Previous reports on arachnid predation of herps are common in the Neotropical región and there are records from the Greater Antilles and from Central and South America (De Armas, 2001; Losos, 2009; Silva-Vieira et al., 2012). The herp predation in the Ctenidae family has been well documented with evidence of predation on Espadarana prosoblepon by Cupiennius sp. (Hayes, 1983), Eleutherodactylus coqui by Oligoctenus ottleyi, Eleutherodactylus zugi by Ctenus vernalis (De Armas, 2001), Anomaloglossus stepheni by Ctenus amphora, Adenomera andreae, Dendropsophus minutus and Boana geographica by Ancylometes rufus, Hamptophryne boliviana by Ancylometes sp. (Menin et al., 2005), Adenomera marmorata by Ctenus medius (Barbo et al., 2009), Leptopelis brevirostris by an unidentified species ctenid spider (Barej et al., 2009), Dendropsophus elegans by Phoneutria nigriventer (Santana et al., 2009), Physalaemus cuvieri by Ancylometes sp. (Maffei et al., 2010), Crossodactylus schmidti by Phoneutria nigriventer (Caldart et al., 2011), Scincella cherriei by Anahita sp. (Aguilar-Lopez et al., 2014), Anolis sagrei by Cupiennius sp. (Fonseca-Hernández & Rodríguez-Cabrera, 2014), and Engystomops pustulosus by a ctenid spider (Gallego-Carmona et al., 2017). These predator-prey interactions reveal an important ecological relationship between ctenid spiders and herps. Notwithstanding, the varied Ancylometes (Ctenidae) genus diet ranges from insects to small vertebrates (Bhukal et al., 2015).
Ancylometes bogotensis Keyserling, 1877 is a ctenid spider with a strong presence throughout Central America and in the north and west areas of South America (Hofer & Brescovit, 2000). In Colombia, this species has been reported in fifteen departments: Bolivar, Boyaca, Caldas, Caqueta, Cauca, Choco, Cordoba, Cundinamarca, Magdalena, Meta, Risaralda, Santander, Sucre, Tolima and Valle del Cauca (Hofer & Brescovit, 2000; Hazzi et al., 2013). This species can reach the adult stage in a period between 205 and 230 days of age, during which they undergo 13 and 14 changes in males and females, respectively. During the adult stage, twice a year they lay between 300 and 400 eggs with a hatch time of 22.7 days (Merrett, 1988).
The hunting microhabitats for the Bogota Giant Fishing Spider are the freshwater bodies in the forest (Lapinski & Tschapka, 2013). They are almost always found on the floor, near creeks and small rivers, where they mainly prey frogs (Dehling, 2007; Acevedo et al., 2018; Auguste et al., 2018) and toads (White, 2015; Salcedo-Rivera et al., 2018). Besides, A. bogotensis has been reported as a predator of some species of crab (Bhukal et al., 2015) and fish (Deacon et al., 2015). It is important to mention that, apart from the event here described, there are no other reports of predation of geckos and lizards by A. bogotensis.
Conversely, the Hemidactylus genus has taxonomically and nomenclaturally complex challenging species and, in some species, their external features vary among individuals of the same species. Hence, some taxa of this genus show wide geographic variation and can be easily confused (Carranza & Arnold, 2006). Accordingly, molecular data are increasingly being used to resolve the taxonomy of cryptic species complexes (Lajmi et al., 2016). Accordingly, Hemidactylus angulatus (Hallowell, 1854) will be considered in this paper as Hemidactylus brookii (Gray, 1845). Other authors have also proposed this taxonomic synonym (Bauer & Gunther, 1991; Weiss & Hedges, 2007; Rosler & Glaw, 2010; Caicedo-Portilla & Dulcey-Cala, 2011). Hemidactylus angulatus is an invasive gecko from Guinea and Borneo that inhabits approximately 29.2% of the Colombian territory and recent estimates have indicated that, in the next 33 years, this species will occupy 72.6% of such territory, affecting native species and the natural ensemble and its ecological functions (Urbina-Cardona & Castro, 2011).
We recorded an adult H. angulatus individual on a black plastic sheet covering a compost pile (internal pile temperature 38°C) that was being preyed upon by an adult A. bogotensis in the Tropical Dry Forest area of Centro Universitario Regional del Norte (CURDN) of the Tolima University (5.0027°N, 74.9095°W, Datum WGS84, elevation 290 m above sea level), in the municipality of Armero-Guayabal-Tolima (Colombia). The spider was recorded grasping the gecko with its two pedipalps and chelicerates on the sides at the base of the head (Fig. 1A). Over a period of five minutes of observation, the gecko tried to extricate itself by moving its body and subsequently shed its tail (Caudal autotomy) while the spider remained attached to its head. Finally, the spider moved a few meters with its prey to the surrounding vegetation, a task for which it was unnecessary to change position, make a new attack or release the gecko at any time (Fig, 1B). It should be noted that the compost was on the ground near a high density of trees, where it is normal to find individuals of A. bogotensis, and to find individuals of H. angulatus in the CURDN buildings.
The gecko was identified according to the criteria of Bauer et al. (2006), who describe strongly keeled dorsal tubercles, separated from one another by approximately the width of one tubercle and tubercles that are usually prominent on the dorsum of the head. The ctenid spider was identified by following the description of the Ancylometes genus (Höffer & Brescovit, 2000), which depicts the form of the epigyne as resembling a bike saddle with its nose pointing backwards. The distribution of the genus in Colombia (Hazzi et al., 2013) and a description of the external characteristics of A. bogotensis (Merrett, 1988), which correspond to a triangular median plate with a narrow prominent protuberance, were subsequently considered for identification at the species level. The genitalia were then dissected following the classic technique (Levi, 1965), in which the straight copulatory ducts with a ventral contact with the spermatheca were observed. This process was performed in the Arachnological Collection of the Natural Sciences Institute (ICN) of the National University of Colombia.
This report broadens our knowledge about the prey of the Ancylometes genus and could indicate that, in areas where populations of H. angulatus and A. bogotensis live together, these depredation events occur. The spider A. bogotensis could be a biological control agent of H. angulatus, limiting its access to forest areas and tropical dry forest successions.
The species A. bogotensis has been described as an important generalist and opportunistic predator (White, 2015). Therefore, to rule out incidental or opportunistic feeding events and to demonstrate that this gecko or other reptiles are frequently found in this spider species diet, more detailed studies would be necessary.