Coleodactylus

Diversity

Coleodactylus is a genus of small South American geckos that consists of 5 species ( Coleodactylus brachystoma , Coleodactylus elizae , Coleodactylus meridionalis , Coleodactylus natalensis , and Coleodactylus septentrionalis ). A sixth species, Chatogekko amazonicus , was formerly attributed to this genus but has recently been identified as being polyphyletic and is now recognized as its own genus ( Chattogekko ), a sister taxon to all other genera in the family Sphaerodactylidae (Gamble er al., 2011). The miniaturized morphology (maximum snout-vent length = 27.4mm) of species in Coleodactylus allows them to occupy ecological niches uninhabited by other lizard species, utilizing tiny prey items which are abundant and not eaten by other vertebrates (Lisboa, Sales, and Freire, 2012). However, due to their small size, they compete with a variety of invertebrate species and are predated on by larger lizards and frogs (Vitt et al., 2005). When threatened, Goias geckos ( C. brachystoma ) will expose their orange ventrum by folding their tail over their body, mimicking local scorpions. This is one of few known examples of invertebrate mimicry by vertebrates (Brandão and Motta, 2005).

Geographic Range

Coleodactylus is distributed entirely withing the Amazon rainforest, east of the Andes. Most species have ranges within north-eastern Brazil. The only species partially distributed outside of Brazil is C. septentrionalis , which can also be found in Guyana, Venezuela, and western Suriname (Vitt et al., 2005). It is possible that C. meridionalis is present in low numbers in Bolivia, but these claims are not confirmed (Langstroth, 2005). The geographic ranges of the 5 species in Coleodactylus overlap with each other very little, likely due to intraspecific competition.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Species in Coleodactylus reside exclusively in the leaf litter of undisturbed tropical forest. The tiny size of the geckos and their brown coloration alows them to exhibit high levels of crypsis amongst the leaves. They also have unrestricted access to small invertebrate prey items in the leaf litter. There is very little variation in temperature within their range, usually between 25° and 30°C. The elevation of their habitat ranges from sea level to 680m.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest

Systematic and Taxonomic History

Coleodactylus is the family Sphaerodactylidae . There are no synonyms for the genus. The most notable change in the systematic history of the genus is the creation of the new genus Chatogekko for Chatogekko amazonicus (previously Coleodactylus amazonicus ) after phylogenetic studies revealed the species was misattributed to Coleodactylus and is not even the most closely related genus. Two species, C. meridionalis and C. brachystoma , had previously been attributed to other genera ( Sphaerodactylus and Homonota , respectively) before being updated and renamed in Coleodactylus .

Physical Description

Coleodactylus is made up of five species of miniaturized geckos. Species in the genus have cylindrical bodies which range in length from approximately 20mm to 28mm (Uetz, Hallermann, and Hosek, 2021). Individuals vary in dorsal coloration from light brown to black, with some species possessing white or light pink spots. The genus can be differentiated from other closely related genera in the family Sphaerodactylidae by a unique combination of diagnostic characteristics. The characteristics include each claw being covered by an asymmetric ungual sheath composed of exactly five scales, smooth dorsal scales, and a nasal process separating nasals which is relatively short as compared to related genera (Gamble et al., 2011). The only exception to these diagnostic criteria is C. elizae which only has four ungual scales on its 4th digit (Gonçalves et al., 2012).

As an adaptation for predator defense, C. brachystoma has a pale orange ventral surface and a tail shape and length that is similar to syntopic scorpions to allow for mimicry of scorpions when threatened (Brandão and Motta, 2005).

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

There is currently no recorded information on Coleodactylus mating systems in the literature.

Coleodactylus are oviparous reptiles. Coleodactylus meridionalis and Coleodactylus natalensis both have recorded clutch sizes of a single egg and can lay several clutches in a single year (Lisboa, Sales, and Freire, 2012). In the only observed hatching of C. natalensis the egg was incubated for 41 days after collection and the hatchling was 11mm in length. No other information on reproduction in this genus is currently available in the literature.

• Key Reproductive Features
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

There is no specific information on Coleodactylus parental investment in the literature. However, most gecko species exhibit little to no parental investment after the female lays the eggs. It would be reasonable to presume similarly low levels of parental investment in Coleodactylus until more information is available.

• Parental Investment
• precocial precocial

Lifespan/Longevity

Reports of lifespan in Coleodactylus are absent in the literature. The closely related genus Sphaerodactylus has species which range in maximum lifespan from 4 to 20 years. Coleodactylus species likely have comparable lifespans.

Behavior

Coleodactylus are diurnal geckos that are active throughout the day. They locomote by either walking or leaping from leaf to leaf. They are passive thermoregulators and do not bask. Individuals in the genus are solitary and no significant social structure or interaction has been observed. All Coleodactylus species are capable of tail autotomy (voluntarily dropping and regrowing tail) and frequently use this as a predator avoidance technique. When threatened, they move very slowly and shyly and will fold their tails over their backs to entice a predator to attack the tail, which is then dropped so the gecko can run away. Coleodactylus brachystoma tails have an orange ventral surface, allowing this behavior to double as Batesian mimicry of sympatric scorpions.

• Key Behaviors
• terricolous
• saltatorial saltatorial
• diurnal diurnal
• motile motile
• solitary solitary

Communication and Perception

Coleodactylus has a very well developed chemosensory system which is used to avoid ants and other noxious insects. They also use visual, acoustic, and tactile sensory systems to perceive their environment, but the quality of each of these systems and the extent to which they are relied upon has not been studied in this genus. Visual Batesian mimicry is used for preditor avoidance in C. Brachystoma .

• Communication Channels
• visual visual

• Other Communication Modes
• mimicry mimicry

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Coleodactylus is an insectivorous genus of pygmy geckos. Owing to their small size, they can take advantage of tiny prey items that are ignored by most other insectivorous competitors in their range. Their diet consists mostly of insects (subphylum Hexapoda ), arachnids (class Arachnida ), and crustaceans (subphylum crustacea ). The species in Coleodactylus who's feeding ecology has been studied in the most detail is C. natalensis . The diet of C. natalensis is most significantly composed of isopods (order isopoda ) and spiders (order araneae ), but has been observed consuming prey from at least 18 separate arthropod taxa. Males and females of C. natalensis do not differ significantly in terms of total number or volume of prey items consumed, but females take advantage of a wider range of prey types than males do. Coleodactylus septentrionalis also predates on a wide range of arthropod prey, but shows a larger preference for termites (order Blattodea ), grasshoppers, and crickets (order Orthoptera ). Coleodactylus also eats insect eggs and their own shed skin. Coleodactylus avoids accidental consumption of toxic arthropods, such as certain sympatric ants, by use of a well developed chemosensory system.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods

Predation

Coleodactylus is predated by a variety of vertebrates and some invertebrates owing to their small size and palatability. Predators that use Coleodactylus as prey include larger lizards, snakes, birds, spiders, and even ants. Coleodactylus exhibits a number of different anti-predator adaptations. This first and most commonly used of which is hiding from predators among the leaf litter. This is aided by both their small size which allows them to easily hide under leaves and their cryptic coloration which allows them to blend in with the leaf litter. Another anti-predator adaptation is caudal autotomy, or tail dropping. When an individual in Coleodactylus is feeling particularly threatened, it may voluntarily drop its tail to distract the predator and allow for easy escape. This is accomplished by voluntary contraction of muscles around the caudal vertebrae of the tail, severing the vertebrae along specialized breakage planes. In some instances, the tail may continue moving after it has been dropped to more effectively confuse a predator. It is not uncommon for Coleodactylus geckos to flip their tail up over their bodies when threatened to entice the predator to attack the tail, adding to the effectiveness of their tail autotomy defense. Tail autotomy is generally a last resort for the geckos as it results in decreased balance and the loss of valuable fat reserves stored in the tail. Other anti-predator adaptations include immobility, locomotory escape, and cloacal discharge.

For C. brachystomata , the behavior of flipping the tail over the body when threatened has additional anti-predatory advantages. The underside of C. brachystomata 's tail is orange in color, allowing the geckos to resemble sympatric scorpions in this posture. This evidence suggests that the defensive posture doubles as a Batesian mimicry defense in this species in addition to the increased effectiveness of caudal autotomy.

• Anti-predator Adaptations
• mimic
• cryptic cryptic

Ecosystem Roles

Owing to their small size, Coleodactylus occupies similar ecological niches to sympatric invertebrates in the neotropics. They predate upon a variety of small invertebrates which are abundant in the leaf litter and rarely utilized by other vertebrates. This contributes to the control of small invertebrate species. Coleodactylus also serves as a valuable prey item for a variety of predators including other reptiles, birds, and larger invertebrates.

Economic Importance for Humans: Positive

Coleodactylus resides exclusively in the leaf litter of forested areas which are uninhabited by humans. As such, Coleodactylus has very little positive or negative economic importance for humans. The genus does consume small invertebrate prey items, helping to control populations which might otherwise grow to become pests. Additionally, The genus occupies relatively unusual niches for vertebrates, making them interesting subject for scientific study.

• Positive Impacts
• research and education
• controls pest population

Economic Importance for Humans: Negative

There are no adverse effects of Coleodactylus on humans.

Conservation Status

Although few studies have been done in regards to the conservation status of Coleodactylus , it seems that populations are relatively stable. There is no evidence that Coleodactylus is of immediate conservation concern, though this may be due to a lack of sufficient data rather than an actual lack of threat to the genus. Like most species in the neotropics, Coleodactylus is likely to be vulnerable to alteration of the Amazon Rainforest. Specifically, the thinning of the canopy due to human actions will increase the temperature of the leaf litter and the forest floor, creating thermally inhospitable habitat for the geckos. There are currently no active conservation measures put in place for Coleodactylus specifically.

Other Comments

The name "Coleodactylus" is derived from the Latin roots "coleo" meaning sheath and "dactyl" referring to the toes. The name is descriptive of the ungual sheath which is used to diagnose the species. The species C. natalensis , C. meridionalis , and C. septentrionalis are named after the geographic range of each species, while C. brachystoma is derived from Latin roots meaning "short mouth" and C. elizae is named after Eliza Maria Xavier Freire, a Brazilian researcher who has contributed a significant portion of the current knowledge on the genus.

Additional Links

Encyclopedia of Life

Contributors

Keith Mauerman (author), Colorado State University, Audrey Bowman (editor), Colorado State University.

References

Brandão, R., P. Motta. 2005. Circumstantial evidences for mimicry of scorpionsby the neotropical gecko Coleodactylusbrachystoma(Squamata, Gekkonidae) in the Cerrados of centralBrazil. Phyllomedusa , 4(2): 139-145.

Freitas, M., D. Fagundes de Franca, T. Lima. 2011. Geographic Distribution: Coleodactylus brachystoma.. Herpetological Review , 42(3): 391.

Gamble, T., J. Daza, G. Colli, L. Vitt, A. Bauer. 2011. A new genus of miniaturized and pug-nosed gecko from South America (Sphaerodactylidae: Gekkota). Zoological Journal of the Linnean Society , 163(4): 1244-1266. Accessed February 12, 2022 at DOI:10.1111/j.1096-3642.2011.00741.x .

Geurgas, S., M. Rodrigues, C. Moritz. 2008. The genus Coleodactylus (Sphaerodactylinae, Gekkota) revisited: A molecular phylogenetic perspective. Molecular Phylogenetics and Evolution , 49: 92-101. Accessed February 12, 2022 at DOI: 10.1016/j.ympev.2008.05.043 .

Gonçalves, U., S. Torquato, G. Skuk, G. Araujo Sena. 2012. A new species of Coleodactylus Parker, 1926 (Squamata: Sphaerodactylidae) from the Atlantic Forest of northeast Brazil. Zootaxa , 3204: 2030. Accessed February 12, 2022 at DOI:10.11646/ZOOTAXA.3204.1.2 .

Langstroth, 2005. Adiciones probables y confirmadas para la saurofauna boliviana. Kempffiana , 1(1): 101.

Lisboa, C., R. Sales, E. Freire. 2012. Feeding ecology of the pygmy gecko Coleodactylus natalensis (Squamata: Sphaerodactylidae) in the Brazilian Atlantic Forest. ZOOLOGIA , 29(4): 293-299. Accessed February 12, 2022 at doi: 10.1590/S1984-46702012000400002 .

Lisboa, C., P. Sousa, L. Ribeiro, E. Freire. 2008. Coleodactylus natalensis (NCN). Clutch size; hatchling size.. Herpetological Review , 39: 221. Accessed February 26, 2022 at https://www.academia.edu/37328576/Coleodactylus_natalensis_NCN_Clutch_size_Hatchling_size .

Oliveira, C., G. Brabosa, I. Campos, M. Guarnieri, S. Ribeiro. 2017. Predation on Coleodactylus meridionalis (Squamata: Sphaerodactylidae) by Ctenus rectipes (Araneae: Ctenidae) in the Atlantic Forest, northeastern, Brazil. Herpetology Notes , 10: 221-223.

Oliveira, C., I. Campos, D. Provete, M. Guarnieri, S. Ribeiro. 2020. Defensive behaviour and tail autotomy in Coleodactylus meridionalis (Squamata: Sphaerodactylidae). Journal of Natural History , 54:33-34: 2209-2218. Accessed March 27, 2022 at 10.1080/00222933.2020.1840641 .

Parker, H. 1926. The neotropical lizards of the genera Lepidoblepharis, Pseudogonatodes, Lanthrogecko, and Sphaerodactylus, with the description of a new genus.. Annals and Magazine of Natural History , 17:99: 291-301. Accessed February 02, 2021 at 10.1080/00222932608633413 .

Ribeiro, L., M. Gogliath, R. Rodrigues, R. Barreto, E. Freire. 2013. Two new records of Coleodactylus meridionalis (Boulenger, 1888) (Squamata, Sphaerodactylidae) in north-eastern Brazil, including a map and comments regarding its geographical distribution. Herpetology Notes , 6: 23-27.

Sousa, P., E. Freire. 2010. Coleodactylus natalensis (NCN). Predation.. Herpetological Review , 41: 218.

Uetz, P., J. Hallermann, J. Hosek. 2021. "Coleodactylus" (On-line). The Reptile Database. Accessed February 26, 2022 at https://reptile-database.reptarium.cz/search?search=coleodactylus&submit=Search .

Vitt, L., S. Sartorius, T. Avila-Pires, P. Zani, M. Esposito. 2005. SMALL IN A BIG WORLD: ECOLOGY OF LEAF-LITTER GECKOS IN NEW WORLD TROPICAL FORESTS. Herpetological Monographs , 19: 137-152.

2021. "Coleodactylus" (On-line). Encyclopedia of Life. Accessed March 12, 2022 at https://eol.org/pages/83281 .