraphrynus (1 sp.), Phrynus (2 spp.), and Heterophrynus (5 spp.). A record of this genus was presented by Barriga et al. (2019) for a cave in Santander, but it was not identified to the species level. Paraphrynus is a common representative of the fauna in Central and North America, and parts of the Caribbean, particularly in the Greater Antilles. However, Paraphrynus is present in Colombia in Chocó, and on insular land, specifically in the islands of the San Andrés-Providencia Archipelago, located approximately 750 km north of the Colombian mainland.

The identification and first description of the male genital of the Heterophrynus guacharo from PNN Los Guácharos provides morphological data, enabling comparisons with other species in the genus and clarifying their taxonomic relationships. Additionally, the discovery of Heterophrynus batesii, H. cervinus, and H. yarigui in hypogean environments expands our understanding of their distribution and suggests their ability to exploit subterranean habitats, though further studies are needed to determine their ecological role in these systems. In Colombia, the cavernicolous fauna of Amblypygi predominantly represented by the genus Heterophrynus, in contrast to other South American countries where the genus Charinus is commonly associated with cave and hypogean environments (e.g., Ravelo 1977; Giupponi and Miranda 2016; Barriga et al. 2019; Miranda et al. 2021). In Colombia, Charinus has been recorded in only one cave in the Caribbean, where C. rocamadre occurs sympatrically with Heterophrynus caribensis (Torres-Contreras et al. 2015).

While this study does not establish definitive distribution patterns, we document species occurrences and provides morphological data for cave-dwelling amblypygids in Colombia. Our records of Heterophrynus guacharo, H. batesii, H. cervinus and H. yarigui reveal or ratifies their presence in hypogean environments, though the absence of troglomorphic traits suggests opportunistic rather than obligatory cave use. While this study does not assess ecological interactions or conservation implications, it establishes baseline distribution patterns that differ from Charinus-dominated cave faunas reported elsewhere in South America (Baptista and Giupponi 2002; Vasconcelos and Ferreira 2017), the apparent dominance of Heterophrynus in Colombian caves requires cautious interpretation—this pattern could reflect sampling artifacts favoring larger amblypygids, a true biogeographical segregation, or undetected microhabitat partitioning with smaller taxa.

These findings underscore the importance of standardized cross-regional sampling to differentiate ecological patterns from potential collection biases, while also calling for focused research on environmental drivers of facultative cave occupation in Neotropical systems. These records highlight the need for further exploration and documentation of Colombia’s cave-dwelling fauna, emphasizing the importance of caves as reservoirs of biodiversity, urging future studies to expand taxonomic surveys across cave microhabitats, and assess the conservation value of these ecosystems through species-specific dependency assessments.

Unlike other Amblypygi species, those of the genus Charinus tend to have more restricted distributions and smaller sizes, which contrasts with the broader distributions commonly seen in other larger Amblypygi, even though troglobitic species are typically larger when compared to other representatives of their respective taxonomic groups with epigean populations. These smaller species may be more adapted to confined cave environments and could be more diverse in Colombia than currently known. Members of Phrynidae are often classified as troglophile or trogloxene species (e.g. Armas 2015), without apparent morphological adaptations to the hypogean environment. Records of these species in caves are limited, with most known from single localities or individual caves, except perhaps for H. cervinus, which is known from at least two well-separated caves, without intermediate localities.

Most Amblypigi cave records are from the Eastern and Central Cordillera and the Caribbean Coast, regions with karstic or calcareous origins, as well as from the Serranía La Macarena/La Lindosa, where cave formations have a non-calcareous origin. This may reflect the limited exploration of karst regions in other parts of the country that have shown high karst potential, which may be due to the Racovitzan impediment (Ficetola et al. 2019), where knowledge gaps persist due to insufficient exploration of biodiversity in difficult-to-access systems and regions such as tropical caves.

We thank the Alexander von Humboldt Institute for financial support, which enabled fieldwork and the completion of this study and Universidad del Quindío (100016837). Funding for Article processing charges (APCs) was provided by the Universidad del Quindío under Grant 100016837. We are grateful to the Colombian Speleological Association (EspeleoCol), La Venta Explorazioni Geografiche (Amazonas expeditions), and Corporación CORALINA (San Andrés and Providencia expeditions). We also extend our sincere gratitude to Lorenzo Prendini (AMNH) and an anonymous reviewer for their insightful comments, and editor Stefano Mammola for his guidance and his valuable literature suggestions, all of which substantially improved an earlier version of this manuscript. Special thanks to Norvey Méndez and Caquetá/Amazonas, Miguel Tavares (Guardianes del Yuruparí) for their support during the Guaviare expedition. Manuel F. López collected the new species, with additional contributions from Jhon Amado, Luis Suárez, Gonzalo Valdivieso-Bohórquez, Oscar Barbosa and Henry Gallo. A Jhon C. Neita (IAvH) for information on catalog numbers. Their efforts were essential to this research.