Description
Colostethus panamansis are small frogs with a male snout-vent length range of 18.8 - 27.1 mm and a female range of 24.9 - 29.3 mm. The skin along the back and sides is smooth, with some texturing on the shanks. There is a distinct and curved tarsal keel. The head width measured at the angle of the jaw is approximately one third of snout-vent length and is equal to or slightly longer than head length. The snout is rounded in dorsal view and the nares bulge slightly. The canthus rostralis is distinct. The eye diameter is slightly less than half the diagonal length of the head. The tympanum is 26 - 41% of the size of the eye and is concealed. The supratympanic bulge ends near where the arm inserts into the trunk. The forearm length is equal to or slightly shorter than hand length. The third finger is swollen in adult males, but not in females or juveniles. Most of the toes are fringed and have moderate webbing, although these traits may vary among individuals. There is a fold on the outer metatarsal. The shank length and foot length are 40 - 47% and 37 - 44% of snout-vent length, respectively (Grant 2004).

DIAGNOSIS:

Colostethus panamansis can be differentiated from other similar species based on coloration and digit webbing. Adult males have either a white or white-and-grey-mottled throat and undersides, whereas male C. inguinalis, Silverstoneia nubicola and Allobates talamancae have a solid black throat and male Silverstoneia flotator have a solid grey throat. Adult male C. latinasus have a dark brown-colored venter, which is darker than the underside of C. panamansis. Females have either a brown throat with white spots or a white throat with brown spot patterns, whereas female C. inguinalis, S. nubicola, and A. talamancae have at most very light speckling. Female C. pratti have solid white undersides. Both sexes of Hyloxalus chocoensis and Ectopoglossus lacrimosus have at most light speckling, unlike the sexually dimorphic ventral coloration of C. panamansis. Male and female C. imbricolus similarly lack sexual dimorphism; each has a solid black venter with white spots, a characteristic not found in C. panamansis. Colostethus panamansis has a dark brown ventrolateral stripe, which differs from the speckled ventrolateral area of C. inguinalis. Colostethus nubicola and C. lynchi have a white stripe that starts where the hind limb inserts in the groin area and extends to the eye, whereas this line extends only halfway to the eye in C. panamansis. Allobates talamancae has a prominent white dorsolateral stripe, which runs from the hind limb insertion towards the mouth, ventral to the eye, that C. panamansis lacks. Hyloxalus chocoensis, E. lacrimosus and Silverstoneia flotator all have extensive toe webbing, while the toe webbing of C. panamansis is significantly reduced. These three species also lack the swollen third toe characteristic of adult male C. panamansis. Colostethus panamansis has more toe webbing than C. pratti and C. latinasus, which lack webbing entirely. Lastly, adult C. nubicola is smaller in snout-vent than C. panamansis. Silverstoneia flotator is even smaller, with snout-vent length reaching only 18 mm in males and 19 mm in females. Colostethus pratti is also slightly smaller than C. panamansis, with maximum snout-vent length of 24 mm in males and 25 mm in females (Grant 2004).

COLORATION:

In life, coloration on the dorsal side of both males and females is a patchwork of lighter and darker brown shades. The throat of adult females is a mottled combination of brown and grey. The underbelly of adult males is generally light and uniform in color, but some adult male frogs have faint speckles or a lightly patterned underside. There is a thick dark brown stripe that starts at the groin and extends to the eye, running ventro-laterally. The tympanum, which is overlain by this stripe, is also dark brown. A pale white lateral stripe runs through the middle of the dark brown stripe. It begins at the hind limb insertion and extends anteriorly, ending just above the forelimb. Adults have a flashy yellow-golden stripe along the hind limb near the groin, which connects to the pale white stripe. There are also yellow flashes in the axilla and on the undersides of the hind limbs. Males have white testes with brown spotting; females have white oviducts (Grant 2004).

VARIATION:

There is some sexual dimorphism. Females are slightly larger than males and vary in ventral coloration. Males also possess a swollen third toe (Grant 2004).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Colombia, Panama

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (7 records).

Colostethus panamansis is found in both Panama and Colombia. In Panama, it is known from several provinces, including Coclé, Colón, Darién, Herrera, Panamá and San Blas. In Colombia, it is known from Parque Nacional Natural Los Katios in the Department of Chocó, adjacent to the border with Panama (Grant 2004). Colostethus panamansis occupies rocky habitats beside streams in the lowlands and in montane forests, at elevations between 600 and 800 m (Duellman 1966).

Life History, Abundance, Activity, and Special Behaviors
Colostethus panamansis is an abundant, diurnal species found in rocky habitats along the banks of streams (Dunn 1933; Grant 2004; Wells 1980).

The species has a biphasic life history with an aquatic tadpole stage and a terrestrial frog stage separated by a discrete metamorphosis (Grant 2004). Young C. panamansis become sexually mature 4 - 6 months after metamorphosis (Wells 1980).

Colostethus panamansis engages in an elaborate courtship ritual involving visual displays, calls and touching. Most breeding occurs at the beginning of the rainy season in May and June, but the species is also known to breed during all months of the year except April and possibly December (Wells 1980).

There are three types of calls made by this species (Wells 1980). Males emit calls to advertise their presence from rock perches within or beside streams, making 2 - 5 quick peeps and then pausing for a few seconds before repeating (Duellman 1966). When another frog enters a male’s territory, male C. panamansis make an aggressive call—a long sound followed by a shorter one—to scare off the intruder (Duellman 1966; Wells 1980). The third type of call is an attack call, a very low chirp made at close range just before the frog engages in physical altercation with another frog. This call is made by both males and females. Both sexes defend territories against frogs of other species as well as same species, with interactions between C. pratti occurring frequently (Wells 1980).

Aggressive exchanges between males defending rocks from intruding males have been observed (Duellman 1966). In several instances, the defending male used an aggressive encounter call and raised his body up onto all fours, presumably as an intimidation tactic. One physical altercation was observed in which the defending male attacked the intruder, knocking him into the water below. Females also defend territories in the dry season and for a few days at a time during the wet season. Like males, they engage in aggressive behavior such as wrestling, attacking or chasing off intruders (Wells 1980).

Females lay as many as two clutches per year (Wells 1980). Mature eggs have a diameter of 1.6 mm and are dark brown (Grant 2004).

Colostethus panamansis lay eggs in leaf litter, defend the eggs, and females later carry tadpoles on their backs to streams or pools (Grant et al. 2006 - AMNH). There can be up to 40 tadpoles on a mother’s back, so females presumably carry the entire clutch in one turn without returning to the nest site (Wells 1980).

Colostethus panamansis is noteworthy in that its skin secretes tetrodotoxin, a sodium-channel blocker. Its discovery, in 1994, represented the first known occurrence of tetrodotoxin production in dendrobatid frogs (Daly et al. 1994).

Larva
Females carry tadpoles on their backs to streams or pools (Grant et al. 2006 - AMNH). There can be up to 40 tadpoles on a mother’s back, so females presumably carry the entire clutch in one turn without returning to the nest site. Tadpoles remain on the mother’s back for up to nine days, growing by 40% in length during this time (Wells 1980). A naturalist, Graham Fairchild, reportedly found a male C. panamansis carrying six tadpoles on its back (Dunn 1940). This account is likely to be an error or a misidentification, as subsequent researchers report that only females nurse in this species (Grant et al. 2006 - AMNH).

The sources of nutrition while tadpoles are in transport are unclear, as yolk reserves of tadpoles found on the backs of females are small. Tadpoles might feed in the water while the mother is submerged, or they might feed on the mother skin (Wells 1980). Interestingly, C. panamansis and one other species, C. pratti, are the only two species in the genus to have female nursing. All other conspecifics have paternal nursing, which is presumed to be the ancestral state (Grant et al. 2006 - AMNH).

Once tadpoles leave the mother, they feed on detritus in the water (Wells 1980).

Young C. panamansis become sexually mature 4 - 6 months after metamorphosis (Wells 1980).

Trends and Threats
The IUCN lists the following threats to the species: loss of habitat by deforestation to create space for new housing development, grazing land or agricultural crops, in addition to pesticide runoff (Grant et al. 2004).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Local pesticides, fertilizers, and pollutants

Comments

PHYLOGENETIC RELATIONSHIPS:

Studies by Daly et al. (1994) and by Wells (1980) purportedly investigate C. inguinalis, which at the time of those studies included populations now known as C. panamansis. Daly’s specimens were collected from El Valle de Antón, Panama, and Wells’ study site was 60 km west of Panama City, Panama, and frogs from these and all other Panamanian localities previously identified as C. inguinalis are now assigned to C. panamansis. Colostethus inguinalis, as currently understood, is endemic to Colombia (Grant et al. 2006 - AMNH; Wells 1980).

ETYMOLOGY:

The species epithet, “panamansis,” is in reference to the species being first collected in Panama (Grant et al. 2006 - Zoological).

There has been some confusion about the correct spelling of the species epithet. Dunn (1933) originally published the species as “panamansis,” which is an incorrect Latinization of a species epithet named for a place. However, the correct Latinization, with an "-ensis" was not utilized until seven years later. This situation was further complicated by C. panamansis being synonmized with C. inguinalis for 35 years, thus preventing a prevailing name to be determined (Grant et al. 2006 - Zoological). When the species was resurrected, Grant (2004) used the correct Latinization, “panamensis”, and later Grant et al. (2006 - Zoological) formally proposed for this name to be recognized by the International Commission on Zoological Nomenclature. However, this proposal was rejected by the International Commission on Zoological Nomenclature (2008), which upheld the spelling of “panamansis”.

OTHER INTERESTING INFORMATION:

Colostethus panamansis has 24 pairs of chromosomes (Grant et al. 2006 - AMNH).

References

Daly, J. W., Gusovsky, F., Myers, C. W., Yotsu-Yamashita, M., Yasumoto, T. (1994). “First occurrence of tetrodotoxin in a dendrobatid frog (Colostethus inguinalis), with further reports for the bufonid genus Atelopus.” Toxicon, 32(3), 279–285. [link]

Duellman, W. E. (1966). “Aggressive behavior in dendrobatid frogs.” Herpetologica 22(3), 217–221. [link]

Dunn, E. (1940). “New and noteworthy herpetological material from Panama.” Proceedings of the Academy of Natural Sciences of Philadelphia 92, 105–122. [link]

Dunn, E. R. (1933). ''Amphibians and reptiles from El Valle de Anton, Panama.'' Occasional Papers of the Boston Society of Natural History, 8, 65-79.

Grant, T. (2004). “On the identities of Colostethus inguinalis (Cope, 1868) and C. panamensis (Dunn, 1933), with comments on C. latinasus (Cope, 1863) (Anura: Dendrobatidae).” American Museum novitates 3444, 1-24. [link]

Grant, T., Frost, D. R., Caldwell, J. P., Gagliardo, R., Haddad, C. F. B., Kok, P. J. R., Means, D. B., Noonan, B. P., Schargel, W. E., and Wheeler, W. C. (2006). ''Phylogenetic systematics of dart-poison frogs and their relatives (Amphibia: Athesphatanura: Dendrobatidae).'' Bulletin of the American Museum of Natural History, (299), 1-262.

Grant, T., Frost, D., Ibáñez, R., Myers, C., Savage, J. (2006). “Hyloxalus panamensis Dunn, 1933: Proposed emendation of spelling from Hyloxalus panamansis (currently Colostethus panamansis; Amphibia, Anura).” Bulletin of Zoological Nomenclature 63(1), 39–41. [link]

Grant, T., Solís, F., Ibáñez, R., Jaramillo, C., Fuenmayor, Q. (2004). “Colostethus panamansis.” The IUCN Red List of Threatened Species 2004: e.T55125A11256591. https://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T55125A11256591.en. Downloaded on 04 May 2020.

International Commission on Zoological Nomenclature (2008). "Opinion 2195 (Case 3303) Hyloxalus panamansis Dunn, 1933 (currently Colostethus panamansis; Amphibia, Anura): original spelling maintained," The Bulletin of Zoological Nomenclature, 65(1), 77-78, [link]

Wells, K. D. (1980). “Behavioral ecology and social organization of a dendrobatid frog (Colostethus inguinalis).” Behavioral Ecology and Sociobiology 6(3), 199–209. [link]

Species Account Citation: AmphibiaWeb 2022 Colostethus panamansis: Panama rocket frog <https://amphibiaweb.org/species/6424> University of California, Berkeley, CA, USA. Accessed Jan 11, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 11 Jan 2025.

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