Slender-Digit Chorus Frog, Narrowmouth Painted Toad
© 2010 Wouter Beukema (1 of 9)
Within the genus Kaloula, a series of steps can be used to identify a Kaloula picta speciemen. Only three Kaloula species (K. picta, K. conjuncta and K. rigida) have the combination of metacarpal tubercles, no yellow coloration on the thigh and the axilla, a lower leg containing a crossbar that is aligned with the thigh when the leg is fixed, and belly glands in males. Among K. picta, K. conjuncta and K. rigida, K. picta can be differentiated by having an inner metatarsal tubercle that is the same size or longer than the first toe (Inger 1954). A further differentiation can be made between K. picta and K. conjuncta because K. picta does not have any dilation of the digits in males or females. Additionally, K. picta differs from K. rigida in the fact that K. picta exhibits no sexual dimorphism in webbing, whereas K. rigida does (Taylor 1966).
In life, K. picta is olive-brown to dark brownish-red in color. It has a dark mid-dorsal pattern and is dark beneath the lateral glandular fold. The limbs are ground-like in color. The legs have a single dark crossbar on the thigh and lower leg. In preservative, K. picta is brown to violet-gray in color (Inger 1954).
There is variation in the dark band on the thigh that continues over the knee on some individuals. There is also variation in the dark crossbar on the lower leg where it can be found to run completely over the leg, not extend all the way, or be broken into spots across the leg. The tibio-tarsal joint may or may not have a large dark spot. The thighs of K. picta may or may not have stratified light and dark areas. These stratified areas may either be well-defined and continuous from behind the knee to the vent or the dark stratum does not reach the vent at all (Inger 1954).
In terms of sexual dimorphism, there are several differentiating traits. First, females are larger than males. Second, males have green vocal sacs on their chin, and in breeding males the throat shifts to a dark yellow green. In females, the throat is a cream color with no vocal sac. Lastly, males have a gathering of single-celled epidermal glands called a “belly gland” on the ventral surface of the body that is along the abdomen region. This collection of cells can take up one-half to five-sixths of the region (Inger 1954).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Philippines
Life History, Abundance, Activity, and Special Behaviors
Males call year round in available standing water and in puddles or pools that form after the frequent rains (Blackburn et al. 2015). Chorus groups can number from a few individuals to several hundred, and individuals in large groups sometimes alternate their calls (Diesmos et al. 2002). Male advertisement calls contain 32 – 37 distinct pulses per call, with a rapid-fire delivery rate of 1.2 calls/sec. A single male’s call sounds to the human ear like a squeaky door swinging on its hinges, a soft ‘whaak, whaak, whaak’; while a group of males of differing sizes alternating their calls resembles the sound ‘ko-kak, ko-kak,ko-kak’ (Diesmos et al. 2002).
Mature eggs can be found in females from mid to late May until March, when the dry season commences. However, the breeding season reaches its peak between July and October, during the heaviest rainfalls. Their breeding behavior is typical of anurans, with males arriving at breeding sites early to form a breeding chorus and females arriving later (Inger 1954).
Kaloula picta uses axillary amplexus with males sticking to females using a gelatinous secretion from their belly glands. Females can lay between 812 – 4029 eggs (Inger 1954).
Like most amphibians, K. picta is an indiscriminate hunter of arthropods, including ants, termites, beetles, crickets, and cockroaches (Inger 1954). One possible predator of K. picta is the snake, Oxyrhabdium leporinum leporinum, which is found in many of the same regions as the K. picta (Brown 2000).
Both male and female individuals of K. picta secrete a thick, sticky mucus from their backs that does not come off handlers’ hands, even with frequent soapy washings, for several days (Inger 1954).
Trends and Threats
Possible reasons for amphibian decline
Predators (natural or introduced)
Maximum likelihood and Bayesian inference analysis of 12S and 16S ribosomal RNA genes and valine intervening transfer RNA concluded that there are five total clades in the genus Kaloula: 1) K. picta; 2) a species from the Samar and Leyte islands; 3) K. rigida and K. walteri; 4) K. kalingensis, K. kokacii, and two species from the Panay Island and eastern Luzon Island; and 5) K. conjuncta conjuncta, K. c. meridionalis, K. c. negrosensis, K. c. stickeli, and two taxa, one from the Mindoro Island and the other from the Panay and Sibuyan islands. Kaloula picta was basal to the clade formed by groups 2 and 5 and together they were sister to group 4. The most basal clade was group 3 (Blackburn et al. 2015).
Kaloula picta is colloquially referred to as the painted narrowmouth toad because of its intricate dorsal markings and slender mouth. Kaloula picta is also sometimes called the slender-digit chorus frog because it possesses skinny toes without widened terminal toe pads (Inger 1954).
Blackburn, D. C., Siler, C. D., Diesmos, A. C., McGuire, J. A., Cannatella, D. C., Brown, R. M. (2013). ''An Adaptive Radiation of Frogs in a Southeast Asian Island Archipelago.'' Evolution, 67(9), 2631-646.
Brown, R. M., McGuire, J. A., Ferner, J. W., Icarangal, N., Kennedy, R. S. (2000). ''Amphibians and reptiles of Luzon Island, II: Preliminary report on the herpetofauna of Aurora Memorial National Park, Philippines.'' Hamadryad, 25(2), 175-195.
Diesmos, A. C., Brown, R. M., Alcala, A. C., and Guyer, C. (2002). ''New species of narrow-mouthed frog (Amphibia: Anura: Microhylidae; genus Kaloula) from the mountains of southern Luzon and Polillo Islands, Philippines.'' Copeia, 2002(4), 1037-1051.
Diesmos, A., Alcala, A., Brown, R., Afuang, L., Dolino, C., Gee, G., Hampson, K., Diesmos, M.L., Mallari, A., Ong, P., Paguntalan, L., Pedregosa, M., Ubaldo, D., Gutierrez, B. (2004). “Kaloula picta”. The IUCN Red List of Threatened Species 2004: e.T57854A11694467. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T57854A11694467.en. Downloaded on 22 February 2017.
Inger, R.F. (1954). ''Systematics and zoogeography of Philippine Amphibia.'' Fieldiana: Zool., 33, 184-531.
Taylor, E. H. (1966). Amphibians & Turtles of the Philippine Islands. A. Asher and Co., Amsterdam.
Thomas, E. O., Tsang, L, Licht, P. (1993). ''Comparative Histochemistry of the Sexually Dimorphic Skin Glands of Anuran Amphibians.'' Copeia, 1993(1), 133-143.
Written by Rebecca Buer, Trevor Clark, Asha Pluton (rnbuer AT ucdavis.edu , tlclark AT ucdavis.edu , aopluton AT ucdavis.edu), University of California, Davis
First submitted 2017-11-07
Edited by Ann T. Chang (2017-11-07)
Species Account Citation: AmphibiaWeb 2017 Kaloula picta: Slender-Digit Chorus Frog <http://amphibiaweb.org/species/2156> University of California, Berkeley, CA, USA. Accessed Aug 19, 2019.
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Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 19 Aug 2019.
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